I've had 3 clutches in my truck in 130K miles:

- the factory clutch
- a first generation SBC with stock pressure plate and DMF
- a second generation SBC with stock pressure plate and SMF

All have been single disc. The SMF SBC setup was put in almost exactly 2 years ago. Well, it's starting to slip. With the Edge box even on just level 1, when I point up hill in top gear and put my foot down it lets go. I can't even use level 2 or higher.

I don't abuse the thing at all. I very, very rarely ever take my Juice off of level 1, mainly just in tight passing situations. Then I put it right back on 1.

The clutch still engages smoothly and feels fine. You'd never know anything is going wrong in normal driving. The growling sound when idling and moving slow with the clutch out is getting a little worse, but it's always done that some since it was brand new.

So what's the deal? Do I have to go to a dual or triple disc to get a clutch that works and lasts in normal driving and occassional towing?

I recomend the dual disc to everyone. IMO a single disc is good for a stcok replacement with no power adders.How many miles on the SMF? I'd call Peter at SBC and see if he'll do something for you. My buddy Justin has the same problems with his single disc.
I'm going on 90K on my dual disc and they have been hard miles. Lots of heavy towing and big tunes :eek:.


Where in CO are you?

Sounds like the answer is "Yes", I wish I would've known that before I bought this single disc, I was led to believe it would get the job done. I only have about 30K miles on it. Probably about 4K of that towing a trailer and load of maybe 6,000lbs. Like I said, it's almost always on Juice level 1 and on those rare occassions I turn it up, it's only briefly, and I never turn it up while towing.

I live in Berthoud, about 40 miles north of Denver.

I'll call Peter. I dunno though, I sure wish there was some alternative to SBC. I'm losing faith in them.

I still think they are the best but ya have to run a dual disc.
Mine towed probably 10-15K mi last summer at the 450-475rwhp range and I was grossing 30,000lbs+ :eek:. I replaced my motor but the clutch was still holding good. Put another 35K on since replacing the motor at the 375-450rwhp level towing the same weight almost weekly and it's still holding. Had 15 hooks to the sled too.

I'm down in your area a lot maybe we should meet up sometime and you can see what you think of a dual disc.

Sounds like the answer is "Yes", I wish I would've known that before I bought this single disc, I was led to believe it would get the job done. I only have about 30K miles on it. Probably about 4K of that towing a trailer and load of maybe 6,000lbs. Like I said, it's almost always on Juice level 1 and on those rare occassions I turn it up, it's only briefly, and I never turn it up while towing.

I live in Berthoud, about 40 miles north of Denver.

I'll call Peter. I dunno though, I sure wish there was some alternative to SBC. I'm losing faith in them.

Your single disc should have got the job done, something is not right. Infact my stock clutch made it 60,000 miles through what you described. My Macs kevlar single disc went 40,000+ miles at 425-475 rwhp, no sled pulling obviously, but it did handle drag racing and pulling trailers. When I replaced the disc it only had 10 thousanths wear :eek:. At the rate it was wearing it would have out lasted the truck. I had SBC make me a disc with feramic material to hold better at over 500 rwhp and that is the only reason I took the old disc out.
IMO you should only need a dual if your sled pulling or above 500 rwhp. I like the quiteness of the single and the fact its easier on the snycros when you shift.
Let us know what Peter says.

All have been single disc. The SMF SBC setup was put in almost exactly 2 years ago. Well, it's starting to slip. With the Edge box even on just level 1, when I point up hill in top gear and put my foot down it lets go. I can't even use level 2 or higher.

Well you said it right here in your statement. Point it up hill in sixth gear and hit the gas pedal. With added power or not you are straining the clutch. Think of it this way, if you had an automatic, what would the automatic do? It would down shift into the appropriate gear to make the climb. Your taller gears are for cruising not pulling. Hope this makes sense.

Peter

I hope you're just refering to single disc setups cause I use 6th all the time. 5th gear is too slow unless you're running 55mph. Even towing 30,000lbs I use 6th :eek:.
I guess that is more proof why dual disc's are the way to go.

All have been single disc. The SMF SBC setup was put in almost exactly 2 years ago. Well, it's starting to slip. With the Edge box even on just level 1, when I point up hill in top gear and put my foot down it lets go. I can't even use level 2 or higher.

Well you said it right here in your statement. Point it up hill in sixth gear and hit the gas pedal. With added power or not you are straining the clutch. Think of it this way, if you had an automatic, what would the automatic do? It would down shift into the appropriate gear to make the climb. Your taller gears are for cruising not pulling. Hope this makes sense.

Peter

All have been single disc. The SMF SBC setup was put in almost exactly 2 years ago. Well, it's starting to slip. With the Edge box even on just level 1, when I point up hill in top gear and put my foot down it lets go. I can't even use level 2 or higher.

Well you said it right here in your statement. Point it up hill in sixth gear and hit the gas pedal. With added power or not you are straining the clutch. Think of it this way, if you had an automatic, what would the automatic do? It would down shift into the appropriate gear to make the climb. Your taller gears are for cruising not pulling. Hope this makes sense.

Peter

Sure it loads the clutch, I understand that. But the motor isn't lugging, I'm talking about over 2000 rpm is where the clutch lets go.

I can make it slip on level ground, too, in 6th gear, on level 2.

So essentially you're saying I can't give it full throttle in 6th gear at even a modest increase in power.

That's not what you told me when I bought the clutch. And the clutch has been working fine until recently.

Y'know, my original clutch lasted 60K miles (like the guy who posted above) with the same Juice box. I've since been through two South Bend Clutches in 70K miles. And now the answer I get is essentially that I shouldn't put a load on it?

You sold me a clutch that you represented would work for me. Now you tell me not to load it?

Obviously buying clutches from you was a mistake.

By the way, the clutch is slipping like this with the truck completely empty and no trailer. I'm taking a trip in another month that'll be 1400 miles or so pulling 6K lbs. Something tells me the clutch isn't up to it.

Y'know, I wasn't particularly mad when the clutch started slipping. Annoyed, yes. A clutch should last longer than that IMO. I'm getting tired of putting clutches int his thing every couple years. That's why I asked how to solve the problem.

But seeing SBC's response is making my blood boil, and the more I think about it, the more it boils. This is a company that sold me very expensive product representing that it would work for me. I told him exactly what I was doing when I ordered it. And it was already the second go-around with an SBC clutch.

Now he has the audacity to tell me it's my fault, that the clutch isn't up to the job? Say what?

Anyone who wants to understand whether or not SBC stands behind their products should read this thread.

They offered to swap me into a sprung hub DD from a solid hub DD for no cost at 30K miles but I didn't because I didn't have time for down-time.

What a shame! This is the problem with the Internet, there is no emotion with the typing. I am not trying to point fingers or get out of anything. Anyone who has dealt with me will tell you that. I am simply trying to explain what can happen with certain conditions. You say you got 60K on the stock clutch and I have seen some only get 30K and others can get 150K...Why do you think that is? As for the 1st clutch you bought, it was an upgraded clutch for the stock DMF. That is all that was available at the time and the flywheel would deteriorate and cause premature clutch problems. This is the reason for the solid conversion, to try and eliminate that factor. We have sold probably 1000 SD MAX CON O. Some people beat the crap out of them and many have good long life. This is our first level upgrade and with what you have for power and what you do with your truck, the clutch should have worked fine. This really should not come to this on the forums when a simple phone call could be made. I am sorry if you felt attacked, that was not my intent. For that I apologize.

Peter

This really should not come to this on the forums when a simple phone call could be made. I am sorry if you felt attacked, that was not my intent. For that I apologize.

Peter

Well, if you notice, I posted this over the weekend, and what I said wasn't accusatory, I specifically asked what it takes to get a clutch that holds up, and I had every intent of calling you Monday morning to discuss it.

But you spoke up here and essentially said it was my fault for giving it throttle in 6th gear, that I'm "straining" the clutch. Well of course it strains the clutch to give it throttle in top gear. Duh. But I thought this was supposed to be a heavy duty clutch that can easily take a measly 40 extra hp over the stock clutch and still hold up. That's what you told me when I bought it.

Yet here I am, less than 2 years and 30K miles into it, and it's already letting go. I didn't even get the same life from it as I got from the bone stock clutch with a DMF. And this is my fault for "straining" the clutch?

That, sir, is a crock of sh*t, and the type of thing someone says when they don't want to take responsibility. If you didn't mean it that way, well, okay, but that's how it sounded.

Can we get past all that and talk about what it takes to get a clutch for my truck that will hold up?

I have no intention of building some monster power beast or sled pulling or anything like that. I use my truck for daily transportation and occassional towing. I want the motor and everything else to last a long time. I run a very modest power increase the vast majority of the time, Juice level 1 which I understand is 40hp. I mainly run that just because without it, the truck feels a little sluggish in normal around town driving. I don't like a real smoky truck and I don't want to cause excessive engine wear so I keep the power turned down.

Towing is the same thing. I'd like to be able to leave it on level 1. I won't turn it above that when pulling any kind of a load because high egt's worry me.

Occassionally I want to turn up the power, usually when I'm on a little two lane road and I need to pass someone. Sometimes I'll do it when someone pulls up to me in a Cummins or Powerstroke as well and they need to be humbled. I turn it right back down when I'm done.

I want the clutch to last 100K miles.

What kind of clutch should I get?

Lets not point any fingers. Give Peter a call and get it taken care of.

Nothing but top-notch service from Peter at South Bend for me. GREAT company to deal with. In fact, I have to get back in touch with Peter, because I just ROASTED my sprung ceramic DDC...

Let me also point out that the failure was definitely 100% my fault. 4000 rpm, rode the clutch out in 3rd 4 Low, 75' later, no more tire spin...

Truck still drives and holds power, but won't go into gear at idle...

It was fun, though...:cool:

tysmith is a very good friend of mine we both have been treated extremely well by south bend, i had one of there single discs in my 7.3, it got hosed with fuel once and 2 days later worked just like new again. i totly expected to have to replace it, but didn't have to. and tyler's lets just say launching his truck with a 15k dead sled didn't go as we expected it to.

by the way sorry for the recomendation on what to try launching it . my bad

Some customers with manny trannys seem to not be very knowlegable about how to use its shifts properly. If you have a DD and are pulling a heavey trailer up the mountains with a tuner in 6th shift, it will not slip . . . but it may will cause a dirve shaft crack.

It is important to use the correct shifts for the correct applications. Guys doing drag racing and sled pulling have learned what/how to use the shifts based on starts, etc. give their type of clutches, power, weight, etc. and part of what they have learned is do slips, cracks, and perfect competition.

Regardless of the type of clutch you have now, you need to pay attention to which shift you need to be using properly. If you have a 6sp do you understand how different it is to 5th speed shift? Really? The 6spd is for crusing, only!

Use the 6spd for easy flat driving or going down the hill/mountain. If you use 6sp for adding speed going fast on a flat road or up a mountain it will have an impact. With a single disc it will slip. On a DD it may well have an impact on the drive line. If towing up a mountain you should be at 5th speed.

I can go up the mountain, not towing, with a DD, but I get up over 60 mph before I shift up to 6sp. I also keep the tunner down for using the 6sp. If you have a SD going up a mountain, do it the same way. If you have already slipped it several times, stay at 5sp and get the tuner off.

I have had a couple customers that have used a tuner on their SD hand have worked find and had no slipping, until they tryed doing speed increase in the 6sp.

The 6sp is not for power. It is for lowering the rpms but keeping speed up to reduce power and fuel. It only works on smoothly driving systems.

So let me make sure I understand this correctly ...

It is the official position of SBC that their single disc, SMF clutch for a Duramax cannot be expected to hold full throttle in 6th gear, on a truck with stock or slightly above stock power. Is that correct?

So let me make sure I understand this correctly ...

It is the official position of SBC that their single disc, SMF clutch for a Duramax cannot be expected to hold full throttle in 6th gear, on a truck with stock or slightly above stock power. Is that correct?

It is not an SBC SD problem. It is about using the 6sp correctly.

Basicly you need a DD. To make a single live you need to shift and give it a second to bite then get on the power. That has been my experience with SBC singles. They will hold power the just dont care to be shifted under power. A DD will be much freindly to that.;)


Ty that sucks about your clutch! I have done that same thing in many different gears even 4th high! Still work. Oh I do have a , Oh nevermind.:eek:

It is not an SBC SD problem. It is about using the 6sp correctly.

Okay, so let me rephrase.

Is it SBC's position that full throttle in 6th gear, at stock or mildly over stock power level, is not "using the 6sp correctly"? And therefore an SBC clutch should not be expected to hold that?

Yes or no?

I'm running a SB DD clutch in my Dmax and it's fantastic. It's very easy to drive and does not make the noises people had scared me about. You do have to pay more attention to engagement because it does grab quickly. Reverse is a little touchy but again it's very managable. I went through the same dilemna of SD vs. DD and I can tell you it shouldn't even be up for debate. Get a clutch that's rated for more than you plan to use.

Best of luck to you.

Frankly, I find this whole line of reasoning from both Deadeye and SBC to be offensive. Telling the customer he doesn't shift properly when he's got a failing clutch comes across as a really weak excuse.

I've read my owner's manual. In NO place does it say that I should not give my truck full throttle in 6th gear. Nowhere. Not once. So you can tell me all you want that it's an improper use, but GM doesn't concur.

Seems to me you're making up a new rule and then declaring anyone not doing it that way is doing it wrong.

Now granted, we're talking 40hp more than stock, and I understand that. I specifically bought an aftermarket heavy duty clutch for that very reason. I would not expect the GM clutch to hold more power than the GM engine was shipped with. I upgraded the power modestly and I thought I upgraded the clutch to match. Now the clutch vendor is telling me no, the clutch cannot hold full throttle in 6th at even a modest increase in power, and asking it to do so is using the 6 speed "incorrectly". Sounds like an excuse to me.

my stock clutch will hold with a full throttle from 35 mph to when ever I let off of it, and that is in level 1 or 2 on the edge. I don't go over level 2 hardly ever ( maybe once a year ) because of fuel prices.

Apparently Deadeye isn't going to respond.

I still want to know. Is it SBC's position that full throttle in 6th gear, at stock or mildly over stock power level, is not "using the 6sp correctly"? And therefore an SBC clutch should not be expected to hold that?

I also want to know where he got this information that it's "incorrect" to give full throttle while in 6th gear. Like I said, there is no reference to any such incorrectness in my owner's manual. This leads me to believe that it's a rule that Deadeye and/or SBC just made up, for the apparent purpose of avoiding responsibility for a product that works no better than stock.

Apparently Deadeye isn't going to respond.

I still want to know. Is it SBC's position that full throttle in 6th gear, at stock or mildly over stock power level, is not "using the 6sp correctly"? And therefore an SBC clutch should not be expected to hold that?

I also want to know where he got this information that it's "incorrect" to give full throttle while in 6th gear. Like I said, there is no reference to any such incorrectness in my owner's manual. This leads me to believe that it's a rule that Deadeye and/or SBC just made up, for the apparent purpose of avoiding responsibility for a product that works no better than stock.


If you want to understand about "full throttle" for a 6spd gear here is some testing you can do that will help you understand.

Go up a mountain highway, at ~50 mph in 5th gear. You will be running at about 2000rpm. This is different for various locations, elevation, tuners, tire sizes, etc. But it should be pretty close. While doing this, if you a boost and egt, check how will it is working and speed, rpms, eng temp, etc.

Now goiing up the same level shift to 6th spd gear. Your rpms will drop down to ~1350 rpms. To keep going at same speed your boost, egt, and eng temp will go up. If you have a stock clutch or a SD you may have it slip. If you do this with a DD you can increase the rpms and speed but will have a much noticable increase in engine noise, boost, egt, engine temp, etc. but it will not slip and will eventually get up to the correct rpms/speed for the DD truck. If you try this with a SD/stock clutch you will likely have clutch slipping.

The whole point of this is to explain that the 6th gear shift needs to be at the proper rpms when shifted, such that it works well and does not create extreme heat and slipping on the clutch, and make it easy for you to understand that the 6th gear is different. It is for crusing.

If you want to understand about "full throttle" for a 6spd gear here is some testing you can do that will help you understand.

Go up a mountain highway, at ~50 mph in 5th gear. You will be running at about 2000rpm. This is different for various locations, elevation, tuners, tire sizes, etc. But it should be pretty close. While doing this, if you a boost and egt, check how will it is working and speed, rpms, eng temp, etc.

Now goiing up the same level shift to 6th spd gear. Your rpms will drop down to ~1350 rpms. To keep going at same speed your boost, egt, and eng temp will go up. If you have a stock clutch or a SD you may have it slip. If you do this with a DD you can increase the rpms and speed but will have a much noticable increase in engine noise, boost, egt, engine temp, etc. but it will not slip and will eventually get up to the correct rpms/speed for the DD truck. If you try this with a SD/stock clutch you will likely have clutch slipping.

The whole point of this is to explain that the 6th gear shift needs to be at the proper rpms when shifted, such that it works well and does not create extreme heat and slipping on the clutch, and make it easy for you to understand that the 6th gear is different. It is for crusing.

Gee, thanks for enlightening me. I've only manual tranny driven diesels for 20 years, I had no idea that lugging my motor at full throttle and heavy load would strain the clutch and elevate egt's and coolant temps.

Rather than make these condescending explanations that amount to diesel driving 101, what I'd like is a direct answer to my question. Is it SBC's position that full throttle in 6th gear, at stock or mildly over stock power level, is not "using the 6sp correctly"? And therefore an SBC clutch should not be expected to hold that?

There are plenty of scenarios where you can do exactly that without overheating things. Empty truck, moving along at 65-70, top gear, give it full throttle. EGT's will rise anytime you accelerate, but in a light load situation not dangerously so.

The STOCK clutch performs just fine in this scenario. Even with +40hp of tuner, my stock clutch held for quite some time. I had to put a new DMF into it at 30K miles (under warranty) and then at 60K miles it was done again, with the clutch finally showing signs it was going as well.

When it finally started showing symptoms of going, I got an SBC. 30K miles later it failed.

I got another SBC, this one the new and improved version with a single mass flywheel. Here I am 30K miles into this one and it's already starting to let go. I'm not lugging the motor, I'm turning 2000rpm, the truck is empty, I give it full throttle, and the tach comes up without a corresponding increase in speed. For 30K miles it's worked fine, and it recently started letting go like this.

Rather than owning up to the fact that the clutch isn't holding, instead I get all this drivel that I don't know how to drive a manual? And you have the audacity to say you're going to teach me?

Do you not realize how that comes across to a long time diesel owner who's always owned and driven a manual? You're talking down to the customer instead of taking responsibility for a product that obviously isn't living up to it's billing. You're essentially throwing fuel onto the fire. I'm restraining myself the best I can, but really, this whole line I'm getting is a royal crock of sh*t, and anyone with a brain knows it.

Frankly, this whole blame-the-customer method of customer service makes my blood boil. The clutch is failing so the customer must be too stupid to know how to drive his truck. It pisses me off.

I wasn't particularly upset when I found out the clutch was slipping. Annoyed, yes, but I posted here genuinely looking for a solution. I want to fix it and I want a clutch in it that will hold up to a modest increase in power and last 100K miles. I thought that's what I was buying when I laid out a big pile of money 2 years ago.

Instead of constructive suggestions or a hint of actually admitting that the clutch wasn't up to it's billing when it was sold to me or an offer to do something for me, I get told I don't know how to drive my truck, and I'm condescendingly told that 6th gear is "different" and someone's trying to "make it easy for you to understand", while they make up new rules about what you are and aren't supposed to do in 6th gear.

This is customer service at it's worst. Making excuses and trying to redefine the rules instead of working on solutions.

I own a business, and if I treated my customers this way, I couldn't expect to stay in business.

I like this forum due to the fact that it's an informative, pretty friendly, level-headed spot. Too bad to see this pissing match going on.

ZFMAX, I agree that something certainly seems wrong from your description: 2k rpm uphill (no other loads on the drivetrain?) -- I'd sure as hell be alarmed if the clutch slipped in that situation.

So, you have a problem -- work to correct it. Give SBC and Deadeye the benefit of the doubt, call them, and work through it. Not meant to inflame, but put the emotions aside and work the problem.

I sincerely hope you get this squared away -- if not, please let us know.

Bill

It sounds like to me that just a dif disc is in order. If the organic is not lasting, you need a ceramic or a feramic disc and be done with it. It only cost me $250 to get mine done.

Wreckingball, Battlemax, I appreciate your comments. Constructive comments, what a concept. Wish SBC would make some.

Battlemax, how long has your ceramic/feramic disc held up? From your sig, it seems you're pushing things a lot harder than me. Do you normally drive at that power level or do you just turn it up to that power level occassionally?

I just had the feramic disc put in 500 miles ago and it should last a long, long time. My old disc was kevlar, which does not hold as well as ceramic or feramic. I pulled running 100 extra hp in 6th gear up hills without problems with it.
I don't normally run at that power level(490+), its only for testing or racing. The only time I ever had that cluch slip was not shifting correctly with 475+whp, and that only happend 2 or 3 times in the past two years. Like I said before it had 40,000 miles and only .010 wear, I still have it as my spare.
I don't understand that your not supposed to use 6th for towing up hills? If your in 6th gear at 1500rpm you are not making enough power to slip the clutch, you cant get any boost at that low of rpm. There is more strain on your clutch in 5th at 2500rpm at full boost then in 6th at 1500rpm.

I hear what you're saying, but really, the clutch has to hold torque, not power. Torque is twisting force. Power is torque times rpm. The clutch cares little how fast it's turning, what matters is how much twisting force it has to hold.

It's been a long time since I bought my Duramax (7 years next month) and saw a dyno sheet, but I seem to remember torque reaching 520 at about 1800rpm and then holding there to the limiter. So basically anything from 1800 or so up should be about the same strain on the clutch.

Yep, torque is the twisting force and hp is how fast it twist with the torque. On a stock engine peak torque is at 1800 rpm like you said but on tuned engines torque peak usually happens after 2,000 rpm and my dyno sheets with allot of diff tunning all peak in the 2400-2500 range, right where peak boost is.

I found my clutch on the SBC web site. It says:

"SD Max Con O - Performance Organic - 400 RWHP, 850 ft. lbs. torque"

"If you are going to be doing any competition such as drag racing or sled pulling, or exceed the torque ratings, please refer to the double disc clutches listed above."

I'm well below the power and torque ratings, and I haven't done any drag racing or sled pulling.

The clutch lasted 2 years and 30K miles. The vast majority of those miles were running around empty.

But of course, it's my fault for not knowing how to shift my truck. What a crock.

I have been running a ferramic single disc and have zero problems. I pull a 8000# travel trailer here in blue ridge mnts. of Va and hardly ever come out of 6Th gear on the highway, My stock clutch never slipped just the Dual mass flywheel would never last, With this SBC setup it has been flawless, I'm Happy with the single disc it works for me and my driving style:)

Sounds like maybe they sold me the wrong disc.

How many miles on your setup?

I pull a 8000# travel trailer here in blue ridge mnts. of Va and hardly ever come out of 6Th gear on the highway

You realize, don't you, that you're not "using the 6sp correctly", right?

That's what you'll be told if your clutch starts slipping. Nevermind that there's no concurring information in your owner's manual or elsewhere, when you install an SBC you have to be gentler on it than you do the factory clutch. SBC and Deadeye are happy to "make it easy for you to understand" this.

If it slips in 6th sooner or later it will slip in 5th too. For something to think about I took my dually with the stocker in it still,hooked 16K behind it and pushed it as hard as possible in 6th and couldn't get it to slip,but down in the lower gears it will slip :rolleyes:.

Has this issue been solved yet?

If it slips in 6th sooner or later it will slip in 5th too.

Exactly. When the clutch starts letting go in the higher gears, it's a leading sign that it's on it's way out. It only gets worse. Been there, done that.

That's why I was so startled when I gave it throttle in 6th gear and it let go. I knew it meant the clutch is showing early signs that it's done. The clutch is only 2 years old and has 30K on it and it's had an easy life. No way it should be going out so soon.

ZFmax I have about 10,000 miles on it so far, Really hope you get this issue solved, Before i bought the single disc i was on here night and day trying to figure out what to buy, DD or Sd But I'm not sled pulling or anything, Thats why i went SD, Me and you are not much different in towing and tuners, Looks to me the SD would be fine:)

I talked with someone at SBC about this. I got the same story, I'm not supposed to give it lots of throttle in 6th. Sigh.

I was polite but persistent, and eventually I got an offer to replace the disc with a "dual-friction", if I pull it out and take a picture of it and send it to them and it really is bad. He said he doubted the pressure plate was damaged but to take a picture of it too and they'd decide. I'd have to get the flywheel ground.

I've been pondering the offer and I don't think I'm going to mess with it. I don't really have the time right now to do this myself, too much on my plate, so I'd have to hire it out, which costs as much as a new Valeo unit. If I wait a couple months I'll have the time to just do the Valeo unit and I won't have downtime and I won't have to mess with grinding the flywheel or worry about re-using a used pressure plate. Plus the Valeo unit comes with a new throw-out bearing. The clutch is only just starting to go, I think it'll last a few more months until the Valeo unit is shipping and can do it all at once with all new parts.

Besides that, after 2 SBC's that each lasted only 30K miles, I'm not that crazy about putting in another. I'm want to ride a different horse.

how many miles on your truck?
could be weak hydralics on the clutch causing the clutch to never dissengage or engage fully and making it slowly burn

how many miles on your truck?
could be weak hydralics on the clutch causing the clutch to never dissengage or engage fully and making it slowly burn

I don't know, but it seems like a longshot to me. I mean, the original clutch went more than 60K miles, about half of that with the Juice box.

I didn't change the throw-out bearing at that time, but I did change it ~30K later when when SBC #1 failed and SBC #2 went in.

There's free play at the top of the pedal travel.

There's never been any sign of oil or hydraulic fluid on the clutch.

there wont be signs of fluid, the pressure will drop and not slave fully dissengage or engage at times, so it kinda slips a lil all the time

my buddy has a sbc sd in his lly with a predator on it and tows 35klbs daily and has over 100k miles on his sbc sd

there wont be signs of fluid, the pressure will drop and not slave fully dissengage or engage at times, so it kinda slips a lil all the time

my buddy has a sbc sd in his lly with a predator on it and tows 35klbs daily and has over 100k miles on his sbc sd

what level does your buddy keep his tuner at for tows? What type of clutch buttons does he have on his SD? Con O, CB, FB?

60hp usally, once in a while tows in the big program and watches egts. CB

Well, the failing SBC clutch made it through the trip OK, pulling a trailer. I probably had 6-7K lbs of trailer and other items in the bed. I kept the juice box turned off.

It doesn't seem to be letting go now, at least not at level 1 & empty. I turned it up from there, saw it starting to slip (obviously I was watching for it), and turned it back off.

The clutch is working, but marginal. Clearly not holding like it was when it was relatively new, what I'm seeing is the early stages of failure, it only gets worse from here. Been there, done that. I imagine if I kept the power turned way down or off it'd work for quite awhile.

I've ordered the Valeo and it's supposed to ship within a couple weeks, I'm sure the SBC will last until I can get the Valeo here and installed.

The Valeo kit is a bargain: $775 with new SMF, pressure plate, disc, throw-out bearing, and bolts. I'd spend nearly that if I stayed with the SBC, even getting the replacement disc under warranty, since I'd still have to buy the pressure plate, bolts, throw-out bearing, and resurface the SMF. And I'd still have an SBC, and I've had terrible luck with them. You live and learn.

I'll post some pics of the SBC when I get it out of there.

I am looking at a Valeo kit for my truck versus the SBC has anyone experience with this company

I wouldn't buy anything except for a SCB dual disc but then that's what I run and they are the best IMO.

ZFmax,
Sorry about the late reply on here. Hope that things did work out for you afterall.
I have the SBC SD FB(button) Clutch and my driving style is exactly like max1 or your self described. Other than the clutch is verry grippy starting in 2nd gear with no foot on the gas (just letting the clutch peddal out slowly) and reversing is a bitch, the Clutch
is holding nicely towing.
I have my 2500# camper on my truck for 8 month of the year without taking it off and a lot of city driving. On weekends I'm towing my 4500# boat through the canadian rocky's and do accelerate going up hill in 6th with the edge set on 2 continiusly.
That thing is holding. Some mountain passes are so long that I drive for almost 1hour straight uphill @ 55-65mph. Ones on top the clutch pedal pressure is a little stiffer than before I started my climb (indicating that their is heat beeing generated)I do believe the CON O clutch is rated at 400rwhp max and the FB (the one I have) is rated at 450rwhp.
Overall I'm happy with my setup because I did a lot of reading on here as well before I
purchased it.
I'll hope that helps you making the right decission what to purchase in the future, if you didn't have already.
Good luck,
B.

What' the word on the Valeo Clutch?

Unproven IMO.

What' the word on the Valeo Clutch?

Go with a DD no matter who makes it (I talked to SB and Valair and the price on there street DD are not that high anymore I am not sure what the prices are for the ZF-6 but for my NV5600 it was 900.00 for a street dd w 3250 plate load, I went a little higher on that when I got mine. I so far am happy with it, it is much better to tow with than the single I had (engages smoother).

I've had 3 clutches in my truck in 130K miles:

- the factory clutch
- a first generation SBC with stock pressure plate and DMF
- a second generation SBC with stock pressure plate and SMF

All have been single disc. The SMF SBC setup was put in almost exactly 2 years ago. Well, it's starting to slip. With the Edge box even on just level 1, when I point up hill in top gear and put my foot down it lets go. I can't even use level 2 or higher.

I don't abuse the thing at all. I very, very rarely ever take my Juice off of level 1, mainly just in tight passing situations. Then I put it right back on 1.

The clutch still engages smoothly and feels fine. You'd never know anything is going wrong in normal driving. The growling sound when idling and moving slow with the clutch out is getting a little worse, but it's always done that some since it was brand new.

So what's the deal? Do I have to go to a dual or triple disc to get a clutch that works and lasts in normal driving and occassional towing?

I'm not a manual powertrains genious, but what do you think holds the clutch against the flywheel and separates it when you depress the pedal? The pressure plate. I've been taught to replace the plate whenever you do a new clutch. I've never seen the factory pressure plate on a ZF6 but I would look into the pressure plate. If you are supposed to have 3000lbs of force and are only getting maybe 1800-2000, that could be why your clutch is slipping. I would look into that factory plate before you blame SBC. It don't matter if you have the best clutch on the market, if your pressure plate doesn't have the balls to force it against the flywheel, then it's gonna slip.

^^^ bingo

The problem is that the Southbend single disk kits come with a stock LUK pressure plate...

ok, so get a different brand...get a stage 3/4 clutch...theres options out there if you switch brands...

I'm not a manual powertrains genious, but what do you think holds the clutch against the flywheel and separates it when you depress the pedal? The pressure plate. I've been taught to replace the plate whenever you do a new clutch. I've never seen the factory pressure plate on a ZF6 but I would look into the pressure plate. If you are supposed to have 3000lbs of force and are only getting maybe 1800-2000, that could be why your clutch is slipping. I would look into that factory plate before you blame SBC. It don't matter if you have the best clutch on the market, if your pressure plate doesn't have the balls to force it against the flywheel, then it's gonna slip.

Before you go lecturing me on the virtues of pressure plates, you should know that SBC ships a stock pressure plate with their single disc kits. I used the one they sent me. If it's inadequate, it's a reflection on the kit that SBC ships.

I agree with you, though, that a heavy pressure plate is a key part of a clutch's holding power. I specifically asked that question of Eaton. They claimed the Valeo kit has a non-stock, heavier pressure plate.

Well, I received the kit, and it's an LUK plate. Is it any different than the stock plate that came with the SBC kit? I'm not sure. I haven't put it in yet. But I'll be comparing them closely when I do.

I opted to have the Valeo disc relined with ferramic kevlar. Hopefully that'll help the holding power as well.

The kit came with a throw out bearing, disc, pressure plate, single mass flywheel, pressure plate bolts, and alignment tool, but no flywheel bolts. It's not only much more complete than the SBC kit, it was also several hundred dollars less, even after having the disc redone. Will it last any better? I won't know for a couple years. But I can't imagine it'll be any worse. I'm really annoyed with the SBC kit. My stock clutch held up better than either one I got from SBC.

It took forever to get the kit, but it wasn't a big deal to me, the truck has been parked most of the winter anyway, and I haven't had to do any real towing with it or anything. They tossed in the disc reline for nothing, since I had waited so long and been patient with them. It's normally only something like $125 though.

The kits are available off the shelf now, though, no more delays.

I'll post some pictures when I get a chance, and also post some pictures of the old clutch.

I'm not a manual powertrains genious, but what do you think holds the clutch against the flywheel and separates it when you depress the pedal? The pressure plate. I've been taught to replace the plate whenever you do a new clutch. I've never seen the factory pressure plate on a ZF6 but I would look into the pressure plate. If you are supposed to have 3000lbs of force and are only getting maybe 1800-2000, that could be why your clutch is slipping. I would look into that factory plate before you blame SBC. It don't matter if you have the best clutch on the market, if your pressure plate doesn't have the balls to force it against the flywheel, then it's gonna slip.

You're 100% right about that!

I've got a single disc SB in my truck and it hasn't slipped yet even on my race tune :)

I've got a single disc SB in my truck and it hasn't slipped yet even on my race tune :)

How many miles on it?

Each of mine worked perfect for the first 30K miles.

You're 100% right about that!

I agree, but if SBC is shipping a factory stock pressure plate in their kit and representing that it can hold 450rwhp and 850 lb-ft, then they're the ones assuming responsibility when it won't. Both of my SBC kits included brand new factory stock pressure plates.

Before you go lecturing me on the virtues of pressure plates, you should know that SBC ships a stock pressure plate with their single disc kits. I used the one they sent me. If it's inadequate, it's a reflection on the kit that SBC ships.

I agree with you, though, that a heavy pressure plate is a key part of a clutch's holding power. I specifically asked that question of Eaton. They claimed the Valeo kit has a non-stock, heavier pressure plate.

Well, I received the kit, and it's an LUK plate. Is it any different than the stock plate that came with the SBC kit? I'm not sure. I haven't put it in yet. But I'll be comparing them closely when I do.

I opted to have the Valeo disc relined with ferramic kevlar. Hopefully that'll help the holding power as well.

The kit came with a throw out bearing, disc, pressure plate, single mass flywheel, pressure plate bolts, and alignment tool, but no flywheel bolts. It's not only much more complete than the SBC kit, it was also several hundred dollars less, even after having the disc redone. Will it last any better? I won't know for a couple years. But I can't imagine it'll be any worse. I'm really annoyed with the SBC kit. My stock clutch held up better than either one I got from SBC.

It took forever to get the kit, but it wasn't a big deal to me, the truck has been parked most of the winter anyway, and I haven't had to do any real towing with it or anything. They tossed in the disc reline for nothing, since I had waited so long and been patient with them. It's normally only something like $125 though.

The kits are available off the shelf now, though, no more delays.

I'll post some pictures when I get a chance, and also post some pictures of the old clutch.


Not to upset you but where do you think Eaton is getting the flywheel from...Not Valeo. :rolleyes:
And yes you got the Luk pressure plate and Luk clutch disc from Eaton, that is how I designed the flywheel and not for no reason. Your trucks are equipped with a concentric slave bearing assembly that has limited travel. Unlike a conventional pressure plate, the Luk's have a self adjusting mechanism in the pressure plate so as the clutch wares the fingers of the pressure plate never move. Pressure plates without this design allow the fingers to move toward the transmission as the clutch disc wares. The concentric slave/bearing will not allow for much movement and would bottom out in due time. This is the reason for using the OEM self adjusting pressure plate. You can change materials on the clutch disc to increase torque capacity of the clutch and you can increase plate load by decreasing friction material, "pounds per square inch". But as I explained in the beginning of this thread, non of this matters if you climb mountains in 6th gear, you will ware clutches out fast. Put a dual disc clutch in and you will ware something else out.

By the way, if they told you you got a higher plate load, they simply lied to get the sale. Shame on them. I will call Dave at Eaton on Monday.

Peter

But as I explained in the beginning of this thread, non of this matters if you climb mountains in 6th gear, you will ware clutches out fast.


Well, first off, the word is "wear", and second, what you actually said was:

"Point it up hill in sixth gear and hit the gas pedal. With added power or not you are straining the clutch. "

And furthermore, I was told on the phone that it wasn't due to wear, it was normal for the clutch to let go in 6th gear. So your story is evolving somewhat.

But in any event, I don't even have to be pointing up a hill, it'll let go on level ground with the truck empty. The hill was just the first place it happened.

These clutches I bought from you, both of which were represented to me as a match for the modest power increase I have, aren't up to the job. The two of them put together lasted about as long as the factory original clutch. That's in the exact same truck with the same driver.

And like I said, please show where in my owner's manual it says I can't give it throttle in 6th gear, on level ground or pointing up a hill, loaded or empty. GM has no such warning. So basically, what you're telling me is that I have to be more gentle on your product than I do on the factory clutch.

Now I realize I'm running 40 more hp than the factory motor. I would not expect the factory clutch to hold more than the factory stock motor puts out (although it held it longer than your product). But when I bought both clutches, they were represented to me as being an upgrade that would work well at that modest power increase. I've found that not to be true at all. I spent a big pile of money with your company and did not get what was promised to me, that's the bottom line.

By the way, if they told you you got a higher plate load, they simply lied to get the sale. Shame on them.

What a coincidence. I had another clutch vendor lie to me as well, when he told me he had a clutch that would work for me. In fact, he did it to me twice.

I've had 3 clutches in my truck in 130K miles:

- the factory clutch
- a first generation SBC with stock pressure plate and DMF
- a second generation SBC with stock pressure plate and SMF

All have been single disc. The SMF SBC setup was put in almost exactly 2 years ago. Well, it's starting to slip. With the Edge box even on just level 1, when I point up hill in top gear and put my foot down it lets go. I can't even use level 2 or higher.

I don't abuse the thing at all. I very, very rarely ever take my Juice off of level 1, mainly just in tight passing situations. Then I put it right back on 1.

The clutch still engages smoothly and feels fine. You'd never know anything is going wrong in normal driving. The growling sound when idling and moving slow with the clutch out is getting a little worse, but it's always done that some since it was brand new.

So what's the deal? Do I have to go to a dual or triple disc to get a clutch that works and lasts in normal driving and occassional towing?

First off, I have never attacked you in this thread but only to explain what could be the cause for the premature clutch failure. You seem to feel I have done so and for that I am sorry. You say your first clutch (stock) lasted 60,000 miles. Why do some people get over 100,000 miles? Driving conditions and styles. Your first replacement clutch with us failed do to the dual mass flywheel not the clutch. Your second clutch from us has lasted close to or as long as the stock clutch with the added power and only slips when under load. As I stated in an earlier post, if you had an automatic it would not allow you to stay in 6th gear on a hard acceleration on flat ground let alone climbing a grade loaded or unloaded. I don't think GM needs to put this in their manuals for the standard transmission trucks as it should be common sense. If you want to drive this way and try to prove to me that it should be OK to do so then by all means continue to do it. We will talk to you in a year or two when your new clutch is done. Or maybe you might listen to a person that has been in the clutch business his whole life with his father and grandfather before him.

Thank you for pointing out my misuse of the word wear, I am so stupid.

By the way, in the quote of yours above, occasional is only spelled with one S

Peter

ZFMAX, your not alone on this one. I bought a single disk ceramic kit from Deadeye to put in the '01 I had and it to didn't live up to the hype. With a 425hp tune it would slip in 6th gear... I wouldn't have cared except it was advertised to hold 450hp and 9xxtq.

I called John (Deadeye) and he basicly passed me off to Southbend who I couldn't seem to ever get on the phone. After several months of trying to get some answers I gave up and ran a mild tow tune.

It just pisses me off that a product is advertised to hold XXXhp and XXX torque, when in reality it won't. Then after a person buys it and finds out that it won't hold they get the run around and a slew of excuses. (like don't use 6th gear, don't lug it, ect) I think that is usually refered to as false advertising, but what do I know.

I guess it doesn't matter to me much anymore since I don't own a Dmax anymore, but I do know I won't be buying anything from Soutbend in the future. I also won't send anymore business there way like I have done in the past either.

My lowly Dodge 6 banger is only at 600RWHP/ 1100 tq. give or take a dyno number or two.

When it came to a clutch I wanted a single disc and knew it would hold. Peter even comfirmed it would hold as long as i did not lug the motor or go WOT up a hill with a trailer in tow. Makes sense to me.

But in the end he suggested for my abuse, a Dual Disc Clutch, and a side benefit would be the ease in backing up trailers.

Never been happier with the service from SBC and their products are beyond reproach.

For every 500 happy people there is always 1 unhappy person with SBC. A pretty good track record if you ask me. And from knowing Peter on a personal level, all i can say is that if he can't solve the issue, it is usually because the customer really isn't doing their part to help solve the problem.

First off, I have never attacked you in this thread

You, and Deadeye, have insulted me repeatedly in this thread, by trying to blame me for your inadequate product and your misrepresentation of same.

Your second clutch from us has lasted close to or as long as the stock clutch with the added power and only slips when under load.

So if it lasted the same as the stock clutch at that power level, why did you lead me to believe it was a heavier-duty clutch than the stock piece? Shouldn't I have reason to believe that it would outlast the stock clutch under the same conditions? Why should I buy your product if it's no more durable than the stock piece?

Does your website not advertise that this clutch will hold 400rwhp and 850lb-feet of torque? I'm far below that, and it didn't hold up for me. How do you explain that?


If you want to drive this way and try to prove to me that it should be OK to do so then by all means continue to do it. We will talk to you in a year or two when your new clutch is done. Or maybe you might listen to a person that has been in the clutch business his whole life with his father and grandfather before him.

Y'know, I'm fifty years old and I've been driving manual transmission diesel pickups for a long time. I've put several hunndred thousand miles on them in fact. Until I got this Duramax, I have never, ever, even once, had a clutch let go on me. Now all of a sudden, with this truck, I can't get more than 30K out of a clutch. Yes, that makes it hard to believe it's all me.

I called you to help remedy that. You represented to me that you had the solution. I forked over big piles of money TWICE because I believed you.

What I got both times was a clutch that held up no better than the factory stock clutch.

Those are the the facts. For you to now come back, and rather than stand behind your words and your product, tell me that I have an unreasonable expectation of my clutch, is offensive to me. Yes, I'm skeptical of what you're saying, but regardless, you represented to me that your products would solve my problem, and you made no mention of any of this. You've essentially chosen to blame the customer rather than standing behind your word and your products.

I have a very direct question that I asked earlier and it went unanswered: Is it SBC's position that full throttle in 6th gear, at stock or mildly over stock power level, is not "using the 6sp correctly"? And therefore an SBC clutch should not be expected to hold that? Yes or no?

Next question, please explain to me how a truck that makes nowhere near 400rwhp or 850lb-ft of torque will cause a clutch with those ratings to slip. Are those ratings not applicable to 6th gear? If not, which gears do they apply to? Do you see at all how that claim could be viewed as misleading, or flat out false, if there are undeclared qualiifiers to it?

As I have stated many times before I have had nothing but good results with my SBC clutches {all dual disc's :D} and my dealings with Peter. He has always treated me good and taken care of me. I smoked one after almost 100K hard miles of towing and probably 30 hooks sledpulling. But hey it's a wear item. IMO they should almost last forever if you're not towing.
Now that said I don't agree that towing in 6th or climbing a mountain in 6th is wrong. I tow in 6th all the time with both trucks and I tow well into the 30K LBS range. My 01 has almost 200,000mi on it and I did just finish rebuilding the trans in it but I think that is more due to all the sledpulling I do with it. It would be rediculous to tow in 5th at any speed above 60mph. That would be a recipe for disaster. With stock tires 65mph in 5th is 3000rpm and that is too high much less thinking about towing at 75mph in 5th. I shift to 6th as soon as I hit 65mph and set my cruise,loaded :D.

It would be rediculous to tow in 5th at any speed above 60mph. That would be a recipe for disaster. With stock tires 65mph in 5th is 3000rpm and that is too high much less thinking about towing at 75mph in 5th. I shift to 6th as soon as I hit 65mph and set my cruise,loaded :D.

That's exactly right. On the highway, I want to go 75. I bought a powerful truck just so I could do that. In these trucks, that means 6th gear.

I wouldn't want to go more than about 60mph in 5th for any length of time. You're winding the motor above that. The only time I'll do that is on a hill.

But if the truck will pull the hill in 6th gear, by just applying a little more throttle, without unusually high EGT's, well, the clutch damn well ought to be able to do that too. The stock motor with the stock clutch, that's no problem at all. With a modest increase in power and a clutch that's represented as a higher than stock performance part, rated at 400rwhp and 850lb-ft of torque, it shouldn't be any problem, either.

In any event, the first time this clutch ever let go, the truck was empty, no trailer and nothing in the bed. SBC tried telling me at the time that there was nothing wrong, and that I was simply asking too much of it. That's what they told me. They've now changed their tune, admitting that the clutch has worn out, and blaming me for using 6th gear. What a crock of sh*t.

I'm still waiting for an answer to my question. Is it SBC's position that full throttle in 6th gear, at stock or mildly over stock power level, is not "using the 6sp correctly"? And therefore an SBC clutch should not be expected to hold that? Yes or no? Do I understand correctly, that we are never to use full throttle in 6th gear with an SBC clutch? Is that company policy?

And why the hell does SBC claim 400rwhp and 850lb-ft? Those are full throttle numbers. Do those claims not apply to 6th gear? If not, what gears do they apply to? First only? First and second? Which ones?

It sounds like you may have a hydraulic problem ZFmax, or the clutch may not have been installed properly. When you went to your second clutch did you have your flywheel turned? If so was a shim put behind the slave to make up for the distance it was turned keeping the tolerances the same? My camaro uses the same principle as these trucks and we have to do the same thing if we get the flywheel turned. I've got a single disc SB in my truck and I've had no problems at all, I can run my race tune and mash it in 6th gear and it just takes off. The only thing is my race tune is exceeding the rating of a single disc SB, I"ll have to go dual disc at some point so I'm on borrowed time but so far it is holding up fine.

It sounds like you may have a hydraulic problem ZFmax, or the clutch may not have been installed properly. When you went to your second clutch did you have your flywheel turned?

Every clutch I've put in it has been with a brand new flywheel.

I've got a single disc SB in my truck and I've had no problems at all,

Interesting. How many miles on it? Each of my SBC single disc clutches worked fine for 2 years and about 30K miles.

I'm not sure how many miles are on it as the previous owner installed it... but its got over 30K miles on it was installed around february 2007.

I'm not sure how many miles are on it as the previous owner installed it... but its got over 30K miles on it was installed around february 2007.

Sounds like you're right a the point where each of mine started showing it's first signs of a problem.

Good luck.

^^^ We'll see, I am already over its rated power on my race tune so I know I'm on borrow time but so far so good. Good luck to you and hope you can get your truck sorted out.

Peter, I'm still waiting for you to answer my questions. I think they're very fair and direct questions. You sell a product, I bit twice, sent you big piles of money both times, don't you think I deserve an answer to some very fair and direct questions?

Is it SBC's position that full throttle in 6th gear, at stock or mildly over stock power level, is not "using the 6sp correctly"? And therefore an SBC clutch should not be expected to hold that? Yes or no?

Do I understand correctly, that we are never to use full throttle in 6th gear with an SBC clutch, even though we may be running far less than the 400rwhp/850lb-ft rating? Is that your company's position? Yes or no?

And if so, what exactly is meant by your claim that the clutch is good for 400rwhp and 850lb-ft? Do those claims not apply to 6th gear? If not, what gears do they apply to? First only? First and second? Which ones?

I sent you my money, twice in fact. You chose to come on here and insult me and you won't even answer fair and direct questions. Why won't you answer my questions?

Peter, I'm still waiting for you to answer my questions. I think they're very fair and direct questions. You sell a product, I bit twice, sent you big piles of money both times, don't you think I deserve an answer to some very fair and direct questions?

Is it SBC's position that full throttle in 6th gear, at stock or mildly over stock power level, is not "using the 6sp correctly"? And therefore an SBC clutch should not be expected to hold that? Yes or no?

Do I understand correctly, that we are never to use full throttle in 6th gear with an SBC clutch, even though we may be running far less than the 400rwhp/850lb-ft rating? Is that your company's position? Yes or no?

And if so, what exactly is meant by your claim that the clutch is good for 400rwhp and 850lb-ft? Do those claims not apply to 6th gear? If not, what gears do they apply to? First only? First and second? Which ones?

I sent you my money, twice in fact. You chose to come on here and insult me and you won't even answer fair and direct questions. Why won't you answer my questions?

There are 2 people that know the complete story. You and Peter.
Why don't you call him. Peter is a consummate professional at what he does, and I KNOW FOR A FACT that he has gone above and beyond for more people than I care to list. Even when it came to a failure of SBC's product (rare) or even a customer who abused the product (most likely)

Having said that, why don't you just call him and get the issue resolved?

It's easy to cause sh** on the internet, it is only a click away, but tell me if you switched shoes, would you even respond to your own posts?
Since you are not getting any solution arguing with yourself on the internet, try doing the human thing and call him in the morning!!!

Having said that, why don't you just call him and get the issue resolved?

It's easy to cause sh** on the internet, it is only a click away, but tell me if you switched shoes, would you even respond to your own posts?


Well, first and foremost, it was Peter and his sycophant crony who came on here and tried to place the blame on me. I posted genuinely looking for a solution. What I got instead was blamed, even though my usage of this clutch is well within the limits he described for me when I bought it and also well within the limits of what's advertised on his web site. So it wasn't me who chose to start this pissing match.

Second, I DID call them, even after Peter came on here and insulted me. I didn't reach Peter, but as I detailed earlier, the only thing they'd do for me is swap the disc if in fact they decide it's worn (remember, at the time they were claiming nothing was wrong with it, now Peter is admitting it's worn out, they've changed their tune).

So like I said, I was looking at the cost of a new pressure plate, getting the flywheel resurfaced, probably should replace the throw-out bearing, bolts, and the time or expense to do the swap. And when I got done with all that, I'd have the same clutch I had two years ago, with no reason to believe it would last any longer. Doing the same thing over and over and expecting a different result is the definition of insanity.

I weighed that against the cost of the Valeo kit and it was damn near a wash, and at least I'd have something that was different.

So yeah, I'm dissatisfied with the SBC product and especially dissatisfied with the way they've treated me, and they chose to do it publicly, so absolutely, I'll respond publicly. That was their choice.

What's more, and this is probably the biggest reason for doing this in public, the answers to these questions are of interest to anyone who's considering an SBC clutch. If SBC doesn't really mean 400hp and 850lb-ft in their ratings, or those ratings only apply to certain gears or certain ways of driving, people need to know that before they make the same mistake I did and send SBC thousands of dollars. Nobody told me ahead of time about any special rules for using the clutch or derating the numbers. I want to hear what the rules are and what the caveats to the power and torqu ratings are, and I want SBC to go public with that information. What's wrong with that? Would you choose to keep that information secret, which SBC is apparently choosing to do?

Peter, I'm not going away. I'm going to keep repeating the questions until I get an answer. These are not difficult questions. They're more than fair and I think anyone considering your product has a right to know this and someone who sent you his hard-earned money twice sure as hell has a right to know this.

Is it SBC's position that full throttle in 6th gear, at stock or mildly over stock power level, is not "using the 6sp correctly"? And therefore an SBC clutch should not be expected to hold that? Yes or no?

Do I understand correctly, that we are never to use full throttle in 6th gear with an SBC clutch, even though we may be running far less than the 400rwhp/850lb-ft rating? Is that your company's position? Yes or no?

And if so, what exactly is meant by your claim that the clutch is good for 400rwhp and 850lb-ft? Do those claims not apply to 6th gear? If not, what gears do they apply to? First only? First and second? Which ones?

Well?

These are the facts:
- SBC is selling a product they represent as holding 400rwhp and 850lb-ft.
- SBC claims that when the aforementioned product is shot after 30K miles of significantly lower power & torque than the rating, it's due to straining the clutch by using 6th gear.
- SBC did not explain this to the customer at the time of purchase
- SBC refuses to explain the 400rwhp/850lb-ft rating, in terms of what gears it applies to and doesn't apply to. So we're left to wonder just what the rules are.

"Caveat Emptor".

Peter, care to explain things for ZFMax??

Is this thread still going, I ran across this thing awhile ago figured it would be settled by now. I SUPPORT SBC. My truck is running fine. TST powermax running full tilt 24-7 towing not towing and holding fine.

Is this thread still going, I ran across this thing awhile ago figured it would be settled by now. I SUPPORT SBC. My truck is running fine. TST powermax running full tilt 24-7 towing not towing and holding fine.


SBC makes a really good dual clutch, its the single disc clutches that are giving some people problems. I think if SBC went to a stronger pressure plate the problem would be solved. SBC Dodge singles hold up very well. I know a guy that was running over 600whp through his feramic single before he went to a dual disc.

Oh yeah I climb mountains in 6th gear also, 5th just isn't fast enough for me. Hell if it had a 7th gear I would tow in that one too. My .02 worth

Exactly :D.

They are the very best clutch on the market IMO but Peter should tell all of us why the single disc's aren't working out for some people.

Oh yeah I climb mountains in 6th gear also, 5th just isn't fast enough for me. Hell if it had a 7th gear I would tow in that one too. My .02 worth

A person just posted that they think SBC singles come with the stock pressure plate? You guys with SBC single disc clutches is this true? Did your pedal feel any harder after the new clutch?

Yes, they come with the stock pressure plate. But that's not something I'm complaining about, they told me up front it was a stock pressure plate.

From my point of view, SBC misrepresented the clutch to me by telling me it would be suitable for my application, while failing to tell me about these unwritten rules for using it. Only now, after I already sent them piles of money twice and had both clutches fail prematurely, I'm being told I wasn't supposed to use 6th gear.

Furthermore, by continuing to claim it holds 400rwhp & 850lb-ft, while still refusing to spell out the rules for using it, they continue to misrepresent the clutch.

Where I come from, that's called "dishonesty".

I have one question. Do you know exactly how much HP and Torque your making? Have you Dyno'd your rig before? If not how do you your not making 415hp and 900 ftlbs?

okay maybe 3 questions.

Yes, they come with the stock pressure plate. But that's not something I'm complaining about, they told me up front it was a stock pressure plate.

From my point of view, SBC misrepresented the clutch to me by telling me it would be suitable for my application, while failing to tell me about these unwritten rules for using it. Only now, after I already sent them piles of money twice and had both clutches fail prematurely, I'm being told I wasn't supposed to use 6th gear.

Furthermore, by continuing to claim it holds 400rwhp & 850lb-ft, while still refusing to spell out the rules for using it, they continue to misrepresent the clutch.

Where I come from, that's called "dishonesty".
It really surprises me that SBC would use the stock plate for the single disc clutches. Do they use a different plate for the dual disc? Well this is obviously the problem with these clutches not holding and wearing out. I was told by CPMac that all his pressure plates for single or dual all use the same 3600lb pressure plate and you can defiantly tell by how stiff the clutch pedal is…. But they also hold 460+ whp with only a single kevlar disc.

So tell them you want a higher load pressure plate and problem solved.

I have one question. Do you know exactly how much HP and Torque your making? Have you Dyno'd your rig before? If not how do you your not making 415hp and 900 ftlbs?

okay maybe 3 questions.

Because I've got a an '02 with only a Juice Edge box that almost never leaves setting 1. Everything else about the truck is stock, air cleaner, exhaust, injectors are the originals, etc. If it was dyoned, I'd be surprised if it made more than about 300hp. I'd be thrilled if it broke 600lb-ft.

Now I won't lie and say I've never turned the box above level 1. I've done it, I admit it. But only with an empty truck, and generally only in a tight passing situation on a 2-lane road. It's very, very rare for me to do this. I never, ever, turn it up above level 1 when I'm towing. In fact, sometimes I turn it down to 0 if I see the EGT's going up.

I told SBC exactly what I was running when I bought each clutch and in both cases I was assured that the single disc clutch was fine for what I'm doing. At no time was it mentioned that I couldn't use 6th gear. Only now, after the second clutch failed prematurely, I'm being told this.

But even now, they won't spell out the rules. Under what conditions will the clutch hold the rated power and torque numbers? First gear only? First and second? I sent them big piles of money only to have two failed clutches, I think they owe me some answers.

Your probably around 400rwhp at level 5 unless you have the "Hot" Juice then you would be at 425+ rwhp.

Yeah, that's what I sorta figured. It's not the "Hot" Juice.

Which means if I turned it all the way up, I'd be at the rating of the clutch

I can count on one hand the number of times I've put it on level 5 in the last 3 years, literally. It's just not something I do very often. My truck is something I need to last a long time. I'm not interested in pushing any limits with it. I have the Edge box just to make it a little stronger in normal driving.

So the question remains, just what does the 400rwhp/850lb-ft rating of the clutch mean? Does that mean 1st gear only? 1st and second? Low range only? The rules aren't spelled out anywhere. They only mention the rules after you've had a failure, and even then, they won't explain them.

After sending them big piles of money on two separate occasions and having two premature failures, I think I deserve some answers. But apparently South Bend Clutch wants to keep the information secret. That way they can keep claiming 400rwhp & 850lb-ft even though you may cause a premature failure at much lower numbers. Where I come from, that's called dishonesty.

Caveat Emptor.

Did anyone ever try the Valeo kit?

^^^ I've got the Valeo kit at home, just haven't had time to put it in yet.

^^^ I've got the Valeo kit at home, just haven't had time to put it in yet.

What is the price on the Valeo clutch? How much power do they say its good for?

What is the price on the Valeo clutch? How much power do they say its good for?

I'm not sure on price, I am testing it for a company. Its a single disc supposed to hold 500HP I believe.

Get it in already and tell us what it will hold :D.

I'm not sure on price, I am testing it for a company. Its a single disc supposed to hold 500HP I believe.

Get it in already and tell us what it will hold :D.

LoL I know I know... just tough finding time... and garage space lol. I started back to school this week so hopefully i'll get it done in a week or so... amazingly enough the southbend that is in it is still holding strong.

if you dont have time to put it in you can always send it to me i will test it for them lol

I finally got the Valeo clutch installed. Working good. We'll see how long it lasts.

Funny thing was that the SBC really wasn't significantly worn. So why it wasn't holding anymore is a mystery to me. It held fine for the first 30K miles.

I really think that whole 400rwhp/850lb-ft rating is total BS. Obviously SBC has unwritten caveats on those numbers that they refuse to spell out. But what I know for sure is that after 30K miles it cannot hold substantially less power and torque than that when in 6th gear. SBC is advertising it dishonestly. I won't do business with dishonest people.

Sorry to hear about your experience with South Bend. Sounds like yours was a unique experience. Everyone I have referred to them have been more than pleased. Dodge, Ford, and GM owners alike.

Peter and his entire staff have been great to deal with.

Good luck with the Valeo unit. Hopefully it gives you many trouble-free miles.

Well, all you have to do is look back through this thread to see it for yourself. SBC, in the form of Peter, blames me for the problems I've had with their clutches, claiming that I broke an unwritten rule about using 6th gear. But he refuses to articulate just what the rules are.

And yet they keep right on claiming this clutch is good for 400rwhp and 850lb-ft. You just have to know what the rules are, which of course, they won't disclose. Until after the failure that is.

Where I come from, that's called dishonesty.

I believe Peter asked you to call him personally. He basically ignores threads when someone won't call him and resolve the issue that way.
I run 2 DD SBC's and wouldn't run another brand. I may upgrade to a
3 disc before next pulling season.

May I remind you, it was Peter who came on here and publicly tried to place the blame for these failures on me, by claiming I violated an unwritten rule when I used 6th gear. So if he's going to make an accusation like that in public, he owes it to me to either back it up with some facts or publicly retract it. To make an public accusation like that and then refuse to discuss it anywhere but privately is cowardice, plain and simple.

Furthermore, people who are considering buying an SBC product have a right to know exactly what he means when he claims 400rwhp and 850lb-ft. Obviously there are some kind of qualifiers to that, because I had premature failure at far less power and torque levels. So what are they? Are those numbers only good in first gear? First and second? Empty? How much load? What size tires? Downhill only? What exactly are the rules?

I believe Peter asked you to call him personally. He basically ignores threads when someone won't call him and resolve the issue that way.
I run 2 DD SBC's and wouldn't run another brand. I may upgrade to a
3 disc before next pulling season.

Kyle, you know what I went through trying to get ahold of Peter or anyone at Southbend for that matter when I mentioned I had a single disk that was having issues.

I left a couple of messages with Peter and one or two with someone the secratary passed me off to. I left my name, number, and the reason I was calling (single disk clutch problems) and never heard from them.

Seems to me that Southbend clutch should either stick with their ratings or not give the impression that there are ratings and warrenty. Not everybody wants a dual disk clutch so why make anyone that wants much over stock power buy one?

ZFMax, Hope the new kit works out for you. If I wouldn't have traded my Dmax off I was strongly considering this kit.

The Beauty of running the Valeo clutch kit is later if he wants to go DD with out Flywheel change

Ya I know. I still don't understand it cause I've almost always gotten Peter anytime I called and if I didn't Mansfeld could answer questions or handle the situation. If I need something they have it done for me asap. Weather it's a rebuild or decals for my trucks.


Kyle, you know what I went through trying to get ahold of Peter or anyone at Southbend for that matter when I mentioned I had a single disk that was having issues.

I left a couple of messages with Peter and one or two with someone the secratary passed me off to. I left my name, number, and the reason I was calling (single disk clutch problems) and never heard from them.

Seems to me that Southbend clutch should either stick with their ratings or not give the impression that there are ratings and warrenty. Not everybody wants a dual disk clutch so why make anyone that wants much over stock power buy one?

ZFMax, Hope the new kit works out for you. If I wouldn't have traded my Dmax off I was strongly considering this kit.

I've got about 3K miles on the Valeo unit now, mostly towing. Working perfect, once the break-in was done. It engages amazingly smoothly.

Given that these single disc SMF kits are all using the same flywheel, and the same factory GM pressure plate, the only real differences are a) the disc, and b) the price.

Valeo certainly wins on price by a big margin.

On the disc, well, I had really bad luck with SBC. Valeo remains to be seen but so far, so good. I had them reline it with Ferramic before they sent it to me. The clutch took so long to get that they threw in the reline for nothing, but it's not that expensive anyway.

What's odd to me is that the SBC I pulled out really doesn't look worn out. It doesn't have any fluids on it either, so I have no idea why it wasn't holding well anymore.

Whatever. After seeing all the excuses and innuendo and vague rules along with a total refusal by SBC to spell out the rules clearly, it'd be a cold day in Hades before I ever did business with SBC again.

I've got about 3K miles on the Valeo unit now, mostly towing. Working perfect, once the break-in was done. It engages amazingly smoothly.

Given that these single disc SMF kits are all using the same flywheel, and the same factory GM pressure plate, the only real differences are a) the disc, and b) the price.

Valeo certainly wins on price by a big margin.

On the disc, well, I had really bad luck with SBC. Valeo remains to be seen but so far, so good. I had them reline it with Ferramic before they sent it to me. The clutch took so long to get that they threw in the reline for nothing, but it's not that expensive anyway.

What's odd to me is that the SBC I pulled out really doesn't look worn out. It doesn't have any fluids on it either, so I have no idea why it wasn't holding well anymore.

Whatever. After seeing all the excuses and innuendo and vague rules along with a total refusal by SBC to spell out the rules clearly, it'd be a cold day in Hades before I ever did business with SBC again.


Just for giggles, send the clutch back to southbend. see if there IS something wrong with the clutch. Or something else. For peace of mind if nothing else.

Just for giggles, send the clutch back to southbend. see if there IS something wrong with the clutch. Or something else. For peace of mind if nothing else.and then have them send it back to ME. Or just send it to me first!!

X2 I'll be in the Denver area this weekend and can pick it up :D.

and then have them send it back to ME. Or just send it to me first!!

X2 I'll be in the Denver area this weekend and can pick it up :D.but you don't want a single. but I do.

Peter can upgrade it for me to a triple :D.

but you don't want a single. but I do.

So why was this clutch slipping?

http://www.aswracing.com/disk.jpg

http://www.aswracing.com/discupclose.jpg

No appreciable wear, no fluids on it (everything was dusty), no glazing, it really looks pretty good.

http://www.aswracing.com/pressureplate.jpg

http://www.aswracing.com/pressureplateupclose.jpg

Likewise the pressure plate looks and feels good. No surface irregularities I can feel at all, no ridge, no sign of warpage, no sign of overheating.

http://www.aswracing.com/flywheel.jpg

http://www.aswracing.com/flywheelupclose.jpg

The flywheel is in good shape too.

I think SBC was wrong, I don't think this clutch was abused at all. They just used that for an excuse to absolve themselves of responsibility for an overpriced, lousy product.

So why was this clutch letting go in top gear?

IMO, the crappy stock pressure plate got weak. That is the part I've always questioned anyway. Why even off an aftermarket unit with stock parts in it?

IMO, the crappy stock pressure plate got weak. That is the part I've always questioned anyway. Why even off an aftermarket unit with stock parts in it?

I have no reason to believe that the pressure plate lost clamp load, although admittedly I have no way to test for it.

Personally I think this is simply a clutch that's not up to it's manufacturer's claims in terms of holding power.

South Bend Clutch CLAIMS this clutch will hold 400 rwhp and 850 lb-ft of torque.

Here we have a relatively low mileage example, that has not been abused, and is not worn out, and it wasn't holding anywhere near that much power or torque. It would let go on a 2002 LB7 with an Edge box set on level 1, truck empty, pointed up a hill, and given full throttle. That's nowhere near 400rwhp and 850lb-ft. Probably 300rwhp and 600lb-ft tops.

Anybody looking at this clutch should look at it as a stock replacement, in my opinion. It should not be considered a performance upgrade. Shame on South Bend Clutch for claiming it's a performance upgrade.

By making these claims on their website, and verbally representing to me that this clutch was an upgrade in performance that would match what I was doing, South Bend Clutch engaged in deceptive sales practices, in my opinion.

By coming on here, after the sale, and claiming I damaged it by using 6th gear (clearly not true), they showed that they're a company unwilling to stand behind their products and claims.

I also think it's deceptive to make claims about holding power, and then come in after the sale and try to say that doesn't apply to 6th gear, when they don't mention that little fact in their advertising and they sure never told me that when they sold me the clutch. And the fact that they STILL won't spell out the rules and tell me what gears the 400rwhp & 850lb-ft ratings are good for, that speaks volumes about what kind of a company they are.

I would do a charge back on my credit card for this POS, misrepresented clutch if it hadn't been so long.

If SBC was an honest company, they'd give me a full refund and stop making these ridiculously false claims for this clutch.

IMO, the crappy stock pressure plate got weak. That is the part I've always questioned anyway. Why even off an aftermarket unit with stock parts in it?

I agree, stock pressure plate will not hold anymore power, or very slightly more with just a different disc in it. That pressure plate is why it was slipping. I still can't believe the money they get for those things either! Hope the new one works well for you.

I agree, stock pressure plate will not hold anymore power, or very slightly more with just a different disc in it.

That's kind of the way the evidence is pointing, at least with respect to the disc that SBC supplied. It's not that it wore out from being used improperly, as SBC claimed. It's really not badly worn at all. But with just a little bit of wear, it can no longer hold slightly more torque and power than the stock engine puts out. That's very telling. It suggests it's really not a performance upgrade.

Even the stock clutch will hold slightly more torque and power than stock for awhile. So just what exactly does the SBC clutch bring to the party? I guess it eliminates the troublesome DMF, but it doesn't actually hold any more torque or power.

Why is it being sold as a performance upgrade then? With a big torque and power rating and a big price tag? Again, I just don't think SBC is being honest. I think they misrepresented what they sell and they owe me a refund.

Whether or not a performance clutch is even possible with a stock pressure plate, I don't know. I don't know enough about clutch facing materials to be able to answer that. I did have my new Valeo disc relined with Ferramic, and it's certainly working great so far, but it's too early to tell. I guess I'll find out.

Not only was the Valeo setup several hundred dollars less than the SBC, it also came with a new throw-out bearing and a clutch installation tool and pressure plate bolts.

All that for $775 from these folks: http://www.eatonclutchsupply.com/product_p/k7234.htm

Compare that to $1300 for the SBC kit, which didn't come with a throw out bearing or pilot tool. The throw-out bearing alone lists for $355! So you're into this over $1600 to get something that's no better than Valeo's $775 kit. What a scam.

Clutch masters claims to have a heavy duty pressure plate:

http://www.clutchmasters.com/shop/?page=shop/browse&MakeModelID=51&MakeID=5&Engine=6.6L+Duramax+Turbo+Diesel&FromYear=1999&ToYear=2006

They also have a dual disc.

Also these guys are advertising one:

http://www.turbotechracing.com/productcart/pc/viewPrd.asp?idproduct=3646&idcategory=5164

Too late for me, my new one is already in the truck, but for someone looking for a new single disc clutch for their truck, this might be worth checking into.

Look I know you're pissed but I think enough is enough. Peter {SBC} and I have discussed this issue before and all it takes is a simple phone call to SBC rather than continuing to post here. Call them and find a resolution. Anytime I have questions or concerns I call them and I never have had one complaint ;).

Look I know you're pissed but I think enough is enough. Peter {SBC} and I have discussed this issue before and all it takes is a simple phone call to SBC rather than continuing to post here. Call them and find a resolution. Anytime I have questions or concerns I call them and I never have had one complaint ;).

So you don't think people should know how these single disc clutches SBC sells hold no better than stock? And how the ratings don't apply to all gears? And how he won't tell which gears the ratings apply to?

Or do you think people shouldn't know that there are better places to buy a clutch? Places that charge far far less? Places that offer heavier pressure plates?

I posted those pictures and all this information because people have a right to know what really happened here. Don't you agree that people should know?

Or is this site about protecting sponsors by keeping people from telling the truth about them? And telling what the alternatives are? If that's what's going on here, you might as well ban me right now, because I'm going to keep right on speaking the truth.

Don't forget, this is Peter's doing. I was looking for answers, not throwing rocks. He's the one who chose to come on here and publicly blame me for what's obviously a misrepresented product. You reap what you sow. Had he instead taken a measure of responsibility for the $2,000 plus he took from me, and decided to help me find a solution, this thread would be very different.

That's kind of the way the evidence is pointing, at least with respect to the disc that SBC supplied. It's not that it wore out from being used improperly, as SBC claimed. It's really not badly worn at all. But with just a little bit of wear, it can no longer hold slightly more torque and power than the stock engine puts out. That's very telling. It suggests it's really not a performance upgrade.

Even the stock clutch will hold slightly more torque and power than stock for awhile. So just what exactly does the SBC clutch bring to the party? I guess it eliminates the troublesome DMF, but it doesn't actually hold any more torque or power.

Why is it being sold as a performance upgrade then? With a big torque and power rating and a big price tag? Again, I just don't think SBC is being honest. I think they misrepresented what they sell and they owe me a refund.

Whether or not a performance clutch is even possible with a stock pressure plate, I don't know. I don't know enough about clutch facing materials to be able to answer that. I did have my new Valeo disc relined with Ferramic, and it's certainly working great so far, but it's too early to tell. I guess I'll find out.

Not only was the Valeo setup several hundred dollars less than the SBC, it also came with a new throw-out bearing and a clutch installation tool and pressure plate bolts.

All that for $775 from these folks: http://www.eatonclutchsupply.com/product_p/k7234.htm

Compare that to $1300 for the SBC kit, which didn't come with a throw out bearing or pilot tool. The throw-out bearing alone lists for $355! So you're into this over $1600 to get something that's no better than Valeo's $775 kit. What a scam.


I still say you should send that sucker to me and I will see if does any better in My truck.:)

You need to call him like he asked you to rather than keep going on, on here. He's not even going to respond here, he told me that on the phone when I called him.
I've spend almost $3000 there and wouldn't go anywhere else for clutches. In fact I'm getting a 3 disc when this 2 disc fails but I competition sledpull and know parts fail/wear out sooner or later under that abuse.
Yes,people need to know but if you had called him you'd have gotten this taken care of rather than this long thread that isn't going anywhere.

So you don't think people should know how these single disc clutches SBC sells hold no better than stock? And how the ratings don't apply to all gears? And how he won't tell which gears the ratings apply to?

Or do you think people shouldn't know that there are better places to buy a clutch? Places that charge far far less? Places that offer heavier pressure plates?

I posted those pictures and all this information because people have a right to know what really happened here. Don't you agree that people should know?

Or is this site about protecting sponsors by keeping people from telling the truth about them? And telling what the alternatives are? If that's what's going on here, you might as well ban me right now, because I'm going to keep right on speaking the truth.

Don't forget, this is Peter's doing. I was looking for answers, not throwing rocks. He's the one who chose to come on here and publicly blame me for what's obviously a misrepresented product. You reap what you sow. Had he instead taken a measure of responsibility for the $2,000 plus he took from me, and decided to help me find a solution, this thread would be very different.

You need to call him like he asked you to rather than keep going on, on here.

If you had actually read the whole thread, you'd know that I DID call him, and all I got was an offer to replace the disk if it really was worn out, which as you can see, it's not. So in other words, I got offered nothing.

What's going on here is that this clutch was misrepresented as having far more holding power than a stock clutch. That's clearly not true. With just a slight bit of wear, it can no longer hold a measly 40hp over stock power level. It holds no better than the stock clutch.

I specifically bought an aftermarket heavy duty clutch because I wanted to run a little more power than stock. I paid a big pile of money for it. Rather than taking responsibility for misrepresenting his product, the clutch vendor is telling me the clutch cannot be expected to hold full throttle in 6th at even a modest increase in power, and asking it to do so is using the 6 speed "incorrectly". What a crock of sh*t. Even the stock clutch could do that.

He's not even going to respond here, he told me that on the phone when I called him.

Well isn't that interesting? He's more than willing to come on line and blame a customer who spent thousands with him and had two terrible experiences. But when the truth actually comes out, and it's shown the clutch wasn't abused, it just isn't up to the job, he won't say a word. Where I come from, that's a dishonest businessman.

Yes,people need to know but if you had called him you'd have gotten this taken care of rather than this long thread that isn't going anywhere.

I DID call him. Read the thread.

Maybe this thread isn't going anywhere. But people have a right to know what he's selling and how they can expect to be treated and what the alternatives are.

I did read it and I called Peter too about this whole issue.

I'm a very satisfyed customer and couldn't be happier with Peter or his product. You and my buddy Justin are the only two I know of with trouble and both with singles.
Maybe it's the CO air. Lol! Sorry just had to throw that in :rolleyes:.

I will agree that being told not to use 6th is BS cause I was told the same thing but never slipped mine in 6th except the day it completely let go after 95K and about 30 hooks. Whick IMO was a long life for how I used it.



If you had actually read the whole thread, you'd know that I DID call him, and all I got was an offer to replace the disk if it really was worn out, which as you can see, it's not. So in other words, I got offered nothing.

What's going on here is that this clutch was misrepresented as having far more holding power than a stock clutch. That's clearly not true. With just a slight bit of wear, it can no longer hold a measly 40hp over stock power level. It holds no better than the stock clutch.

I specifically bought an aftermarket heavy duty clutch because I wanted to run a little more power than stock. I paid a big pile of money for it. Rather than taking responsibility for misrepresenting his product, the clutch vendor is telling me the clutch cannot be expected to hold full throttle in 6th at even a modest increase in power, and asking it to do so is using the 6 speed "incorrectly". What a crock of sh*t. Even the stock clutch could do that.



Well isn't that interesting? He's more than willing to come on line and blame a customer who spent thousands with him and had two terrible experiences. But when the truth actually comes out, and it's shown the clutch wasn't abused, it just isn't up to the job, he won't say a word. Where I come from, that's a dishonest businessman.



I DID call him. Read the thread.

Maybe this thread isn't going anywhere. But people have a right to know what he's selling and how they can expect to be treated and what the alternatives are.

You wont ever get a straight answer out of SouthBend on a failed clutch! A friend with a powerjoke went with their recomendations and his failed on a stock truck. Many,Many phone calls and they just want to sell him the same clutch kit. He went back to stock ford clutch and hasnt had 1 problem since. Hope ur new clutch works better for u.

Well, you live and learn I guess.

It's a shame I had to spend over $2,000 with SBC on two different clutches, for a total of only about 60K miles of service life, before I learned it, but hopefully my experience will keep someone else from making the same mistakes.

Bottom line, I feel pretty confident in saying that the single disc SBC clutch should really only be considered a stock replacement unit, not a high performance upgrade. It should not be expected to hold any more torque or power than the stock clutch, despite the 400rwhp & 850lb-ft ratings. Those ratings are total BS.

Furthermore I feel equally confident in saying that you can buy an equivalent clutch elsewhere for far, far less money.

Caveat emptor.

Just a side note on this new Valeo/Eaton clutch. I've noticed that at each new clutch I've put in, the stiff pedal syndrome after sustained highway driving is minimal at first, but it quickly returns as the clutch breaks-in. With roughly 10K on the clutch now, I would expect it would be coming back by now, based on previous experience.

Well, I went on a trip over the New Year's weekend, that included one non-stop freeway leg of about 400 miles. When I went to go push in the clutch, it was absolutely completely normal.

Another thing about this Valeo/Eaton that I didn't mention, it's break-in period seemed longer than I remember on the others. I really had to baby it for probably 500 miles, I could easily make it let go. But once it got broke-in, it's shown plenty of holding power, no signs of letting go at all.

Time will tell if this clutch holds up better than the SBC's, but so far, I'm encouraged.

You whine more than my ex-girlfriend. If you had sent the unit back to Southbend Clutch, and Given Peter something to work with, I have no doubt in my mind that he would have done everything in his power to make you a satisfied customer.
Instead, you chose the path of 'the poor consumer taken advantage of' and chose to whine whine whine on here about your issues without giving them a fair shake to inspect the product to see if it was faulty, and do an RMA/Refund/Replacement on it.
I believe you got EXACTLY what you deserved. If anyone makes a claim that a companies part fails, you send the product back to them. It's that simple. Anytime I have ever had a product fail to meet expectations, or fail outright, the product goes back to the manufacturer BEFORE any discussion takes place.
As a consumer, YOU and YOU ALONE failed to live up to that basic requirement. In this case YOU got to reap what YOU sowed, and got to reap the bitter harvest you so richly deserved.

PS, if you feel pissy at me for saying what a lot of other people on here are thinking, so be it.

I've got a Valeo single disc waiting to go in once the weather gets a little more bearable here. I'm on a single disc SB right now... it doesn't like my race tune anymore. But it did hold the race tune for quite a while but I did expect it not to hold at some point.

Well said Jonathan :cool:

You whine more than my ex-girlfriend. If you had sent the unit back to Southbend Clutch, and Given Peter something to work with, I have no doubt in my mind that he would have done everything in his power to make you a satisfied customer.
Instead, you chose the path of 'the poor consumer taken advantage of' and chose to whine whine whine on here about your issues without giving them a fair shake to inspect the product to see if it was faulty, and do an RMA/Refund/Replacement on it.
I believe you got EXACTLY what you deserved. If anyone makes a claim that a companies part fails, you send the product back to them. It's that simple. Anytime I have ever had a product fail to meet expectations, or fail outright, the product goes back to the manufacturer BEFORE any discussion takes place.
As a consumer, YOU and YOU ALONE failed to live up to that basic requirement. In this case YOU got to reap what YOU sowed, and got to reap the bitter harvest you so richly deserved.

PS, if you feel pissy at me for saying what a lot of other people on here are thinking, so be it.

PS, if you feel pissy at me for saying what a lot of other people on here are thinking, so be it.

Actually, I laughed when I read it. Someone's whining about me whining, I thought it was pretty funny.

BTW, my post was all about how my Valeo clutch is working, not about SBC.

Actually, I laughed when I read it. Someone's whining about me whining, I thought it was pretty funny.

BTW, my post was all about how my Valeo clutch is working, not about SBC.


Glad the new clutch is holding up for you. Good pics too. :)

i am having problems with my sd sb called peter directly and told him what was going on and he helped me more than i asked for,i've got nothing but good things to say about southbends service! he didnt talk down to me at all and treated me with nothing but respect and went out of his way to make sure i was happy!

Glad he fixed you up. I was certain he would :cool:.

i am having problems with my sd sb called peter directly and told him what was going on and he helped me more than i asked for,i've got nothing but good things to say about southbends service! he didnt talk down to me at all and treated me with nothing but respect and went out of his way to make sure i was happy!

My trucks stock for now. All I really wanna do is a decent tuner and exhaust. Do I really need a SBC double disk? Would a single disk hold up fine? I drive the truck pretty hard sometimes, but dont do a lot of towing and never do truck pulls, and I drive it at least 50 miles a day. I'd really like the DD kit but dont think I can afford it. I know SBC has quality shit, I just want the right clutch.

You need a DD. SD's are not good for any tuner in my openion. I won't recoment a SD to anyone :(.

My trucks stock for now. All I really wanna do is a decent tuner and exhaust. Do I really need a SBC double disk? Would a single disk hold up fine? I drive the truck pretty hard sometimes, but dont do a lot of towing and never do truck pulls, and I drive it at least 50 miles a day. I'd really like the DD kit but dont think I can afford it. I know SBC has quality shit, I just want the right clutch.

My trucks stock for now. All I really wanna do is a decent tuner and exhaust. Do I really need a SBC double disk? Would a single disk hold up fine? I drive the truck pretty hard sometimes, but dont do a lot of towing and never do truck pulls, and I drive it at least 50 miles a day. I'd really like the DD kit but dont think I can afford it. I know SBC has quality shit, I just want the right clutch.I would recomend the dd i have just a van aaken stock,110 and 230hp with the most aggressive sd sb makes with a s.f. and ive had it slip so going with dd. you should call and talk to peter at sb he would know better than me,imo i would waite and go with the dd to avoid possible problems down the road, if it was me.

Dang what a long thread when a simple phone call would have worked. I am fixin to have to buy a new clutch believe I will go with the SBC DD setup. ZF MAX not trying to upset you anymore than you already are but if your new clutch fails it maybe time to evaluate driving habits my .02.

Dang what a long thread when a simple phone call would have worked.

A phone call was made and SBC offered to replace the disk if the disk was prematurely worn out. You must've missed that post.

ZF MAX not trying to upset you anymore than you already are but if your new clutch fails it maybe time to evaluate driving habits my .02.

Guess you missed the pictures, too, because the most recent SBC clutch was not worn out when I pulled it out.

The issue isn't wear, the issue is that it lost holding power. SBC thinks they shouldn't be expected to hold when in the upper gears, they stated that in this thread. That's what this is about.

Wow, SB should pay to send this ZF guy to driving school and maybe a physics class while they're at it.

Maybe we should start a poll ...

How many people believe a clutch shouldn't be asked to hold 6th gear?

How many people believe a clutch shouldn't be asked to hold 5th gear?

Maybe we can attach a thread to it explaining the physics involved with going WOT uphill in 6th with a load...

What if it's letting go with the truck empty and no trailer?

I'm very interested in your explanation, since I can't seem to get one out of SBC. Please explain the 400rwhp & 800lb-ft ratings. Which gears do these numbers apply to? First gear only? First and second?

Reason I ask, I have a truck that has far, far less torque and power than that, and yet with a barely worn SBC clutch, the clutch would let go in the upper gears, with an empty truck and no trailer. So if that's normal operation, I need to understand which gears those torque and power ratings actually apply to. Thanks in advance.

By the way, I've since swapped to another brand clutch, and the issues are gone. But I'm still very curious about the SBC 400rwhp and 800lb-ft ratings. Please explain them.

How about you just sell me your truck and you buy a Dodge ;). I need a crew cab ZF6 :D

How about you just sell me your truck and you buy a Dodge ;). I need a crew cab ZF6 :D

Sure, you want to buy it after I fixed the clutch :)

It wouldn't even come close to holding the power I run through my D-Max's. I'd pull the Valeo right out ;). I only run DD's and shortly Ill be trying a DDD :D


Sure, you want to buy it after I fixed the clutch :)

I don't think I've ever run up a hill in 6th @ WOT with a load but I have goosed it empty. IMO, the clutch shouldn't slip. My stock clutch doesn't but it only has 15k on it along with a warranty covered DMF and I don't have any power adders.

IMO, the clutch shouldn't slip.

OK, so the vote is 1 for holding (bictalon), and 1 for slipping (azoilburner).

Any more votes?

The conditions are:

6th gear
pointed up hill
empty & no trailer
modest power boost over stock (Edge Juice level 1 which is +40hp)
full throttle
Using an SBC SD SMF clutch rated at 400rwhp & 800lb-ft

Is it unreasonable to expect that to hold or not?

For those of you who think not, under what conditions would you expect it to hold? First gear only? First and second only?

i dont think if you dont even own a zf truck you should be suggesting driving lessons to anybody! we all know how hard it is to jump in a automatic and put it in D and push the go go pedal to make it move. my piont is that you can only beat a dead horse so long and this one is barried the guy has got a couple good pionts but couldnt seem to get them resolved with sb.one way or another he has got a clutch he is happy he is happy with now so leave it alone!!!!!!!!!!!. im not saying he is right or sb is right but now it is what it is. i personly have nothing but good things to say about sb clutch. but as long as people keep making smart a$$ comments especailly ones that dont even have a manual transmisions about the guys driving hes never going to shut up!!!!!!!!!!!!!!!!!!!!!!!!!

OK, so the vote is 1 for holding (bictalon), and 1 for slipping (azoilburner).

Any more votes?

The conditions are:

6th gear
pointed up hill
empty & no trailer
modest power boost over stock (Edge Juice level 1 which is +40hp)
full throttle
Using an SBC SD SMF clutch rated at 400rwhp & 800lb-ft

Is it unreasonable to expect that to hold or not?

For those of you who think not, under what conditions would you expect it to hold? First gear only? First and second only?

I would say it should hold and if you send it to me I will test it and see if it is just your truck or a bad clutch.:D

Hmm, I seem to have misread the initial post... all of the subsequent banter on the next 15+ pages got me thinking that you were talking about pulling a trailer uphill in 6th and trying to accelerate. I see, and hope, you meant an empty truck the whole time.

I'm still going to err on the side of driver being the culprit. One has to bear in mind that 6th gear, especially in a diesel transmission (and yes wallybly, I know what I'm talking about with the zf6 and many other manual transmissions) is a cruising gear, designed solely for optimizing the low end torque of the engine at a constant power setting, ie cruising long distances. To produce an acceleration the engine must produce, and the clutch must transmit a power excess (remember from high school physics: F=ma). Once the truck is up to cruising speed, no power excess is required because you are no longer accelerating. The engine and clutch only have to overcome rolling friction and aerodynamic loads allowing the truck to operate at or very near the frictional limits of the clutch if that is what is desired. The ZF6 has a 0.5:1 ratio 6th gear, which is an OVERDRIVE meaning that the motor is now turning slower than the output shaft. What this means is that you are putting an excessive load on the clutch which is designed to hold this gear in a cruise setting, not for hard acceleration. When you try to accelerate hard in this gear you are pushing the engine torque against a force greater than the holding power of the clutch. Yes, the clutch may be advertised to hold 800lb/ft, but to accelerate quickly in 6th you are asking the clutch to transmit a power excess greater than it's own supply of friction. Another way to think about this is to flip the final drive ratio around and look at it back to front. If you go from 0.5:1 -- 1:2 you can see that the rear wheels clearly have the mechanical advantage. You should be able to execute a gradual acceleration, but to expect the clutch to hold a hard 6th gear uphill acceleration is kind of silly, especially when you factor in that you now have gravity working against you in addition to friction and aerodynamic loads. You have six gears for a reason. Think about semi-trucks, some have up to 18 different gears divided into high and low range groupings. You said earlier ZF that you have driven diesels for 20 years...(ZFMAX: "Gee, thanks for enlightening me. I've only manual tranny driven diesels for 20 years, I had no idea that lugging my motor at full throttle and heavy load would strain the clutch and elevate egt's and coolant temps.) and admitted that you understood that you were straining the clutch. What I'm trying to figure out is if you are so knowledgeable on trucks, why are you expecting the clutch to hold 6th, especially when you are goosing it at 2000rpm when you have ALL of the trucks power instantly on tap, and traveling uphill? From 4th gear on in the ZF6 you are no longer multiplying the torque of the motor. 4th is 1:1 and 5th is 0.75:1.... After fourth gear you are asking the clutch to fight a loosing battle when it comes to acceleration. Clutches are designed to specific standards to hold a specific amount of torque under specific conditions. Very simply, if you exceed those conditions, you will damage the component. I suspect that your continuing troubles with your truck are the result of constant bad driving habits. Just downshift once in a while.

i dont think if you dont even own a zf truck you should be suggesting driving lessons to anybody! we all know how hard it is to jump in a automatic and put it in D and push the go go pedal to make it move. my piont is that you can only beat a dead horse so long and this one is barried the guy has got a couple good pionts but couldnt seem to get them resolved with sb.one way or another he has got a clutch he is happy he is happy with now so leave it alone!!!!!!!!!!!. im not saying he is right or sb is right but now it is what it is. i personly have nothing but good things to say about sb clutch. but as long as people keep making smart a$$ comments especailly ones that dont even have a manual transmisions about the guys driving hes never going to shut up!!!!!!!!!!!!!!!!!!!!!!!!!

Since I don't currently drive a ZF truck I shouldn't make comments about manual transmissions... ok, I see the reasoning, but by your own logic, since you can neither spell nor form a coherent sentence it kind of follows that maybe you shouldn't be posting on an internet message board. Read the posts. He was given a few explanations and obvious solutions to his problem and tried to pull the, "Customer is Always Right" card and immediately began bashing his clutch supplier instead of acting like an adult and taking the input while trying to reason through the issue. I've been wrong lots of times. It sucks, especially when I've convinced myself I'm right. But I confront the issue and don't go bashing a good business on a public read board. Now if you want someone to get really pissed at, read the posts about all the problems TxChris and others have had trying to get GM to honor their warranty.

Very very well spoken azoilburner. :exactly:

Just wanted to make a correction, I had the wrong set of gear ratios in front of me when I wrote my post. My point still stands.

Gear ratio correction:
4th- 1.31:1
5th- 1.00:1
6th- 0.72:1

sorry to agitate you i hope i spelt that appriotely cause we know that is what this reeeally about right i guess they should just ban me from making comments because of my grammer lol;). i dont agree with how he attacked peter or sb, like i said before i had a problem with with my clutch and peter went above and beyond to help me. i guess everbody reads things different i totally understand what your saying working against the clutch when in od or double od, the way it sounded to me that it was being said that you shouldnt accerlate in 6th gear but if your at highway speed and you drop to 5th you will be on the governer uphill or not imo. atleast in mine. i understand if he said he was on a 8% grade and this happened. i dont remember if he really explained what mph or the grade or not its been so long since i read through this i dont honestly remember. my piont was this thread just keeps repeating itself with the same comments with different people saying them right:confused: look at that my dumb non knowing how to spell a@@ figured out how to use them smiley thingeys lol! now if i could just figure out how to set up my garage:rolleyes:

Unloaded, it shouldn't have been an issue... Unless, possibly, it was a really, really steep hill... 30% or steeper grade, kind of hill, or something else is causing problems.

Keep a close watch on the new clutch, and if it happens to crap out at roughly the same mileage (hopefully it doesn't!), then the problem is likely to be something else.

While I've got an entirely different vehicle, the concept is still the same, bone stock (well, close enough... air filter, muffler, and hypertech tune don't count, lol), and going up a hill, my truck bogs if I don't change gears, but it doesn't slip no matter how hard I stab the throttle, and my pressure plate likely has a broken spring or two, so it SHOULD slip... I've even exceeded my clutches towing capacity (though, I didn't exceed 55 MPH, and never went above 4th) and in 3rd gear, full throttle up a hill to KEEP going my speed, it didn't slip... (Though, I will admit, it didn't help my pressure plate, lol)

Any aftermarket clutch should be able to handle the driving that ZFMax has, provided there's no hidden issues he has yet to find.

Gear Ratios:
Reverse - 5.23
1st - 5.79
2nd - 3.30
3rd - 2.10
4th - 1.31
5th - 1.00
6th - 0.72

jc

Gear Ratios:
Reverse - 5.23
1st - 5.79
2nd - 3.30
3rd - 2.10
4th - 1.31
5th - 1.00
6th - 0.72

jc

Kinda makes the point even stronger when you list em....... oh well.

One has to bear in mind that 6th gear, especially in a diesel transmission (and yes wallybly, I know what I'm talking about with the zf6 and many other manual transmissions) is a cruising gear, designed solely for optimizing the low end torque of the engine at a constant power setting, ie cruising long distances.

Wow, you understand physics even less than I do. 6th gear does nothing to "optimize the low end torque" of the engine. The engine produces just as much "low end torque" in 1st gear as it does in 6th.

Second, I have looked all through my owner's manual, and I can't find a single word to substantiate what you say. They don't have any warning at all about using 6th gear. So basically what you're saying is that there are unwritten rules, and when you step outside these unwritten rules, you're abusing the clutch.

Clearly that clutch wasn't abused; I posted actual pictures of it and the wear is minimal and there's no sign of fluids on it, either. It simply isn't capable of holding the torque that the engine is capable of producing. Which calls into question the 800lb-ft rating. If the clutch can't be expected to hold 800lb-ft (and I'm nowhere near that), exactly what conditions does that rating apply to? First gear only? First and second only? You're holding yourself out as a physics expert since apparently you took a class in high school, by all means, please explain it to me.

To produce an acceleration the engine must produce, and the clutch must transmit a power excess (remember from high school physics: F=ma).

Well, you're close, that's not actually the formula that applies to rotating bodies, but it's similar. But the clutch's holding power really doesn't have to do with the power it's transmitting, it has to do with the torque that's being applied to it and the load on the other side. Power is torque times rpm; unless the clutch has some kind of centrifugal assist mechanism, the rpm it's turning isn't a factor in it's ability to hold.

When you try to accelerate hard in this gear you are pushing the engine torque against a force greater than the holding power of the clutch.

Again, the ability of the clutch to hold is not a function of power, it's a function of torque and load. The clutch is insensitive to the rpm.

Yes, the clutch may be advertised to hold 800lb/ft, but to accelerate quickly in 6th you are asking the clutch to transmit a power excess greater than it's own supply of friction.

Now we're getting to the heart of the issue. The 800lb-ft rating has an associated load figure, agreed? So what exactly is the load? Or in other words, in exactly which gears can this clutch be expected to hold 800lb-ft of torque?

You're using an awful lot of vague generalities: What, exactly, does "excess greater" mean? How are we, the consumers, supposed to apply this information?

You should be able to execute a gradual acceleration, but to expect the clutch to hold a hard 6th gear uphill acceleration is kind of silly, especially when you factor in that you now have gravity working against you in addition to friction and aerodynamic loads.

So what exactly is "gradual"? Isn't all acceleration "gradual" to some degree? You're using very imprecise terms for someone preaching about physics.

What I'm trying to figure out is if you are so knowledgeable on trucks, why are you expecting the clutch to hold 6th, especially when you are goosing it at 2000rpm when you have ALL of the trucks power instantly on tap, and traveling uphill?

Again, you're confusing torque and power. At 2000 rpm and the throttle open, I have all available torque but not all available power.

But I'm asking you what I asked Peter, and never got an answer to: what, exactly, are the rules? Under what load conditions can the clutch be expected to hold the 800lb-ft rating? First gear only? First and second only? You're not answering that question. Peter wouldn't answer it either.

From 4th gear on in the ZF6 you are no longer multiplying the torque of the motor.

The error about the 4th gear ratio notwithstanding, the statement is inaccurate. You're still multiplying the torque. The transmission in 6th gear starts multiplying the torque by a number that's less than 1, but it's still a multiplication. The differential continues to multipliy the torque by 3.73. So your statement is just flat out wrong.

After fourth gear you are asking the clutch to fight a loosing battle when it comes to acceleration.

What exactly does that mean? Are you saying the truck should not be asked to accelerate in any gear above 4th? Could you show me where it says that in my owner's manual? Or are you just making it up?

Clutches are designed to specific standards to hold a specific amount of torque under specific conditions.

Could you tell me what those standards and conditions are? SBC won't tell me.

Very simply, if you exceed those conditions, you will damage the component.

How am I supposed to know if I've exceeded them if I don't know what they are?

And what if I haven't damaged it, but it just won't hold any more?

I suspect that your continuing troubles with your truck are the result of constant bad driving habits. Just downshift once in a while.

If my truck can easily pull a hill without downshifting, I expect the clutch to be able to do so also. I described my application to Peter when I ordered the clutch (actually clutches), and he said this was the clutch for me.

Now, after the fact, he (and you) are telling me there are vague, unwritten rules for using the clutch that I violated. And to this day, no one will spell them out.

Sounds like an excuse to me.

The factory clutch lasted twice as long as either SBC clutch with the same person driving.

ZF, I don't know how to help you dude. I give you sound, simple explanations of the concepts involved here and you insult my intelligence. I can tell, from your heavy use of wikipedia and physics for dummies that you don't have a clue what you are talking about. You sound like a kid who pulls a new big word from the dictionary each day and uses it incorrectly to sound smart. I would love to help you understand these concepts (I've had a teensy bit more than a high school class worth of education in physics and mechanics, and materials, and dynamics... ad nauseum) but your head is so far up your ass on this that I believe you are beyond help. Find an engineer (other than myself), or any reasonably intelligent person to help you (I tried to contact Dr. Seuss to translate for but, he died a few years ago) and they will explain how and why I am correct. I hope you don't go broke fixing your truck while you learn about it. Good luck to you and good day.

ZF, I don't know how to help you dude. I give you sound, simple explanations of the concepts involved here and you insult my intelligence. I can tell, from your heavy use of wikipedia and physics for dummies that you don't have a clue what you are talking about. You sound like a kid who pulls a new big word from the dictionary each day and uses it incorrectly to sound smart. I would love to help you understand these concepts (I've had a teensy bit more than a high school class worth of education in physics and mechanics, and materials, and dynamics... ad nauseum) but your head is so far up your ass on this that I believe you are beyond help. Find an engineer (other than myself), or any reasonably intelligent person to help you (I tried to contact Dr. Seuss to translate for but, he died a few years ago) and they will explain how and why I am correct. I hope you don't go broke fixing your truck while you learn about it. Good luck to you and good day.

Aw, c'mon AZ, I was counting on you to tell me what the exact rules are. Don't cop-out on me!

I'm certainly not a physicist; no argument there. I took 4 semesters of physics and calculus as part of my engineering curriculum, but that was 30 years ago. I basically have to go look most things up anymore. I was counting on you, the expert, to provide me with some actual data. All I got was a bunch of incorrect statements and zero data. What a disappointment :(. C'mon, don't let me down!

I don't have any numerical data for your specific issue. All I aimed to do was illustrate the concepts and give you a good idea of why hard accelerations with a diesel engine in the 6th gear of your transmission are hard on the clutch. I understand your frustration on the accuracy of the clutch ratings, but if you truly are an engineer you should be able to reason through the issue. I think a good question to ask, to clarify the torque rating of a clutch, would be to ask if the clutch is actually capable of stopping an engine that is putting out 800 or less pounds of torque or if both sides of the clutch mechanism must be free to rotate. If they tell you that the clutch should be able to stall (stop the motor dead if one side of the clutch is fixed and completely unable to turn) up to 800ft/lbs then I'd say you've got an argument...

All I got was a bunch of incorrect statements !

None of my statements were incorrect. Once again, as the engineer that you claim to be you should immediately understand what I'm talking about. Go back and read what you wrote in contest of some of my statements... you are the one who is incorrect.

Good luck.

Wow, you understand physics even less than I do. 6th gear does nothing to "optimize the low end torque" of the engine. The engine produces just as much "low end torque" in 1st gear as it does in 6th.

.


This statement is patently FALSE, and as an engineer, you might be damn good, but you don't know sh_t about engines.

While the Duramax Diesel DOES produce copious amounts of low end torque, it does so against a LOAD. The reason is simple. In the lower gears, your mechanical advantage is greater, and it produces less loading at the flywheel.

Secondly (and this IS the most important part) with less loading, you will not develop maximum boost from the turbocharger (thanks Corky) and therefore your torque and horsepower at the flywheel will be less than in a taller drive ratio where you get loading of the drivetrain, maximum boost from the turbocharger, and MAXIMUM power from the engine.

Which, if you care to argue the point, dyno your truck in 2nd or 3rd gear, then dyno in 4th 5th and 6th.

Unlike a naturally aspirated engine who's power is more or less consistent regardless of gear or load (especially in a gasser) a TURBO diesel engine relies very much on load for higher exhaust temps, for boost. Without the turbocharger's boost, you will NOT develop max power or torque.

Turbo Diesel engines have been rated at flywheel HP and torque yes, but they are rated at an SAE load on an engine dyno. Without that load, the correct HP for a Duramax Diesel (LB7) would be 200BHP and around 350 lbs-ft of torque.

None of my statements were incorrect. Once again, as the engineer that you claim to be you should immediately understand what I'm talking about. Go back and read what you wrote in contest of some of my statements... you are the one who is incorrect.

Good luck.

As the engineer you claim to be, you should know that precise wording is critical. Using "power" where you should be using "torque" is incorrect.

But still, I'm extremely disappointed. I thought you were going to give me a physics lesson and explain the limits of the 800lb-ft rating. Instead you just posted a bunch of vague generalities with incorrect terminology with absolutely zero data. I'm not impressed.

While the Duramax Diesel DOES produce copious amounts of low end torque, it does so against a LOAD. The reason is simple. In the lower gears, your mechanical advantage is greater, and it produces less loading at the flywheel.

Uhh, you're confusing mechanical advantage with load. In the lower gears, the motor has more mechanical advantage. But it's entirely possible to increase the load as much or more than the additional mechanical advantage gained in the lower gear. Hold your foot on the brake if you don't believe me. You can build plenty of load, enough to stall the motor in fact.


Secondly (and this IS the most important part) with less loading, you will not develop maximum boost from the turbocharger (thanks Corky) and therefore your torque and horsepower at the flywheel will be less than in a taller drive ratio where you get loading of the drivetrain, maximum boost from the turbocharger, and MAXIMUM power from the engine.

I fully understand that diesel engines produce more boost, and therefore more torque, when you put them under load. But again, you confuse mechanical advantage with load. The engine can produce just as much boost in 1st gear as it does in 6th if you take the load up to offset the mechanical advantage of the lower gear. Watch a boost gauge while you powerbrake with an automatic sometime if you don't believe me.

Uhh, you're confusing mechanical advantage with load. In the lower gears, the motor has more mechanical advantage. But it's entirely possible to increase the load as much or more than the additional mechanical advantage gained in the lower gear. Hold your foot on the brake if you don't believe me. You can build plenty of load, enough to stall the motor in fact.



I fully understand that diesel engines produce more boost, and therefore more torque, when you put them under load. But again, you confuse mechanical advantage with load. The engine can produce just as much boost in 1st gear as it does in 6th if you take the load up to offset the mechanical advantage of the lower gear. Watch a boost gauge while you powerbrake with an automatic sometime if you don't believe me.

I am not confused at all. Using your described scenario, the motor will not produce it's rated power as a FUNCTION of the load put on it. C'mon calc major, I was using your own test case ;)

If load and rpm are/were not a function, the clutch would not hold EITHER 1st gear or 6th gear. The point would be moot.

Thanks Juice for getting into this.

Now, to ZF-
I don't remember if i stated it in my initial response or not, but I was using the terms torque and power interchangeably to illustrate the OVERSIMPLIFIED example i gave you. If you read my explanation, without looking for off the wall (and incorrect I might add) objections to my arguments, that all of the points I've made are valid. You are making "what/if" types of objections. For example, you tried to make the point that after fourth the transmission IS STILL multiplying torque. You attempted to validate your reasoning by providing the basic definition of a ratio. You forget that ratios are present, especially in mechanical applications to display MECHANICAL ADVANTAGE. Yes, a 0.72 drive ratio is still mathematically a multiple, however, it does not MULTIPLY (increase, as the term is used in engineering) mechanical advantage, in fact, it is a representation of LOST mechanical advantage (proving my point and making you look even more irrational). Then you try to rebut Juice's argument by introducing a situation that is irrelevant to the argument. No shit, increase the load and you offset mechanical advantage. But, your whole issue here has supposedly been with an UNLOADED truck.... Tell me good sir, now that there are constraints (unloaded truck, uphill, whatever torque YOUR TRUCK produces) on the argument, how can you rebut without citing minor wording issues for your disagreement? The arguments against you are sound. Don't let me down now.

Now that I think about it, let's be as exact as possible from this point on. We can use degrading performance differentials, materials arguments, precise wording, Sesame Street Simple prose if you choose... whatever. Debunk the sound physics arguments against you, then we'll delve into the intricacies of clutch system development and rating.

Thanks Juice for getting into this.

Now, to ZF-
I don't remember if i stated it in my initial response or not, but I was using the terms torque and power interchangeably to illustrate the OVERSIMPLIFIED example i gave you. If you read my explanation, without looking for off the wall (and incorrect I might add) objections to my arguments, that all of the points I've made are valid. You are making "what/if" types of objections. For example, you tried to make the point that after fourth the transmission IS STILL multiplying torque. You attempted to validate your reasoning by providing the basic definition of a ratio. You forget that ratios are present, especially in mechanical applications to display MECHANICAL ADVANTAGE. Yes, a 0.72 drive ratio is still mathematically a multiple, however, it does not MULTIPLY (increase, as the term is used in engineering) mechanical advantage, in fact, it is a representation of LOST mechanical advantage (proving my point and making you look even more irrational). Then you try to rebut Juice's argument by introducing a situation that is irrelevant to the argument. No shit, increase the load and you offset mechanical advantage. But, your whole issue here has supposedly been with an UNLOADED truck.... Tell me good sir, now that there are constraints (unloaded truck, uphill, whatever torque YOUR TRUCK produces) on the argument, how can you rebut without citing minor wording issues for your disagreement? The arguments against you are sound. Don't let me down now.

Now that I think about it, let's be as exact as possible from this point on. We can use degrading performance differentials, materials arguments, precise wording, Sesame Street Simple prose if you choose... whatever. Debunk the sound physics arguments against you, then we'll delve into the intricacies of clutch system development and rating.

you are welcome.

I think we are talking to an architect here though. engineers will usually listen :)

I think we should all go out and dyno our trucks in gears 1-3.. it'll make our clutches live longer.. AND we can then SNADBAG at the hot street drags!!!!:D

Speaking of which, I tried to make my SBC slip tonight. seems that some loose nut behind the wheel started out in 4th (oops) instead of 2nd..

I slipped the holy hell out of that DD to keep the engine from stalling. And no issues at all :)

I guess i just don't abuse it enough to get me one of them complaint threads going!

:Get_him:Yal lost me several post back lol but i am really enjoying the good reading keep it up.

Thanks Juice for getting into this.

Now, to ZF-
I don't remember if i stated it in my initial response or not, but I was using the terms torque and power interchangeably to illustrate the OVERSIMPLIFIED example i gave you.

No engineer would do that. You were using them interchangeably because you didn't know the difference.

If you read my explanation, without looking for off the wall (and incorrect I might add) objections to my arguments, that all of the points I've made are valid.

I'm waiting for you to make a point. So far all I've heard is a "excess greater". An engineer works with facts and figures; you've presented none, only vague generalities that are riddled with wording errors that show that your really don't understand the subject matter anywhere near the level you'd have us believe.

So let me ask you again. If I have a clutch that's rated to hold 800lb-ft, and it lets go at substantially less than that, what exactly are the conditions under which I can expect it to actually hold 800lb-ft? Is that first gear only? First and second? What is it?

See if you can answer that with specifics, not "excess greater" and "gradual". Saying things like that only reveal your lack of knowledge.

You are making "what/if" types of objections. For example, you tried to make the point that after fourth the transmission IS STILL multiplying torque. You attempted to validate your reasoning by providing the basic definition of a ratio.

No, I never attempted to define "ratio". You're as imprecise in your reading as in your writing.

You forget that ratios are present, especially in mechanical applications to display MECHANICAL ADVANTAGE. Yes, a 0.72 drive ratio is still mathematically a multiple, however, it does not MULTIPLY (increase, as the term is used in engineering) mechanical advantage,

So you're saying multiplication can only increase a number? Man, my 3rd grade teacher had it wrong :)

Then you try to rebut Juice's argument by introducing a situation that is irrelevant to the argument.

6th gear does not "optimize low end torque", whatever that means. Increasing load will increase boost and thus torque, but you can increase load in ways other than taller gears. The laws of physics are what they are, they don't give a whit how badly you and juice misunderstand them.

No shit, increase the load and you offset mechanical advantage. But, your whole issue here has supposedly been with an UNLOADED truck....

Your statement that 6th gear optimizes low end torque was made without any reference to load. I took it as a standalone statement, and in that respect, it's flat out wrong. It's not the gear that "optimizes" torque (another imprecise term), it's load. 6th gear is just one way to increase load. There are others.

Tell me good sir, now that there are constraints (unloaded truck, uphill, whatever torque YOUR TRUCK produces) on the argument, how can you rebut without citing minor wording issues for your disagreement? The arguments against you are sound. Don't let me down now.

Well, I'll tell you what, if you can actually state something that's not riddled with inaccuracies, I'll rebut it ;) So far, this is an exercise in explaining terminology to someone who has no idea.


Now that I think about it, let's be as exact as possible from this point on. We can use degrading performance differentials, materials arguments, precise wording, Sesame Street Simple prose if you choose... whatever. Debunk the sound physics arguments against you, then we'll delve into the intricacies of clutch system development and rating.

I ask again: under what conditions should an 800lb-ft rated clutch be expected to hold 800lb-ft? Simple question, can you give an answer?

No engineer would do that. You were using them interchangeably because you didn't know the difference.



I'm waiting for you to make a point. So far all I've heard is a "excess greater". An engineer works with facts and figures; you've presented none, only vague generalities that are riddled with wording errors that show that your really don't understand the subject matter anywhere near the level you'd have us believe.

So let me ask you again. If I have a clutch that's rated to hold 800lb-ft, and it lets go at substantially less than that, what exactly are the conditions under which I can expect it to actually hold 800lb-ft? Is that first gear only? First and second? What is it?

See if you can answer that with specifics, not "excess greater" and "gradual". Saying things like that only reveal your lack of knowledge.



No, I never attempted to define "ratio". You're as imprecise in your reading as in your writing.



So you're saying multiplication can only increase a number? Man, my 3rd grade teacher had it wrong :)



6th gear does not "optimize low end torque", whatever that means. Increasing load will increase boost and thus torque, but you can increase load in ways other than taller gears. The laws of physics are what they are, they don't give a whit how badly you and juice misunderstand them.



Your statement that 6th gear optimizes low end torque was made without any reference to load. I took it as a standalone statement, and in that respect, it's flat out wrong. It's not the gear that "optimizes" torque (another imprecise term), it's load. 6th gear is just one way to increase load. There are others.



Well, I'll tell you what, if you can actually state something that's not riddled with inaccuracies, I'll rebut it ;) So far, this is an exercise in explaining terminology to someone who has no idea.



I ask again: under what conditions should an 800lb-ft rated clutch be expected to hold 800lb-ft? Simple question, can you give an answer?

Yuh, jooze iz shur dum he kant evun spel defunishun of tork eider. o wayt i got me uh caluculus buk here sumwhayre.

OK. an 800 lbs-ft clutch will not hold when you exceed it's rated capacity in either engine load OR by TOWING something where you are making 800LBS-FT that shou shouldn't be towing in the first place like 45,000lbs of trailer.


And not to worry about brainpans, I have met many an engineer or architect who hold master Ctech and bachelors degrees who were and are complete idiots. I won't go so far to accuse you of the same, you are doing a fine job alllll by yourself.

Go dyno 3rd gear with your new clutch, then dyno 6th. Then come back and tell me how wrong i am.

Till then keep blabbin', this is getting more and more amusing by the minute.

Again Juice makes a valid point.

My use of torque and power interchangeably would make sense to an engineer or anyone else reasonably educated in the sciences as an attempt to illustrate a point.

I already told you ZF, I was presenting an oversimplified case, in which I expected you to understand that by optimizing the low end torque of the motor, I meant making the best use of what it is producing. Again, by simplified, I mean simplified and nothing else. Yet again, you attack with grammatical arguments, and not, sound scientific rebuttals. Please, save yourself the embarrassment and stop trying to prove a non existent point.

From what I've been able to read, he's not putting out 800ft/lbs...

Though, if he's at 750-ish, the extra load from 6th gear, even unloaded may be enough to bump it a bit over 800...

Still, though, looking at his pics, it looks like the clutch just lost holding power... It's not worn out.

OK. an 800 lbs-ft clutch will not hold when you exceed it's rated capacity in either engine load OR by TOWING something where you are making 800LBS-FT that shou shouldn't be towing in the first place like 45,000lbs of trailer.

So you're saying it's either 800lb-ft at the engine -OR- it's 45,000lbs of trailer? Huh? Where did you get that number?

Come on, guys, I'm asking a very simple question. Two people who hold themselves out as physics experts ought to be able to answer it, right? I mean, if two physics experts can't answer it, how in the world are dummies like me supposed to know what it means?

So I ask again. If I buy a clutch that's rated for 800lb-ft of engine torque, how do I know how much torque I can apply to it under what conditions? Does that 800lb-ft apply to first gear only? First and second? Empty truck? Loaded truck? How much load? Downhill only? Uphill to a certain grade?

What are the conditions?

I have a situation where I'm making maybe 600lb-ft, an empty truck, and the clutch can't hold 5th or 6th when pointing up a hill. So I need to know what this 800lb-ft rating means. Can you answer it?

Or is spewing a bunch of wrong physics riddled with imprecise wording and inaccurate terminology the best you can do?

Are you guys capable of admitting that you have no idea what the answer to the question is?

Still, though, looking at his pics, it looks like the clutch just lost holding power... It's not worn out.

Precisely! This isn't a case of the clutch being worn out, this is a case of the clutch not holding. Which is why I'm asking the question. Just how much can be expected of this clutch? It has an 800lb-ft rating. What does that mean? Does that mean I can only apply 800lb-ft to it if I'm in 4 low and have an empty truck?

SBC came on here and said I exceeded the capability of the clutch by using 6th gear. So I just want to know what the rules are. Nobody is willing to explain them to me, even the self-proclaimed physics experts.

Buyer beware.

You and I both know it would likely slip in 6th on the dyno ;).



Go dyno 3rd gear with your new clutch, then dyno 6th. Then come back and tell me how wrong i am.

Till then keep blabbin', this is getting more and more amusing by the minute.

I guess I'm just not understanding ZFMax's issue. I've got the same clutch he had in my truck. When the truck was stock there was nothing I could to do make it slip with the clutch fully engaged. ZFmax... question... when you had the second southbend single disc installed... did you have the flywheel cut? What I'm thinking is if you did have the flywheel cut down you changed the amount of clamp pressure available and threw off the measurements. I towed a 10,000 LB military vehicle on a double axle trailer with my truck bone stock, even up grades with my foot through the floor on the accelerator in 6th gear it did not slip. Now that my truck is EFI live tuned it will still hold my big race tune with over 900 RWTQ with the truck empty and pinning it in 6th gear on the highway. Just recently I am now able to slip the clutch by doing the same thing... which was expected of course because I am putting grossly more power out than the clutch is rated for.

I am gonna steal this thread for a second. I started a new thread below this one with a question need some help before i spend any money just wanna make sure i buy what i need thanks.

ZFmax... question... when you had the second southbend single disc installed... did you have the flywheel cut?

Nope. The first South Bend clutch was designed for and used with a stock brand new DMF. When that clutch failed at roughly 30K miles, Peter assured me that it was because of the DMF and all I had to do was send him another big pile of money for the SMF version and I'd be good to go. Unfortunately, I was foolish enough to do that. But it came with a brand new SMF, and that's what it was installed with, and that's what's in the pictures.

What I'm thinking is if you did have the flywheel cut down you changed the amount of clamp pressure available and threw off the measurements.

I don't see why grinding a flywheel would change the clamp load. But regardless, it wasn't ground, it was brand new.

I towed a 10,000 LB military vehicle on a double axle trailer with my truck bone stock, even up grades with my foot through the floor on the accelerator in 6th gear it did not slip. Now that my truck is EFI live tuned it will still hold my big race tune with over 900 RWTQ with the truck empty and pinning it in 6th gear on the highway. Just recently I am now able to slip the clutch by doing the same thing... which was expected of course because I am putting grossly more power out than the clutch is rated for.

You're having much better luck with SBC products than me!

So you're saying it's either 800lb-ft at the engine -OR- it's 45,000lbs of trailer? Huh? Where did you get that number?

Come on, guys, I'm asking a very simple question. Two people who hold themselves out as physics experts ought to be able to answer it, right? I mean, if two physics experts can't answer it, how in the world are dummies like me supposed to know what it means?

So I ask again. If I buy a clutch that's rated for 800lb-ft of engine torque, how do I know how much torque I can apply to it under what conditions? Does that 800lb-ft apply to first gear only? First and second? Empty truck? Loaded truck? How much load? Downhill only? Uphill to a certain grade?

What are the conditions?

I have a situation where I'm making maybe 600lb-ft, an empty truck, and the clutch can't hold 5th or 6th when pointing up a hill. So I need to know what this 800lb-ft rating means. Can you answer it?

Or is spewing a bunch of wrong physics riddled with imprecise wording and inaccurate terminology the best you can do?

Are you guys capable of admitting that you have no idea what the answer to the question is?

The 45000 number, easily figured out. Since you are an engineer, who knows his calculus, it's just a simple derivative away from answering.:rolleyes: But for the record, since YOU were spewing hypotheticals I thought it might be a cogent way to ask a simple question. I guess it wasn't.

You and I both know it would likely slip in 6th on the dyno ;).

Darn, so that's why I can't dyno worth a damn.

And so ZF dude understands, most dyno operators prefer to dyno in the 1:1 ratio in the transmission as it NEGATES any advantage of artificial loading through gearing on the dyno that can give slightly inflated numbers. Mostly though, single charger guys benefit from this. In this manner the only multiplyer is the rear end ratio;)

But

If you have a ginormously humangious <---- (scientific term of mine) single or God forbid, Twin turbos... most times a 1:1 ratio does not cut it because there is not enough time to get the turbo hot enough and the engine loaded enough before it simply runs out of rpms, and the turbo (s) are not providing enough air for the engine to reach is maximum potential.

I guess I'm just not understanding ZFMax's issue.
(No shizzle, joint the club ) I've got the same clutch he had in my truck. When the truck was stock there was nothing I could to do make it slip with the clutch fully engaged. ZFmax... question... when you had the second southbend single disc installed... did you have the flywheel cut? What I'm thinking is if you did have the flywheel cut down you changed the amount of clamp pressure available and threw off the measurements. I towed a 10,000 LB military vehicle on a double axle trailer with my truck bone stock, even up grades with my foot through the floor on the accelerator in 6th gear it did not slip. Now that my truck is EFI live tuned it will still hold my big race tune with over 900 RWTQ with the truck empty and pinning it in 6th gear on the highway. Just recently I am now able to slip the clutch by doing the same thing... which was expected of course because I am putting grossly more power out than the clutch is rated for.

About the only issue here is that there was a problem with a product and the consumer FAILED to work with the manufacturer to resolve the problem.
So now we have a never ending thread about a supersmart engineer who can't use a phone to resolve the issue, can't send the clutch back to get an RMA on the product, and finally someone who can't let the topic drop because he is still looking for someone to agree with him.

And by the looks of things, he isn't going to either.

I had thought engineers were smarter than architects.... maybe they are smarter but they have less common sense.

I'll agree with ZFMax, If southbend really had a clutch worth a shit it would hold up to its power ratings no matter the gear the transmissionis put in. Looks like to me there are a few of you here whoring for southbend.

It's not up to the customer to bend over backwards to get some service. I don't know how it works where some of you are from, but usually if a company is really that good they'll bend over backwards to keep a customer. They usually don't give some **** and bull story about not using overdrive, or pulling to much, or bla bla bla...

In the end it all boils down to the fact that if his motor is making XXX amount of power and XXX lbs of tq that's what it makes. It can't be "loaded" down more in a different gear, it is what it is. All the transmission does is allow the driver to multiply that HP and TQ to the ground. It is very possible to put the tranny in low gear and load it down until the motor stalls, how is that not "loading" it down as much as overdrive?

I have read this whole story thru and I am by no means an engineer or a physics expert. I am however a fairly decent junk iron mechanic. All that being said explain this one to me in my tractor there is a 4 cyl 65 hp diesel which is less than half the size of what we have in our trucks. Also it has a DD clutch setup that is almost twice the size in our trucks. So less power and more clutch (friction area) and i can make it slip in a high enough gear on incline loaded or not but in a lower gear loaded or not it is a lot less likely to slip. Not saying that i could not find enough incline or enough load to make it slip in the lowest gear. I said all that to say this giving the right situation it is possible to mess up any claim of any clutch sooner or later a coupling between a power source and a transmission or pump is gonna slip. Or twist something else up in a ball. Just my 2 cents

So now we have a never ending thread about a supersmart engineer who can't use a phone to resolve the issue, can't send the clutch back to get an RMA on the product, and finally someone who can't let the topic drop because he is still looking for someone to agree with him.

I called them, and was told that if the clutch wore out prematurely, they'd replace the disc only. As the pictures show, it's not worn out. So what is there to "RMA"?

I had let it drop, others keep dragging it back up.

And by the looks of things, he isn't going to either.

I falsely got my hopes up that some self proclaimed physics experts were going to explain the 800lb-ft rating to me. All I got was a whole bunch of incorrect terminology and vague generalities (excess greater gradual!) and numbers like 45,000lbs pulled out of the air and never explained.

Why don't you and AZ just admit that you're as clueless as me and you have absolutely no idea what the 800lb-ft rating actually means?

After all the braggadocio about your knowledge, all the put-downs and insults, all the posturing and trying to make people think you know something, the bottom line is that you don't know any better than I do under what conditions that rating applies and what the rules are for using this clutch. All you've accomplished here is to grandstand your ignorance.

Which is my point exactly. I, too, am totally ignorant on the 800lb-ft rating and what it means. All I know is that I sent these people more than $2,000, on two different clutches, and got a total of about 60K miles of service life for my money. Rather than stand behind their product, South Bend Clutch chose to come on a public forum and tell me that I broke some unwritten rule about how to use my clutch, and they won't even tell me what the rules are when I ask. They have refused to tell me what the 800lb-ft rating means and what the rules are for achieving that much holding capacity from the clutch, or even 600lb-ft, which is all I asked it to hold.

Now if you want to defend that behavior, and hold SBC out to be an honorable business, you're welcome to do that, it's a semi-free country. Likewise I'm free to point out the facts when you distort them. Get used to it, because I'm not going away.

I'll agree with ZFMax, If southbend really had a clutch worth a shit it would hold up to its power ratings no matter the gear the transmissionis put in. Looks like to me there are a few of you here whoring for southbend.

It's not up to the customer to bend over backwards to get some service. I don't know how it works where some of you are from, but usually if a company is really that good they'll bend over backwards to keep a customer. They usually don't give some **** and bull story about not using overdrive, or pulling to much, or bla bla bla...

In the end it all boils down to the fact that if his motor is making XXX amount of power and XXX lbs of tq that's what it makes. It can't be "loaded" down more in a different gear, it is what it is. All the transmission does is allow the driver to multiply that HP and TQ to the ground. It is very possible to put the tranny in low gear and load it down until the motor stalls, how is that not "loading" it down as much as overdrive?

Re read the post I made where you are not making any boost. Without the aid of the turbo, yes, you can load the motor down, but typically you will stall out or rev out before you even come close to making maximum boost and power. Even pulling on a stuck tractor at the farm, 2nd gear, low range I can only achieve 15lbs of boost. Where did the other 30lbs of boost go? I was loaded wasn't I ?:)

If I were a betting man, judging by the colour in the pictures I'd say the ONLY reason for that clutch to fail would be insufficient plate load. But that point is irrelevant, because ZF chose not to send the unit back to SBC. SBC takes care of their customers.

But you have to give them something to work with :)





Personally, I am not a fan of single disc clutches. It's not that they can't hold up to power (they can) but if you tow a fair amount (i do) then you will slip and chatter the hell out of them, and wreck them in short order.
It was suggested to me on more than one occasion to go with a double disc.
Having made the purchase at 40,000 miles... I now sit at 75,000 miles, and the clutch is still going strong.

DD's do have some slight disadvantages. They rattle a little bit. Shifting is slightly slower with more rotational inertia, and occasionally you need to do an aggressive launch to keep everything happy. A DD Clutch needs to be abused occasionally if it starts to get a little grabby. :)

I'll agree with ZFMax, If southbend really had a clutch worth a shit it would hold up to its power ratings no matter the gear the transmissionis put in. Looks like to me there are a few of you here whoring for southbend.

It's not up to the customer to bend over backwards to get some service. I don't know how it works where some of you are from, but usually if a company is really that good they'll bend over backwards to keep a customer. They usually don't give some **** and bull story about not using overdrive, or pulling to much, or bla bla bla...

In the end it all boils down to the fact that if his motor is making XXX amount of power and XXX lbs of tq that's what it makes. It can't be "loaded" down more in a different gear, it is what it is. All the transmission does is allow the driver to multiply that HP and TQ to the ground. It is very possible to put the tranny in low gear and load it down until the motor stalls, how is that not "loading" it down as much as overdrive?

Very well put, thank you. And, I'd add that coming in with this excuse after telling me this clutch was fine for me and after selling me two of them that didn't work out isn't what I'd call an honest business practice.

But that point is irrelevant, because ZF chose not to send the unit back to SBC.

So in your view, I should send it back even though they've told me they won't cover it?

Okay, I will. It's not doing me any good sitting around and I sure as hell ain't going to use it again.

I'll let you know what they do about it. But they've already told me they won't do anything.

So in your view, I should send it back even though they've told me they won't cover it?

Okay, I will. It's not doing me any good sitting around and I sure as hell ain't going to use it again.

I'll let you know what they do about it. But they've already told me they won't do anything.

That would be great. Seriously. I would hold any company to task for a faulty product, or problem if it was theirs. The best way to do that is to get them to check it out.

And then swing the hammer!:D I would really like to know what happened to the unit, as I have only ever seen 3 failures of their clutches!

Urban Legend it's not, we had a VP44 CTD that made 460RWHP.... it also developed over 1000 lbs-ft of TQ. It made no sense . We had to reverify those readings on different dynos, until it became clear that no single disc would hold this truck while towing. We had to do DD.

Re read the post I made where you are not making any boost. Without the aid of the turbo, yes, you can load the motor down, but typically you will stall out or rev out before you even come close to making maximum boost and power. Even pulling on a stuck tractor at the farm, 2nd gear, low range I can only achieve 15lbs of boost. Where did the other 30lbs of boost go? I was loaded wasn't I ?:)

If I were a betting man, judging by the colour in the pictures I'd say the ONLY reason for that clutch to fail would be insufficient plate load. But that point is irrelevant, because ZF chose not to send the unit back to SBC. SBC takes care of their customers.

But you have to give them something to work with :)





Personally, I am not a fan of single disc clutches. It's not that they can't hold up to power (they can) but if you tow a fair amount (i do) then you will slip and chatter the hell out of them, and wreck them in short order.
It was suggested to me on more than one occasion to go with a double disc.
Having made the purchase at 40,000 miles... I now sit at 75,000 miles, and the clutch is still going strong.

DD's do have some slight disadvantages. They rattle a little bit. Shifting is slightly slower with more rotational inertia, and occasionally you need to do an aggressive launch to keep everything happy. A DD Clutch needs to be abused occasionally if it starts to get a little grabby. :)

You were the one that said there would be no boost. It is very feasible to be in low gear pulling out said stuck tractor, and be making full boost. We are talking about a stock turboed mildly tuned motor here. Not a big single or an all out race motor. Either way it doesn't matter the motor will still only make XXXHP and XXX TQ when full loaded and as long as that is less than or at the rating of the clutch there should have been no problem.

I guess it basicly comes down to the fact that maybe southbend shouldn't be selling single disk units if they don't feel that they are up to the task. Or maybe they shouldn't rate them for more than stock clutches...

I still wish ZFMax good luck with his new clutch! I'd recomend that everyone just let this thread rest. Everybody has their mind made up and it's obvious that no one is going to change theirs, so lets all just agree to disagree.:)

Either way it doesn't matter the motor will still only make XXXHP and XXX TQ when full loaded and as long as that is less than or at the rating of the clutch there should have been no problem.


See, that's the way I see it, too. Absent any other spelled out, written rules to qualify the conditions, a person ought to be able to take the clutch ratings as a statement of how much the clutch can hold regardless of the load.

Basically, to me, the numbers mean that if your motor makes less than the clutch rating, you'll stall the motor before you slip the clutch.

If there are qualifers on the ratings, like for example they don't apply to some certain gear or load level, then those ought to be spelled out.

And they ought to be spelled out up front, before a person buys the clutch. Coming in after the clutch fails to meet the customer's expectations, and proclaiming these rules to exist, while still refusing to spell out what they are, is bullshit, and I'm calling it. And I don't care how many South Bend sycophants defend the practice. That's a dishonest way to run a business where I come from.

And they ought to be spelled out up front, before a person buys the clutch. Coming in after the clutch fails to meet the customer's expectations, and proclaiming these rules to exist, while still refusing to spell out what they are, is bullshit, and I'm calling it. And I don't care how many South Bend sycophants defend the practice. That's a dishonest way to run a business where I come from.

I'm not a sycophant, that's far too sophisticated a term . And I am far too young to be a groupie, and not cute enough to be qualified with the term cheerleader.

But you are right. It's your truck and the clutch failed for whatever reason.

You slimed SBC on here because it failed. Adding insult to injury, you failed in your responsability to send back a defective product to see if it actually was defective. Do you not get that?

I own my own business. I have to stand behind products when they fail, sometimes at my own expense when the manufacturer decides not to, just to maintain my reputation. But if the client does not help me to help them, my options become severely limited in what can be achieved. The client has self limited their own best interests? And for what reason?
It certainly can't be principle's , for if it were, we would be reading this thread differently.

It would be a thread to the tune of 'Well, I got a bad clutch, but the manufacturer is standing behind it' That kind of thread was possible had you only followed through and sent the damn clutch back.

But you did not.


I am glad that you are sending it back now. Perhaps there will be a resolution for you in it. Cutting off your own nose to spite your face does not make for a happy outcome.

You slimed SBC on here because it failed.

Not until after they "slimed" me, accusing me of causing the issue, with absolutely no data to back that up. They were accusing me before I even pulled it out of the truck!

Adding insult to injury, you failed in your responsability to send back a defective product to see if it actually was defective. Do you not get that?

They said they wouldn't take it back. Did you not get that? Or do you just choose to ignore it?

I am glad that you are sending it back now. Perhaps there will be a resolution for you in it.

I'm sending it back now in spite of their stated refusal to do anything to help me.

I'll report back what they do.

Peter and I have discussed this numerous times on the phone because I wondered what was up. Seems all storys have two sides and this one darn sure does ):h.

Peter and I have discussed this numerous times on the phone because I wondered what was up. Seems all storys have two sides and this one darn sure does ):h.

Well by all means, let us in on his side! Because I have no clue what it is, other than I wasn't using the 6-speed correctly.

Well by all means, let us in on his side! Because I have no clue what it is, other than I wasn't using the 6-speed correctly.

You can't drive worth sh...:eek:):h:stick_out:lol2:

So in your view, I should send it back even though they've told me they won't cover it?

Okay, I will. It's not doing me any good sitting around and I sure as hell ain't going to use it again.

I'll let you know what they do about it. But they've already told me they won't do anything.

and if they do not want it back have them send it to Me:)
really, I need a new clutch

Cruising the boards on a lazy Sunday morning I came across this jewel of a thread. As an Engineer I HAVE to step in here and defend the profession. Please what ever you do don't lump us in with physicist, those guys do NOT work in the real world and use pure theory with no testing and validation.

As an engineer, I and quite a few of my collueges would approach the issue of clutch torque ratings very simply. You take the torque rating of the engine and design a clutch to handle that torque. HP is a function of torque and RPM, it is used to assign a numerical value on "work" lift 10 lb's 10 times vs. lift 100 lb's once, both would have the same HP, but much different torque values. A clutch doesn't care how much HP is produced, it only cares about torque as RPM has no bearing on clamping capacity.

Now the big point I want to make is......how in the world does the clutch know what gear the tranny is in? It "see's" torque from the engine and transfers it to the input shaft of the trans that's it. I can make 650 ft/lb's of torque in every gear and the clutch won't know the difference. The only condition that changes is how long the clutch see's 650 ft/lb's of torque which I believe is the source of the issue at hand. In lower gears the vehicle is going to be able to accelerate as torque multiplication (after the clutch) is giving the engine/trans combo the torque needed to accelerate the mass. This means the clutch is going to see 650 ft/lb's for less time than if it's parked in 6th gear at full load.

Why should this matter? Well it appears to me that the clutch is constantly slipping at full torque and needs less duty cycle to keep from over heating. In my mind.....that clutch is not rated for the torque it's being asked to transfer or something has happened to the clutch to alter the amount of torque it can handle.

Aftermarket companies have a tendency to rate their products by slapping them behind a vehicle and trying them out a couple of times in some kind of competition such as drag racing or sled pulling in this case. Sure this clutch might survive a short blast down a sled track or a 1/4 mile, but it's not going to last against full torque for long periods of time. Pulling a grade at full throttle be it 4th,5th or 6th gear is the same as doing a 1/4 mile run constantly. A company should specify under what conditions their torque ratings apply. A constant load situation is going to take a completely different set of design conditions than a short duty cycle situation where a small amount of slippage might not effect the clutch.


Disclaimer: I don't own a ZF truck, I've got an allison with much smaller clutches that seem to hold up just fine to 650 ft/lb's in 6th gear for long stretches.;)

I do work in the natural gas industry specifically on engines that make max power for years on end, so I kinda know a thing or two about designing for longevity.

Sorry to double post, but I wanted to keep these two thought trains separate.

Now to put on my failure analyst hat. If we had some pictures of the failed clutch we might be able to track down the root cause of this particular failure. They might have been posted but quite frankly I skimmed the last 10 pages as it was all bickering and no tech.

What we need to know:

How much friction material was left on the clutch?

Was the thickness equal on the pressure plate and flywheel sides?

Did either side look to be glazed?

Did the friction material appear to be chunking, cracking, or otherwise failing?

How did the flywheel and pressure plate look? Blueing, cracking, hot spots?

This clutch started out with enough holding capacity to handle the amount of torque the OP was making, then something changed. The clutch assembly lost friction for one reason or another and that is going to be the root cause of the failure. My guess is that the clutch disk either ran out of friction material, the material broke down because of heat, or something mechanical happened to either effect clamping force or the friction surface of the flywheel or pressure plate warped reducing contact. The questions posted above will lead us in the right direction.


We can try to bring this thread back to facts and actual tech.....or you guys can continue bickering like a bunch of school girls......

Sorry to double post, but I wanted to keep these two thought trains separate.

Now to put on my failure analyst hat. If we had some pictures of the failed clutch we might be able to track down the root cause of this particular failure. They might have been posted but quite frankly I skimmed the last 10 pages as it was all bickering and no tech.

What we need to know:

How much friction material was left on the clutch?

Was the thickness equal on the pressure plate and flywheel sides?

Did either side look to be glazed?

Did the friction material appear to be chunking, cracking, or otherwise failing?

How did the flywheel and pressure plate look? Blueing, cracking, hot spots?

This clutch started out with enough holding capacity to handle the amount of torque the OP was making, then something changed. The clutch assembly lost friction for one reason or another and that is going to be the root cause of the failure. My guess is that the clutch disk either ran out of friction material, the material broke down because of heat, or something mechanical happened to either effect clamping force or the friction surface of the flywheel or pressure plate warped reducing contact. The questions posted above will lead us in the right direction.


We can try to bring this thread back to facts and actual tech.....or you guys can continue bickering like a bunch of school girls......


http://www.dieselplace.com/forum/showpost.php?p=3519815&postcount=115

There's the pics :)

Thank you very much, I agree with ZFMax that clutch does not appear to be hurt in any way. Without any obvious clutch problems the only other item could be that the throwout bearing is some how staying slightly engaged which should show up on the new clutch. I assume the new clutch is doing just fine which points back to the original design of the clutch.

So this clutch is designed for 800 ft/lb's........intermittently or there is something wrong with this particular clutch. Soft spring, bad mix in the friction material, ect..... Either way I think SBC is responsible for taking care of this. It's either their bad design or their bad materials and workmanship. Just my un-biased opinion as an informed outsider looking in.

SBC would have had the origonal poster treated Peter with courtesy on the phone when he first called him. Peter and I have discussed this numberous times on the phone and it boils down to this. Treat Peter rudely and he'll give you the cold shoulder sure as hell, ;) treat him fair and he'll be your friend and take care of you ;). Simple facts.
I'm still curious why the O/P thinks this new clutch is better :confused:.

Either way I think SBC is responsible for taking care of this. It's either their bad design or their bad materials and workmanship. Just my un-biased opinion as an informed outsider looking in.

SBC would have had the origonal poster treated Peter with courtesy on the phone when he first called him. Peter and I have discussed this numberous times on the phone and it boils down to this. Treat Peter rudely and he'll give you the cold shoulder sure as hell, ;) treat him fair and he'll be your friend and take care of you ;). Simple facts.
I'm still curious why the O/P thinks this new clutch is better :confused:.

Back the whinny bitch train up......I don't have nor do I want ANY thing to do with high school BS that has gone on since the original issue has come up. Neither party handled the situation well at all and that has NOTING to do with why or how this clutch failed.

The OP should have very well sent the clutch back once he pulled it, at least he could have resold it to recoup some of his cash.

At the same time SBC's claim that he abused the clutch by using heavy throttle in 6th gear is COMPLETE BS which is more to the point that I wanted to discuss.

Back the whinny bitch train up......I don't have nor do I want ANY thing to do with high school BS that has gone on since the original issue has come up. Neither party handled the situation well at all and that has NOTING to do with why or how this clutch failed.

The OP should have very well sent the clutch back once he pulled it, at least he could have resold it to recoup some of his cash.

At the same time SBC's claim that he abused the clutch by using heavy throttle in 6th gear is COMPLETE BS which is more to the point that I wanted to discuss.

LMAO... more koolaid anyone?

Since the clutch supposedly went back a long time ago, where is the result?:confused:

:rolleyes: See signature.........


I'm going to assume the "results" will never see the light of day.

Cruising the boards on a lazy Sunday morning I came across this jewel of a thread. As an Engineer I HAVE to step in here and defend the profession. Please what ever you do don't lump us in with physicist, those guys do NOT work in the real world and use pure theory with no testing and validation.

As an engineer, I and quite a few of my collueges would approach the issue of clutch torque ratings very simply. You take the torque rating of the engine and design a clutch to handle that torque. HP is a function of torque and RPM, it is used to assign a numerical value on "work" lift 10 lb's 10 times vs. lift 100 lb's once, both would have the same HP, but much different torque values. A clutch doesn't care how much HP is produced, it only cares about torque as RPM has no bearing on clamping capacity.

Now the big point I want to make is......how in the world does the clutch know what gear the tranny is in? It "see's" torque from the engine and transfers it to the input shaft of the trans that's it. I can make 650 ft/lb's of torque in every gear and the clutch won't know the difference. The only condition that changes is how long the clutch see's 650 ft/lb's of torque which I believe is the source of the issue at hand. In lower gears the vehicle is going to be able to accelerate as torque multiplication (after the clutch) is giving the engine/trans combo the torque needed to accelerate the mass. This means the clutch is going to see 650 ft/lb's for less time than if it's parked in 6th gear at full load.

Why should this matter? Well it appears to me that the clutch is constantly slipping at full torque and needs less duty cycle to keep from over heating. In my mind.....that clutch is not rated for the torque it's being asked to transfer or something has happened to the clutch to alter the amount of torque it can handle.

Aftermarket companies have a tendency to rate their products by slapping them behind a vehicle and trying them out a couple of times in some kind of competition such as drag racing or sled pulling in this case. Sure this clutch might survive a short blast down a sled track or a 1/4 mile, but it's not going to last against full torque for long periods of time. Pulling a grade at full throttle be it 4th,5th or 6th gear is the same as doing a 1/4 mile run constantly. A company should specify under what conditions their torque ratings apply. A constant load situation is going to take a completely different set of design conditions than a short duty cycle situation where a small amount of slippage might not effect the clutch.


Disclaimer: I don't own a ZF truck, I've got an allison with much smaller clutches that seem to hold up just fine to 650 ft/lb's in 6th gear for long stretches.;)

I do work in the natural gas industry specifically on engines that make max power for years on end, so I kinda know a thing or two about designing for longevity.


The statement in bold is to funny. This is in 6th cruising down the highway, step on the gas to pass someone and your truck AUTOMATICALLY down shifts. Now for the mountain grade...again your truck AUTOMATICALLY down shifts. You seem like a smart guy, lets figure out a way to keep your truck from down shifting and have you climb a mountain with a load in overdrive and I bet you will be buying yourself a new Allison on the other side. I don't mean to be rude here but OMG people think about what you are saying before you post. By the way, the OP never sent his clutch in as he stated.

Peter

LMM guy i am a little confused and not trying to be a smart A** by any means. I am curious tho why does load not have to do with the ratings you described? If we are just turning a gear box in any gear your scenario seems correct but we are talking about a clutch in a vehicle here. So wouldnt more load by a higher gear come into play? Again i am just curious.

I don't think so... the engine is still going to transmit the same torque no matter what load you have on it. Say if I'm on a loaded dyno, I will only put so much torque out, if I have a 15,000 pound trailer the engine is still only going to produce "x" amount of torque. Unless my thinking is just ass backwards... :)

LMM guy i am a little confused and not trying to be a smart A** by any means. I am curious tho why does load not have to do with the ratings you described? If we are just turning a gear box in any gear your scenario seems correct but we are talking about a clutch in a vehicle here. So wouldnt more load by a higher gear come into play? Again i am just curious.


Especially uphill. We are not talking about a stationary motor in a pump, or a milling application, we have an additional load on the clutch opposite the motor that varies depending on axle gear ratio (which determines the mechanical advatage of the load against the motor) and in the case of THIS scenario incline which introduces additional load depending on the grade and rate of acceleration attempted. I asked a question earlier (which ZF decided to ignore) about how clutches are rated. It would be interesting to hear from a qualified party as to how automotive clutch hold ratings are determined, are there dynamics involved or is it just a flat rating that the clutch will hold a xxx ft/lb load (think stationary clutch with a lever on it)?

Especially uphill. We are not talking about a stationary motor in a pump, or a milling application, we have an additional load on the clutch opposite the motor that varies depending on axle gear ratio (which determines the mechanical advatage of the load against the motor) and in the case of THIS scenario incline which introduces additional load depending on the grade and rate of acceleration attempted. I asked a question earlier (which ZF decided to ignore) about how clutches are rated. It would be interesting to hear from a qualified party as to how automotive clutch hold ratings are determined, are there dynamics involved or is it just a flat rating that the clutch will hold a xxx ft/lb load (think stationary clutch with a lever on it)?


Most likely rated with a constant power output and constant load... And most likely rated for brake torque, not torque at the wheels.

LMM guy i am a little confused and not trying to be a smart A** by any means. I am curious tho why does load not have to do with the ratings you described? If we are just turning a gear box in any gear your scenario seems correct but we are talking about a clutch in a vehicle here. So wouldnt more load by a higher gear come into play? Again i am just curious.


A clutch is nothing more than a coupling between two mechanical shafts. Rating this coupling with a Ft/lb rating is stating that this coupling can withstand so much torque before the coupling slips. The rating itself has no motion or speed function, ft/lb's is a force so at what engine speed that force is made has no bearing what so ever on the coupling. Now of course we know the engine makes torque, not the other way around. If the axle some how imparted more torque on the clutch than the engine produced......the motor would turn backwards and we all know that just isn't possible without stalling the engine.

Lets do an example: I know that my truck can maintain 60 mph with 22,000 lb's of weight in 4th gear at ~2,500 rpm the truck is "powered out" or can not accelerate any further. The engine is making 600 ft/lb's of torque. Now lets say that the same setup is now hauling 40,000 lb's and the speed is 30 mph and the truck can not accelerate any further. The engine is still making 600 ft/lb's of torque, but now at a lower speed as the "load" is greater on the output shaft of the trans. We had to down shift to a lower gear, which multiplies that 600 ft/lb's of torque enough to over come the load applied to the drivetrain. There is no more torque being produced by the engine or transfered by the clutch, there IS more torque being transfered by the output shaft of the trans, the driveshaft, rear end, and wheels because that torque is being multiplied by the lower gearing.

Now lets apply this scenario to the infamous 6th gear that mysteriously burns up clutches. In 6th gear we may only be able to maintain 60 mph with 10,000 lb's of weight. Same torque being made by the engine, same torque seen by the clutch, less torque coming out of the end of the trans so the truck can do less work.

There is not some how more torque being extracted out the engine, just the maximum torque that the engine can produce is being transfered through the clutch to the transmission. If the clutch slips, it's because the clutch can not withstand the torque being produced by the engine.


The statement in bold is to funny. This is in 6th cruising down the highway, step on the gas to pass someone and your truck AUTOMATICALLY down shifts. Now for the mountain grade...again your truck AUTOMATICALLY down shifts. You seem like a smart guy, lets figure out a way to keep your truck from down shifting and have you climb a mountain with a load in overdrive and I bet you will be buying yourself a new Allison on the other side. I don't mean to be rude here but OMG people think about what you are saying before you post. By the way, the OP never sent his clutch in as he stated.

PeterThe statement in bold is to funny. This is in 6th cruising down the highway, step on the gas to pass someone and your truck AUTOMATICALLY down shifts. Now for the mountain grade...again your truck AUTOMATICALLY down shifts. You seem like a smart guy, lets figure out a way to keep your truck from down shifting and have you climb a mountain with a load in overdrive and I bet you will be buying yourself a new Allison on the other side. I don't mean to be rude here but OMG people think about what you are saying before you post. By the way, the OP never sent his clutch in as he stated.

Peter

Peter,

Do you really want me to explain to you how an automatic tranny works? The trans downshifts because the ECM recognized that I want to accelerate and in order to make the truck go faster I need more torque exiting the transmission......which is what gear reduction accomplishes. Same explanation above applies to an automatic......only the ECM knows that in order to accelerate you need to downshift hence the reference to it as being automatic.

Seriously your BS is pretty weak......can YOU explain how 6th gear some how makes the engine produce more torque than it does in other gears?

So LMM Guy I was correct in my statement that with the ZF6 no matter loaded or unloaded, it is just a question of how long the clutch can hold that torque before it slips? Unloaded it will hold the power longer, loaded it's not going to? I dont think i'm explaining myself well enough for anyone besides me to understand lol. I just know I'll be upgrading the clutch soon, and Peter I'm going to call you, single disc doesn't like 940+ RWTQ :) I think the southbend single disc did very well for as long as I've had it in, I knew when I got the truck EFI live tuned that it would be on borrowed time because I am exceeding its power rating by quite a bit. However it has held for a suprising long time.

I understand how an automatic transmission works. For example, an AT (automatic transmission) will automatically downshift for two reasons, to accelerate or maintain speed, the ecm calculates load based upon throttle position and vehicle speed. Using these values the ecm tells the trans (using various sensors and solenoids) to downshift, up-shift, or maintain each gear. When a vehicle is equipped with a manual transmission the vehicle operator takes the place of the ecm. An AT shifts from gear to gear not only to keep you moving but to keep itself alive. Or save itself from load, the part you are leaving out of your argument. There has to be a weak point somewhere in the transfer of power, in an AT it begins with the torque converter, in a manual it begins with the clutch. Neither will stand up to constant lugging whether it's behind 12 ft lbs or 1200 ft lbs. As the vehicle operator, or ecm, you must operate your vehicle within certain parameters based upon load, just simply to keep it from dying. If an AT does not down shift when needed the line pressure will drop and temperatures will rise thus burning up the trans.

This is for the LMM Guy engineer: Your theory on a clutch sees the same load no matter what gear ratio in the trans only works if you have the vehicle loaded to the maximum amount in each gear so that the vehicle is stuck at peak torque and can't go any faster in that particular gear.... This is not a real world driving situation with these trucks though. The higher the transmission gear the higher the load on the clutch and the faster it gets to max load. Say you hook up to a 20,000lb trailer and accelerate through the gears, 1st gear you can run up to 3500rpm, 2nd gear you can get 3500 rpm, 3rd gear you get 3000rpm, 4th 2800rpm, 5th gear you get 2500 rpm and in 6th gear you can only go 2200 rpm. This shows there is more load on the engine and clutch in the higher gear ratios, if there wasn't then it would still be able to pull the same rpm no matter what gear its in. You can say that 600ftlbs is equal in every gear and it is BUT its able to accelerate in the lower gears and its being stopped in the higher gears which is generating more force.
Another variable is boost, a turbo diesel in the low gears will likely never see max boost on the road, and never see max torque the engine is capable of unless you are able to load it to the max it can pull in a lower gear but thats not real world. If I take my ZF truck and floor it in 2nd or 3rd gear it will not see max boost, even though it can take up to 3 or 4 seconds to get through those gears. If I floor it in 6th gear it will hit max boost much quicker which is telling me the engine and clutch see more feed back load and that makes a clutch slip.
So even though an engine that makes 600ftlbs in every gear it will be much more likely to slip the clutch in the higher gears because of the resistant load its going against. Like I said unless the vehicle was loaded to the max amount to only be able to hold peak torque rpm in ever gear. It would require much heavier loads to do that in the lower ratios though and would not be an even test then
That is why will be way more likely to slip in the higher gears of the transmission.

There has to be a weak point somewhere in the transfer of power, in an AT it begins with the torque converter, in a manual it begins with the clutch. Neither will stand up to constant lugging whether it's behind 12 ft lbs or 1200 ft lbs. Really, are you saying that a clutch can not stand 12 ft/lb's of torque if the engine is "lugged" as you call it? You expect people to swallow this crap? As the vehicle operator, or ecm, you must operate your vehicle within certain parameters based upon load, just simply to keep it from dying. If an AT does not down shift when needed the line pressure will drop and temperatures will rise thus burning up the trans. Really,line pressure will drop? Why will it drop? What makes the line pressure magically go down when the pump is still pumping away just like it is all the time. If you have the slightest idea how an auto-tranny works this would make ZERO sense to you.

Battle Max,

Say you hook up to a 20,000lb trailer and accelerate through the gears, 1st gear you can run up to 3500rpm, 2nd gear you can get 3500 rpm, 3rd gear you get 3000rpm, 4th 2800rpm, 5th gear you get 2500 rpm and in 6th gear you can only go 2200 rpm. This shows there is more load on the engine and clutch in the higher gear ratios, if there wasn't then it would still be able to pull the same rpm no matter what gear its in. You can say that 600ftlbs is equal in every gear and it is BUT its able to accelerate in the lower gears and its being stopped in the higher gears which is generating more force.

This is the exact point I was making, the load very well does increase as the truck goes faster, aero loads and friction increase as you go faster. The point you missed is that the act of changing gears adjust the torque ouput from the tranny, the engine is NOT making any more torque in any of those gears, just the engine torque is gettig multiplied by the gear ratio's in the tranny.......which are AFTER the clutch. In the lower gears you have enough power to accelerate the truck.

Another variable is boost, a turbo diesel in the low gears will likely never see max boost on the road, and never see max torque the engine is capable of unless you are able to load it to the max it can pull in a lower gear but thats not real world. If I take my ZF truck and floor it in 2nd or 3rd gear it will not see max boost, even though it can take up to 3 or 4 seconds to get through those gears. If I floor it in 6th gear it will hit max boost much quicker which is telling me the engine and clutch see more feed back load and that makes a clutch slip.

Now we're getting to the meat of your point and this is a VERY real world scenario. You are 100% correct, if the truck is not fully loaded it will not make full boost......which means it is NOT making full torque. Now lets relate this back to SBC's torque rating claim....they are claiming a particular torque rating but saying that doesn't apply in higher gears. The ones you yourself said are the only ones you can make full power in. So saying that a clutch is good for an engine that is capable of making 850 ft/lb's of torque, but only in the lower gears where the engine can NOT make that power is being MISLEADING. The clutch is NOT good for 850 ft/lb's. It's good for quite a bit less than that but by fudging the numbers they can slap a higher rating on it and sell it to guys who don't understand what they are buying.


The whole point I was making is that the engine is only capable of producing so much power, in order to make ALL of that power the truck has to be fully loaded. Of course when we take 600 ft/lb's of torque and multiply it by a ~3 to 1 first gear ratio and then a 3.73 rear gear ratio the truck will have enough power to accelerate and will not make full torque as the truck moves ahead. In the upper gear you have less torque multiplication which means the engine is able to make closer to it's max torque up until you power out the truck and it's making it's max torque but not accelerating. This is the same load on the engine and clutch whether it's second gear with 40,000 lb's or 6th gear on an empty truck pulling a 6% grade.


The clutch can NOT receive more torque than the engine is capable of putting out without turning backwards. It can't be done no matter how you argue it.

Battle Max,



This is the exact point I was making, the load very well does increase as the truck goes faster, aero loads and friction increase as you go faster. The point you missed is that the act of changing gears adjust the torque ouput from the tranny, the engine is NOT making any more torque in any of those gears, just the engine torque is gettig multiplied by the gear ratio's in the tranny.......which are AFTER the clutch. In the lower gears you have enough power to accelerate the truck.



Now we're getting to the meat of your point and this is a VERY real world scenario. You are 100% correct, if the truck is not fully loaded it will not make full boost......which means it is NOT making full torque. Now lets relate this back to SBC's torque rating claim....they are claiming a particular torque rating but saying that doesn't apply in higher gears. The ones you yourself said are the only ones you can make full power in. So saying that a clutch is good for an engine that is capable of making 850 ft/lb's of torque, but only in the lower gears where the engine can NOT make that power is being MISLEADING. The clutch is NOT good for 850 ft/lb's. It's good for quite a bit less than that but by fudging the numbers they can slap a higher rating on it and sell it to guys who don't understand what they are buying.


The whole point I was making is that the engine is only capable of producing so much power, in order to make ALL of that power the truck has to be fully loaded. Of course when we take 600 ft/lb's of torque and multiply it by a ~3 to 1 first gear ratio and then a 3.73 rear gear ratio the truck will have enough power to accelerate and will not make full torque as the truck moves ahead. In the upper gear you have less torque multiplication which means the engine is able to make closer to it's max torque up until you power out the truck and it's making it's max torque but not accelerating. This is the same load on the engine and clutch whether it's second gear with 40,000 lb's or 6th gear on an empty truck pulling a 6% grade.


The clutch can NOT receive more torque than the engine is capable of putting out without turning backwards. It can't be done no matter how you argue it.


I agree.

I know when a clutch is getting weak in almost any vehicle it will hold in the lower gears but not in the higher gears. Even though the most toque the clutch will ever see is the max the engine can deliver it has to do with the resistance in the higher gears that makes it slip. Kind of like a dyno if I understand correctly? You can take a load dyno and depending on the load you give the engine and the acceleration rate you let it gain rpm, you will get different torque/hp numbers out of the engine.

I agree.

I know when a clutch is getting weak in almost any vehicle it will hold in the lower gears but not in the higher gears. Even though the most toque the clutch will ever see is the max the engine can deliver it has to do with the resistance in the higher gears that makes it slip. Kind of like a dyno if I understand correctly? You can take a load dyno and depending on the load you give the engine and the acceleration rate you let it gain rpm, you will get different torque/hp numbers out of the engine.

Exactly, this is why inertia dyno's don't play so well with diesels. The "load" an inertia dyno puts on the vehicle is a constant as you're just spinning up a big drum. For diesel trucks it's not enough to get to full boost. With an eddy current dyno you can pick a load and hold the vehicle there. This is why you'll see different dyno numbers when looking at a superflow vs. a mustang dyno. This is also why you usually use a 1:1 gear ratio as it loads the engine enough to make full power.

SBC would have had the origonal poster treated Peter with courtesy on the phone when he first called him.

Wow, that's amazing. On one hand, I've been raked over the coals multiple times for supposedly not calling, and on the other hand I'm being accused of calling and being rude. Which is it? It can't be both!

The truth is I called once and only once, before the clutch was removed, and did not get to talk to Peter. The person I talked to was cordial and I was cordial. He offered to replace the disc if and only if it was worn out and assured me the pressure plate and flywheel would be fine. I thanked him for his offer, but after thinking about it for a few days I decided that no, after spending over $2000 on two different SBC clutches and getting a grand total of about 60K miles of service life for my money, it was time to ride a different horse.

Anyone saying I called SBC, talked to Peter (which I didn't), and was rude to him, is lying, and that's a simple fact. Considering the way Peter has blamed me in this thread, and refused to take any responsibility at all for his product that doesn't work as advertised, I can't say I'm surprised. What I am surprised about, though, is that a moderator on the board would repeat such a nonsense story and represent it as fact when he wasn't there himself.

Personally, I think LMM Guy was right on the money when he said aftermarket companies try the product at some torque level and if it seems to work they slap a number on it. I truly believe that's the way this product was done.

I apologize to the board for not yet shipping the clutch. I unexpectedly lost my job and money has been tight and it ain't cheap to ship this thing. But I got a new job and I'll have it shipped within a week. We'll see if Peter stands behind it or if he continues to make up stories like this nonsense that I called, talked to him, and was rude.

(before anybody calls me out for saying I lost my job, while previously saying I owned my own business, well, both were true, I was doing both at the same time)

Post #42 is when I reported on the one and only phone call I made to SBC on this issue. Here's the post:

I talked with someone at SBC about this. I got the same story, I'm not supposed to give it lots of throttle in 6th. Sigh.

I was polite but persistent, and eventually I got an offer to replace the disc with a "dual-friction", if I pull it out and take a picture of it and send it to them and it really is bad. He said he doubted the pressure plate was damaged but to take a picture of it too and they'd decide. I'd have to get the flywheel ground.

I've been pondering the offer and I don't think I'm going to mess with it. I don't really have the time right now to do this myself, too much on my plate, so I'd have to hire it out, which costs as much as a new Valeo unit. If I wait a couple months I'll have the time to just do the Valeo unit and I won't have downtime and I won't have to mess with grinding the flywheel or worry about re-using a used pressure plate. Plus the Valeo unit comes with a new throw-out bearing. The clutch is only just starting to go, I think it'll last a few more months until the Valeo unit is shipping and can do it all at once with all new parts.

Besides that, after 2 SBC's that each lasted only 30K miles, I'm not that crazy about putting in another. I'm want to ride a different horse.

When Peter refused, in this thread, to spell out the unwritten rules you must follow to have the clutch hold it's rated torque and power, I figured I was probably dealing with a dishonest businessman. Now to find out he's claiming I called, talked to him, and was rude, well, he confirmed it. He has chosen to make up a false story as rationalization, rather than do the right thing and stand behind his product. That's dishonesty where I come from.

I bought this http://www.clutchmasters.com/index.p...=GetPage&id=33

Info on site is not up to date I spent lots of time on the phone figuring out that this might be the best single disk, heavy duty pressure plate setup around. (according to manufactures propaganda at least) lol. Stage 3.5 is 8 button ceramic on one side and kevlar on the other.
Dont find any complaints about it, waiting for it to arrive.

Thanks ZFMAX for the pointer

http://www.clutchmasters.com/index.php?module=site&action=GetPage&id=33

It occures to me that this controvercy is very valuable, to me at least. Much like politics, Liberal <> Conservative or in your case Democrat <> Republican the discourse is the thing, we need them both, lies and all. Without it I might be looking at installing a substandard over rated over priced product or electing a criminal ;)

Thanks all :D

Tech is one thing. This is a gripe session. Thread closed.