For those of you interested in replacing the POS DMF with a single disc kit here is some more info.

I spoke with Peter today and things are moving forward. The flywheel is getting close to done and some clutch parts are being shipped in from overseas. Obviously, shipping tends to lengthen the process but he should have those parts in about 3 weeks. Once every thing shows up and are successfully inspected and approved (by Peter) the assembly will beging. Rough guess for the first kit (prototype or production?) will be in a month or 6 weeks.

I will keep in touch with SBC and make additional posts.

Great to hear.thanks for the info.

Good to hear, I'll be following with great interest.

Thanks Deadeye. This will be the first year I will be towing heavy (12K lbs) on my new trailer. I can now slip the factory POS clutch while pulling the trailer empty and going downhill! Looking forward to seeing the product.

If you do some heavy towing with a single disc kit make sure you got you power chip turned down. Have not tested this, obviously, but don't want to create a problem.

I'm towing 15000 and waiting for the single disc so I can use my tuner when I tow. I was under the impression that a single dics was good up to 400+ HP.

SoCal;

It will hold more than that. Maybe not problem at all. You can use your tuner but turning it up all the way with a heavy load may have an impact. Don't know until some one has tested it.

Maybe with your elevation no problem at all. . . .

FYI you guys may want to check post #7:

http://www.dieselplace.com/forum/showthread.php?t=67312

I got a chance to talk to Peter at SBC yesterday and got some updates on the development of the single disc kit.

As I mentioned earlier posts, the SMF will be sand cast and then key points on the flywheel will be machined by CNC to ensure correct fitting. Currently the casting company is developing a hardwood (maple?) example of the DMF for impression in the casting sand. Not certain which exact wood is being used but once more castings are planned the cast impression flywheel can be made of plastic or billet aluminum. That way they last longer as they get compressed into the sand.

The sand cast SMF will look a lot like the DMF and will likely weight about the same. However, SMF that South Bend is having made now is going to have some changes since it will be “single mass” (solid) and the outside dimensions need to be identical to the DMF to fit the other parts. Some material around the crankshaft bolt holes will be removed. This will make up for the difference between the “hollow” interior of the DMF vs the solid interior of the SMF. The bolts well be easy to get to and, of course, no re-indexing of the back side of the flywheel since it is one piece.

Once cast SMF is received it will have to go thru critical CNC machine. The first time this is done it will have to be ensured as correct. This may take some time. Each cast SMF will go through a balancing process. Small amounts of material will be drilled out to balance the flywheel. This will have to be done on each cast SMF because sand cast metal is not as consistent as billet metal. This process will likely take another month, or more if any challenges are encountered.

The single disc kit will be using an oem pressure plate. This should help reduce costs. The stock clutch plate will fit but should not be used as it has not sprung hubs and it will cause rattle and wear, and can trash clutch plate. There will be a couple different options for clutch plate materials for this kit and I will provide more info later for these.

As to power, the Ford 6.0 uses the same type of SMF and clutch kit and a PP that is also oem. The size of the bell housing is what limits the Duramax to 12”. The Ford clutch is 13” diameter and holds over 500 rwhp.

Peter is very confident about how well this will work and, though we do not know yet, the cost should be significantly less than the DDC or even the other aftermarket SDC.

I will keep you all posted as more data is available,

Good Luck,

BTW, I just learned that a DDC Street kit will be coming up soon. :ro) :ro) :ro) Look for another post.

Won't the OEM pressure plate limit holding capacity severely? Will there be an option for an aftermarket PP to go with the single disk unit in the future?

Won't the OEM pressure plate limit holding capacity severely? Will there be an option for an aftermarket PP to go with the single disk unit in the future?

Obviously, yes, any PP has limitations. However, the oem PP is not the problem. It is the flywheel which allows slipping. As I noted earlier, the Ford 6.0 uses a very similar PP made by the same company (Valen) and does over 500rwhp with the SMF/SDC which SBC makes for Fords and which is similar to the one for Duramax. My guess is that the Duramax SDC will hold similar amount or rwhp.

In order to get a different, stiffer PP for the SDC would require more development, more cost for customers, and a different clutch and probably flywheel. There is only so much space in the bell housing which limits dimensions of the parts. I you want more rwhp there are already other options. Check out the DDC Street that is comming soon.

dieseldummy your right the factory pressure plate is a big limiting factor in holding capacity. I don't know what deadeye is thinking but the factory dual mass flywheel doesn't slip it's the clutch, if the dual mass flywheel was to slip it would have to break the two pieces completely loose from each other. Also the ford 6.0 may use a valeo clutch (not Valen) but the factory Duramax clutch is made by LUK. Also all newer Fords use a 13 inch clutch so what they hold is completely irrelevant since the pickup version Duramax's will only accept a 12 inch clutch, the 4500 series trucks and up with Duramax do have a 13 inch clutch though.

Obviously, I am the only one on this forum that mis-spells :D

And CPMac is correct the Luk is stock and the Valeo (oooooh I spelled it right) is aftermarket. As a I posted above, all PPs have a limitation. Given enough power, every PP can be made to slip. However,

It is the DMF not the PP that causes slipping on stock power or even some extra module power. Once the DMF cannot stay indexed and starts to wobble it loses is hold and starts the slip. Think about it:

When dealers replace the flywheel and use the current clutch and PP (and I have done the same) the slip stops, for a while. If it was a PP that caused the slip, it would slip right away with a new DMF. Granted, the PP is not as strong as some aftermarket ones but it will hold better with an SMF.

The 4500 is 13" but what does that have to do with this issue? If the Ford SMF/SDC is essentially the same (and includes an OEM PP), except for being a little larger, and holds 500 rwhp, and is the 90% aftermarket kits bought for Ford 6.0s, then it is a reasonable example that the South Bend Clutch SDC for the Duramax will hold a fair amount of additional horse power.

If the Duramax 12" clutch was a significant limitation in holding power then the dual disc kits would be a lot less strong as well.

Anyhow, I have seen DMFs (before they broke down) hold 400 on a load dyno. So I expect the SBC SDC will hold more than that. But this kit is designed to be a reliable stock replacement not a sled pullin or drag racin modification. If you want to do that buy a stronger kit, pay more, and quit worrying about having to do a replacement later.

Ether way, when you get a kit from SBC you are getting it with a warranty, and from a company that has been making flywheel/clutch kits for diesel trucks much longer than their competitors. They will answer your phone calls and questions, send new replacement or repair parts when needed, and will be around a long time. They provide instructions for their products, and I provide detailed installation instructions for my customers for the kits they buy.

SBC product quality? Here is an example provided by SBC: A modified Dodge sled puller used a SBC SMF/DDC similar to the one for the Duramax (feramic now available from SBC) for four years and about 40 pulls. (Yes it was a slightly larger diameter.) When they started reworking the truck the following winter they sent the kit back to SBC to check it out. It was worn, but not worn out or damaged.

BTW, the truck owner did NOT have to pull the tranny out after every 10th pull to remove any shims (to keep from slipping as the clutch plates wear). The SBC kit has no shims, the floater plate moves itself as necessary. At least to me, it seems to be a less difficult product for installation and maintenance.

Deadeye you are wrong. When the dealer replaces the flywheel and uses the old clutch it will still slip just like before. The flywheel does NOT affect that.

And for the rest of your comments since this is a SBC clutch thread I won't address but you trying to mislead the general public by your false statements is really wrong and you should quit it.

Deadeye you are wrong. When the dealer replaces the flywheel and uses the old clutch it will still slip just like before. The flywheel does NOT affect that.

And for the rest of your comments since this is a SBC clutch thread I won't address but you trying to mislead the general public by your false statements is really wrong and you should quit it.

No sir, you are wrong. Let me see if I can explain it. You have a two piece flywheel that is held together by tin plates that are containing springs. The primary part of the flywheel is bolted to the crank and the secondary part of the flywheel is where the pressure plate is bolted to with the clutch disc being squeezed. Now, when new you have minimal rotation of the secondary part of the flywheel. The primary never moves because it is bolted to the crank. When the springs in the flywheel start to loosen and the tin plates start to deteriorate the secondary portion over rotates to a bottoming out state. This causes a jult to the clutch enabling it to break loose. When the flywheel is new under moderate horse power, it more or less bounces on the springs relieving the shock to the system. Under hard acceleration the flywheel actually starts to separate (primary from the secondary) causing more issues as well as clutch pedal/hydraulic problems.

Eliminating the DMF and replacing it with the solid flywheel will offer a much more positive engagement as well as better holding power do to the lake of movement caused by the DMF.

To get to the real point, yes higher clamp loads on pressure plates will offer more holding power but also creates other problems such as engagement/hydraulic issues. trying to get to much out of something instead of moving them up to a clutch that is more suited for the situation.

What starts to happen is the single disc begins to deteriorate quicker. The pressure plate wares faster. The overall life of the clutch is lessened dramatically. This is why we would then move them into a dual disc. This will offer the longevity that they need. Pressure plates do not have to have these extreme plate loads if you know the mathematics of a clutch. If you lessen the amount of friction area with high quality material you gain ponds per square inch. Think of it this way. Put a 5 lb weight on a pencil with the flat side down. How much weight is applied to the square inch area. Now, flip the pencil over and repeat the process. How much force is applied at the point of the pencil? pounds per square inch.


Peter

Deadeye you are wrong. When the dealer replaces the flywheel and uses the old clutch it will still slip just like before. The flywheel does NOT affect that.


dealer replaced my dmf and not anything else and it held great for awhile






Peter


nice post, glad to see you here finally

Peter,

Thanks for your response. And for all the facts and details.

Nice post Peter. Good info for sure.

Obviously, yes, any PP has limitations. However, the oem PP is not the problem. It is the flywheel which allows slipping. As I noted earlier, the Ford 6.0 uses a very similar PP made by the same company (Valen) and does over 500rwhp with the SMF/SDC which SBC makes for Fords and which is similar to the one for Duramax. My guess is that the Duramax SDC will hold similar amount or rwhp.

In order to get a different, stiffer PP for the SDC would require more development, more cost for customers, and a different clutch and probably flywheel. There is only so much space in the bell housing which limits dimensions of the parts. I you want more rwhp there are already other options. Check out the DDC Street that is comming soon.

I just wondered because I seemed to recall a couple guys here using a south bend aftermarket PP and disk on their DMF. If that were the case then I really couldn't see the reason for using the stock PP. I'm interested in this because I don't want a dual disk clutch. I think it's plain ridiculous for what I do. My stock DMF with 35K on it is holding fine with what I do so maybe you can see where I'm coming from here.

Peter you are wrong. Deadeye said that when replacing a factory DMF with a new one that the clutch would hold again and it will not. I will see if I can explain it to you. When your factory clutch is new it will hold 800 or so rwtq, after a while (or even quickly with abuse or big hp) the clutch will slip causing some of the organic material to be worn away. Once that happens the heat from this wear causes the fiberglass material to come closer to the surface and the static coefficient to drastically change. Once that happens the clutch will only hold 550 or so rwtq. Of course better materials like you use in your clutches can change the situation completely or beefing the static load of the pressure plate could change the situation also.
To prove your wrong I can show you that it has nothing to do with the DMF since in my own truck I removed a slipping clutch disc and replaced it with one of your Ferramic discs and then the clutch wouldn't slip with over 1000 rwtq (yes I have the dyno sheets also). The DMF is not the problem, I agree though that you have the discs that can work in a single application and use the factory pressure plate and hold a considerable amount of power. But I know that isn't the only answer, the static coefficient of your ferramic disc is good but combined with the slip coefficient it makes for a bad driving setup (shudders terribly while engaging). I think somewhat of a happy medium or increased static load of the pressure plate and a better quality disc would work fine.

Peter I'm really glad you made a direct reference to the price of the Mac's clutches I designed. You stated the single disc clutch with solid flywheel replacent is ridiculously priced in your opinion? Have you looked at your prices lately? Your single disc clutches for Dodges that are rated similar to what the Mac's single is rated for are priced from $900 and up. That doesn't even come with a flywheel. The Mac's single disc clutch is rated for 450 hp and has been tested over 550 hp is $1644. It comes with a billet flywheel that is sfi approved and is the same flywheel that the Mac's dual discs use if you ever want to upgrade. I realize that is a lot of money but you add the price of a billet flywheel to your Dodge or Ford kits and tell me where we would be then? I know they don't need a flywheel since they both come factory with a flat solid flywheel but unfortunately I couldn't come up with anything other than a billet flywheel to use in the Mac's kits. I wanted to get the cost down when I was designing the clutches and I contacted you personally and several other companies but none of you wanted any part of the Duramax since there weren't enough truck with six speeds at the time. I tried to get cast flywheels made but they needed a minimum order that would have wrapped up $100k and I was small and couldn't justify that since it was rumored GM was coming out with a fix. When I first heard you had one of my clutches at your shop and were working on building a Duramax clutch my first thought was good finally a company with enough backing and resources to get an equal and cheaper product out but I have to tell you I'm still dissapointed.

Deadeye you are wrong. When the dealer replaces the flywheel and uses the old clutch it will still slip just like before. The flywheel does NOT affect that.

And for the rest of your comments since this is a SBC clutch thread I won't address but you trying to mislead the general public by your false statements is really wrong and you should quit it.

I once had a 92 Ford that quit pulling.....I thought the clutch went out. The shop told me the problems was the DMF. They replaced the DMF, and put the old clutch back in......it worked fine. I can not see why it would not be the same with the GM DMF:confused:

BigOL3 the GM flywheel can fail and quit pulling also. I had one break and the pieces (springs, plates) wedged between it and still pulled me home. When a flywheel breaks the pieces can't easily get out from between the two halves so it's really hard for the Duramax flywheel to quit pulling completely. Deadeye first said that the flywheel slipped which is a common misconseption since some other DMF's have a friction ring internal to limit tq but the Duramax DMF does not. Basically what I'm saying is if the flywheel slips then it has broke completely but most people don't get to that point.
Before anyone had any upgrade for the clutch I would occasionally replace just the clutch disc after mine would start slipping and it would last quite a while again with the old pressure plate and DMF. Like I stated before the pressure plate is a big limiting factor (not the only one) and the factory DMF won't slip unless it completely breaks in half.

Gearhead what were the circumstances of your clutch holding again? What power level did it hold?

Gearhead what were the circumstances of your clutch holding again? What power level did it hold?

my flywheel was making a lot of noise and I had to remove the Edge all together, after they installed the new flywheel (I also tried to get them to replace the clutch and pp but they only would do the flywheel under the 3-36) I put my Edge back on and it held up to level 4 for a long time. normally only run it in level 3 though

Gearhead- o.k. so the flywhl was making noise, but wasn't slipping; correct?

yes it was slipping very bad. as stated I had to remove the Edge because of slipping

I understand gearhead. I have never seen one do that. After it started slipping again with the new flywheel would it hold the lower levels of the juice? or would it even hold with the Juice off?

The last time my DMF was replaced the disc was reused and it looked to be in reusable shape,But I knew it had been slipped alot and sure enough it slipped right away and has since.If I was to do a warranty DMF replacement again(which I won't)I would pay for a new disc.The next time my tranny is unbolted a flywheel that won't fail and a pair of discs that won't slip will be going in.My 2 cents.

I understand gearhead. I have never seen one do that. After it started slipping again with the new flywheel would it hold the lower levels of the juice? or would it even hold with the Juice off?


it will hold up to level 3 now, 4 is pritty iffy

BTW, the truck owner did NOT have to pull the tranny out after every 10th pull to remove any shims (to keep from slipping as the clutch plates wear). The SBC kit has no shims, the floater plate moves itself as necessary. At least to me, it seems to be a less difficult product for installation and maintenance.


:confused: ............thats funny.. :rolleyes: i have 25 - 30 hooks on mine......+38500 miles of hell... towing and things....

I will put the exact same clutch, disks and all back in this year, just remove a few shims... much cheaper than buying new disks....

I only removed the clutch to test a new single disk, disk i had made to try for the winter while i was not hooking...

I sell both Mac's clutches and SBC products and am happy with both.. as for which clutch to buy..that depends on application and the personal preferance.....

For me and my rough treatment the Mac's DD puller is what i like because i can adjust it and it dosent cost anything but my time to take it apart...

The SB clutch is simpler with no shims but you loose your adjustability....still agood product though..

as for a mac's dd slipping? there has been 2.:( . One, the pp bolts were not tightened by the installer:badidea: ...

and 2, :cool: there was a bundel of wire hoding the cluth peddle from reterning all the way to the top:idea:. This one was fixed personaly by the dealer that sold the clutch...(even though the customer did the original insall).He drove to the customers house, moved the wires, removed the clutch,reshimed the clutch, re-installed the clutch and all..... :Handshake
other than that.......Flawless:ro) .
Drive um like ya stole um boyz.....:ro) ....



SBC or mac's........Its up to you...But for Peat-sake....NO MORE DMF..

SBC or mac's........Its up to you...But for Peat-sake....NO MORE DMF..

:exactly:

Can someone tell me when the SBC single disc will be out and how much cause I don't want to drop 2 grand on a clutch? Holly hijack.

A while. Been waiting for what seems like forever. But good things come to those who wait. (I hope!)

Wow... that was a lot to catch up on! Pulled 22K daily and my last and worst DMF lasted only 17K and yes the DMF slipped like hell not the disc or issues with the PP. On examination the thing was glazed so badly due to excessive heat it would be impossible for the low grade steel GM uses having the capability to hold any power...heat degridation to tinsil strength is also a factor in DMF. Material choice here is critical...so be it if it causes a little noise...no big deal. This combined with what Peter stated about the DMF's damaged springs and bottoming out allowing momentary disengaugement causes the slipping to occur. Bottomline...THROW out the POS DMF and no matter which clutch you choose as your product of choice you no longer have to worry about whether it was the PP or DMF slipping....RIGHT!!

Wow this one turned into a little pissing match, I personally like the idea of SBC to use their SMF and use OEM PP and sprung clutch plate. That is what I have been waiting for. I don't have any power chips and don't need anything stronger than that. Also like the fact the it should be reasonably priced because of that.
I have had issues with my DMF and PP and slave cylinder. And I realize that the DMF has caused any and all of these problems because of the heat and vibration it puts on the PP and slave cylinder. (clutch plate looked brand new but replaced it twice anyways) And I think I will be a customer when you get it done.
The last time just had DMF and slave cylinder replaced, back in with original PP and clutch plate, it's been 21K since and have never slipped the clutch

Get that thing built already. Jim

now I just want to be clear, when you pull your clutches down for slipping the disc is fried correct? when we had dad's done here a few months ago there was no friction material left just metal to metal. I have the old flywheel , no spring broken as far as i see , I was thinking of machining some shims to place between both have of the flywheel. boring 6 to 8 holes around the radias of the flywheel with threads and bolting both halves together using shims to get everything true then machining the face and having it balanced for when it goes boom again. also installing the clutch disc with the springs in it to have some give. am i way off base here? just remember twenty years from now when these are old rigs and gm changes everything again and again no one will remember all this exept for a few so take it easy on one another.

:confused: ............thats funny.. :rolleyes: i have 25 - 30 hooks on mine......+38500 miles of hell... towing and things....

I will put the exact same clutch, disks and all back in this year, just remove a few shims... much cheaper than buying new disks....

I only removed the clutch to test a new single disk, disk i had made to try for the winter while i was not hooking...

I sell both Mac's clutches and SBC products and am happy with both.. as for which clutch to buy..that depends on application and the personal preferance.....

For me and my rough treatment the Mac's DD puller is what i like because i can adjust it and it dosent cost anything but my time to take it apart...

The SB clutch is simpler with no shims but you loose your adjustability....still agood product though..

as for a mac's dd slipping? there has been 2.:( . One, the pp bolts were not tightened by the installer:badidea: ...

and 2, :cool: there was a bundel of wire hoding the cluth peddle from reterning all the way to the top:idea:. This one was fixed personaly by the dealer that sold the clutch...(even though the customer did the original insall).He drove to the customers house, moved the wires, removed the clutch,reshimed the clutch, re-installed the clutch and all..... :Handshake
other than that.......Flawless:ro) .
Drive um like ya stole um boyz.....:ro) ....



SBC or mac's........Its up to you...But for Peat-sake....NO MORE DMF..

Interesting. I assume beside just hooking 30 times you actually pulled 30 times? According to CPMac I would have to change the shims about every 10th pull. Of course that was a long time ago . . . maybe things have changed?


BTW, how do you sell SBC kits if you don't buy them from SBC (according to SBC)?

just curious . . . .

now I just want to be clear, when you pull your clutches down for slipping the disc is fried correct? when we had dad's done here a few months ago there was no friction material left just metal to metal. I have the old flywheel , no spring broken as far as i see , I was thinking of machining some shims to place between both have of the flywheel. boring 6 to 8 holes around the radias of the flywheel with threads and bolting both halves together using shims to get everything true then machining the face and having it balanced for when it goes boom again. also installing the clutch disc with the springs in it to have some give. am i way off base here? just remember twenty years from now when these are old rigs and gm changes everything again and again no one will remember all this exept for a few so take it easy on one another.


I actually thought about that before but didn't do it. Let us know how it comes out.

BTW, how do you sell SBC kits if you don't buy them from SBC (according to SBC)?

just curious . . . .

He's a Master Distributor for one of SBC's largest distributors.

Interesting. I assume beside just hooking 30 times you actually pulled 30 times? According to CPMac I would have to change the shims about every 10th pull. Of course that was a long time ago . . . maybe things have changed?

lol.........Around here we refer to Pulling as "Hooking"..and i think if someone pulls much they know that..

He probibly said 10 hooks ...(Pulls) as a worst case thing... i have always told people 15 or more...(for the worst case).. If someone tells him they would be 600 -700hp and Hooking (pulling) all of the time he prolly went conservative... for a stock charger ,450- 500 hp once in while, truck you will get more hooks..(pulls) on an adjustment than a 600- 700 non-street truck. and as you learn how to Launch and drive it you become EZer on a clutch... If a person has never had a Pulling clutch before we keep that in mind as well...

i was just sharing my experiences.......and tryin to clear some things up...

[/COLOR]

He's a Master Distributor for one of SBC's largest distributors.

:thankyou2 ...thanks bud.. I must have been typing my last reply while this one was poasted:cool: ...oops

Duramaxedout "Your DMF slipped like hell but not because the disc or PP" You are wrong. I agree that your flywheel was probably glazed but the heat that caused that was from from the clutch slipping not the motor overheating. The tensile strength of the flywheel didn't degrade until the heat of the slipping clutch caused it to. Sure it made it worse after the clutch started slipping but it was the effect not the cause. GM put a very good clutch in the Duramax. It holds more than stock power even after some abuse. But when the clutch does slip it's cause is more power than it was designed for. Either changing the disc material, pressure plate load, or combination of both can fix the problem for those with excess power.

Jimsbcs when I first started building Duramax clutches I designed one to use a GM self adjusting pressure plate similar to the Duramax pp with a sprung hub center and standard organic lining. It had stock pedal effort, stock feel engagement, and less transmission rattle than a solid disc clutch. I offered it to several but nobody ever wanted one since it would only be guaranteed for stock power levels. So after a while I just quit talking about it but now there are more and more 6 speed trucks which equals more people with different needs.

Farmer0 1 Yes you are correct that when the clutch is slipping it definately needs a new disc. Even after the factory clutch starts to slip you can go back to stock power levels and the clutch will still hold but if you keep slipping it then it ends up like the one you took out. As for your flywheel idea it would be quite a chore to do it but it's possible it could work. The factory flywheel doesn't have a lot of flat areas to work with so you'd probably have to machine some flat spots to put the shims. Another issue would be there isn't room with the factory flywheel for a sprung hub clutch disc.

Deadeye I never told you that you would have to reshim your clutch after 10 times of sled pulling. I told you that you should at least get 10 sled pulls without having to shim it. Anyone that sells clutches knows that everyone and every situation is different on a clutch. I tried to tell people the worst case scenario when I was selling clutches. I can take any manufacturers clutch and sled pull 100 times and it still be in good shape or if I wanted to I could take any manufacturers clutch and demolish it without even hooking to the sled. When you ordered your clutch you told me you were going to be between 600 and 800 hp and were going sled pulling. If you were 800 hp and actually did sled pull then it's very possible it could need shimmed after 10 hooks but it's really impossible to know for sure. Last I knew you were 6??hp and had never sled pulled and if that is the case you could have bought a street clutch.

CPMac, you still got any of them kits that nobody wanted? Jim

Duramaxedout "Your DMF slipped like hell but not because the disc or PP" You are wrong. I agree that your flywheel was probably glazed but the heat that caused that was from from the clutch slipping not the motor overheating. The tensile strength of the flywheel didn't degrade until the heat of the slipping clutch caused it to. Sure it made it worse after the clutch started slipping but it was the effect not the cause. GM put a very good clutch in the Duramax. It holds more than stock power even after some abuse. But when the clutch does slip it's cause is more power than it was designed for. Either changing the disc material, pressure plate load, or combination of both can fix the problem for those with excess power.



Farmer0 1 Yes you are correct that when the clutch is slipping it definately needs a new disc. Even after the factory clutch starts to slip you can go back to stock power levels and the clutch will still hold but if you keep slipping it then it ends up like the one you took out.

CPMac,
Since I am not a mechanic, I would never consider agrueing with you about how a clutch works. But my experience with MY TRUCK is vastly different from your 2 bold print statements above.

My clutch/dmf was replaced twice, under warranty......my truck was 100% totally stock.....no extra HP. The problem was the dmf....according to dealer. Once the problem started, it did not get better.....until replaced. I did not get the J/A until 95K miles.

BigOL3 if you say yours is different from what I've seen I believe you. I have been around a lot of these and never seen one act any differently but I'm positive it's possible just not normal.

The clutches I've taken apart that slip under stock power had the clutch disc completely worn out. It was always a case that someone couldn't turn the power down once it started to slip. I've never seen a stock clutch that wouldn't hold stock power even after being slipped 20 or so times.

I'm sorry if it seemed I was calling you a liar but that was definately not what I meant. Earlier when I questioned you I did so because you posted your flywheel was making a lot of noise, I didn't notice you said it was slipping also. Basically when the flywheel is making that growling noise it can not be slipping since the noise comes from what Peter described as the springs being overworked. When the springs are being overworked in the flywheel the clutch isn't slipping. When the clutch does slip the flywheel noise goes away since it doesn't have much load left on the flywheel. I wasn't sure before we were on the same page so that's why I asked. And when I made the last statements I should have stated that I meant that to be the normal scenario.

Out of all the stock flywheel that I have seen fail under stock power levels the most noticable issue was a rattling noise while depressing the clutch pedal while setting still. But I always changed them when they started doing that instead of waiting which could cause flywheel noise while accelerating with stock power levels. Is this similar to the way your flywheels started going bad?

BigOL3 if you say yours is different from what I've seen I believe you. I have been around a lot of these and never seen one act any differently but I'm positive it's possible just not normal.

The clutches I've taken apart that slip under stock power had the clutch disc completely worn out. It was always a case that someone couldn't turn the power down once it started to slip. I've never seen a stock clutch that wouldn't hold stock power even after being slipped 20 or so times.

I'm sorry if it seemed I was calling you a liar but that was definately not what I meant. Earlier when I questioned you I did so because you posted your flywheel was making a lot of noise, I didn't notice you said it was slipping also. Basically when the flywheel is making that growling noise it can not be slipping since the noise comes from what Peter described as the springs being overworked. When the springs are being overworked in the flywheel the clutch isn't slipping. When the clutch does slip the flywheel noise goes away since it doesn't have much load left on the flywheel. I wasn't sure before we were on the same page so that's why I asked. And when I made the last statements I should have stated that I meant that to be the normal scenario.

Out of all the stock flywheel that I have seen fail under stock power levels the most noticable issue was a rattling noise while depressing the clutch pedal while setting still. But I always changed them when they started doing that instead of waiting which could cause flywheel noise while accelerating with stock power levels. Is this similar to the way your flywheels started going bad?

OK, I've been following this thread for awhile with interest. My new '06 LLY/6 sp manual is due in at my dealer in about three weeks. All I really need to know is if the stock setup is more than adequate under "normal" conditions". I don't expect to chip the truck (but who knows..), it's my daily driver (construction work) and my traveling rig; I tow occassionally but not to the limits.

I like manuals, hate automatics. I just want to drive the truck and have fun, and not worry about the dang clutch. Is that realistic?

all I know is dad's dmax 6speed went 25k then went out . pulling 26 foot house trailer maybe a couple of thousand miles total and heavy loaded fifth wheel flatbed loaded maybe 5-6 ton on trailer a couple of thousand miles. this pu is stock. he's always had stick shift pu. he had a 78 chev 350 gasser for about 4 years with an auto was a real piece of work. never had a clutch go out on anything like this. of course never had this much power either.

jimsbcs I'm sorry I don't have anything anymore.

tettruck generally the stock clutch will last very well with stock hp and generally the stock flywheel will fail. I've seen stock flywheels with stock power fail @29k miles without ever pulling a trailer. Usually the more you use the truck (pull trailers, bale bed, haul heavy loads) the faster the flywheel will fail. I have also found flywheels that have lasted 90k miles with 90% heavy trailer pulling and were still good but that isn't very likely. I have also found hydraulic throw out issues to cause clutch failure. Farmer01's dad's truck seems like an unusual case. If his truck was stock hp and the flywheel didn't fail but the clutch disc was shot I wonder if hydraulic issues might have helped it fail?

I'm sorry if it seemed I was calling you a liar but that was definately not what I meant. Earlier when I questioned you I did so because you posted your flywheel was making a lot of noise, I didn't notice you said it was slipping also.

No problem.....I did not take it that way. I just had to differ with you about the slippage being caused by extra HP, and cured by returning to stock power. That definately WAS NOT the case with my truck.

the clutch felt normal until about 150 miles before it failed, he was going up cabbage hill just out of La Grande oregon with his 26 ft house trailer. couldn't way 6000 lbs when one of the fellows following him saw a puff of smoke come out from dad's pu. they told him because they were just commenting on how it did not smoke out the exhaust like his old 87 did. made it over the grade and about an hour down the road pulled into rest area said pedal was half way to the floor and felt strange and clutch would not completly release. he called me on cell phone told him to stay out of OD keeper down around 60mph and stay out of the throttle. he left the rest area shifting with out clutch made it as far as Biggs Junction maybe 100 miles , stopped to fill up would not move. other fellows towed him off the off ramp to a parking lot and I went to fetch him. had the slave cylinder replaced with clutch because of heat build up and the way it felt at the time it went. this thing, before this trip, never gave us any warning signs. by this time all friction material was gone from disc. Bone stock motor , tires , hubcaps.

Farmer0 1 it definately sounds like the slave cyl. was the culprit in your case. I've seen a few do the same thing but if that's the case your dad shouldn't have any more problems unless the flywheel fails.

BigOl3 I wonder how many more are out there that have had clutch slippage with stock hp. The only cases I've seen before were similar to Farmer0 1's and seemed to be caused by the hydraulic system. Since the only thing you changed was the flywheel I wonder if there are any others. I've never had a stock clutch that wouldn't hold a hot edge easily until it was abused and that is a big difference from what you've encountered.

Deadeye I never told you that you would have to reshim your clutch after 10 times of sled pulling. I told you that you should at least get 10 sled pulls without having to shim it. Anyone that sells clutches knows that everyone and every situation is different on a clutch. I tried to tell people the worst case scenario when I was selling clutches. I can take any manufacturers clutch and sled pull 100 times and it still be in good shape or if I wanted to I could take any manufacturers clutch and demolish it without even hooking to the sled. When you ordered your clutch you told me you were going to be between 600 and 800 hp and were going sled pulling. If you were 800 hp and actually did sled pull then it's very possible it could need shimmed after 10 hooks but it's really impossible to know for sure. Last I knew you were 6??hp and had never sled pulled and if that is the case you could have bought a street clutch.

Actually, yes you did. And that was the reason I didn't do any pullin once the clutch plate slipped and wore thin AFTER THE FIRST MONTH, and repair parts showed up 6 months after promised.

Anyhow, this has nothing to do with this thread . . . which was started to provide information about the SBC SDC product to members, not to provide a space for posting our disagreements . . .

BigOl3 I wonder how many more are out there that have had clutch slippage with stock hp. The only cases I've seen before were similar to Farmer0 1's and seemed to be caused by the hydraulic system. Since the only thing you changed was the flywheel I wonder if there are any others. I've never had a stock clutch that wouldn't hold a hot edge easily until it was abused and that is a big difference from what you've encountered.

From what I have read here, I was under the impression there were a lot of failures while running stock HP. BTW, they did not replace JUST the flywheel, but rather the whole clutch assembly....twice.

Actually Deadeye I told you after I reshimmed your clutch when I came to your house that your clutch was in condition to do anything you wanted and you know it. Yes the discs had wear but the clutch was reset to maximum capacity and I told you to go pulling and sent you replacement parts for your peace of mind several months later.

And you are right this has nothing to do with any SBC clutch and I wouldn't reply but this is the only means of communication that you will reply to me on. Your post on page 2 you stated that the other manufacturers clutch had to be removed and reshimmed every 10th hook and that is not true. I'm sure you could have misunderstood me and it could be an honest mistake. I believe you should share your experiences but when your memory gets fuzzy I want to make sure to help you remember correctly. If you would just answer my phone call then I would call and talk with you when your off base but since you won't I have no other means. Everyone knows you didn't feel you received good service from me when I was selling clutches but that should have nothing to do with the facts.

Duramaxedout "Your DMF slipped like hell but not because the disc or PP" You are wrong. I agree that your flywheel was probably glazed but the heat that caused that was from from the clutch slipping not the motor overheating.

HUH, I said nothing of the motor overheating??? Yes, glazing is a result of the clutch slipping as a result of the design. Sorry, but I didn't fall off the ZF-6 tree yesterday been through 5 DMF's and we did all the R&D for the SBC kit. So when my flywheel was completely glazed it should still hold level 1 hp...not in my truck and it progressively got worse and worse and yes hard lauches even slipped it STOCK but when torn down still indexed and working properly. In another, totally misaligned but still held power but just made lots of noise. I have seen worse DMF's in terms of damaged springs, clips...completely wobbled out of balance and could still hold more power than what I was putting to mine...so it's not the flywheel's crappy cast iron material? Hence the feramic/ceramic buttons on the SBC kit...eliminates this from ever happening. Once a steel flywheel is slipped and heat glazed it will never be the same again unless milled. Totally off topic, sorry for the hi-jack.

I sure hope buy R&D you dont mean research and development because i'm pretty sure Peter did all the work on the clutch kits i know he had a few kits go out for testing but at his expense of course.

Exactly what I meant, feel free to reach out to Peter on the R&D details if you like. It was a joint effort among the three of us...Deadeye, Peter and myself.

Duramaxedout your statement about your flywheel being glazed was the culprit of your clutch slipping was off so I wanted to make sure you understood that it got that way as a result of the clutch slipping in the first place. I didn't know if you thought that motor heat or something else caused the slippage so I wanted to make sure you understood.

Yes I say your stock clutch assembly would have held stock power even after it slipped the first time. I think your statements prove what happend to yours to cause it to slip. There are a few trucks out there that may slip with stock hp but not very many. The normal stock clutch will hold 800 rwtq until slipped or abused then it will hold about 500. If you continue to abuse it then it will get progressively worse as you stated. If you turn the box off and drive normal it will continue to hold stock levels.

And your statement about hard lauches slipping the clutch stock are totally wrong. The clutch or flywheel neither slips while launching hard.

CPMac: Great to see you around here.

Just wanted to let you know that I have nearly 70,000 miles on the flywheel/ clutch/PP that you put in my truck -- still holding strong with zero issues.

I couldn't be happier -- THANKS!!!

CPMac what type of clutch setup do you install? I'm located in NW Ark and looking for someone locally to install a good clutch setup to use pulling with my Hot Juice setup.


Thanks,
GTMAN

yellowgtman I don't currently sell any type of clutch. I'm thinking about getting back into it but until then I would be willing to help a fellow dieselplace member with an install. There are a few shops around this part of the country I could recomend you to also. In my personal opinion I still would recommend a Mac's clutch over the competitors for all applications since they are still a more refined and tested setup. But I'd be willing to help with any install and the shop's that I would recommend sell both brands.