The 6-speed transmission appears to be OK. The clutch/flywheel components are (borderline) junk in my opinion. Way too many problems. There are several on the forum that have a lot of experiences with the unit. Forum poster "CPMac" comes to mind. Maybe PM him and query. He probably knows the current state of affairs. Edited by: OC_DMAX

 

I can't say about the ZF since I've only read some postings here about them.


If you get an LLY however, the increased power is not available with the manual trans. It's restricted to the LB7 power output...

I'm not sure how that would affect things if you plan on putting a programmer or module set up on it, but from what I've been reading and the reason the LLY is restricted, the clutch/flywheel setup just can't take the power as OC_DMAX has said.

 

Besides that, how are you supposed to drink your coffee, eat a donut, and talk on the phone all at the same time and still manage to throw that stick around.


Gotta love that downshifting in tow mode.


Allison all the way!!

 

Besides that, how are you supposed to drink your coffee, eat a donut, and talk on the phone all at the same time and still manage to throw that stick around.

Edited by: Zeeb

 

so you cant turn up the 6spds as hot as the allison? prolly a stupid overlook on my part, but why not? And whats this downshifting in tow mode?


Oh bout the multi-tasking....my phone calls are never important enuf that i couldnt take it down to throw a stick....i drink so much coffee that i usually just run it in an IV.... and when it comes to eating somthing, if its humanly possible ill find away to eat it!

Thanks for the input!

 

And whats this downshifting in tow mode?

The Allison shifts down to slow your load when you have it in "Tow Haul" It is one of the coolest things about the truck. It has really impressed some of my Buddy's when we have been pulling a heavy load. The Allison shifts down Exactly when I would if I had a 6 speed!

 

I guess with approx. 25 % power loss through the allison and only 10 % through the zf it really doesnt matter to get a little less power output. But I would be worried also to get this bad clutch components.
I have no idea why they made such a bad transmission because normally the "Zahnrad AG Friedrichshafen" (lake constance, Germany) is well known for quality work throughout. I was thinking to get one myself, but I really trust the people here in this forum.....seems german quality is going down the drain, hard to accept...

 

but do you still have all the available systems to turn them up? ex. edge banks ect? can you still put all the good stuff on a 6 spd or are the sytems designed to the auto?.....also why is the lly limited to the lb7 output?


sorry, im still a bit confused, and dissapointed about the reliability of the 6spds

Jared

 

There are two reasons I went with the Allison:


Couldn't get rear DVD option with Manual


The large amount of stop-n-go driving I do daily.

 

The only reason I can think of why they knock the power back to LB7 numbers on the 6-speed is that the manual just can't take the extra torque of the LLY. This would concern me, if I was considering a manual, that an extra 70 lb-ft of torque would put the 6-speed at risk especially since some of these programmers can add over 200 lb-ft.


I've also heard, but don't quote me on this, that an Allison equiped truck can be a little quicker since it shifts so quick and smooth whereas a manual can lose RPM between shifts and therefore also lose some momentum. Feel free to back me up or shoot me down on this anybody.

 

The manual can take the torque, it's the dual-mass flywheel that folks are having trouble with. Mine went bad at about 30K miles (no power box at the time). Replaced under warranty. Fortunately, it's covered under the 100K warranty as well.

I read somewhere on this site that GM has now told dealers to hold off replacing flywheels, as a new version is in the works that'll supposedly cure the problem. So there's hope.

With respect to the clutch, I know some folks who are pushing the power are having some issues. But at stock or mild boosted levels of power, it seems to work. I've been running a Juice w/attitude for awhile now and I have yet to slip the clutch. Granted, I normally run at power level 1, response level 4, and I only dial it up on rare occassions (passing on a little 2-lane, racing a Dodge, etc). It's never caused my clutch any grief. I think used in moderation, it's fine. If you want to run at 120hp of boost all the time and hammer on the thing, you're likely to have issues. But the same is true of the Allison, no?

If I had it to do over again, I'd still buy the 6-speed, I really prefer it. And I expect there will be a better flywheel available before my warranty runs out.

 

Dosen't mater whether it's a ALLI or ZF 6 when you push the HP up both will require upgrades. The ZF 6 upgrades are working out very well. My ALLI has been upgraded and it also works very well. Both are equal as far as HP mods and trans upgrades go.

 

Does anyone have a 6spd and regret it? ZFMAX, the flywheel set up is coverd for 100,000? How likely is it that i would break it before the 3yr/36000 warrenty was up>? How soon is a good fix gonna be available from GM? any ideas?


THanks for the info, very helpful!!!


JAred

 

Well, I can't speak for the '04 warranty, but on my '02, yes, the flywheel is considered part of the engine and therefore it's covered by the 5 year/100K mile warranty. That's not an assumption, it specifically says the flywheel is covered.

Initial flywheel failures seem to happen in the 30K to 50K mile range for the most part. That's just my perception from reading this board, I have no hard data to back it up. Mine started making a loud growling noise in the first inch or so of clutch pedal movement. And then a slight growling noise just sitting there idling in neutral.

I dunno when they might have a better one, my information is second-hand. Somewhere on this board there's a post about it. Someone went to go get a new flywheel and GM told the dealer the noise won't hurt anything and to hold off replacing it because they're about to release a better one. That's the sum total of what I know about it. The thread shouldn't be too hard to find, it wasn't that long ago.

The Allison doesn't make sense to me. You pay an extra 2 grand for one less gear and less control over what gear you're in. Oh, but you get grade braking that's almost as good as what you can do with a manual. Yep, that makes it a good deal. I just don't get it.

The ZF is a terrific tranny. Shifts nice and as strong as an anvil. If they get this flywheel issue sorted out, it'll be perfect.

 

Since the manual does not have the hp/tq ratings of the LLY is it actually an LB7? Does it have any of the changes the LLY had glow plug/injector etc. changes?

 

Oops, the thread I was referring to was on another site

 

I expect upgrading the zf6, once the design and testing is completed, will be much less expensive than upgrading the Alli with ATS or Suncoast.

 

Since the manual does not have the hp/tq ratings of the LLY is it actually an LB7? Does it have any of the changes the LLY had glow plug/injector etc. changes?

An LLY is an LLY...

They just use the computers to restrict the HP. The Allison equipted trucks also have restricted power levels in 1st and 5th gears.

 

I love my ZF6

 

The manual trans is a very good trans, just add the proper clutch and pressure plate and your fine.One with more holding power. I put 350hp to the rear wheels stock clutch ok no load, but pull heavy load clutch would slip, added centerforce clutch and pressure plate and i was fine. Would pull 10,000 pounds like the truck has nothing behind it. IT gives it 900 foot pounds of holding power. THE d/a LLY setup only has 600 in first and fifth gear, power is reduced in those gears, with 900 in 2-3-4-gears. I like a manual but i drive a big truck all day so i bought an auto,now. Good luck either way.

 

The 6-speed transmission appears to be OK. The clutch/flywheel components are (borderline) junk in my opinion. Way too many problems. There are several on the forum that have a lot of experiences with the unit. Forum poster "CPMac" comes to mind. Maybe PM him and query. He probably knows the current state of affairs.

If anything is to be called "junk" it should be the Allison. I know some people swear by them and some swear at them too. FOr what is cost if should be fool proof and it is far from that. A manual a pretty much proven and reliable and so are the clutches. People that tend to have poor opinions of the manuals and particulairly the clutch durabilty, do not really "know" how to drive a stick. There is a lot of torque in a 8.1 or Dmax and if you bring RPM up a lot and slip clutch a lot under take off load there will be a lot of heat generated from fricton in slipage which can be detrimental to clutch life. IF you are good you can start out at a idle or a litle above it and greatly limit this slipage and heat. If you drive in properly and minimized high torque slipage you will get a few hundred thousand miles out of the clutch assembly with ease which is more than can be said about the Alision for what I have seen and read.

 

A double disc will cost you 2500 dollars and will hold anything that is out there now. An ATS level III will cost you just under 4000 and probably hold the same. Just depends on how much you want to exercise your right arm.

 

It can take the extra torque fine..don't let these people scare you. I have been running a 110 quad chip that kicks the power and TQ to well over what an LLY makes and the clutch is fine. Heres a question for all the alli owners...when you fry your tranny..can you fix it yourself...I know personally I can change a clutch or fix a manual trans internals. One of the members also makes a heavy duty clutch...real trucks have standard shift...but the allis are faster from a stop..and the 6 speed feels alot faster from a roll. I would definitely buy the 6 speed again.

 

I have the ZF in my truck because I'm not shiftless.

 

Personally, I would never own a Diesel, whatever the brand, with a automatic as they seem to do so much better overall with a stick with the ones I have driven many times over the years.