My buddy has a 2003 Chevy ex-cab 3500 drw Duramax/ZF-6. He ask me to post this question. He said his clutch has been slipping & then it is very hard to push. Our local GM dealer is saying it is not under warranty cuz its the pressure plate or somthing. I know I dont have a lot of details but has anyone had or heard of this??? :help2:

Thanks,
Gittyup

Definately need more details, is this happening after it heats up pulling a heavy load or just normal around town driving? If happens without heating up under a load he better get it checked out asap, doesn't sound good. Has he changed or checked his fluid?

Definately need more details, is this happening after it heats up pulling a heavy load or just normal around town driving? If happens without heating up under a load he better get it checked out asap, doesn't sound good. Has he changed or checked his fluid?

Definately need more details, is this happening after it heats up pulling a heavy load or just normal around town driving? If happens without heating up under a load he better get it checked out asap, doesn't sound good. Has he changed or checked his fluid?

mine did that also, new flywheel, glutch and preasure plate.

Go to another dealer or complain to gm if now other option. That is if he is under 100K miles, this should be covered I think.

It is happining all the time I think. Also I forgot to tell you all he has an Edge juice w/ ***. I dont know if this matters or not?!? I told him my Allison is doin' fine w/ the juice):h... he did not find that as funny :mad: as I did.

Well I'll talk to him tomorow so I will try to get some more info from him.

I know a bit about this since it has happend to me and I now have the problem fixed (search for hard pedal, clutch slip). In a nutshell, the clutch can be slipping due to several issues but if he is Juiced above 90hp that is likely part of the cause. Additionally, the dual mass flywheel (DMF - oem) is POS. ~70% of duramax handshakers have had hard pedal/slippin clutch/rattling flywheel. GM has not solved the problem. Excessive heat causes the hydraulic fluid between the master and slave cyl to heat up. This causes back pressure on the pedal. If you 'stand' on the pedal it will collapse and, likely, it will have to be pulled up with the toe of your foot. After that the pedal pressure should go back to "normal". The heat that causes this problem may come from some slipping of the clutch due to long hiway driving, towing, or extra hp/fast driving. However, I suspect that it has more to due with the DMF causing heat that somehow transfers to the slave cyl.

I had the pedal kit replaced due to hard push and constant squeaking. The squeaking quit but the hard pedal kept comming back. Running stock the clutch would not noticeably slip but the pedal would eventually get hard.

I had the flywheel replaced with a SMF and a dual disc clutch . The hard pedal disappeared. The clutch slipped on day and the rps would jump up 1000 but the speedo didn't change. This was at 35mph. I didn't expect to get 20 miles home. Once pulled out, once side of a clutch plate was nearly trashed. I don't know how hot all that got but the pedal never got hard like the stock. However, the clutch pedal on the new kit required a much stronger leg to operate it.

The oem DMF is the weakest part of the drivetrain and tends to rattle and break a lot. The stock clutch plate has a very small non-metal pad and cannot generate nearly the slipping heat that the dual disc pad did (the whole kit is steel - it squeaks all the time shifting and launching - steel against steel).

Back to square one. Based on all this experience, I believe that slipping is somehow connected directly connected to the DMF fault and is causing either heat to expand the hydraulic or somehow pushing back on the slave cyl, hydraulic, master cyl, pedal.

Anyhow, once the slipped dual clutch was fixed it has never slipped again noticeably and the clutch pedal has never hardened.

Hope this helps.