Clutch Diagnosis Question

[Green71]

I have recently purchaced my new daily driver, a 1995 2 Door Chevy Tahoe Z71 5speed stick. It has around 148,000 miles on it. The PO said he replaced the clutch, but I believe there are some issues with it. There is some pretty good chatter when starting from a stop going forward and also in reverse. This only happens when the engine is at running temperature. Mind you, i also have a 1971 Blazer with a sm465 in it, which i drove for 4 years before getting the Tahoe in April of this year. I Drove the Blazer with its old clutch and with the new one i installed while rebuilding the drivetrain........no chatter whatsoever....even with the old worn clutch. So i am ruling out driving style/ not knowing how to operate a clutch . So i was thinking maybe there is a broken finger on the diaphragm or maybe the clutchplate/flywheel is glazed or pices broken off the clutchplate. Sorry for the long post but wanted to get the facts and history in for a good diagnosis . Any help with figuring this out is greatly appreciated, i just wanna know what im looking at before i tear everything apart . Thanks again.

 

[rumbly truck]

What do the motor and transmission mounts look like ?

 

[Green71]

Thanks, yes i forgot to add that, and it does matter. The mounts are in good condition......

 

[73k5blazer]

What type of clutch did he use? Who did the work? Was the flywheel resurfaced? How long ago was it replaced?
Cheap re-mans won't last very long, and if he took it to a shop, that's probably what he got. Not resurfacing the flywheel will produce the chatter too. Again, if he took it to a shop, a good lot of them will skip this step, because you'll never know until 10000mi down the road when it starts to chatter again.

If the chatter is that bad, you know you have *some* issue, only way to find and and correct it is to pull it. I know, not the answer your looking for, but that's the pain of the truth.
BTW, I use LUK Clutches all the time, never had one single issue with them yet. I have used centerforce too, but the disc is a LUK in most cases for them. Always get a full set (pressure plate, throwout bearing, disc), never use a re-man, always resurface or replace the flywheel if it's out-of-spec.

My bet's on the flywheel not being resurfaced. This will almost always produce the chatter problem. Even if the flywheel shows little sign of burns or , a certain disc wears into a certain flywheel, when disc is replaced, the flywheel needs a new surface to properly wear in the disc. Trouble usally shows 5-10k after installation if you don't resurface the flywheel. I wouldn't think it would be a broken finger, that would produce hard pedal, pedal notchyness, unreliable engagment/disengagment. Pure chatter is a sign of a cheap clutch disc, weak plate, or flywheel issues, or as most things are, a combination of all or any of those.

 

[Kiwi John]

Might have a broken spring on the friction plate?
Thats those little sideways springs that sit around the splined centre of the clutch plate. We call them 'anti-rattle' or 'anti-chatter' springs.
Definately sounds like you've gotta drop the clutch out and have a look. Should be pretty obvious when you get it apart. Good Luck.

 

[89GMCSuburban]

Yeah, those are the dampener springs. They reduce the jerking from the clutch, but more so, protect the clutch disks from being ripped apart. The springs break from lugging the engine most, at least that's what I see the most. Is it grabbing as well, or just making noise?

 

[diesel4me]

Chatter- ing...

Many cases of clutch chatter in newly installed clutches is due to letting the tranny hang down while installing it,bending the disc slightly...many shops use no tranny hoist,but instead use 2 gorilla sized mechanics to wrestle the tranny back in place--and use no "guide pins" to help it go in straight,and take the weight off the clutch disc splines..I've put many in by myself,and I bent a few discs,until I got a tranny jack adapter for my floor jack,and started using long bolts with the heads chopped off for guide pins ... I lived with the slight chatter,but it drove me nuts..and wasn't a big sellig feature when it came time to sell my K5....

All the other causes listed can cause clutch chatter too--rusted U-joints can too,believe it or not..one truck I did a clutch on,the collar the throwout bearing slides on was loose on the tranny,and it was all scored--the clutch looked fine,but I replaced it,and the collar and throwout bearing anyway,since it was apart,and the customer already paid for it..