I have an 89' manual 6 speed with 120xxx miles. The clutch was fine (original dual mass) when I bought it 2 years ago, just engaged pretty high when letting off the pedal. This year it started chattering in reverse and a little in first, getting worse as the months go by. When it's cold it's limited to no chatter. Once it warms up it starts to get pretty bad, reverse feels and sounds horrible unless you revved it high and slipped it a lot. 2nd gear up is perfect and catches good. I figured the clutch was on its last leg so I purchased the steel single mass flywheel conversion kit from carolina clutch and took it to the dealer so it would be done right. They put it in and tell me that it has real bad chatter and they determined the pressure plate was warped. Carolina clutch is sending me new parts but I'm wondering if it's something else with the car thats causing this or ruining parts. I'm digging myself a pretty big hole filled with labor charges now and I just want to make sure the 2nd time is done right. Im thinking outside the box, maybe the clutch fluid is really bad or their mechanic said if it's not the parts its possible to be the clutch master cylinder. Do you guys have any ideas? Suggestions? Do you think it could just be the parts were defective? Is there anything else I should have checked out? I move in 2 weeks as well so time is not on my side and it's been in their shop for a month. I have pics of the parts if need be.

 

A clutch m/c won't cause chatter. It's very possible you got a bad part. Google clutch chatter and you'll learn a lot. I've had a couple of odd ones over the years. One was flywheel bolts that were a little too high and hitting the disk. The other was a bad crankshaft with too much end play. Way too much. Hopefully yours will be just a bad PP.

 

I hope your right, I'm just paranoid they will put the new parts in and it won't solve anything so I'm trying to get 1 step ahead just in case

 

Just because it was done at a dealership doesn't mean it was done right.

Not a corvette, but some time ago I bought a used 1ton pu (Chebby) diesel. Almost immediately the clutch pedal went to the floor- it blew the slave cylinder. Previous owner said he had previous probs w system so we took it to the dealer to fix. Now, this pu wasn't 20+years old like our C4's, so techs should still have had a clue on how to fix it....

After about a week of "we're still working with adjusting the slave cylinder" and other BS they finally called and said it was ready. Not 2 weeks later it happened again so they replaced the system again. Again it took far too long to fix, but they finally got it. Again it blew very quickly. After a few more times they finally told me they would no longer honor their repair and if it blew again tough s**t. I bought an aftermarket set and when I went to fix it I figured I'd check the clutch as well, as it had a REALLY heavy effort to depress the clutch pedal. (at least 1 or two times the dealer had supposedly pulled the trans to check it all out as well). When I got it apart I noticed the clutch fork didn't seem right. It turned out the problem was the ball on the clutch fork needed to be greased periodically (info is in the service manual) but had not been done because no-one could see the zerk fitting above the exhaust crossover pipe.

So the dealer 1, didn't maintain the vehicle properly; 2, didn't diagnose the problem correctly; 3, didn't even know how to properly do what they did to try and fix the problem anyway; (btw, every service manual I referred to for my work told me the clutch master-slave system was non-adjustable. So much for taking a week to "get it adjusted". They also told me the master, slave and line all came as an assembled unit and could not be obtained separately... more BS I found out later.)

Now, I'm not saying this dealer you're working with is as worthless as the one I was dealing with, but remember our cars are antiques to them, and the dealer mechs are primarily trained to work on the newer models to deal with warranty chit. Maybe you have a mech there that's been there a couple decades and remembers how these cars are... If not maybe you can find someone in the area who does have the experience you need. Too bad about your time crunch. I know how it goes.

Good luck.

 

Thanks for the reply, I'm learning the hard way that they might not know everything. Where I'm at right now it was pretty much the best option,most car places are pretty shady (currently in a border town). I just want to get back on the road!

 

A new warped ? flywheel, well I suppose everything and anything is possible, but in my own experience, I found a small burr on the crank end was enough to throw out the flywheel over 0.040" at the outer edge. I also dealt with a clutch after TWO shops and one well intentioned boyfriend attempted to repair a clutch with so much chatter that the car was undriveable. Turned out to be a worn out thrust bearing on the crank shaft. So the moral here is, a clutch job involves more than just replacing parts, the crankshaft needs to be checked for end play and the outer rim of the flywheel needs to be checked for run out. Neither is hard to do; and either, or both, is way easier than pulling the trans and doing the whole job over again

 

At 120K your dual mass was most likely beyond spec in movement, and may have even started to leak. So that was most likely the cause of your chatter there.

I'm not sure about their diagnosis of a warped plate. The whole purpose of the dual mass flywheel was to absorb the natural chatter inherent in the ZF transmission, especially the pre '94 black tags, which you have.

With the single mass you are going to have chatter when the car is in neutral and the clutch is out. If it goes away when the clutch is engaged, or when you're moving in gear, it is probably normal. The only remedy I've heard of is a countershaft shim, but I'm not sure if it is available for the black tags. Note: The sound is best described as rocks in can, and it definitely could be mistaken for a problem.

As old as these cars are, it is very possible that the tech at the dealership is not aware of this little bit if info on this transmission, and naturally thought something must be wrong. These things are not quiet with the single mass flywheels, just a fact of Corvette life.