bondtimbond

I started a thread like this in the C2 section but know that this question applies to C3's as well so I am posting here also:

I am looking for words of experience with clutch disks. Long story short I have been wrestling with clutch chatter problems on my 67 327 Vette but the same applies to C3 cars also, and I have pulled things apart now for the third time! Somewhat independent of that problem, I discovered that different clutch disks and different facing material on the disk can result in either smooth engagement or abrupt engagement. The photo attached shows the difference in an older GM disk (on the left) from around 1985 or so that I removed from my car, and a new LUK disk on the right. When I installed the new disk, I noticed that the engagement was much less smooth and downright grabby feeling. Even with some drive time it never did smooth out. When I pulled out my trans the second time last year (uugh!), I put back in the original disk shown on the left. The result was a much smoother engagement.

Now I have the clutch out again for the chatter problem, and I have purchased all new AC Delco clutch hardware. With new kit is actually a SACHS unit and disk with Valeo friction material. I have to decide which disk to put in...

Here is what I am looking for input on from this Forum: Are most people happy with the feel of your clutch after recent clutch hardware changes with disks that look like the one in the right of my photo shows?? I am trying to decide whether to put back in the original disk again (which has some life left but does show some wear), or put in the new SACHS disk that came with the kit. If the general feeling is that folks are happy with the newer clutch disks and have no problem with engagement, then I will put in the new disk.

Attached below is a photo of the two types of disks. The one on the right is a LUK disk, but my new Delco/Sachs disk looks similar. Any comments and experience would be greatly appreciated!!

77BuffaloVet

Great thread!!! No responses...ugh...Try posting this in C3 Tech/Perf as well...

I am dealing with some chatter right now. I have been too lazy to try and adjust it...It's a challenge to try and slip the clutch in and out without it chattering...

I hope that some other people will jump in on this!!!

Chris

stingr69

The only time I ever had chatter, it was due to another issue - loose engine/tranny mounts. check the condition of the mounts.

-Mark.

GD70

I get chatter once in a while. Mostly in reverse because I usually don't fully engage the clutch backing out of my driveway. Also happens when engine revs are low when engaging. When I give it some gas as I let out the pedal it's smooth mand usually none when fully warmed up.
I've checked motor & tranny mounts and all are solid.

big_G

Clutch grabbing and chatter on engagement can often be caused by a warped/uneven flywheel. Anytime I change a clutch I have the surface cleaned up.

...Roger...

While it is possible for the disc to be the problem thats usually not the case for me.Lets talk about other things you have done to eliminate the chatter.Corvettes seem to be more prone to chatter than other Chevys with the same clutch set.In other words you could take engine and trans from Camaro or say Chevelle that did not have a chatter problem and put it in a Corvette and it might chatter.Hmmm-Why? Here are a few issues I look at:flywheel surface,flywheel runout(most common),pilot bushing,pressure plate surface,pressure plate surface runout or flatness,poor springs or fingers in plate,bellhousing trans hole alignment to center of crankshaft(crucial),crankshaft pilot bushing hole not on center "sometimes" because the crank came from an automatic trans car(this is becoming more common and a PITA),bad clutch fork,trans mount,bad tailshaft bushing and worn out differential snubber bushings.
EDIT-Oh forgot about crankshaft end play-oh yea !!!

bondtimbond

Thanks for the replies. I have good news in that I think I have finally fixed my problem! In the course of the last year or so, I have checked just about every items mentioned in this thread, but still had chatter.

This weekend I reinstalled everything with another new clutch and pressure plate set. This time I used a AC Delco set (made by SACHS) part number 381146. I also had the flywheel resurfaced again by a different shop, and also balanced as a set with the clutch parts. All of this I had done before, but this time used a different shop. They got the runout of the flywheel down to .002" (from .004 or .005" before). I installed the new clutch plate that came with the kit, which looks like the one on the right in the photo at the start of this thread.

On first drive engagement seems smooth and no chatter so far. I am crossing my fingers. I suspect that my first clutch set which was by LUK, had a defective pressure plate. That would be my guess. My flywheel runout is nice and low now, but wasn't too bad even before so I am not sure that was the problem. Thanks to all for the comments!