RustInPeace

I have a 94 zf6, its an early 94 with a black tag zf I guess I got a left over from 93, mods are le2 heads le emissions cam le ported intake and full bolt ons.

Just recently it has developed a vibration when releasing the clutch, the whole car shakes, sometimes its very noticeable other times not too bad, it does this in first taking off from a stop. When driving and shifting gears everything is smooth, if I rev up a little higher before releasing the clutch at a stop it doesn't do it. I have not noticed any vibrations when reving it up in neutral the vibration occurs right when the clutch starts to grab about half way up, with the pedal fully pressed or released it is fine.

Previous owner said he had the clutch replaced in the low 60k mile range, not sure if it was actually done or not, he didn't have any reciepts, car now has 70k on it.

Any ideas what might be wrong?
Thanks

Captain rags

I may be wrong but as an old “not so up todate mechanic” I would guess the springs in the actual clutch plate are shot.
Owner 96 C4 LT4

sailorsteve

C4's from '92 on use a solid clutch disc. They have the dual mass flywheel instead of a sprung disc.

As for the op's problem, one possibility is a loose component in the driveline, maybe the c-beam.

Mohammed_z

what's the difference between a solid clutch disk and a sprung one ?

can you use any of them on the zf ? or only the solid one will fit ?

383vett

Not sure of the solution to your problem, but what you are describing is called clutch chatter.

856SPEED

and being the PO did a clutch job, I am sure they may have upgraded to a clutch that has a higher friction surface, causing chatter at low RPM when the clutch is released, reverse gear may be worse, especially on an incline......

RustInPeace

Thanks for the replies, so assuming it is just clutch chatter is this something normal and not something I should be worrying about?

Cliff Harris

Is the free play in the clutch adjusted correctly? If it's too tight it can screw up the throwout bearing, which can cause clutch release problems.

I fixed my clutch chatter by replacing the disk.

sailorsteve

A sprung disc has a row of springs in a circle in the hub to reduce vibration and smooth the engagement. A sprung disc is redundant with a dual-mass flywheel.

Clutch chatter is not normal.

There is no provision for adjustment. The hydraulic system is self-adjusting. The throwout bearing is always engaged with the pressure plate.

bjm206

Sometimes you can get the chatter to go away by changing the way you release the clutch and the engine speed at release for a while.

The chatter is caused by a wear pattern (flywheel and/or disc and/or pressure plate) that creates an easily excitable natural frequency in the drive line. By changing the release technique for awhile you can sometimes (not always) create a new wear pattern that will stop the chatter when you go back to your old release technique. The new technique needs to be chatter free.

I had this happen on my car a few years ago.