Clutch Failure Analysis - Need your Help! (pics inside)

[JohnZ]

There are a number of variables to consider, but I don't care for the "mirror-finish" on the flywheel; have never seen a flywheel done that way before. Flywheels are surfaced on a machine like a Blanchard grinder, not a lathe, and should have a surface finish much like you see on a brake rotor.

I would agree that the heat damage is probably a result of slippage, which is normally associated with the linkage adjustment not providing adequate pedal free play. Free play ensures that the clutch is fully engaged and the TO bearing isn't touching the fingers, and is the primary criteria for linkage adjustment.

Two other factors to consider are 1) The TO bearing installation on the end of the clutch fork, with both the fork AND the anti-rattle spring in the groove on the bearing - it can be installed wrong (see below), preventing correct free play adjustment, and 2) Using the correct TO bearing - all Corvettes use the 1-1/4" bearing, NOT the 1-3/4" bearing used on passenger cars and trucks.

 

[Old Bull]

You never mentioned if you checked the pilot bushing / bearing. I have seen at least one case where a new pilot bushing was installed with the wrong ID (oversize) After exhausting all other possibilities in chasing down a vibration we discovered the oversize bushing. This condition didn't keep the transmission input shaft correctly centered and thus the clutch disc was never centered, thereby causing the vibration. This would certainly cause chattering and poor clutch engagement. Just a thought.

 

[tigernut]

Brian,
I found this LUK clutch troubleshooting pdf file on their website while researching clutches.

It is 7Meg in size and seems very good. Alot of pictures on possible clutch conditions.

Check it out and see if it helps you:
http://www.luk.com/publish/OR/get.rendered?t=rel%20PubLanguage&i=17772&a=PubFile&schema=luk_internet

Doug

 

[carrollm]

Looking at your picture, It looks like you had some HOT SPOTS. I've seen this happen when the clutch gets put together with greasy hands. I wipe my flywheel down with alcohol before it goes together..


64 Mike

 

[allcoupedup]

tigernut- thanks for the link... my conversation with LUK should be soooo much fun

carrollm - nope, this one was wiped down with lacquer thinner before assembly. I was super careful as I had been warned.......

I received some info offline about warped springs and the pressure plate spring fingers being uneven causing uneven engagemen/desengagement -- this sound like what i have. Either way, I doubt I'LL get my money back and nobody is going to pay for my flywheel except ME.:cry

Brian

 

[wishuwerehere82]

After looking at your pictures again and again, I see a reflection on the flywheel surface that looks like almost a mirror finish. The flywheel should not be that smooth. A mirror finish won't grip to the clutch plate. I think this is where all of your chatter was coming from. The flywheel was slipping and transferring all the holding torque to the pressure plate when you let out the clutch. A new set ought to fix the problem.

 

[allcoupedup]

it was as smooth as glass

 

[wishuwerehere82]

I wish you had put that picture first,it would have taken all the guess work out of it. Smooth is not good. Glass is worse.
I wouldn't mind my wheels looking like that, but not a flywheel.
Everyone else agree?

 

[JohnZ]

I wish you had put that picture first,it would have taken all the guess work out of it. Smooth is not good. Glass is worse.
I wouldn't mind my wheels looking like that, but not a flywheel.
Everyone else agree?

Yup, as I posted up above in #21.

 

[tigernut]

Brian,
Here is a brand new GM 400 flywheel I just installed on the back of my motor. You can see the finish compared to yours: