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Well, theres that noise you haven’t been able to find!
look at the keeper spring on the back of the fork to see that the spring wasn’t mangled when somebody last changed the clutch.
sometimes they get only one finger of the spring on the ball, and it does that
Last edited by coupeguy2001; Jun 13, 2020 at 09:46 PM.
I just had mine apart with 118k and it looked nothing like that. I wouldn’t put that back in the car. Agree with the others that mentioned to check the fork as well. I used wheel bearing grease on it, in retrospect I wish I used a really tacky marine grease that I have.
It's probably fairly normal wear, and I would still replace it. FWIW, I used CRC Brake Caliper grease. Seemed to work really well as it's made for a similar use.
I talked with ZF Doc about it and he recommended replacement of the stud and fork. The stock DMF I took out is on the borderline of free play so i'll need to decide if it's time to pull the trigger on a new clutch setup or not. Tough call because it was working well previously, but with the trans out already it would be an ideal time to tackle it. Here's what the parts looked like after 100k:
Disk PP DMF
Last edited by 9T3VETTE; Jun 22, 2020 at 09:21 PM.
If you replace the flywheel, you'll almost certainly change to a single-mass unit. That means you shouldn't use the solid-hub disk in the picture: you'll want a disk with a sprung hub as is now commonly sold for a single-mass conversion or for LT1-powered 4th-gen F-bodies. If that's the original Valeo pressure plate, I'd consider asking if ZF Doc would resurface the friction surface and legs for you and throw it back in. Those are better quality units than the replacements that are now all made in China in one factory. Ditto on the throwout bearing: the original ones with "INA" stamped on the green seal are way better than the Chinese-made garbage that seems to come in all kits these days. For the pilot "bearing," I'd use a new bronze oilite fluted bushing instead of the needle bearing that often gets sold.
Thanks for the feedback Matthew. Luckily I was able to score an NOS INA throw out bearing on eBay a few months ago.
Question about the DFM free play measurement - I assume when measuring free play, the rotational distance considered is only that which is able to freely rotate. Meaning, the end point in each rotational direction is as soon as spring resistance is felt? If so, i'm at 25mm, below the 35mm FSM spec for replacement. That would significantly alter my plans for a clutch replacement (i.e scotch pad the DFM, get a new disk, and have ZF machine the PP).
Thanks for the feedback Matthew. Luckily I was able to score an NOS INA throw out bearing on eBay a few months ago.
Awesome!
Question about the DFM free play measurement - I assume when measuring free play, the rotational distance considered is only that which is able to freely rotate. Meaning, the end point in each rotational direction is as soon as spring resistance is felt? If so, i'm at 25mm, below the 35mm FSM spec for replacement. That would significantly alter my plans for a clutch replacement (i.e scotch pad the DFM, get a new disk, and have ZF machine the PP).
I've literally never messed with a DFM because my C4 came with a single-mass aluminum flywheel already installed. Best I can do is paste the procedure as written in the factory service manual:
Assuming the DMF is ok, best way to freshen it up is with a scotch brite pad?
I talked with Bill and he said no easy way to resurface the OEM pressure plate. He suggested buying a clutch kit, sending him the pressure plate, which he’ll exchange for a optimized unit with the leg standoffs machined correctly. Think it was a $140 service..
Assuming the DMF is ok, best way to freshen it up is with a scotch brite pad?
That's what I've seen others do, yeah. I never had to mess with that, even on my single-mass flywheel, because it was aluminum with a replaceable steel friction surface.
I talked with Bill and he said no easy way to resurface the OEM pressure plate. He suggested buying a clutch kit, sending him the pressure plate, which he’ll exchange for a optimized unit with the leg standoffs machined correctly. Think it was a $140 service..
That would solve one of two main issues with the new replacements these days. The other is uneven finger height on the diaphragm, where the throwout bearing rides. When you get the new clutch in your hands, just use and sight and feel to make sure all those ends are at the same level. If not, send it back. If so, send it to Bill.
Last edited by MatthewMiller; Jun 25, 2020 at 07:56 AM.
If that well-used DMF is near the limit for lash, I would not reinstall it, as it would likely fail long before the next clutch replacement interval would occur. New DMFs are nearly unicorns now, and if you're lucky enough to find one, expect to pay big $ to acquire it. Various SMF solutions exist. I went with the extra-weight billet steel SMF from Spec with a goal of minimizing any gear rattle that might occur without a DMF to dampen the vibrations. It worked out well for me. As Matthew Miller noted above, swapping in a SMF will also require the use of a sprung-hub disc. Bill Boudreau has also identified a procedure that can minimize gear rattle -- contact him for advice about that.
Wear
