I have had flywheel bolts back out as well - I now loctite and safety wire them. This past weekend after a race on Saturday, I went to bleed my clutch slave as my shifting was getting very notchy and engagement was right off the floor. I have a 2 inch inspection hole drilled in my trans bellhousing and noticed my pressure plate bolts were loose. Tightened each one of them by rotating the driveshaft and reaching in with a 6mm allen (thanks Flink). Engagement went back to normal. Best hole I have ever drilled. Each of those pressure plate bolts was properly torqued and new bolts were used. I suspect there is an imbalance somewhere which is likely the cause of the original issue with the flywheel bolts backing out. It is not a UUC flywheel btw.
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I will apologize now, as I cannot see the pictures well on my phone. That being said, I'm a little surprised that no one has commented on an over-revved clutch disc. I have seen it MANY times, mainly in cars with relatively new track drivers. Not to comment on the experience of to OP, either.
In the braking zone for a corner, it is not uncommon for a driver to select the lower gear, or even skip a gear on the way down, if it's a big slowing zone. Even if the clutch pedal is not released, the clutch disc has to spin up to the appropriate revs to match the road speed of that gear. Clutch discs do t generally like to go past 8500RPM or so, unless modified.
So, what happens is the clutch rivets cannot contain the friction material and it falls off of the disc. I have no explanation at the moment, but it is invariably the flywheel side of the disc, not the pressure plate side.
i have seen this failure at least 20 times over the years. It could happen on a money-shift, even if the clutch pedal is not released, as the disc still spins up.
Something to consider.
Would loose flywheel bolts be the result of that? We all seem to think that was the cause.
In my case, it was a 330 with an M54B30 with a 7k RPM...which is deadly for those engines but that's another subject.
So if I pushed the redline on my S54 to 8500+, I should be looking at what type(s) of designs to reduce the chances of the clutch disc coming apart?
I will generally ask my clutch builders bond and rivet the facing to the disc face. The bonding makes the clutch actuation slightly less progressive, as you lose the flat spring that's under the facing, but it's minor.
The loose bolts might be an unrelated issue, especially if there were some that were still tight and the flywheel wasn't moving around. However if it was, that'll do lots of nasty things. I've seen this kind of failure in cars with a solidly mounted flywheel.
You're referring to a marcelled disk with a cush spring. That's typically done with a solid flywheel to make engagement smoother... industry standard, that's what you will find in Genuine BMW disks and aftermarket disks.
Dual mass flywheels usually use a solid backing plate for the material simply because they do not need the marcel/cush spring.
What we have done at UUC, and can do by special order at no cost, is provide a solid unsprung disk with our clutch kits for lightweight flywheels. For track cars, you're unlikely to notice a difference. For street cars, the engagement will feel a little quicker and may have a tiny bit of judder during initial engagement in 1st gear.
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NOT with that company any more.
I still like the center springs on a street car, or even an occasional track day car. I may be wrong, but I think it's gentler to the drivetrain parts. I can live with out the marcel spring, but this is only my opinion.
Btw Rob, I have a Stage 2 setup ready to go into my Euro M3 over the winter. I purchased it from another BF.com member, and I will likely have my clutch guy make me a disc for it, just for insurance.
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