Auto_Werks 3.6

Earlier this month I had to have the clutch disc relined in my track 951. I reinstalled it, did about an hour of break in and an hour of dyno time. On the way home from the dyno it started making some new bad sounds that turned out to be the car's efforts to liberate itself from the flywheel. Talk about an un-fun surprise on a 951. I don't see any real root cause for the failure, I had used new hardware, loctite, and torqued to 66 ft lbs. I'm sending all the clutch and flywheel parts out to be balanced, upgrading to ARP bolts, and hoping for the best at this point. There is one other thread in the archives, but I don't think there was a smoking gun on his either.

Tom M'Guinn

Yikes, sorry about that. I wonder if debris got caught up between the flywheel and crank, causing loose bolts once it wore away? Did you torque in stages in a star pattern? Did you use factory bolts -- I once had a reputable 944 parts place unknowingly send inferior aftermarket bolts.

Auto_Werks 3.6

The hardware definitely came from pelican parts, they have two options for brand other than the $11 per pc porsche brand. I think I got the "GERMAN" ones. My friend put the flywheel up, and said it felt a little strange going on, and asked me to check it. I didn't see anything wrong, and I figured the bolts would pull it up if there was any misalignment. Hindsight I wish I would have pulled it off again and started over.

I always do a star pattern, and I usually run around in a circle at the end as a sanity check to make sure none were missed. I got the torque specs from Lindsey's website, and I believe it is in two steps, but I can's swear that we did multiple steps.

The biggest bummer was the car ran fantastic on the dyno, and we were literally resetting the EBC to get ready for an autocross when it started making noise.

There are probably more than a handful of people doing 370 ft lbs on a stock flywheel, without shaking them off... at least I would assume


For what it's worth; your theory, or some sort of misalignment, or just plain mis reading the torque wrench are my leading theories.

MAGK944

My torque wrench has adjacent markings for Newton-meters and foot-pounds. Once I had to re-torque in foot-pounds what I first did in Newton-meters, luckily I caught it before everything was fully assembled. Easily done, and now I am hard wired to double check.

gruhsy

You could check the calibration of your torque wrench. They can drift and also go out if dropped.

rlm328

I had them back out on a Cayman S. The clutch was the original one. The engine and transmission had never been out of the car.

So I guess I am saying stuff happens.

URG8RB8

Tom:

Have you seen the 9-Products aluminum flywheel "Shim"? I am wondering if this is Ryan's issue. They would not go to the trouble to make this piece if there was no need.

Auto_Werks 3.6

Eric, this was a stock flywheel, and spec (Sachs) pressure plate... I thought the shim was for aluminum flywheels?

Chris White

Balance shaft delete?

Auto_Werks 3.6

Chris, unfortunately no, it still has the balance shafts. I was doing some 20 PSI pulls with it before the trouble started, and it felt SMOOTH. like, really happy... right until it went wrong

URG8RB8

Sorry, just saw this Ryan, I thought it was an Aluminum FW, but none the less I would like to know more about this "Shim"

Maybe Chris White has used this device?

Chris White

never had a problem without as long as you torque it correctly. If you plan on taking the flywheel off repeatedly then its a good idea.

Chris White

OK - I was asking because balance shaft delete engines have a lot of high frequency vibrations that can cause fasteners to back off.
I think the 'it went on weird' statement has some deep meaning here....

Tom M'Guinn

That's the most likely cause I'd bet. Something wasn't seating or there was debris or something, which settled in once the motor ran causing loose bolts. You'll probably never know for sure, but that would be my guess.

As for shims, those are typically used to compensate for machined flywheels. On some cars, if you machine material off the friction face of the flywheel, the clutch hydraulics and/or mechanicals may not reach the flywheel without problems, so a shim can be used to bring the friction face out to the stock location. Never heard of that being an issue on the 944, but I suppose possible (especially with an aftermarket flywheel that may or may not line up exactly like a stock flywheel).

URG8RB8

This is the item I was referring too. I see what you are talking about Tom. When they said bolt I assumed incorrectly the FW was too thin and the bolts would bottom out before tightening.