At VIR Saturday Clutch seperated
 

I was at my first track weekend this year at VIR three day with PCA Zone 2
. Why would my clutch disc separate with no real sign of a failure before it happened. It was a Porsche clutch the paint marking still on the pressure plate side. The Flywheel side delaminated. Three chunks of fiber disc, was all that came out.

I recently replace the spec clutch disc which showed even wear both sides but was some what glazed. I smelled at the last auto cross I was at in November. I talked to several people I tracked with and it was suggested I try a 987 clutch plate because the were beefed up a little to handle the increased HP in the newer models.

http://i1199.photobucket.com/albums/...ps6zxld0ra.jpg

http://i1199.photobucket.com/albums/...psyuhe4bqe.jpg

http://i1199.photobucket.com/albums/...psc5vd0owa.jpg

You can see the numbers in second photo. The presure plate may be ruined as well the fingers are packed with fiber. I guess I'm going back to a full Spec 2 setup

Dang, hope you are back on the road soon!

Did you rev match when you downshifted.

Yes, Blip and shift all down shift.

I noticed that only the outer edge of your friction material looks like it had made contact with the flywheel / pressure plate.

This raises questions:
1. Do you think you got the surfaces seated/broken in adequately?

2. Did you replace clutch disc while re-using the old, worn pressure plate or flywheel, or did you replace those components as well? (If you reused them, what condition were they in?)

3. Do the pressure plate and flywheel friction surfaces completely cover the friction material, or is there some friction material that overhangs the mating surfaces?

Comparing to a "stock 986" clutch disc (for new Sachs 5-speed unit, see attached for comparison) the 987 one you show has some differences. Maybe mismatching the 987 clutch disc with the 986 flywheel and pressure plate caused this problem.

In case it helps, the outside diameter of this pictured 986 5-speed clutch disc is 9-7/16".

Odd that the wear is that way on both sides; only at the outer 1/2 of the friction material. Maybe that was a defective disk?

Not an expert, but just like a brake rotor, the outside of a spinning disc will have higher surface speed, more heat, more wear, and higher centrifugal forces.

You are spot on. We see a fair number of used (and abused) clutches, and they do tend to show a shiny wear pattern towards the outside edge of the disc, so that is nothing unusual.

The disk is the same surface size as the Spec disc. There is about 3mm of clearance to the inside on the flywheel and about 2mm inside and outside on the pressure plate so the metal surfaces are larger than the disc is. I ran a straight edge around the pressure plate with a steel scale and could not see light through the edges. The finger were all at the same height when measured with a digital vernier. The surface was clean no burns but smooth it did not have any hashing like a new disc usually shows. I lightly sanded the surface to add some texture. The fly wheel was new. the old one had too much play.

I had something similar happen years ago. We suspected the disc had been dropped during shipping, which resulted in a small dent to the edge of the friction surface. We noticed it prior to installation but ignored it. The disc lost part of one side shortly after installation

I saw this once. A friend going downhill in 1st gear just stepped on clutch and proceeded to coast very fast downhill. Clutch disk was probably spinning 30k rpm when it exploded.

I posted this in video's But it is the run when I broke.

http://986forum.com/forums/video-center/60966-pca-zone-2-fast-lap-then.html