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Old 03-22-2016, 05:38 PM   #1
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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.
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2003 Black 986. modified for Advanced level HPDE and open track days.
* 3.6L LN block, 06 heads, Carrillo H rods, IDP with 987 intake, Oil mods, LN IMS. * Spec II Clutch, 3.2L S Spec P-P FW. * D2 shocks, GT3 arms & and links, Spacers front and rear * Weight reduced, No carpet, AC deleted, Remote PS pump, PS pump deleted. Recaro Pole position seats, Brey crouse ext. 5 point harness, NHP sport exhaust
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Old 03-23-2016, 03:58 AM   #2
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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.







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
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2003 Black 986. modified for Advanced level HPDE and open track days.
* 3.6L LN block, 06 heads, Carrillo H rods, IDP with 987 intake, Oil mods, LN IMS. * Spec II Clutch, 3.2L S Spec P-P FW. * D2 shocks, GT3 arms & and links, Spacers front and rear * Weight reduced, No carpet, AC deleted, Remote PS pump, PS pump deleted. Recaro Pole position seats, Brey crouse ext. 5 point harness, NHP sport exhaust
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Old 03-23-2016, 01:17 PM   #3
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Dang, hope you are back on the road soon!
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Old 03-23-2016, 03:38 PM   #4
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Did you rev match when you downshifted.
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Old 03-23-2016, 04:12 PM   #5
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Yes, Blip and shift all down shift.
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2003 Black 986. modified for Advanced level HPDE and open track days.
* 3.6L LN block, 06 heads, Carrillo H rods, IDP with 987 intake, Oil mods, LN IMS. * Spec II Clutch, 3.2L S Spec P-P FW. * D2 shocks, GT3 arms & and links, Spacers front and rear * Weight reduced, No carpet, AC deleted, Remote PS pump, PS pump deleted. Recaro Pole position seats, Brey crouse ext. 5 point harness, NHP sport exhaust
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Old 03-23-2016, 08:37 PM   #6
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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".
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Last edited by jakeru; 03-23-2016 at 08:43 PM.
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Old 03-24-2016, 03:54 AM   #7
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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?
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Old 03-24-2016, 08:06 AM   #8
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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.
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Old 03-24-2016, 08:16 AM   #9
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Quote:
Originally Posted by stephen wilson View Post
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.
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Old 03-24-2016, 01:03 PM   #10
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Quote:
Originally Posted by jakeru View Post
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".
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.
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2003 Black 986. modified for Advanced level HPDE and open track days.
* 3.6L LN block, 06 heads, Carrillo H rods, IDP with 987 intake, Oil mods, LN IMS. * Spec II Clutch, 3.2L S Spec P-P FW. * D2 shocks, GT3 arms & and links, Spacers front and rear * Weight reduced, No carpet, AC deleted, Remote PS pump, PS pump deleted. Recaro Pole position seats, Brey crouse ext. 5 point harness, NHP sport exhaust
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Old 03-24-2016, 04:56 PM   #11
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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
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Old 03-24-2016, 05:07 PM   #12
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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.
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Old 03-26-2016, 04:31 AM   #13
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I posted this in video's But it is the run when I broke.

PCA Zone 2 fast lap then
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2003 Black 986. modified for Advanced level HPDE and open track days.
* 3.6L LN block, 06 heads, Carrillo H rods, IDP with 987 intake, Oil mods, LN IMS. * Spec II Clutch, 3.2L S Spec P-P FW. * D2 shocks, GT3 arms & and links, Spacers front and rear * Weight reduced, No carpet, AC deleted, Remote PS pump, PS pump deleted. Recaro Pole position seats, Brey crouse ext. 5 point harness, NHP sport exhaust
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