vetracer

I just had a very bad experience after installing an Exedy Mach 500 Stage 2 clutch kit in my otherwise stock 2011 Mustang GT. The clutch was installed with a new flywheel, hydraulic cylinder and SS lines. It was installed by pros at one of the best Mustang shops in South Florida. I drove the car several weeks to get over 500 miles of break in on the clutch friction surfaces per the instructions, no hard shifts, nothing over 4000 rpm, etc.

Exedy markets the clutch as a racing clutch suitable for light track applications. HPDE events with a stock engine certainly fall in that category. After braking in the clutch I went to my first Track Day in America HPDE event at PBIR. FYI I have an auto blip installed to rev match the engine rpm during down shifts. My shift light is set at 6500 rpm and I never go over 7000 rpm redline.

Ten minutes into first session on track the clutch failed. I had the car towed to the shop who had just installed clutch. We were all shocked when we took it apart and found that the clutch disk had grenaded itself putting a piece of shrapnel through my transmission bellhousing. These are supposed to be SFI 1.1 certified clutches. The friction material was mostly intact but the steel disk plate was destroyed. It appears the rivets all sheared off the sprung hub.

Given the damage caused by the failure I cannot say with certainty what caused the disk to disintegrate. As a piece of shrapnel with enough kinetic energy flew out of the clutch with enough force to blow a hole in the bellhousing I can safely assume the failure was immediate and catastrophic. If not I would have felt the imbalance in the clutch assembly. Whatever it was it happened instantaneously. Much to my surprise I found the outer disk was made up of 8 separate segments of .041” thick steel equivalent to several sheets of paper thick. Note Exedy is made by Daiken, a Japanese supplier to the likes of Toyota and Honda. Now paper thin steel may work on a 150 HP Honda but not on a 412 HP Mustang. It appears that one or more rivets holding one of the friction disk segments to the sprung hub failed causing a chain reaction failure of the entire disk. Whatever the cause, this failure should not have happened.

Track events are different from drag racing. Shifts are not banged between the gears and the transmission is down shifted as well as upshifted and is done multiple times per lap. More to the point track events with upshifts and downshifts apply cyclic reverse shear loads on the disk rivets, the rivets under shear in one direction when upshifting and under shear in the other direction when down shifted. To have them fail in such a short time raises the question of the design, quality of the materials and processes used in assembly.

SVOGT302

Yikes, I'm planning on replacing my chattering/noisy Spec1 Stage One clutch with the Exedy Mach 5.... I will hold off to see their response.

SVOGT302

Any update?

crjackson

I don’t think the OP is coming back. I’d like to know how this turns out also.

SVOGT302

Looks like you are right, I hope he's OK.

dj050894

I would like to know how this turned out as well, hope the OP comes back with an update. Maybe a mod can send him an email?

I've had an Exedy stage 3 in my car for about 35K miles with no issues. I've been a big fan so far. I don't think they make the stage 3 clutch anymore though.