Kevlar is Not Bullet Proof

by on Dec.13, 2010, under Daytona

2010-12-08_19-58-35_467The TU Kevlar clutch that I installed back in ’06 failed. It had been slipping for a few weeks, but it was holding as long as I didn’t go over 5psi of boost or so. Eventually any boost would make it slip, so I broke down and replaced it with this one from SPEC. It is their “Stage 3+” which has a full-faced ceramic-type disc with a supposedly-modified pressure plate. The pedal feel is just like stock, so I am skeptical about that last part. It holds well, but the real test won’t be until the summer tires are back on.

The Kevlar clutch was very chattery, especially while backing up. If I tried backing up a hill, the motor would practically try to fly out of the engine bay. I also experienced a bizarre problem on two occasions where I could not release it. This was in heavy stop-and-go traffic. I suspect the disc warped because it started working again once it cooled-down. I expected better longevity from the Kevlar lining. It should have lasted much longer than the 35k I got out of the ceramic puck clutch in the CSX, but it failed right around the same time. It did have a stock-like feel in terms of engagement. As long as the RPMs were high to avoid the chattering, the engagement was smooth and easy to manage.

The SPEC clutch is “grabby”, just like you would expect from a ceramic type, but not “chattery”. In other words, the pedal has a very narrow band in which you can slip it especially at low RPMs. When you do slip it however, it does not chatter or at least not very much. Backing up is not a problem, other than avoiding a stall. The Kevlar disc had a lot of run out form the sloppy spline and that may have contributed to the problem. The SPEC disc was tighter, but still had some run out.

While the clutch was out, I replaced the 3-4 shift form pads again. I also replaced the fork. I noticed the new pads on the 1-2 fork were also starting to crack, right over the groove carved into the fork while the pads were blown 2 years ago. So I replaced that fork as well with another good set of pads. I also swapped 3rd gear and its syncro with another used one that looked better. It’s nice to have 3rd gear again.

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