Clutch Brand/Longevity

Kevin Butler · **Posted:** Thu May 01, 2008 9:58 am

I removed the clutch from my buggered track car engine last night to put on the replacement motor. I got concerned by the material thickness I saw so I contacted the manufacturer this a.m.

Spec Stage 2+ clutch
Torque rating: 300 ft-lbs
Friction Material: Kevlar on one side, Carbon Fiber on the other.
Original Friction Disk Thickness: 0.310"
Current Friction Disk Thickness: 0.293"
Permitted Disk Wear: .020" - .025"

That leaves me with .003" - .008" of life left. Let's assume .003" for worst case. I've got 20 events on the clutch - no ideas what mileage that represents.

.017/20=.00085" wear per event.
.003/.00085=3.5 events remaining.

Since the motor is out I think I should definitely replace the worn component(s)

Do I A) replace just the material disk? B)replace the whole clutch?

Is this kind of life comparable to what some of you other guys are getting? The car is only putting out ~180 ft-lbs of torque, but it does get used hard 100% of the time.

If this is a crappy life span, what clutch products have you guys had good luck with?

TIA

DickRasmussen · **Posted:** Thu May 01, 2008 12:31 pm

Do you know whether the disk material wears in a linear manner versus the first wear is more like smoothing the texture?

How much do you slip the clutch? i.e. lots of slip to keep the revs up or too much slip when shifting due to too slow release when letting the clutch out (relative to the rpm change that the clutch must force to happen if the revs aren't matched)?

Do you double clutch downshifts or at least "match revs" before releasing the clutch? If not, that makes for more wear.

Any signs of overheating the disk or the flywheel/pressure plate?

Check the "flatness" of the pressure plate and flywheel. They tend to wear "bell shaped".

Dick

Ryan Holton · **Posted:** Thu May 01, 2008 1:24 pm

Kevin Butler wrote:

what clutch products have you guys had good luck with?

TIA

ACT

If they can make something a DSM can barely break, its tough stuff.

Kevin Butler · **Posted:** Thu May 01, 2008 1:28 pm

I had the flywheel lightened and resurfaced at T Hoff. After installing flywheel and clutch, I drove ~300 miles around town. Then I went to the Feb Tarheel HPDE. When I stopped in Durham to get fuel, there was substantial smoke coming out from under the car.

After that, no more smoking. The clutch has always performed great. No complaints. I shrugged off the smoking at the gas station as "break-in" phenomena, since they recommended 500 mile break in.

I'm not much for slipping the clutch. I go ahead and let it out. I do heel and toe with a matching blip. I like to think I'm pretty smooth with H&T since one instructor did ask me if I had H&T'd for a hard braking zone. However, I have barked the tires a time or too under the same conditions.

I was kind of tired last nite when I was looking the clutch/flywheel over, but nothing jumped out at me. No discolorations or wavey appearing clamping surfaces.

Aaron Buckley · **Posted:** Thu May 01, 2008 2:20 pm

I know a lot of people who have had good luck with ACT clutches also. That being said, I would likely replace the entire clutch instead of just the disc. Pressure plate, throwout bearing, etc. considering it's out and easy to get to, and will give you good piece of mind. - AB

JamesFeinberg · **Posted:** Thu May 01, 2008 3:11 pm

I had an ACT clutch in the old turbo Miata for awhile and although I can't remember exactly which one. It was definitely one of the heavier duty ones. It never slipped but the pedal pressure was a touch obnoxious on the street especially in stop and go traffic. I never noticed it much unless I had just hopped out of one of my stock Miatas but more than a few people commented on it after driving the car.

I eventually replaced it with a Star brand clutch (at least I think that was it-- I can check for sure when I get home) and while the pedal effort was near stock and it never slipped either, it was ultra grabby and I hated it for the most part. Starting with that clutch on a big hill from a dead stop was always interesting and most people who drove it stalled it on the first try at pulling away.

Jim

Karl Shultz · **Posted:** Thu May 01, 2008 4:00 pm

ACT. I had two of them in a row in the old Integra, and the second was only because I already had the trans out to install the LSD. It was tough, streetable, and not all that expensive either.

Bernie Baake · **Posted:** Thu May 01, 2008 5:41 pm

Kevin Butler wrote:

Do I A) replace just the material disk? B)replace the whole clutch?

B) replace the whole clutch!!!!!

Adam Ligon · **Posted:** Thu May 01, 2008 11:27 pm

Agreed replace the whole clutch, otherwise you are going to see reduced performance from the set up with a used presure plate. It may also fail long before your new disk does.

As for brands, I have seen way too many SPEC clutches fail when pushed hard, so cant recomend them at least in their VW/Audi fittments.

I am out of the loop a bit so what is this set up for? becuase even with my caveat about SPEC above many brands may make good clutches for one make and not so much for another.

Jason Mauldin · **Posted:** Thu May 01, 2008 11:42 pm

I've had good luck with ACT and Centerforce clutches.

I ran a clutchmasters in my Talon. The first one failed within 2000 miles, but they replaced it for free, I don't remember the failure, but I consider that to be good customer service. The replacement lasted up until the point that I did some additional HP mods and overpowered it. I don't remember the mileage and can't really fault it for failing under those conditions.

My current clutch is a Centerforce, and I've had it going on 4yrs and ~25K miles now. I'm not exactly putting a lot of power through it though.

And I agree with the other guys. Replace the whole clutch.

Kevin Butler · **Posted:** Fri May 02, 2008 12:35 am

At present, it's a track only car in SM2 trim. It could become my next autocrosser as well. Hell, the way fuel prices are going up, I may have to start driving to events again.

I took a closer look at the components tonight. The pressure plate is bronze, black & brown in streaks with a wavy surface. The waves are annular, as if you threw a stone in a pond. I'd say it got really hot.

The flywheel feels smoother, definitely no annular waviness to it. It does seem discolored, but it's a light bronze, blue. I don't think it got as hot as the pressure plate. I tried to see how flat it was, but I couldn't find any thing in the tool box that I thought was flat to begin with. When I set a cheap Harbor Freight cast aluminum angle from an adjustable ruler on it, it wanted to rock, regardless of orientation. I feel like I can see 3 lower spots about 120 degrees apart from each other on the flywheel surface.

Both surfaces on the clutch disc are really smooth. When you compare it to a stock clutch, there are no grooves left in the pads, but you can see faint ghosts of what was there and their sufaces have a glazed appearance.

From appearances, this thing got really hot and I'm pretty sure it was from when I took it on its first long trip 2 years ago from Greenville to VIR. And it's difficult to understand why. It was continuous engagement most of the trip. I went through Durham before stopping for gas and seeing the light smoke. I really don't think it possible to slip the clutch enough to generate enough heat to cause smoking. It's not like I hadn't driven a straight drive before.

Regardless, I think it's amazing the clutch still works as well as it does. I'm wondering if the flywheel didn't get resurfaced when I had it lightened. I can't help but think there must be something I did wrong regarding the install but I don't know what. It was my first clutch. I just bolted it in, felt comfortable about what I did and it seemed to work fine.

At 3 hrs driving time per event, 20 events we're only talking 60 hours of track time. I can't help but feel that's pretty disappointing. I need to learn from what ever mistake I made and avoid repeating it.

Since it seemed to work fine before I yanked the motor out, maybe I'll just keep running it until it lets go. If it lasts longer than I think it will, maybe that will prove it recieved the heavy damage early in it's life.

MarcusMcRae · **Posted:** Fri May 02, 2008 9:38 am

FWIW a lot of the people on the bimmerdouche forums complain about spec clutches sucking.

I am getting ready to give a clutchmasters kit a try.

Kevin Butler · **Posted:** Fri May 02, 2008 9:59 am

I've been lurking around Miataturbo.net lately. They did a group buy with Clutchmaster not too long ago. I don't think anyone is happy with them.

MarcusMcRae · **Posted:** Fri May 02, 2008 10:16 am

Kevin Butler wrote:

I've been lurking around Miataturbo.net lately. They did a group buy with Clutchmaster not too long ago. I don't think anyone is happy with them.

Great.

Which version were they complaining about?

Kevin Butler · **Posted:** Fri May 02, 2008 10:19 am

Talked to Spec again this a.m. and described my observations to them. They said I would definitely see the heavy discoloration on the pressure plate. If the flywheel surface had not been properly prepared, I would have experienced chatter. So in a nut shell, all the conditions I have observed seem normal. Except for the rapid wear.

Needless to say, I'm pretty disappointed with the lack of life I got out of the Spec clutch. I guess it's time to pony up for an ACT.

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