Rattle and chatter are 2 totally different things. The twin disks rattle quite a bit when the clutch is pushed down (all of them, from Exedy to Power Enterprise to ATS) - its the disk movement.

Chatter on the other hand tends to be inherent to clutches with minimal to no springs on the center hub, as well as driving style. All of these units require a bit more throttle input when going from a dead stop than the standard OEM clutch.

Adam

 

"the RPS clutch supposed to be a single-disk carbon?

I'm thinking that might be a more affordable solution in comparison to the ridiculously-priced twin-disk clutches. "

I spoke w/ RPS a few weeks ago:

Currently,
RPS carries a Max 2900lbs PP and a street disc, 6 puck
sprung, and a 5 puck sprung (pentagon disc). Call
your nearest dealer to get one.
JT
PS: C/C Twin is in the works will release late spring.

--- "rpstc@sprynet.com"

JT said there is no such thing as a single carbon, it won't work. The one coming out in spring will cost about $4000.

The VR 4 guys, Brian Lafuente (GT Pro), Matt Monette (Dynamic Racing), Mike Mahaffe (Altered Atmosphere), all swear by Rob's (RPS) clutch. JT who works with Rob says to beware of cheap carbon/carbon clutches because carbon materials can vary as to their effectiveness and producing one costs a lot of money if the right materials are used.

I had a vr4 with the c/c and slipping the clutch did no damage to it and it was much easier on the drive line. It was nice because I could modulate the clutch with the RPM to keep the car between peak torque and HP. From a stop or rolling I could keep the tach at 5000 rpm and feed the clutch out. It was like a sling shot. 4 wheel burnouts whenever I wanted (Off the line of course).

It's drawbacks were extreme pedal stiffness and it made so much noise it was embarrassing. I had the occasional neighbor tell me to get my car fixed. It was a crunching/ groaning sound.

The clutch took it's toll at the track due to it's stiffness, maybe 1/10 of a second per shift.

 

Thanks, Wrench. I don't know a whole lot about clutches so I'm trying to learn as much as possible.

 

Just know what you are getting into.

See if you can drive one before you buy. Stiffness and noise can ruin the experience. Remember these cars get raves for the being user friendly.

Some one should make up a rating scale on noise, stiffness as close to stock, cost, reliability, #of evo installs, etc... . That would be a big help in deciding which one would work.

From what I've read, it seems like the Exedy is on top, but I've never driven one.

I don't know much more about them than you do. Each car is different.

 

There are many single disk carbon clutches from the Japanese firms, Exedy and others included, for the Evo. They are all sub $2000.00. To me, a single just does not have the driveability nor the power holding capacity many people need, so the twin becomes the natural choice - their only drawback is the pricetag.

As for the pedal feel, each of the twins out for the Evo - from Exedy, Power Enterprise, Cusco, ATS, Ogura, and others all have pedal feel very similar to stock. Reason is that by using increased friction surface area, they can decrease pressure plate clamp loads. These are all top shelf firms.

 

So Adam, which carbon/carbon do you prefer, ranking the clutches by the following criteria?

stock pedal feel, noise, reliability, cost, in that order, assuming of course all clutches can handle lots of high RPM slips with out degrading clamping ability up to say 4 or 500 hp.

 

Personally, I've found the twin plates to be far easier to modulate than any high clamping single plate I've tested. The only downside to them is the rattling when the clutch is disengaged. No biggie to most but some may take offense.

shiv

 

No clutch can handle repeated high rpm slips - this is a surefire way to burn ANY clutch, be it a 911 Twin Turbo, and Evo or a Vette. As with any other clutch, it's a matter of modulation, as Shiv pointed out. get the launches right, and these twins will easily hold 500 + hp at the wheels (some even more). get it wrong (ie excessive slipping) and you'll burn the disks and glaze the flywheel. Over time thsi will severely limit the lifespan.

I agree with Shiv as the twin disk driveability 0- as I have said all along,t he twins are MUCH easier to drive day to day than the single disk units, though you can easily get used to a single disk as well (the single tends to be a bit grabbier, whereas the twins are much smoother from a dead stop). Once the car is moving, they feel nearly identical in gear to gear shifts (1-2, 2-3, etc).

My preference is the Cusco unit, as I feel it combines the best mix of driveability, cost, and quality. We package these for $1549 shipped including an OEM throwout bearing and our stainless, coated clutch line. Exedy is a good unit as well thouhthe disks are not quite up to task as the Cusco carbon faced ones are (Exedy uses a ceramic-metal mix, Cusco is a carbon metal mix). exedy does offer full carbon fiber faced disks as well, ala ATS, but they are not offered for sale in the US, and the prices in Japan are ridiculous for them. I love the HKS one as well, as its quite easy to drive, nt overly nosiy, but as of 1/1/04, HKS items all took a price hike across the board to due the falling US dollar value. While it's still a great unit (it has not changed), at current pricing, it's a poor value (~$200 more than Cusco, not including the throw out bearing).

The pinnacle in clutch offering from where I sit is the ATS twin carbon - they are truly awesome units, can hold all the power (even in twin disk form) that any Evo can realistically push out, converts you to pull to push (nice for drag racing, not really a factor for any other type of driving IMHO). We sell the ATS twins for about$500 more than the Cusco. ATS also ofers a carbon faced single for about $1500 as well that we offer.

All the twins exhibit similar noise - whent eh clutch pedal is depressed, the disks rattle around a bit. Sounds sort of like "muted marbles in a cofee can". To me, if the car makes the power where the twin is needed, or the owner uses the car in situations where a twin is a good investment (ie road race) then this is aone of those small tradoffs and its totally worth it. Other than that, so far all the twins I ahve driven on an Evo have exhibited near stock clutch pedal effort, whcih is a primary reason for going twin.

Adam

 

The other big advantage to twin plate clutches is that you can shift the gears *quickly*. Whereas, the two high clamping single plates I've tried caused major grinding when trying to shift quickly. The one we tried on our 550+hp shop car was so bad that we had to reschedule our drag strip test for fear of destroying the transmission. It took the strength of a gorilla and the patience of a saint to row up and down the gears. From that day forth, I don't recommend or offer anything but twin plate clutches. I personally use the Cusco on our car but the Exedy clutches we've sold/installed work just as well.

Regards,
shiv

 

twins who doesnt want twins

 

well i've definitely decided that twin is the way to go, thanks for the very helpful information adam and shiv. you guys are great.

 

no sweat, and let us know if you need one..we got loads of the Cusco twins in stock and still on special

 

Considering some people have mentioned the retaining ring (??) popping off the pressure plate w/ some Exedys and HKS twin clutches, would you see the same problem happening w/ the ATS push-style clutch?

 

The ATS does not have this retaining ring that is attached to the pressure plate. Instead of having a fork PULL the retaining ring away from the pressure plate, it uses a fork and converter ring to push against the pressure plate splines.

 

Exactly.

And as for the Exedy I have counted less than 5 people this has happened to....I would not consider that to be a major issue at all and can be chaulked up to any number of possible scenario's, including just bad luck. I have never heard of it happening with the Cusco clutch, nor with the HKS clutch