mavila

iTrader: (58)

What does everyone running a high hp single use for a clutch? I've run a Centerforce for over 5 years with no problems whatsoever. A couple of trips to the dragstrip and probably nearly 100 track days (road courses) and it has held up fine. However, I've had stock twins putting out only about 300-320 rwhp. I'm guessing it doesn't have too much life left and may not be able to handle the 400+ rwhp I hope to have soon. Although the car is mostly a track car, I DO drive the car to and from the track and it sees the occasional weekend drive. What is working for people?

I have done a search and found this thread, which seems to be one of the more useful ones:

https://www.rx7club.com/showthread.p...hreadid=238440

However, I'm still looking for more firsthand reports, experiences, and recommendations. Thanks in advance, Mike

IRPerformance

iTrader: (41)

Centerforce won't wold up. Mine went out witin 5k miles of going single turbo. I would recomend the exedy twin disk if you can afford it.

FC Alex

I'm guessing you're building an all around car because it sees both drag strip and road course. Well the question you have to ask yourself first is do you want to slip the clutch of the line or are you gonna dump? If you decide to dump it make sure you have some braces, and welding done, or else your LSD may not live for long. I've always preferred slipping the clutch. You don't risk as much, the only real risk you take is burning up the clutch. I recommend either a twin disk or actually a 4 puck sprung clutch. Those are two good types of clutches you can use to slip.

Sponge Bob Square Pants

Don't go with Centerforce or you will regret it. You're lucky you haven't had problems in the 5 years of use. Generally they seem great for mildly modified cars, but when you start putting some serious power to the ground they destroy very fast.

If you can afford them, here are 2 of the best options for a street/strip car making big power:
Exedy Twin Plate
OS Gilken Twin Plate
(or triples)

r71

iTrader: (3)

I've heard the exedy twin plate gives you the grip, but feels like stock. It also comes with the flywheel.

Sponge Bob Square Pants

You've heard correct

BoostedRex

Exedy, OS Giken, or ORC twin plate clutches are the way to go. Nothing better out there from what I have experienced. But I know there are more experienced people out there than I. Please do speak up so we can get even more opinions. Laterz.

Zach

rex u.k

Or Cusco twin, same as Exedy twin and they come as pull type unlike the OS Giken which needs a n adapter and ends up costing a small fortune.

dvls-7

If budget is not really an issue, there is also the Tilton twin disc. It is a bit more, but im a firm believer in you get what you pay for.

spoolin93r1

i've got an ACT extreme s/s clutch that i bought from the rx7 store. it's lasted 20k miles so far and doesn't slip a bit. still holds good enough to give me 1.66 60ft times at the track. pretty stiff, but works great

mavila

iTrader: (58)

Clearly some of the single turbo owners here have deep pockets when it comes to their cars. I'm impressed - that's a decent showing of hands recommending a $1500 clutch. It's really worth the extra money? I was actually leaning towards one of the ACT setups at 1/3 the price. Other than cost, are there any downsides to something like an Exedy?

spoolin93r1

i've spents a crapload of money on my car and i still can't bring myself to pay that for a clutch. my act has lasted and proven itself. and it was only $500. trust me, you can't go wrong, unless you drag constantly

Sponge Bob Square Pants

It always comes down to money in the end.
How much power will you be making?
What type of driving/racing is it for?
How reliable and long lasting do you want it to be?
These factors can determine whether it really is worth spending the extra $1000 on a different clutch.

There's no 2 ways about it. If you want to hang with the big boys you have to spend the big bucks.

BoostedRex

Ease of driving is BY FAR better with a twin disc setup! I have had bad experiences with ACT clutches. I think that it was just bad luck for me though. I have seen several cars do great and last a long time with an ACT setup. But when my FD is finished, there will be either an Exedy or an ORC twin disc in mine. They are stronger, more durable, and much much much more streetable than a puck from ACT.

Zach

mavila

iTrader: (58)

For the ACT owners (and a quick search and perusal of the forum would lead one to believe there are a lot out there), exactly which ACT setup are you using for approximately what power level?

mavila

iTrader: (58)

Here's more food for thought. In my quest for knowledge and research on clutches, I cam across a very good article in Grassroots Motorsports on clutches and clutch selection ("Stranger Than Friction," GRM, April 2004). They detail some of the great benefits to a multi-disc clutch. However, they also point out the compromises.

"For one thing, the added friction surfaces and smaller diameter mean that multi-disc clutches wear out much faster than single plate clutches. Extended disengagement from street use will wear out a multi-disc clutch even faster because of radial clearance between the posts and the floaters. When the clutch is disengaged, the floating plates rattle against the posts and wear out."

Other quotes: "If there is a synchronized transmission behind the clutch, it is very difficult to use a multi-disc clutch successfully."

"You should avoid multi-disc and large diameter clutches on a street car or a race car with a synchronized transmission, unless you have no other choice." A car with a dog-ring transmission, like a Liberty or a Hewland box, can use any clutch successfully, since there is no friction involved in changing gears."

Comments anyone? Anyone espousing the Exedy actually have one on for any real length of time?

maxcooper

Mike,

Take a look at the Exedy Hyper Single, too. It is a single-disc clutch with a construction that is similar to a multi-disc (app-specific flywheel, forged alum clutch cover). It uses a sprung disc with pucks. It should hold a lot of torque (pucks), with reasonable pedal effort (cover design & stiffness), lug along okay (sprung hub), and the engagement is supposed to be streetable though surely it is at least moderately abrupt considering it has pucks.

Howard Coleman and I both bought these clutches recently. Howard has his car working now and I think he is pleased with it. They can be found for ~$900, which isn't too bad considering you get a light steel flywheel as part of the package.

-Max

DCrosby

I bought the whole chebang from SR Motorsports... they cut me a deal, can't say I'm unhappy with them, can't say I'm impressed either...

Anyway back to the clutch, It's an ACT Street / Strip Clutch, with an Extreme Pressure plate, and lightened flywheel. 8.5 lb + counterwight or something....

I bought it with the intension of running, up to 500 RWHP, and they said that the extreme plate holds 650. So I figured that would put me in a 20 % safety margin since I have lowered my expectation since then down to 400-450. Since I still am working on my single I can't comment on high HP wear and tear, but it holds well, and is very streetable, allthough it does take more pressure to push the pedal, which makes L.A. stop and go traffic a Pain, but only if it's severe....

mavila

iTrader: (58)

Max, thanks again for your input. The marketing description for that clutch reads, "The EXEDY HYPER SINGLE CLUTCH is a new generation clutch set for light to moderately tuned vehicles up to 400 HP. The EXEDY Hyper Single Clutch is ideal for limited street driving and road circuit cars."

I know you do your homework and are very technical, so I'm wondering why that first sentence doesn't give you pause. I think we're both hoping for rwhp numbers north of that soon . . .

96Rx7

I got the OS Giken - twin plate. It's good but a bit hard if you are in traffic.

XSTransAm

I have been using the act heavy duty pressure plate setup for my car running 300whp with no problems... clutch feels great.

I just got the act setup with the heavy duty pressure plate for my single turbo setup as reccomended by my friend at act. Its rated for 450lbs of torque and isnt gonna grab and shake your teeth like a puck clutch will.

Mike

maxcooper

I am aware of the 400 HP published rating (400 or so TQ, really). My understanding, based on rumors of a conversation someone had with an Exedy engineer (how's that for rock-solid proof! ), is that the actual capacity is around 600 ft-lbs.

Perhaps you do need a 600 ft-lbs capacity clutch for a car that has around 400 ft-lbs of torque (which is more than a 450 RWHP RX-7 has anyway). The momentary torque the clutch must hold on a hard launch or shift is greater than the engine's torque rating, for example, since the momentum of the rotating assembly adds its own contribution. The Exedy rating may be a dynamic rating of "if your car has 400 HP...", where the ratings other clutch companies publish might be the simple mechanical limits of the clutch (will hold 400 ft-lbs... but will slip if you drop the clutch on your car with 350 ft-lbs, since the momentary torque will be greater than 400 ft-lbs).

-Max

XSTransAm

I meant to say i just got the extreme pressure plate, lol

part - XT00

FB II

damnit, you guys are lucky. i dont know what clutch to get for my turbo fb. :/ damn 12a motors

LETHAL RX7

iTrader: (1)

Im switching to the exedy twin disc sprung hub. I have a heavy act with a cintered iron disc and nothing will slip it but it is a paaaaain to drive. the metalic disc that was in the car was fine to drive but it slipped on the dyno. One thing to consider is when picking a clutch. figured the TQ or HP at the crank bc thats the HP or TQ that the clutch sees not the RWHP.
Greg