i have previously posted much of the following but felt, based on my recent experience (600 miles) w the clutch package that the info was sufficiently valuable so as to deserve it's own thread. i have no commercial relationship here... 'just trying to be helpful


exedy is the racing division of Daikin. Daikin does over a billion $ in revs selling oem clutches/drivetrain parts to little known companies like GM F Toyota Mazda...

Daikin makes the rx7 pressure plates that others (ACT etc) mod and sell in the aftermarket.

Exedy is essentially the R&D arm of Daikin. i unfortunately know this because i spent too much time looking at clutch package options for my engine package that will running shortly.

options narrow greatly when hp heads north of 450 rw.

you either generally retain drivabilty (you can slip the disc) w an organic disc and then shred it or you give up drivability ( clutch is either engaged or not) and have a non-slipping clutch.

lousy trade off as you have already gathered...

i looked carefully at double discs, having run a Tilton during my road racing career. when i say looked carefully i mean i called and talked extensively to the engineering people at many of the clutch outfits.

i was already to buy an ACT XT pressure plate and organic disc but Judge Ito, my engine builder, said the pressure plate wouldn't hold my motor, something he had proved less than a week prior.

i talked to kevin fujioka, head tech guy for exedy in michigan. he pointed me towards the Exedy Hyper Single. it is a super cool design... very similar to a double disc in the sense that the cover is forged aluminum and sits on 6 pedestals. the forged cover allows exedy to alter the lever ratio and deliver a clutch that will hold 600 ft pounds of torque w near oem pedal pressure. the back of the pressure plate has cooling fins cast in it for air flow. because it is not encapsulated in a pressed steel cover you do get airflow. the flywheel is chrome moly steel something i really like. i have this thing about exploding cheesy aluminum flywheels and my legs. the disc weighs the same as oem so shifting is easy on the syncros. the disc has 6 big fat springs in it which should help the driveline. the material is a Daikin designed/patented cerametallic. due to the nature of the material there are no rivets which remove material surface area. kevin fujiyoka says that the engagement of the Hyper Single is much easier than their twin disc.

sounds pretty good......... we will see in a week assuming Judge Ito gets my motor together thursday which is looking probable. i did find a forum member in the U K that runs the Hyper Single. he said the pedal was virtually similar to stock...

i will report when i actually know.

the good news is that the package is reasonably priced. i bought mine thru morepowerracing everett wa for. get this, $887. (that of course includes the flywheel). you will need to talk to neil and mention my name to get that price. they advertise it at $987.

the bad news is there may not be many in the country and Exedy's U S facility in Mich ships them in by boat. 90 days...

exedy mich 734 397 6607 Tricia is the go to person and is aware of U S inventory.


THE ABOVE WAS WRITTEN A FEW MONTHS AGO/////

as of july 8 i have over 600 miles on the clutch and it is absolutely AMAZING! very close to oem pedal and it engages smoothly! i often forget it isn't your basic oem unit which, considering it is a 6 puck cerametallic, is way beyond my most optimistic hope. all that and it holds 600 ft pounds.

wow do i love the Exedy Hyper Single.



howard coleman

 

a couple of my drifting guy friends use the hyper single and like it alot! if you got the money get a hyper twin

 

unlike the Hype Single, the Hyper Twin has no springs and uses carbon. Kevin Fujioka says the engagement is more harsh. Kevin is a developmental engineer for Exedy.

obviously the Twin will work better in some applications.

my point is that the Hyper Single will hold the torque, not shread, and is drive-able.

it is very reasonably priced given that it is a completely differently (forged aluminum vs stamped steel etc, etc)designed clutch than the usual garden variety that many use...

howard coleman

 

Thanks for the report. Off hand do you know the weight of the flywheel?

 

We have one on one of our shop cars here it isn't bad, there was very little material on it though.

 

Howard, you wrote me on the Big List a while ago when you published this. I had already gone with the ACT Extreme. It's slipping a bit, just as you said it would. I'm going this way next time (with the Howard discount, hopefully). I'll just take this one until it wears out, then dump it and the SR light flywheel and get this setup.

Thanks for publishing.

Beast

EDIT - I wonlder what Xcessive (Ralph) uses on his monsters? that new unit he has in insane....

 

Might as well just get the twin disk. Works great and also feels very streetable. Its one of the only clutches that will hold single turbo power and feel close to stock. I've installed two twins, both had sprung disks so it may be an option.

 

The website lists the weight as 12lbs, but doesn't specify whether that includes the counterweight (I assume it does since they do note that one is required).
http://www.coximport.com/exedy/flywheel.html

 

i did weigh the unit before installation:

stock flywheel, pressure plate and disc is 35 pounds.

Exedy unit is 25 pounds but you need to add the counterweight which i forgot to weigh. what does the CW weigh?

components:

stock flywheel 20
exedy 12... (CW needs to be added)

stock pressure plate 13
exedy 10

stock disc 3
exedy 3

as per my digital scale.

howard coleman

 

The CW weighs about 4 lbs, perhaps a tad more.

I weighed my Hyper Single, too. I got 27.0 lbs for the flywheel, cover, disc, and all the hardware, including the bolts that hold the flywheel to the counterweight. So I figure the whole thing is just over 31 lbs with the counterweight.

I haven't weighed the flywheel from the Hyper Single separately since it came assembled (cover, disc, flywheel).

My car is still apart, so I don't have any feedback about how it works when driving. I am very encouraged by Howard's report, though, since I have been worried it will be a bit grabby for street driving.

-Max

 

For a moment, I thought howard was Max Cooper, the Weigher of All Things Automotive, Keeper of Measurements, Master of the Scale. Then Max jumped in, and all was right in the world again.....

Max knows the weight and airspeed of an unladen sparrow, African AND European....



Either one looks good, and I'm willing to give up my 9.5lb flywheel to get some f'ing grip.....

 

Max,
so when w your car be making noise? (i know it is off topic but we all want to know)

howard coleman

 

My short block is assembled. I am really just waiting for my turbo kit to arrive. My new goal is to have it running again by SevenStock (Sept 10). I really hope to have it running much sooner, but I haven't made much progress in a long while.

-Max

 

I put the Exedy Triple disc in my cym. Very streetable and yet takes a pounding. A bit of chatter, but no biggie.

 

I am getting the twin plate sprung unit, after felling the petal in the car Steve Kan drove for the SCC street car challange

 

If you want a REAL badass clutch, buy a ORC clutch from Japan, that's what they use on GT cars. I think it's like a $1700 twin plate clutch and flywheel combo, and that's good for 700hp, and the triple plate and flywheel combo is like $2200 msrp, and it's good for over 1000 hp.

 

The Exedy is good for the same Hp

 

I have the orc triple in my 20b fc. It holds very well and isnt that bad to drive with in traffic. I'm pulling my car apart this week and sending the clutch to my friend in AZ. I have an ATS carbon triple in the other room that is going in the car.

-Destin

 

I'd be interested in your impressions of the ATS carbon. Be sure to start a new thread when you have some info.

 

ErnieT
what clutch combo do you have in 10sec car?
and how streetable is it?

 

^^your 10sec car ^^

 

In that car I had the ACT 6puck w/ the extreme pressure plate. It was fine for the street for me. But opinions vary on streetable.

 

I pulled a customers engine yesterday and found it had the exedy twin plate clutch. I was suprised because we always thought when he bought it that it had a single plate clutch it was quiet not on/off in it's operations very smooth especially compared to my hks twin plate.
I will definitely get a exedy twin next time round.

 

I am wondering why the ACT Extremes are not working for people? Has anyone had one fail prematurely that does NOT drag race? It seems to me that even if the claimed 537ftlb rating is optimistic by ten percent, that is still far more torque than all but a few members generate. I have the Extreme with an FD disc in my FC currently, but I was only making ~300ftlbs before I began my new project(bigger turbo/huge road race slicks). I was going to go to the 6 puck with the Extreme plate. I am trying to figure out if it is drag launches that are killing these clutches, or if they simply cannot hold the claimed power. I think this is especially strange since the ACT HD PP for a Supra(not even the extreme) is capable of holding ~750ftlbs with a bronze 6 puck(not ACT) I know the clamping forces are different, but if the plate for the Supra can hold that much torque I think it is very strange that these are failing at such relatively low torque numbers. Comments? I am going to try to get the manufacturer of the Supra disc to make one for my FC, we shall see... Carl Byck

 

Man, that's a damn good price on the unit - it's barely more than a "normal" clutch and light flywheel.

Any pictures of it?

How's the flywheel for driveability? Dunno if you've driven "standard" aluminum flywheels before - they're pretty easy to drive, really. Does it rev and feel basically like an aluminum flywheel?

This is also a pull-type clutch like stock, right? I've seen some multi-disc clutches that had hardware to convert to a push-type clutch.

Good info! Thanks!

Dale