I wanted to give a brief writeup on my experience with the Exedy Hyper Single clutch. N-Tech Engineering did a great job with the installation (thanks Ryan!) and it was problem free, something I haven't been used to with the local shop. I had no worries with these guys which is a nice change of pace. The old clutch had been an ACT Extreme pressure plate, OEM organic disk and a lightweight flywheel (SR Motorsports 9.5lb.). That clutch lasted about 70K miles including 25K with a single turbo installed. Daily driven. The Exedy's build quality is really amazing. A work of art and a shame that no one will be able to see it once installed. It comes with all the mounting hardware needed. The chromoly flywheel is SFI 1.1 approved and good for 15, 500rpm. The flywheel itself isn't flat on the backside but rather concave with material positioned where it's needed for strength and where it's not for lower inertia.

My initial impressions after rolling away from N-Tech were "wow, this is a lot different from my last clutch!" And that'll pretty much sum up my experience with this clutch over the initial 500 miles. Essentially what makes it different is the engagement window is VERY narrow compared to the stock disk. Pedal pressure actually changes as you swing through that engagement window. It'll go very light, firm up, and then light again as the clutch pedal approaches the floor. This lets you know where you are in the engagement range. Truth be told, I need to adjust my pedal a bit so that it engages sooner off the floor.

Modulation. When I first attempted to shift/drive away in first, modulation didn't exist. It took me about two days (I'm a slow learner!) to really be able to get away cleanly. It took me another two to be able to do it on a consistent basis. I probably managed to stall it quite a bit in the first few days. Anyone driving a puck-style clutch will be familiar with this Once I figured out the sweet spot for engagement, slipping the clutch a bit while rolling away from a dead stop became a no-brainer. In fact, I could probably take a passenger around for a ride and they would not know it was a 6 puck clutch disk. The driver on the other hand, will be well aware it's not an organic disk. Yes, once you're used to it it's great, but this is not your father's OEM organic disk. If you're the least bit hard core, it's a non-issue. If you'd rather be driving an automatic Benz, don't bother with this clutch.

Noise. The clutch makes an almost supercharger-like whine when you push the clutch pedal in at rest. Totally silent otherwise. Groans a bit at low, low, crawl speeds without full engagement. Shuddering is easily controlled.

Shifting. Shifting is in a different world compared to the ACT/organic combination. It's so much quicker which means you're out of the power much less. I think this setup would actually be worth a bit of time on a road race course. Power transmission is definitely "crisp" but not harsh. You are well aware it's a puck clutch. Snick, snick, snick. Very nice.

Power! I've managed to get a few boosted runs in around town. Holds the power just fine. Non issue. It holds the power so well I'm in need of much better rubber to put that power to the ground. Sure it'll spin in 1/2 2/3 shifts, but it'll spin coming into boost in 2nd gear, something it did not do EVER with the GT40 turbo (did it with the modified T78 I used to run). I'm convinced my clutch has been loosing its grip for some time.

The one thing I haven't been able to practice on is making hard, quick launches from a stop. This is mostly due to the fact it's season down here in Florida and your grandmother is clogging up the fast lane. I'm confident that with a bit of practice, quick launches will be fairly easy due to the fact you can modulate this clutch. Sure, it's a bit of an on/off switch but that's just due to the narrow engagement window. Once you learn to operate in that magjc window, things are very good.

There was a bit of conern over the weight of the clutch package as compared to my old setup (it's 2.5lbs more). My butt dyno seems to think I have a bit more low-end power than before. I believe the heavier flywheel makes engaging the 6-puck from a standstill a bit easier than with a lighter flywheel. Motor still revs like crazy but it "may" be a tad slower than before. Midrange seems very, very strong and boost seems to come on a bit sooner. It may be the mass is more centralized than the ACT. The cover/disk combination on the Exedy is identical in weight to the ACT/Organic which surprised me and brought a chuckle from Nick. He still thinks I'm crazy for spending $900 on a clutch. I'm sure the RPS (which i ordered initially) would have been very nice. I just couldn't wait til mid-December to get that clutch in as it was on backorder. In the end, I'm happy which is all that matters.

My only concern at this point is how long this clutch will last. The six puck has very little material on the mating surfaces (which helps to improve shift speed and keeps inertia low) and I"m wondering how well it'll wear daily driven. But only time will tell! If I had to do it over again, AND I had another $400 lying around, I would have gone with the twin plate as it's rebuildable. This clutch is not. Anyway, enjoy and I hope this helps people with their own clutch decisions. Unfortunately, I left my pics on the computer at work. I'll try to find them and post a few.

 

They are great clutches I have them on a few cars here, my only concern is the same as yours very, very little material.

 

michel.

thanks for the interesting evaluation.

i have 2200 miles on my exedy hyper single. i am hitting the road again tomorrow after reinstalling my motor. i loved the package from the first engagement. since i have had it out of my car 4 times this summer i have had a chance to keep an eye on it and wear so far isn't discernable. as to rebuildable... i will just buy a new disc when i need one. all components are available separately.

lovin it.

howard coleman

 

Thanks for the report Michel. And thanks for the initial research Howard. I can't wait to finally drive my car with the Hyper Single one of these days.

-Max

 

The twin is a little more slipable than what you discribed, but both are great clutches.

Edit: I had to move my SO's RX8 out of the garage last night and the pedal feel on her clutch was almost non-existent campared to my twin. Mine was more like pushing against the diving board at the pool in camparison.

 

I just went through the same exact experience, except with a t78. The clutch really bites hard, but after a week of driving it feels broken in and now it is nearly like a stock clutch.

Howard, where can I buy the seperate materials to essentially rebuild it. I was unaware they were available. I makes since though, I don't see why they wouldn't offer them.

 

Exedy's catalog, which is excellent as to engineering details, has a section near the rear entitled "Repair Parts."

literally every piece of the clutchset down to the bolts has a part number.

Exedy's direct number 800 346 6091 (Michigan)... they can send you a catalog and let you know what is in stock in the USA. you must buy thru an Exedy dealer.

i have no connection w them other than i really like their clutchset.

howard coleman

 

Howard, Exedy's own manual on the Hyper Single states it's not rebuildable. I suppose you could throw another disk in there if necessary but the flywheel and pp may be out of spec. It'd be fairly tough to resurface the pressure plate surface and get it square.

I've attached the PDF file on the Hyper single. I can't find it on their site any longer but it's some good reading.

 

as you probably are aware...

aluminum flywheels utilize a steel friction insert that may be "replaceable-rebuildable." often it is better and cheaper to replace a warped aluminum flywheel than attempt to install a new insert.

chrome moly flywheels do not use a friction insert and as such the flywheel itself will need to be replaced should warpage occur.

as previously mentioned i really like chrome moly flywheels as i value my legs and feet. aluminum is a great material for radiators.

as to rebuildable.... there is no difference between the twin and single. each unit is composed of parts and each part is available for purchase to renew the clutchset.

howard coleman

 

I'm aware I also put some serious miles on an aluminum flywheel with no ill effect to said flywheel. I believe it was SFI approved as well. I think for road race work, the aluminum stuff is better as it'll allow for a quicker revving motor. I think something like the Exedy w/an aluminum flywheel for roadrace would be just about perfect. For drag racing with heavy, sticky slicks, definitely chromoly.

Anyway, if you wear through the original six puck disk, it'll need to be replaced. If you replace the disk, the flywheel will need to be resurface honed (if there's enough material) to do it correctly as will the the pressure plate's surface (which would be impossible). I am assuming the pressure plate's mating surface cannot be replaced, but correct me if I'm wrong. So if you have to replace all the same items at once, you're purchasing a new clutch set! The twin disk stuff has intermediate plates which facilitate component replacement. It may be the Hyper single's flywheel and pressure plate stay true even after the disk wears out. But again, to do it right would require resurfacing or replacement. The pressure plate is an integral unit which I would think only a very, very skilled machinist could bring up to spec again. By machining the PP's surface, you're removing material and possibly throwing things out of whack.

Sorry bout the PDF file guys....guess it was too big of an attachment and it didn't upload. If you're interested in the PDF, send me an e-mail at rx7tt95@aol.com and I'll get it out to you.
Michel