Hello,

I am looking for a clutch recommendation for a 2004 Z06. The car is twin turbo'd and recently put 637HP to the wheels. The owner (sadly, not my car, I'm just the helper) is doing a lot of research but I feel he is caught up on the marketing side of it rather then the real world application testimonials.

With my research, I am suggesting a Textrailla clutch (though not sure on which disc).

The car is a street car but hopefully will make it to the track once I talk him into it (drag and maybe auto-x... perhaps the road course to play too).

He likes the feel of the stock clutch but knows he needs something to handle the power.

Which clutches/mods do you guys think would be required for our application?

Thanks!

- Greg

 

I like the Ram twin disk clutch. I have been running one in my Z06 for over a year now. The clutch is great and is the closest to stock I have found. With the stock disk the clutch will handle up to 900 ftlbs of torque and can us other disk for more holding power.

 

my cousin has the textralia clutch in his car (though it doesen't even have close to the hp your making) and it feels pretty nice, and i've never read any bad reviews for it. i would look into that if i were you.

 

Thanks for the quick replies.

I'm glad you brought up the dual disc clutch. I've heard that there may be an issue with the dual discs causing wear on the synchros in the Tremec due to the added weight. It makes sense that the extra inertia due to the extra weight could cause more work & wear on the synchros.

Thoughts on this?

- Greg

 

I did a lot of research and my new clutch is going in as we speak. I had a RPS clutch with aluminum flywheel. They are TOAST! In it's place, Textralia twin with the carbon/kevlar discs. Also replacing the throw out bearing and slave. I'll let you know how it goes. I'm just shy of 600rwhp and visit the track 4-5 times a year.

 

I have never heard of that. I do know that the ram twin comes with an aluminum flywheel to cut down on the weight. I figure with that it is not much heavier than the stock unit with a steel flywheel.

 

The lighter flywheel definitely is a good thing, but wouldn't help in what this issue is. The flywheel is connected to the motor while the clutch discs hang on the input shaft. When engaged, it is all one rotating mass. But when the clutch is depressed, the flywheel/pressure plate assembly rotate freely from the clutch disc(s) and input shaft. When shifting the synchros do their best to match gear speeds before the shift.

The problem as I understand it is unique to Corvettes because of the transmission being located in the back and all the extra weight of the super long input shaft.

It is hard to believe a clutch disc would make much difference, but apparently some Tremac builders are attributing worn synchros to the dual disc setups.

 

Have you considered the Cartek clutch? Feels like stock and will easily handle the power.

 

Centerforce Dual Friction 12" Clutch has been great for my Z06 for 30k miles with no problems at all. I'm at 557 to the wheels and it's still going strong. That 800+ RWHP Corvette that was in Vette Magazine last year is running the same Centerforce as I am. The pedal effort is the same as stock, but it's obviously alot stronger than stock.
I would atleast check it out

 

The input shaft is not that long. While the transmission is in the back of the car the clutch is still at the front by the engine. The actual weight supported by the input shaft is nothing more than two disk, and the floater plate. It is hardly any weight to be worried about. The most I could see it doing is damaging the couplers on the driveshaft, but most of those get ate up due to power and wear. I think what you are hearing about for these clutches is just a myth. I know many people who are operating with twin disk clutches without any issues.

 

I'm around the same power level and I run a McLeod twin disc wuth great results. I think compared to the other twins out there its a little more expensive initally but when you need a rebuild, and you will eventually need one, its only $500 and you have yourself a brand new clutch again.

I've used other twin discs in other cars and have to say the construction of the McLeod is top notch. They use two full face organic discs so the engaugement is super smooth with no chatter like you get with metalic discs. That makes it very nice for daily driving. Their intermediate plate are quadruple strapped with heavy duty bolts and dispite repeated low 1.5 - mid 1.4 60's hasn't broke yet. The pedal pressure is higher then stock which is to be expected to hold the amount of TQ these are capable of but its still very easy to drive on the street. I also run their adjustable master cylinder.

are some pics from the last time I had mine rebuilt to give you an idea of the construction.

 

I have a Exedy twin and I like it a lot, it is supposed to handle quite a bit a power, the pedal is slightly firmer than stock and there is not much chatter if any at all. The Tex clutches are also very good, you should most likely go with the Exo-scale Tex (might be mis-spelled) which is their twin. Good luck as I know picking a clutch can be a pain.

 

The support of the weight isn't the concern. The concern is the rotational mass that the synchros have to slow down in order for the gear speeds to match before it will shift into gear. If you take and bicycle wheel and spin it up to 20 mph then try to stop it by hand, it is fairly easy. Now do the same thing with a motorcycle wheel. It will be much more difficult. Having the driveline on the front of the trasnmission does create more rotating mass for the synchros to work with (as does any other rotational weight that is added to the front of the transmission).

I do believe in our situation, it likely isn't a concern because the amount of driving the car sees (not much). But it is a real documented problem. Check the back of the latest issue of Super Chevy. Their is an article by Rockland Gear (an authorized Tremec rebuilder). We have also spoke directly with Tremec and they agree that it is an inherent problem with the Corvette design. Not to mention that those who have upgrade clutches in their car are likely to be more spirited drivers. This could be why Tremec and Rockland Gear are seeing higher synchro failure rates with the dual disc clutches.

The fact is that if you take two identical transmissions and have one setup "normally" and the other setup like a Vette, given the exact same conditions, the Vette setup will wear out the synchros sooner. Any rotational weight removal off the front input shaft will increase synchro life.

Hmmm... that makes me think of something else too... carbon fiber driveshaft. We might have to look into getting one of them to help ease the concerns.

- Greg

 

Another vote for Centerforce Dual Friction. Holding my 525 RWTQ and feels better than stock!!

 

Interesting, it makes sense considering the additional mass would create more inertia. I will have to go and take a look at that article.

 

I love my Centerforce.!!

 

All theres is, is a LS7 clutch. And if I were to uprade, I would put a performance clutch in rather then a factory item. BTW I dont think they feel like stock. Ask RobZ, he just had one put in his car recently. When I was in his, it didnt feel like stock. Like a stock 07 Z06, yes. but not like an 01-04.

 

When mine is ready for a clutch I plan on going with the LS7 unit. Can't beat it for the price. All I plan for is about 450rwhp at most from this car so it should hold great.

I am coming from the cobra world where they were having alot of luck with Spec setups. Why isn't anyone running them in these cars? They were holding the 600+rwhp cobras all day long with great driveability.

 

If you launch the car, stay far away from the LS7 clutch.

Ranger

 

Not quite. You would be a fool to think that. Do you think just an ls7 clutch is going to handle RobZ's launches? Not likely. I don't have to ask his about his clutch, I have one myself. It does use the stock slave and master but if it can hold as well the aftermarkets then who cares. I got it for its ability to perform, not to put a part in that I can say is a "performance part".