The clamping force of a stock clutch setup would be fine on your car with a set of stock tires. If your clutch is fully engaged and your power is fully engaged, the wheels will spin before the clutch slips. This is providing that you haven't damaged your clutch before hand with improper engagement.

I have raced for 30 years and many cars included boosted engines with stock clutches alot less quality than the Porsches, and more than 700 rwhp. Your clutch will not slip once engaged. When you down shift hard and engage the clutch, do the revs on the engine go up abruptly or does the clutch slip? There is a lot more torque to the clutch on an hard downshift than you could ever get on acceleration.

If you are blowing clutches, it is happening somewhere in between unengaged and engaged.

 

Sorry you are incorrect here. We have done it many times and it is no fun when you are on the dyno making a run and it starts to slip. It does and will happen depending on the setup. I don't think any one is arguing the fact that if you are not released and hit boost at all it is gone. The fact remains that clutches can and will slip if you have a) wrong type of material on the disc b) not enough clamping force. While I may not have been racing for 30 years I too have been doing this for a while.

 

Any reason not to use the Sachs disc and pressure plate with the stock flywheel? I like heavy flywheels in a daily driver.

 

Thank you for the response. However, I will say that my statement does not come from reading ads/magazines so much as it does from working with modified turbo cars over the years. I have seen clutches come and go when more hp and tq is added only to realize that the stock pressure plate couldn't hold. I was only taking an educated guess on what the clutch on the 996TT could hold based on what other users on this forum seem to be experiencing. Obviously my guess was wrong. Thank you for providing me with a more inside look into the stock specs of the turbo's clutch.

 

No, that would be fine.

 

My clutch started slipping the second summer of driving the car. It made no sense to me. I would only hard launch it from a stand still 15 or 20 times per day. It went at about 25,000 KM.

 

The Turbo's clutch seems undersized, less than 9 1/2" disc diameter. This is about 2" smaller than an American car with 400 ft. lbs of torque would have. It takes a premium clutch with a lot of clamping force to compensate for the small diameter.

 

Stephen,

The stock clutch works on mine. It must be your driving habits.

This is a stock Porsche clutch, isn't it Stephen?

 

LOL, Um sure..right Chad. Maybe if my stock clutch had looked that my 4th gear pull on the dyno would have not shredded my clutch.

BTW, the 2 disc system is not the friendliest clutch on the world to drive on the street!

 

A slipping clutch is the result of torque being applied to it which overcomes its clamping force. I believe the stock clutch is only rated at 500lb/ft torque.

The simple truth is that once you exceed the clutch's clamping force you will BURN IT. It doesnt matter which clutch you have or what driving habits you have.

Granted, bad driving habits just accelerate the wear of the clutch, but if your engine is too powerful for the clutch, it will slip.

 

CJV,

That's a beautiful thing. What is that rated at? 1200lb/ft?

 

Very well said Victor, I could`nt have put it better my self.

Neil

 

So the general opinion is that I "might" have too much power/torque for a oem clutch. I have right under 500HP. I know it isn't from bad driving habits, I am very carefull on the street. I don't drag race, ever! The car does see the track on a regular basis, down-shifts are common.
My decision is not to go with the Sachs, and stay with the dealer for the work.
Thanks.

 

The clamping force of the stock Porsche pressure plate is more than enough regardless of HP. If you have burned the clutch, pressure plate or flywheel due to improper engagement of the clutch, then all bets are off. But assuming the clutch system has not been ruined:

If you have a huge amount of power in the engine, your wheels will break long before your clutch even is tempted to slip. There is little chance a clutch will slip with ANY amount of HP even if you are driving on some obscenely large slicks. You are more likely to twist a shaft or axle before the clutch. If a good stock clutch is engaged fully, IT WILL NOT SLIP AT ALL, no matter how much power you are pushing through it. Your weak point is the tires.

The only benefit a better pressure plate has on a powerful car is how quickly it will get the plate to clamp down against the flywheel. Once it is clamped, it is clamped and will not move. If I replace my clutch, it will be with the stock setup.

 

You can't be serious with a statement like that??? Please.. tell me you are joking?

I think you better re-read what you wrote...

All clutch/pressure-plate combinations are rated for a specific torque/hp application. You start at stock, up to kevlar/carbon, carbon/carbon, etc, etc. Each material provides different friction ratings which affects how much power they can take before slipping. Basically, as the clutch gets hotter, its effectiveness goes lower. If you are running an underrated clutch, it will slip when it is heated up.

By the way, before the power makes it to the ground (to the tires), it has to go through the drivetrain (clutch/flyweel).. The clutch WILL slip before your tires break lose.

Why do you think guys on this board running 650hp, 700hp, 750hp are forced to run twin-disk, or carbon/carbon clutches??

Do you think the CGT with 627hp would work with the stock 996TT clutch? Obviously not otherwise Porsche wouldnt have gone to all the trouble of putting that hair-trigger carbon clutch in there.