Think you got clutch problems?, Have you seen this, Brad? Options

[meursault]

I occasionally help out with this 914 racecar that's putting out 400+ horsepower, normally aspirated. Either the motor or the driver has found a way to blow apart just about everything involved with putting that power to the wheels. Recently the car has been having clutch problems. Factory race clutch packages which supposedly handle 500 horsepower aren't cutting it.

The car was at Fontana this weekend. I was about to go up to join the race crew when I learned that the car broke...again...so I stayed behind and helped when the car came back.

Here's what awaited us as we began to investigate. Hmm, clutch is stuck in a state of engagement. Spline area of the clutch disk sits askew. And what's that copper stuff trying to poke out of the clutch package at the lower left?

[TMorr]

Marc,

Yes, it is Hayden. The PTBT is just the abbreviation for Pretending To Be Tracey, my partner at Windrush, who is actually the registered user on this Forum.
The racing clutches designed for the type of cars we are all involved with are all (well mostly) push center style.
The CART cars and F1 cars use even smaller pull center clutches - but their release mechansim and bellhousing is all so unique, the application is not likely to filter down to club level cars.
A pull center clutch can be built more compact as the diaphram spring is edge pivoted (around it's perimeter) rather than a rocker style pivot, used in the push center clutches.
I have heard of an AP club level clutch, similar application to the Tilton's, that uses a pull center, but I have not had one to look at. It would be a standard pattern 5.5"Ø 8 bolt pattern for uniformity, of that I feel confident.
The 915 bellhousing is designed for either push or pull center clutch. The 911's all used pull center and the 912E used a push center. Our WEVO cable release mechanism set-up is a more refined derivitive of the 912E set-up
The packaging is so tight for length that we could not make a 3 plate set-up for the 915 without it being considerably more costly and probably hydraulic. However, the CWP in a 915 and other internals are not likely to accomodate anything above the torque capacity of a 2 plate clutch, so it's moot.
We have packaged a 3 plate Tilton 5.5"Ø carbon clutch in a short 930 bellhousing, that was tight, but we can do it. All the clutch parts are sititng on the bench, but we have not manufactured the very unique hydraulic release mechansim parts. In that case the motor, transmission and clutch are all about the same capacity - upwards of 600 ft/lbs of torque!

Regards

Hayden PTBT