JBrown

Time for a clutch. I have a short bell housing 930 tranny with lower gears.
I have a clutch in there right now that is either in or out. One of those racing clutches.
I have about 400rwhp. I was thinking of going with an alluminum fly wheel.
What do you guys think and what clutch do we recommend. I want something that is more like stock but has the beef to hold the power. What do you guys think.
What are the positives and negatives of the alluminum fly wheel.
Thanks John

A930Rocket

Some guys line the alum flywheel. Others say it doesn't idle as well with it.

I would use a Kennedy Engineering Priducts (KEP) stage one or stage two clutch set up. Cost us the same. You can use a stock disk or their Kevlar dusk I think it is.

I've got 400 rwhp with a stage two and been happy with it.

911rudy

If you want drivability go with a clutch that is as close to the OEM that you can find. I was out this weekend and had to start on a hill at a light. With my OEM clutch I was able to slip it with very low RPM and ease off from a dead stop on a hill. The ON or OFF clutches are much more difficult to do that with. On the track they are superior. You have to decide where and how much time you will be using your car.

maxwedge528

i have a short bell 930 trans in a 71 911. the car has almost with 600 chp and over 550 ft-lbs torque. the 911 coupe weighs in at almost 2250 pounds. i use a KEP stage 2 pressure plate and a stage 2 organic disc. works well for me on the street. stage 1 is good for 530 ft-lbs torque and the stage 2 pressure plate is good for 615 ft-lbs torque.

Mark Houghton

I use a KEP stage 1 PP and Sachs spring centered disc to support about 375 HP. Feels really no different than the stock.

Guns951

I have a super light flywheel and if I clutch it from over 3,500 RPM it would stall each time, had to raise the idle to 2k RPM to keep it from dying each time I clutched. But it revs like a damn sportbike due to the super low weight of the rotating mass.

Peter Carroll/Toronto

I run a stock spring centered clutch with the material replaced by Kevlar. It is nice and easy on the street and has endured 8 years of track abuse without any problems.

I also have a lightened flywheel and 935 pressure plate (KEP I believe) on a RUF 5-speed (based on the 4 speed 930 transmission).

I have to say the combination of lightened flywheel/pressure plate is one of the single best mods you can do to a 930. Yes you have to set the idle a little higher. And yes it will stall more easily around town... But Wow what a difference it makes to driveability both on and off the track.

The 930 comes with a 50lb flywheel. You have to shift the thing in crazy slow motion or you will destroy your transmission in no time. With the lightened combination, you still can't speed shift, but you can do shift at a speed that feels natural. Fast enough that the car does not lose boost!

I just replaced all the bearings in my transmission after 8 years of hard track use. The synchros were still perfect! I used to go through synchros like water...

JBrown

Peter what flywheel are you using and how high do you have to set the idle.
Thanks John

Peter Carroll/Toronto

I don't recall if it was from KEP or if my engine builder did it. I run a 964 based engine so it may be different.

I think my idle is around 1200rpm. A fast idle is better for engine cooling anyway so it never bothered me.

I also have a lightened crank so I suspect that contributes to the free revving as bit. Probably not a lot.

The only downside to all of this lightness is the car can stall when you lift off the gas approaching a stop sign. You can compensate by keeping the clutch engaged until the last moment. It's a small annoyance.

Bottom line, if you have the transmission off, the lightweight flywheel and pressure plate is must do mod. The difference it made to the character of the car was a big surprise. And it paid for itself by skipping the next 2 synchro rebuilds.