Modified 944 Turbo Clutch Choices

cda951 · #11

Good info about the Centerforce clutch, that could be my next move.

My 951 with 930 sport disc and stock pressure plate and lightened stock flywheel (about 5# lighter) is still holding well over 300 lb-ft of torque (probably close to 400 lb-ft at 19 PSI) after ~15K miles but I don't expect this to be the case forever . . . .

Darwin · #12

Tom wrote: Thu Dec 26, 2024 7:50 am
Bill wrote: Wed Dec 25, 2024 3:27 pm I put a Centerforce clutch in my car at 68k miles. The car now has 120k miles and the clutch is still functioning like new. My car has an 8 lb lightened flywheel and dyno’s at 380 rwhp with zero chatter or slip. The Centerforce pressure plate is quite unique as it has weights that fly out as RPM increases which increases clamping force on the flywheel (check their website). So the net result is the clutch pedal requires less force on your leg when applying, but increases clamping as rpms increase. When I purchased the clutch & PP in 2002, Centerforce rated the clutch to 700 hp, yet as I stated the pedal effort feels just a little bit firmer to apply than the stock 951 clutch. I do not know if Centerforce still makes this clutch for our cars, but I will definitely check when I eventually need a new one, as it has been a great clutch.

Hard to know if they are still the same, but I can vouch for the clutch in your car. It felt every bit as smooth as stock. With these cars, I think the key is to add clamping force to the pressure plate but stick with stock-like friction materials on the disk.

@Tom What is in your 951 right now? I have a southbend modified factory PP with a factory disc that was relined by them with "better" material. I am less than happy with the driveability. It isn't horrible but I'd much prefer smoother engagement characteristics.

Tom · #13

Darwin wrote: Thu Jan 02, 2025 8:03 pm
Tom wrote: Thu Dec 26, 2024 7:50 am
Bill wrote: Wed Dec 25, 2024 3:27 pm I put a Centerforce clutch in my car at 68k miles. The car now has 120k miles and the clutch is still functioning like new. My car has an 8 lb lightened flywheel and dyno’s at 380 rwhp with zero chatter or slip. The Centerforce pressure plate is quite unique as it has weights that fly out as RPM increases which increases clamping force on the flywheel (check their website). So the net result is the clutch pedal requires less force on your leg when applying, but increases clamping as rpms increase. When I purchased the clutch & PP in 2002, Centerforce rated the clutch to 700 hp, yet as I stated the pedal effort feels just a little bit firmer to apply than the stock 951 clutch. I do not know if Centerforce still makes this clutch for our cars, but I will definitely check when I eventually need a new one, as it has been a great clutch.

Hard to know if they are still the same, but I can vouch for the clutch in your car. It felt every bit as smooth as stock. With these cars, I think the key is to add clamping force to the pressure plate but stick with stock-like friction materials on the disk.
@Tom What is in your 951 right now? I have a southbend modified factory PP with a factory disc that was relined by them with "better" material. I am less than happy with the driveability. It isn't horrible but I'd much prefer smoother engagement characteristics.

I have a KEP1 and cup disc. The South Bend PP is good, but I bet they sold you their "Feramic" disc material. I had the Southbend PP and Feramic disk for a while. As you say, it's not horrible, but not factory smooth. If the PP is still fresh, I'd just switch out the disc for a cup or 930 disc.

Darwin · #14

Tom wrote: Thu Jan 02, 2025 9:00 pm
Darwin wrote: Thu Jan 02, 2025 8:03 pm
Tom wrote: Thu Dec 26, 2024 7:50 am

Hard to know if they are still the same, but I can vouch for the clutch in your car. It felt every bit as smooth as stock. With these cars, I think the key is to add clamping force to the pressure plate but stick with stock-like friction materials on the disk.
@Tom What is in your 951 right now? I have a southbend modified factory PP with a factory disc that was relined by them with "better" material. I am less than happy with the driveability. It isn't horrible but I'd much prefer smoother engagement characteristics.
I have a KEP1 and cup disc. The South Bend PP is good, but I bet they sold you their "Feramic" disc material. I had the Southbend PP and Feramic disk for a while. As you say, it's not horrible, but not factory smooth. If the PP is still fresh, I'd just switch out the disc for a cup or 930 disc.

I'd have to dig up my receipts, and maybe Chris can chime in here (he helped me get it) but I believe it was a hybrid/ceramic type disc. I only ever plan to run ~15psi so I'd say 350-400hp? I'd really like a less chattery clutch!

Tom · #15

Darwin wrote: Fri Jan 03, 2025 1:28 am
Tom wrote: Thu Jan 02, 2025 9:00 pm
Darwin wrote: Thu Jan 02, 2025 8:03 pm

@Tom What is in your 951 right now? I have a southbend modified factory PP with a factory disc that was relined by them with "better" material. I am less than happy with the driveability. It isn't horrible but I'd much prefer smoother engagement characteristics.
I have a KEP1 and cup disc. The South Bend PP is good, but I bet they sold you their "Feramic" disc material. I had the Southbend PP and Feramic disk for a while. As you say, it's not horrible, but not factory smooth. If the PP is still fresh, I'd just switch out the disc for a cup or 930 disc.
I'd have to dig up my receipts, and maybe Chris can chime in here (he helped me get it) but I believe it was a hybrid/ceramic type disc. I only ever plan to run ~15psi so I'd say 350-400hp? I'd really like a less chattery clutch!

Yeah, the KEP1 with cup disc is perfect for your car. Factory smooth, no slipping. Be sure to get you flywheel surfaced too. If you have the Feramic disc, which was all the rage for a while, that material (sintered iron?) is harder on the flywheel than an organic disc. If you want to save money (maybe) and don't mind the possibility of doing it twice, you could try a cup disc and resurfaced flywheel, with the southbend PP. I'd say there's a reasonably good chance the extra PP clamping force would be enough for your power level.

Wojo7 · #16

djtalon wrote: Mon Dec 09, 2024 7:46 am All,

I have a modified, about 325hp at the wheels 89 Turbo. What is best choices for clutch ?

Thanks
Dave

I was running a 930 disc and KEP stage Light PP and it was great behind 345whp, when I built my 3.0 I upgraded the PP to a stage 1 and re used the 930 disc, it’s holding great and is smooth as stock. If I had to do it again I’d just buy the stage 1.

Tom · #17

Wojo7 wrote: Sun Jan 26, 2025 3:35 pm
djtalon wrote: Mon Dec 09, 2024 7:46 am All,

I have a modified, about 325hp at the wheels 89 Turbo. What is best choices for clutch ?

Thanks
Dave
I was running a 930 disc and KEP stage Light PP and it was great behind 345whp, when I built my 3.0 I upgraded the PP to a stage 1 and re used the 930 disc, it’s holding great and is smooth as stock. If I had to do it again I’d just buy the stage 1.

Welcome to Carpokes Wojo7 -- it's been a while

KEP apparently changed the names of their various pressure plates, and/or added some additional options, but if your Stage 1 is the same as mine, I wholeheartedly agree -- there's really no downside. Maybe a bit more stress on the firewall, but it's really only the KEP 2 that seemed to cause firewall issues.

Jc951 · #18

As I plan on doing my clutch in the near future and plan to upgrade it for a future engine swap, can you confirm if the KEP1 and cup disk or 930 disk would be good for me after reading through these posts? I'm concerned with high rated clutches as being too hard and don't want to have a "leg" day while driving the car, but want to make sure that it should be more than enough. Driving is mostly spirited back roads, but just started to do DE events.

Right now its 2.5 turbo motor making about 305 whp. Future plan for this year is to do an 01e transmission swap and then an 07k swap down the road to make around 4-450whp, but more than likely will dial it back to a nice 385 or so as I don't want to go too crazy.

Thanks

Bergerac · #19

Is anyone running the Sachs motorsports disc with the KEP pp? Supposedly good for 520nm

choochbamboozle · #20

Just looking for a little advice. Last year I put this Spec stage 2 clutch kevlar package on my 944T. The first 500 miles of break-in went just fine. Clutch was silky smooth. At 800 miles I started getting shudder which only got worse with more miles and drove me nuts. I pulled the clutch last weekend and I do see some issues. (See pics). Flywheel might have been out of spec. I do see some grease on the clutch center. I might have overdone it lubing the Tork tube shaft and it migrated to the kevlar. I was wondering if the minor pressure plate discoloration should be a worry since I'd like to re-use it and go with a Turbo Cup Disc and new flywheel. About 1,200 miles on the whole setup. Thanks.