Bri Bro

I would love to get to the bottom of this issue. Using basically stock OEM components, some have NO problems until crossing over the 350-400hp and others seem to have problems with anything over 300hp.

So, that is it?

The pressure plates with the same names have different clamping force?
The space between the flywheel and clutch is different on some cars?
The thrust bearing is allowing the flywheel to move?
Some setups (similar upgrades) can make more torque then others?
Assembly issues?
Dumb luck?

What you think??

theedge

KEP. Every Spec equipped car ive driven has had a ****ty clutch feel, to me at least. KEP is very even in its pedal pressure, none of that springyness part way through.

blown 944

Driving habits and age of the pressure plate would be my guess. I have had luck if I don't try to launch or grab gears. If I do either the stock parts are done. The same can be said of some aftermarket parts IMO.

DDP

I agree with Brian. KEP all the way. If you have Spec in your street car and you like it, it's because you haven't had anything else. I don't say that to be a jerk, it's simply true. For a track car, it doesn't matter because clutch issues (besides slipping) are just drive-ability. For a street car, Spec is a terrible choice. And it's not because Spec doesn't make quality components, I don't mean that. It's because there is no reason for a street car to come with such an aggressive clutch disc. That's what makes it terrible on the street because you can't slip it.

The best choice is to get a KEP Stage 1 or 2, depending on your power output, than get an organic disc, Cup is fine. Or go the South Bend route have have their Organic/Kevlar (I think, can't remember exactly) material installed on a Cup disc. This will hold good power while still allowing slip for clutch modulation which is essential in day-to-day driving. Sure the pedal will be heavier, but you must sacrifice something for more power.

I had a cracked KEP pressure plate which wasn't a joy to have to replace, however they did replace it free of charge (as they should have).

Tom M'Guinn

Well as of 4:30 this afternoon, I am now uniquely qualified to give a first hand comparison of stock, spec, southbend and KEP clutch set ups, since I have now tried each of them, in that order, on my car.

The stock clutch has great street manners of course, but started spinning when my 2.5 motor hit 350rwhp+/-.

SPEC: My 4-puck spec was a nightmare on the street, and I wouldn't want it on the track either. Engagement off the line was terrible with some violent shudder if not very careful. Downshifting would also bring nasty shudder if you didn't match revs carefully. I used a Sachs PP with the spec disk, and the PP was modified for greater clamping force, so the pedal was slightly firmer than stock. This clutch did hold 500rwhp without slipping, so it did hold well.

SOUTHBEND: I used there Feramic/Organic material on a cup disk, and their Sachs pressure plate modified for greater clamping force. This clutch had good street manners, but developed a tab bit of shudder when starting off. Not bad at all, but not factory smooth. The pedal pressure is very slighly firmer than stock, but without a side by side comparison you'd never notice. This clutch held 19psi on my car without slipping, which is about 425rwhp on a dynojet. Never tried more, so never found it's limits.

KEP1/CUP DISK: Factory smooth engagement right out of the box. Not a hint of shudder (so far anyway). Pedal pressure is noticeably stiffer than the southbend, but not terrible. My 85 911 with mechanical clutch was MUCH stiffer. Very easy to drive with perfect street manners. Have not tested its holding capacity, but KEP says it will hold 530 ft lbs (say 450rwt). Time will tell. If it holds 450rwt, this is my favorite so far hands down.

Paulyy

Thanks for a proper clutch comparison! now all you need to do is put that in it's own thread and get a sticky. so no more clutch threads.

gruhsy

What different SPEC setups have people tried? There is a fair amount of options when I bought mine.
I would tend to think there would be some significant differences depending on what component you chose.

I know with KEP you have either the KEP 1 or KEP 2 and their prices a really reasonable when I called them.
Don't know anything about the Southbend other than what all of you have posted.

I don't mind my SPEC setup. The pedal is easy and does not chatter at all. My 86 stock clutch used to slip once in a while but sold that one back in 95.

Jason

333pg333

Does this look familiar to you guys? I thought it was the S/B stuff but am now thinking it was one I bought some time ago from Markus Blasak?

Paulyy

Just a note: When you tell clutch specs, you should be telling them in torque specs not horsepower specs.

Tom M'Guinn

That disk does not look like my old Southbend disk. Southbend also painted the Sachs pressure plate red (at least on mine). South Bend sells modified Sachs pressure plate -- just like Gomes sold, and from what I hear, Blasak. If pedal pressure is any indication, the Gomes PP and the South Bend are modified to about the same pressure -- would bet Blasak is the same.

Tom M'Guinn

Agreed -- edited post.

JET951

that was your Blasak clutch Patrick

333pg333

Thanks guys. I think that had kevlar in it and it would occasionally slip when hot, but cool down and go back to normal.

blown 944

That's the same disc used in the spec stg 2 iirc

xtaC

This is my Spec 2 that I got from LR.