A good 930 clutch for my turbo conversion.

[smurfbus]

The seller just replied to my email (well his email was full so I made a paypal dispute and he replyed to that) and it gets even more complicated to what I've read from here that 615 friction disk works with 574PP:
"The 88 1861 999 615 [ZF disc] is the ONLY correct match for the 88 3083 999 574 [934/935 PP]"
"615 disc TO 594 pp = NO"

Seller says:

Hallo, pressureplate 999574 and 999594 is complett the same 999574 is just with release bearing and 999594 is with separat release bearing, so itīs all the same.

pressure plate 999574 is not longer manufactured by Sachs Performance and is replaced by pressure plate 999594 + release bearing

The 615 disk that came with the box is 8.8mm

[smurfbus]

The seller still insists that 574 is discontinued and IS THE SAME as 594 NOW!
This can't be true, they can't change items (574 to 594 spec) drastically with same #number can anyone confirm this for me?

i spoke the Sachs Performance before ordering your parts, and they confirm that the pressure plate is the same with both numbers 999574 and 999594 is the same

- European Clutch and Flywheel Distribution GmbH & Co.KG

This is what Sachs online catalog says for that 615 disk:

"SACHS Performance 881861 999615
detailed view
BIG
Clutch Disc Performance
Model year to : 08/1977
only with : 883083 999574
Hub Profile: 23,3x26,3-23N
Number of Teeth: 23
Parameter: 240TD
Diameter [mm]: 240
max. transmittable engine torque: 480 Nm
torsion damper plate with organic facings"

[TurboKraft]

Originally Posted by smurfbus

The seller still insists that 574 is discontinued and IS THE SAME as 594 NOW!
This can't be true, they can't change items (574 to 594 spec) drastically with same #number can anyone confirm this for me?

Utter nonsense. If that seller insists they are the same, he is wrong.

Yes, the 574 includes a 930 release bearing while the 594 does not, but that is not the only difference.
Put the two pressure plates side-by-side and there are measurable differences, not the least of which is the dimension between the friction surface and the perimeter mounting surface.

It you use a 574 with a standard disc, it will drag, never fully release. We went through all this and documented it in Tom's UBER930 build. The combination of the 574 plate + 615 disc successfully held over 600ft.lb. at the wheels on that car and several since.

Is the 574 discontinued? Quite likely it will be, as every year their availability is reduced. It's a motorsports part from 40+ years ago, very doubtful there's much demand to justify the manufacturing expense.

[Porsche 935]

Is my math right? 450nm is about 350 ft lbs of torque? I think the 934's were low to mid 500 torque back in the day. I guess some are lucky to hold that kind of power with that disc, but I have bought many over the years and it won't hold 600+ for me. I guess it may depend on how aggressive your power curve is and how much air flow is going into the motor. 15-20 psi of boost on a turbo flowing 51 lb minute is much different from 2 that flow 60 lb.

[TurboKraft]

Originally Posted by Porsche 935

Is my math right? 450nm is about 350 ft lbs of torque? I think the 934's were low to mid 500 torque back in the day. I guess some are lucky to hold that kind of power with that disc, but I have bought many over the years and it won't hold 600+ for me. I guess it may depend on how aggressive your power curve is and how much air flow is going into the motor. 15-20 psi of boost on a turbo flowing 51 lb minute is much different from 2 that flow 60 lb.

*shrug*
It has always worked for us.

Your car sounds pretty aggressive. Are you running the 930 long bell housing 4-speed?

[Porsche 935]

No shortened 930 box with custom gear set. It held ok with twin 48mm wheels, then I had a set made that were 51mm each and if you kept it under 22psi it was good. now I run twin 60mm and 25psi and a solid disc. Hold very well, wouldn't want to get stuck in stop and go traffic. HAHA Tried to get a nice twin disc set up made but no one seamed serious about helping me. Not sure if the shortened bell housing has enough room for twin disc, so if you want to play with the big guys you have to make sacrifices.

[smurfbus]

And here is the answer straight from Sachs:

ZF Sachs and ZF Sachs Race Engineering are still in partial LockDown :-(

A lot of parts aren't available, production is planned to be running from August 17th again...

883083.999574 - not available yet
881864.999838 - available in 48 h
883082.999594 - not available yet
1861.568.331 - not available yet