Definitive statement on 930 clutch selection.

[reclino]

I am no expert, but hope to provoke some of our experts to chime in on this. I am at the point of needing a clutch pressure plate for my engine build as it's going with the rotating bits to get balanced.
I thought I had the expensive option all figured out
RUF 5 speed SACHS sport pressure plate, 88 3083 999 594. "must be paired with"
SACHS sport friction disk 88 1861 999 615

Now there seems to be some debate on this as TurboKraft responds with

"The -594 aka "Ruf clutch" isn't cheap, but you'll save a lot of money by not specifying the -615 disc because it's the wrong one. You need only the basic early 930 disc, -331 part number in Sachs' catalog."

So who can break this down and explain this real simple like. Keep in mind I am an engineer, so repeating yourself and using all caps can be helpful 👍😀

[reclino]

There seems to be 2 distinct factory clutch pressure plate options for the 930,
the early aluminum one up to 1977 930 116 021 00 SACHS 3082 073 131

the later heavy cast iron one 930 116 021 03 Sachs 3082 090 131

From the factory manual the early clutch has a lower force spring than the later one.




So the first question I have is what is the torque "rating" of the early 1977 clutch pressure plate?
Whats the torque rating of the later cast iron pressure plate?

Is the sport pressure plate simply the early aluminum housing with the later spring diaphragm and an extra "strap"???

I have one of each of these factory pressure plates sitting on the shelf in the garage, but don't think the 1977 pressure plate is going to hold up to the torque output of the 3.3 engine with a bigger intercooler and up to .9 bar boost. I figured I would have more fun driving a light weight clutchl but now am wondering if I know enough to make a good selection.

[reclino]

Maybe a moderator can do this the right way but I am copying and pasting the response from Chris at TurboKraft about this clutch issue.

TurboKraft
Posts: 2,709
Location: Phoenix, AZ
Okay, once more for the record:

Using all Sachs-manufactured parts
88 3082 999 594 = "Ruf" pressure plate
+
930 116 014 02 = 1976-77 930 clutch disc, organic with spring hub, ~10.0mm thick
+
930 116 081 11 = 930 release bearing


IF you're making over 500whp or simply want the strongest pressure plate Sachs makes:
88 3083 999 574 = 934 pressure plate + 930 release bearing (included)
+
88 1861 999 615 = 934 street disc, organic with spring hub, ~8.5mm thick


To fit into a 1978-88 long bell housing transmission, add:
* aluminum ring gear spacer
* stainless release bearing extension


Which ring gear to use? The one that matches your bell housing, i.e.
1976-77 short bell housing = 1976-77 starter ring gear
1978-88 short bell housing = 1977-88 starter ring gear



and maybe a moderator can put a sticky on this or something, help stop the misinformation
Yesterday 08:40 PM

[gsxrken]

A Pelican Pelican Parts Forums - View Profile: Frank Hanrahan has that pressure plate you want 88 3082 999 594. I know because he sent it to me and I sent it back. Probably shouldn’t have, lol. Reach out to him via PM.

You’d need to get the adapter kit from Turbokraft. In fact I’d just call Chris on your questions above, and then post the resolution here for posterity. You can find parts for slightly cheaper than TK, but you will not find a better value. There’s nothing like lying on your back under the car saying “WTF?” to yourself and being able to call TK to get unstuck.

[Porsche 935]

This was sent to be from Sachs when I went to replace my 934 disc. Hope it helps people in the future.
Thanks for your inquiry.



The clutch-disc 881861.999615 has a thickness of 7,8mm.


We are happy to answer any further questions you may have.



Best Regards from Hamburg, Germany

[smurfbus]

I measured the one that was sent to me and it was around 8.5mm

[356911930]

Great information, thanks Chris!

One more question about the "RUF" Pressure plate and the 930 116 014 02 = 1976-77 930 clutch disc, organic with spring hub, ~10.0mm thick

Q: How much torque and horsepower will the set-up hold before you need to go to the 934 clutch parts?

Thanks,

Rahl

[Kraftday]

Strange change in my clutch behaviour, IIRC KEP1/2+kevlar disk

> 88 3082 999 594 : Clutch Pressure Plate Cover - "RUF 5 Speed" - Lightweight Sport Heavy Duty Version - 240mm (1976-1977) PORSCHE 911 Turbo Carrera / 930 4-SpeedTransmission "Short, Low Profile" - Aluminum Pressure Plate - ZF SACHS PERFORMANCE
+ High Clamp Load / Torque Capacity rated at 580+ ft/lbs with organic disc. Moderate Pedal Effort
+ Also used with lightweight options for (1978-1988) 930 Turbo with adapter or with G50 Short Bell Housing Transaxle Conversions
+ Replaces PN: 930 116 021 00 - Clutch Pressure Plate (~54% Increased Weight)
+ Replaces PN: 930 116 911 00 / 3000950004
** NOT for use with PN: 881861 999615 : Clutch Disc SACHS Performance

> 930 116 014 02 / SD255 / 1861 568 331 : Clutch Disc (Spring Hub) 240 mm SACHS
*CONFIRMED CORRECT MATCH PP

> 930 116 081 11 / SN3838 : Clutch Release Bearing - SACHS



930 116 020 80 : Starter Ring Gear Adapter Extension - MODE Inc
* Features clearance holes (underside) for pressure plate cover limit pins, enabling use of 78-88 930 Ring Gear