924Board.org

[Carrera]

My clutch has started to feel a bit sticky from time to time. I've been told its the clutch fork that has worn flat from where the curves used to be.

As my turbo is also most likely due a rebuild a serious option is that the engine will come off the coming winter and both the turbo and clutch will be renewed. This is still a bit in the air due to the heavy finances involved

Anyway, now to the point.
- If I understand correctly the clutch kit for a 931 is actually the same as for 944S and 944S2, am I right?
- Any idea where to locate a new clutch fork? Afaik its no longer available from Porsche...
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931 S2, 1981

[morghen]

911 clutch ?
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Supercharger and EFI kits
https://www.the924.com

[ideola]

[Carrera RSR]

The simple answer is.........

If your 931 is a S1 running non DITC flywheel then this



If an S2 with DITC flywheel



All still available from Sachs circa €500-600
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252

[ideola]

Not completely accurate.

DITC has no impact to compatibility of the clutch disc, the pressure plate, or the throw-out bearing. Not sure what source that is or why it's spec'ing different part numbers.

The only compatibility issue is with late US-spec S2 cars that came with the rubber-damped clutch disc. It requires a different flywheel and different pressure plate (because the dish of the flywheel is different, requiring a different configuration of the clamping surface on the pressure plate).

The part numbers that matter:
Spring damped disc, compatible with all S1 cars, and with all S2 cars except for very late 1982 US-Spec cars: 931 116 011 04

ANY car equipped with this spring damped disc can use this pressure plate: 931 116 001 02

ANY car equipped with this spring damped disc can ALSO use this pressure plate: 915 116 001 27 This is the 915 part I referenced in my earlier post, and happens to be the one specified for the 937 (a.k.a. M31.50 engine code), it is COMPLETELY interchangeable with the 931 part number and provides 50% add'l clamping force.

ALL cars regardless of disc or pressure plate use this throw-out bearing: 931 116 082 04

Certain cars (as far as I've been able to determine, only on very late 82 model year US-spec) had the rubber-damped disc, part number 944 116 012 08; PET however does not indicate based on VIN which cars this applies to, so you have to know ahead of time if you have this disc, because if you do, you have a different flywheel. I have never seen this on a Euro-spec car, only on US-spec cars, but I'm not confident that ROW cars in late 82, 83 or 84 might not have also gotten the 944-based rubber damped clutch disc. According to PET, it is exclusive to engine code M31.03, which I believe is ONLY the US market.

This disc has a different DITC-compatible flywheel with a deeper dish, which as a result requires a completely unique 931-only pressure plate, part number 931 116 001 03. I have done side by side comparisons, and even though the rubber damped disc is a 944 part number and common to the early 2.5L cars, I have not found ANY 2.5L-based pressure plates that are interchangeable onto the 931 platform.

As indicated above, the Sachs KF200-02 is completely compatible with ALL cars EXCEPT those with the rubber centered disc. I have not found another alternative kit for the rubber centered setup outside of the OEM parts. In fact, even OEM parts for this setup are not available in a kit, can only be ordered as piece parts.

The Ford Bronco II (1986 and other adjacent years) clutch disc part number is FMD-001, and it is COMPLETELY INTERCHANGEABLE with the 931 116 011 04 clutch disc. I have also seen some Ford Bronco II clutch packs designated as "Heavy Duty", but I don't believe it has anything to do with the disc itself, because this is the only disc-only part number I've been able to find.
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erstwhile owner of just about every 924 variant ever made

[Carrera RSR]

Dan, the question was i assume to RoW 931 as carrera is in Finland and we know the US cars are different. The above screen shots are direct from Sachs through research by Max at Frazerparts a UK Porsche parts specialist. This was done because of the confusing and conflicting information regarding what would/would not work with my S1. There is a cut off date of June 1980 between the two clutch kits.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252

[morghen]

i have two ROW 931 engines, one S1 and one S2 and they both have the rubber clutch disc
_________________
Supercharger and EFI kits
https://www.the924.com

[peterld]

Dan and Carrera RSR are both right!

In the ROW 931/932 the change from S1 to S2 (DITC) brought with it the rubber centred clutch, and its partner, the stepped flywheel.
However, in the USA cars, the first S2 models had a similar clutch/flywheel arrangement to the S1 cars, with the addition of the timing teeth around the circumference of the flywheel, and the impregnation of the metallic sensor in the flywheel.

Thus if you want to use your flywheel for timing or continue to use CIS/DITC, BUT are after better clutch/pressure plate options, then you need to source an early USA S2 flywheel.
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80/81 932/8 ROW

[ideola]

I don't know why the Sachs information has different part numbers. But I can assure you that the 931 116 011 04 disc works for the S1 car, and that the 931 116 001 02 & 915 116 001 27 will both work with this clutch disc.

To repeat, there is NOTHING related to DITC on the clutch setups, so DITC has no bearing on which setup you need. The only thing you need to be concerned with is whether you have the rubber centered disc and the related flywheel, which according to PET were ONLY for M31.03 coded engines (and actually, only for a limited number of them).

Morghen, if you had an S1 with a rubber centered disc, I can only conclude that a previous owner switched out the flywheel and clutch pack.
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erstwhile owner of just about every 924 variant ever made

[Carrera RSR]

I was under the impression the flywheels are different between the S1 and S2 not just the sensor trigger in the starter ring needed for DITC. RoW S1 = spring dampener, S2 = rubber dampener, therefore the need for flywheel/clutch differences. So I agree, DITC does not dictate the difference but by nature of other components used on DITC equiped cars.

I took the above advice from a Porsche technician and a Porsche parts supplier.

I have a RoW clutch and flywheel assembly but not had a chance to check in detail.
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252

[morghen]

actually both my engines are S2...got confused for a moment there
_________________
Supercharger and EFI kits
https://www.the924.com

[ideola]

The S1 and S2 flywheels are different in some respects, but as it relates to how clutch actuation functions, they are completely interchangeable (EXCEPT as noted above for the version that requires the rubber centered disc).

So, in other words, you can put an S2 flywheel on an S1, which actually has the benefit of shedding a few pounds of weight (there are weights listed here elsewhere, don't recall them off hand). From a clutch actuation standpoint, you can also put an S1 flywheel on an S2 car, but this would obviously require another solution for ignition management since the S1 flywheel lacks the sintered insert and ring gear that is on the DITC equipped cars...so for example, if you had an S2 car that you were converting to EFI, there is no reason you can't use an S1 flywheel on it.
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erstwhile owner of just about every 924 variant ever made

[gegge]

The 951 fork is identical to the one one sitting in the 931 bellhousing. Think I posted a picture a while ago. Same axle as well IIRC.

If the throw-out bearing or clutch release bearing was uniqe to the 931? Not quite so, in fact all 944/944S/944S2/924S except from the 951 used the same bearing.

Why not try to find the lightweight version of the 915 pressureplate? Even more clamping force and a lot less rotating mass.
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Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

[ideola]

[gegge]