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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11723 Location: PacNW
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Posted: Tue Mar 23, 2010 12:46 am Post subject: Clutch Disc Options |
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I'm growing concerned about Sachs (it's a sachsual problem).
My buddy pulled the motor from his race car following a clutch failure, and found that several rivets had failed and a large piece of friction material had come loose. He related that many 944 Spec guys had seen this failure over the last several years. . .clearly a manufacturing defect.
Needless to say, I am not eager to install a similar disc from the same manufacturer. What other reasonable options are there?
*I'm aware of the Bronco option. . .I am curious about discs actually intended for the 931* _________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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fiat22turbo
Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR
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Posted: Tue Mar 23, 2010 3:04 am Post subject: |
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Contact Clutchnet. They make everything in house and their clutches survive 400+hp turbo cars and their slipping drag launches (keep in mind the stock engines put out 175hp and getting a FWD car to leave the line with a 1.8 second 60-ft is impressive)
Centerforce used to be a go to for clutches until it was discovered that they were merely reboxing Sachs clutch discs with their own PP. Not sure if they still do. Clutchnet came to the rescue and can likely come up with something for us, if they don't already have something ready to go.
Just checked their site, they have nearly any configuration you'd like. _________________ Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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ic932
Joined: 11 Feb 2005 Posts: 1104 Location: UK
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Posted: Tue Mar 23, 2010 3:17 am Post subject: |
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I wasn't aware that there were any other options "intended" for the 931?
However, if you are lucky enough to source a late 82' (ROW at least) flywheel then that opens up the 944 aftermarket world. The reason being this flywheel is use in conjuction with the rubber centred type clutch discs.
Well worth considering if you run a dogleg box. I read somewhere that this was Porsche's answer to the syncro problem?
BTW, rubber centred clutches get a bad rap IMO. Bad owners who think wear parts should live forever!
If you are paranoid get your new disc re-riveted... |
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Shurick
Joined: 15 May 2005 Posts: 524 Location: Russia, Moscow.
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Posted: Tue Mar 23, 2010 6:06 pm Post subject: |
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Had a ClutchNet disk in my 931. It was a pain to drive and death to transmission mounts.
Now I have a SPEC (stage 2) disk and pressure plate installed but haven't tested it yet. _________________ WBR, Shurick
'79 931 -- intercooled K26-3060-6.10 turbo @ 1.2 bar, EFI+EDIS, 951S brakes, stripped interior, 951 look.
'86 924S -- R.I.P.
https://www.instagram.com/ru_pacecar/ |
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fiat22turbo
Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR
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Posted: Tue Mar 23, 2010 11:25 pm Post subject: |
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Can you go look at their site and tell us which disc you had?
Sounds like a 3 or 4 pick race clutch. Which pressure plate did you use with it? _________________ Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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peterld
Joined: 10 Dec 2006 Posts: 946 Location: Noosa Heads QLD Australia
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Posted: Wed Mar 24, 2010 12:47 am Post subject: |
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Rubber centred clutches and also flywheels are a fact of life in modern cars - they seamingly make gearchanges lighter and easier and stop the gear chatter, particularly in neutral. However they have a history of failing when the rubber starts to disintegrate through misuse, oil contamination, etc.
Porsche used them in 924s,then 944s and eventually in 911s. There are many documented horror stories out there.
Having said that, my track car still retains it's rubber centered clutch disc. This is still the original clutch disc!!!! Every time the motor comes out I check it and consider changing to something else, but always the disc still has plenty of life in it and the rubber is not compromised. So I chance it one more time. One day I guess the 30yo clutch will fail and leave me stuck in gear.
If memory serves me correctly, the 911/915 clutch is supposed to fit 931s, however buying off the rack is never as good as having a clutch rebuilt or made to your specs by a reputable local clutch guy - if you have one handy. One of the few automotive trades which hasn't yet disappeared and isn't too technically/digitally/electronically challenged if you discount all the trickery of modern twin clutch semi auto gearboxes. _________________ 80/81 932/8 ROW |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Wed Mar 24, 2010 2:59 am Post subject: |
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I have been thru every Porsche listing on ClutchNet's site, and they do not carry a disc that will work for our cars...they either have the wrong spline diameter, spline count, or outer diameter. I contacted them recently about doing something custom and never even got the courtesy of a return call.
Centerforce and Spec are the only companies I am aware of that advertise an aftermarket option; Centerforce have a bad reputation, and Spec are SPENDY, and apparently only available as a complete kit (pressure plate, clutch disc and throwout bearing), although I've not yet inquired about purchasing a disc only.
The 915 pressure plates (the full iron and hybrid alloy-iron) are direct fit replacement and purportedly offer 2x clamping force over the stock 931 cover. I seem to remember bass gt posting that the all alloy version requires some mods, but can't recall the details ATM. _________________ erstwhile owner of just about every 924 variant ever made |
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McGyver
Joined: 24 Feb 2009 Posts: 354 Location: Jelenia Gora - Poland
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Posted: Wed Mar 24, 2010 6:26 am Post subject: |
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As I remember Sachs made two types clutch discs for 931:
931 116 011 04 - spring damped
944 116 012 08 - rubber damped
So if rubber takes more damage why don't use that plate with springs? It's more compatibile with sports cars and stronger, and dont so sensitive than rubber one. Maybe changeing gears can be felt much stronger but it's sports car
I have one 931 clutch with springs as spare and something in my car I don't really know which type but I check this when I swap to 931 engine again. _________________ 931 82' - 5000km after full engine rebuild
SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car
www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible) |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Wed Mar 24, 2010 6:30 am Post subject: |
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The rubber and spring types aren't interchangeable as the flywheel changes as well. _________________ erstwhile owner of just about every 924 variant ever made |
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McGyver
Joined: 24 Feb 2009 Posts: 354 Location: Jelenia Gora - Poland
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Posted: Wed Mar 24, 2010 6:58 am Post subject: |
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You right. I didn't noticed that before. Maybe someone can post some photos what are differences between this two types of flywheels? If I can get mine from some box I can make photo session of that spring type clutch _________________ 931 82' - 5000km after full engine rebuild
SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car
www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible) |
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ic932
Joined: 11 Feb 2005 Posts: 1104 Location: UK
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Posted: Wed Mar 24, 2010 7:39 am Post subject: |
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Michal, Porsche made a descision to use a rubber-centred clutch sometime in 82'. From what I read many years ago (I can't provide a ref.) they introduced this disc as a direct responce to premature gearbox syncro wear. Strengh is all well and good but if the longevity of the "weakest link" (syncros.. if this is indeed the case) , then what good would a clutch be if it contributed to this premature wea,r no matter how impressive it's clamping force? |
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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11723 Location: PacNW
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Posted: Wed Mar 24, 2010 4:10 pm Post subject: |
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ideola wrote: | I have been thru every Porsche listing on ClutchNet's site, and they do not carry a disc that will work for our cars.... |
Was there a Bronco disc listed?
_________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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daniel
Joined: 18 Jun 2009 Posts: 669 Location: Sydney, Australia
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Posted: Wed Mar 24, 2010 5:29 pm Post subject: |
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My 944 had a rubber centre clutch, failed shortly after buying it. I replaced with the sachs recomended replacment which is a normal spring centre clutch. No dramas at all
Daniel _________________ Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet |
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Shurick
Joined: 15 May 2005 Posts: 524 Location: Russia, Moscow.
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Posted: Wed Mar 24, 2010 10:30 pm Post subject: |
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fiat22turbo wrote: | Can you go look at their site and tell us which disc you had?
Sounds like a 3 or 4 pick race clutch. Which pressure plate did you use with it? |
It was 6 pick with spring hub. I used it with S1 stock pressure plate and flywheel. _________________ WBR, Shurick
'79 931 -- intercooled K26-3060-6.10 turbo @ 1.2 bar, EFI+EDIS, 951S brakes, stripped interior, 951 look.
'86 924S -- R.I.P.
https://www.instagram.com/ru_pacecar/ |
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Smoothie
Joined: 01 Jan 2003 Posts: 8032 Location: DE (the one near MD, PA, NJ)
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Posted: Wed Mar 24, 2010 10:57 pm Post subject: |
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More on the different flywheels here - http://www.924board.org/viewtopic.php?t=21820 _________________ "..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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