yoni_d

Hi all,

I have to replace my clutch in my 1980 928S 4.7 and I came across with SPEC in Pelican parts. They recommend the stage 1 for regular driving style which is what I do.
I read several reviews but I wanted to hear from you if you have any experience with this clutch (for my model it is the one with 2 discs).
How long it holds, is it indeed smooth or the car still vibrates when shifting to 1st / reverse (mine is vibrating like crazy), etc.

Any feedback will be appreciated.
Thanks!

Rob Edwards

At the risk of asking the obvious, how do you know you need to replace the clutch? Have you checked the position of the release arm in the inspection hole? Do you have the clutch out and the discs are worn out? Not sure what to make of bad vibrations when shifting into reverse- the whole car's shaking, or you're getting bad vibrations through the shift lever? Perhaps the reverse synchro is shot and you're grinding teeth on your (NLA) reverse gear(s)? Or your shift coupler bushings are worn?

Sorry, that's like 6 questions. But more info is needed.

GregBBRD

SPEC builds clutches for high performance use and they tend to be more severe than stock (chatter.)

Stock clutch pieces largely still exist, with the exception of the intermediate plate, which is not available new, but can be found used or rebuilt.

As long as you can get the stock Porsche/Sachs parts and you have a relatively stock engine, use the factory pieces.

yoni_d

Hi Rob,
No need to be sorry - those are great questions.
Few years ago I took the clutch a part with my friend who is familiar with the car and we sent all the clutch parts to be renewed and balanced. This had almost zero effect on the problem. All the bearings were changed too and according to my friend everything was in place (release arm as well). The Vibration are only when starting to drive or when downshifting from 3rd to 2nd. There are no vibration in the shift lever nor the pedal. We also replaced the bearings in the drive shaft and checked the gear. Everything was checked and still it shakes when shifting into 1st or reverse like crazy.
My friend gave up so I went to a garage which handles old Porsche cars and they said that according to the way it shakes, there is probably a need to replace it. My master clutch cylinder started to leak as well (although it is not related to the problem) so maybe it is a sign to replace everything and start from scratch. I am not going to replace the flywheel and the release arm - hope it is ok..

GregBBRD

Either the flywheel or the release are could also be your issue. Do not automatically rule those pieces out.
Since you have done this job before and the problem was not solved, you really need to have someone super familiar with the pieces, so they can figure out what the actual problem is.

yoni_d

Thanks Rob! What do you mean by "the release"? Are you referring to the release arm / release bearing?

yoni_d

Thanks Greg!
I am still haven't decided about the clutch type but aside from the 2 discs, pressure plate, pilot and release bearings, should I replace anything else? What is usually recommended?

GregBBRD

Replace anything/everything that is worn abnormally.
For instance, if the flywheel surface is covered with black "hot spots", it needs to be replaced. Resurfacing "hides" the hot spots, which are deep into the base material and can not be removed by resurfacing. Same thing with the intermediate plate. The T/O fork could of had (probably has had) the plastic bushing worn out at sometime during it's life. This can allow the fork to twist some and wear on side. This will result in the T/O bearing to be pulled crooked....which will cause clutch chatter.

Unfortunately, determining what is bad and what can be re-used in the clutch mechanism takes years of careful observation and lots of trial and error. I've had many, many clutches in and out two or even three times, in my "early" years, getting them to release properly or getting pieces that worked properly, together.

On many parts of these cars, there's simply no substitute for experience. The clutch is one of these areas. The transmission is another.

Finding someone with this "928 experience" is really tough.....always has been.

yoni_d

Yeah, finding someone who really knows those cars is tricky - especially where I am from. I think that I will go with the Ball cap bushing for fork and also clutch guide tube on top of the obvious parts.
What do you think - should I try the SPEC stage 1 or should I go for the Sachs one? I also have an option to buy the pressure plate by Sachs and after market discs. However, I do not know the manufacturer of those discs so I dont really know how they are aside from the fact that 928intl say that should be as the original ones.
What do you think?

islaTurbine

I'm no expert like Greg and others but I have recently gone through the whole clutch, TT, and transmission on my '78. Here's some links of threads that I created, read, and/or participated in and which were of great help. You'll notice that there are many posts from Greg in them and here's my recommendation: Read what he has to say, then read it three more times to get a thorough understanding of it, and then implement every piece of his advice. And then reread it again to make sure you didn't muck it up.

Oh, and two more things.
1. Pony up and buy the Porsche-labeled "sticky grease".
2. Make sure you have a release arm that's compatible with your throwout bearing. The new -09 release arm is not compatible with the new pilot bearing for an OB double disc clutch (despite what Porsche says).

https://rennlist.com/forums/928-foru...s-1978-ob.html

https://rennlist.com/forums/928-foru...osport-uk.html

https://rennlist.com/forums/928-foru...-question.html

https://rennlist.com/forums/928-foru...hing-lube.html

https://rennlist.com/forums/928-foru...disc-gaps.html

https://rennlist.com/forums/928-foru...tch-parts.html

https://rennlist.com/forums/928-foru...h-dilemma.html

https://rennlist.com/forums/928-foru...ce-please.html

https://rennlist.com/forums/928-foru...e-balance.html

GregBBRD

I'm not going to be much help, with this.
I use stock discs with stock intermediate plates and stock pressure plates. I've "paid my dues" and redone this job so many times, I'm not sure I can count that high. I've got a very structured system (pieces, lubrication, adjustments, prayer, and voodoo) that I can now do and be virtually guaranteed that it will work the first time, every time.
Not much experience with anything else.

jcorenman

Sachs is the manufacturer for the original Porsche 928 clutches. They will be same as factory. 928 Int'l can be trusted, and pay attention to what GregBBRD and islaTurbine have posted.

captainOCD

Included with my transmission was what I believe is a spec stage 2 clutch. I've never had anything but this clutch in my car, but it does seem to engage a bit aggressively, not so much that you can't get used to it though. Mine doesn't chatter when going forwards, but it does quite a bit when reversing (definitely clutch since it goes away when the clutch is fully engaged). I'm wanting to say that it gets a lot better after driving some, but I honestly can't remember at this point.

https://rennlist.com/forums/928-foru...l#post16025517

GregBBRD

Reverse is the real test of clutch chatter in all 928's. For some reason, all clutch chatter is worse in reverse.

Old engine and transmission mounts
New engine and transmission mounts. Seems to make no difference.

Someone smarter than I (doesn't take much) may know why.

yoni_d

Guys, I cant thank you enough for all that info, tips and links. I will do my homework and hopefully with the new clutch I will have less shattering. I think that the "Voodoo" part Greg mentioned is the key for all this mystery
Now I just need to decide between the Sachs pressure plate + unknown discs manufacturer that 928intl has to offer or the SPEC stage 1 that Pelican is offering.