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Okay, so here's the biggest and most terrifying thing I need to fix on my 928... The clutch! And I'm incredibly confused as to what parts to order.
The car is actually in fairly good shape, but was neglected poorly for the past few years. It has just rolled over to 80k miles. I've been driving it as a rolling project for the past 3 weeks since I've purchased it and I've been doing a lot of work to it, including removing a massive mouse nest from under the air filter/in the engine valley (gross).
(yes I bought that cheesy keyring and yes I put the tried and true continental radio in as the car came with a gross 90s kenwood with flashy blue lights)
The engine runs perfectly and has a new timing belt / water pump, fresh oil and coolant and all of the electronics in the car work (even the sun roof), the AC however doesn't work and when I got the car the clutch was very obviously worn and on its last legs as the clutch would only take at the very end of pedal travel, it doesn't slip once engaged and I thought I could live with it for a while, however in the 3 weeks I've been driving it, it has gotten worse, a lot of gear grinding once it heats up, jittering on pull off and even worse, after a long drive it got stuck in gear as I was parking it and I couldn't release it until it had cooled off a bit, when the clutch is engaged there's an audible squeaking from under the car (pilot bearing?) I'm at the point where I'm afraid that driving it more is going to do damage, for sure it needs a new clutch, but I'm finding it very difficult to figure out what parts to order, it's a 1984 928S the part that's confusing me is I'm not sure if it's dual disc or single disc? Some parts sites have more than one option, any advice would be greatly appreciated as this is going to be an expensive endeavor and I'd prefer not to make any mistakes ordering pricy parts that don't fit.
Please, help me give this car the love and attention it deserves, I'm bringing it back from the brink and hope to make it as perfect as possible to preserve it and keep it on the road
You'll get better advice from the knowledgeable members, but the '84 will be dual disc. Do you have the Porsche parts catalog (known here as the PET)? That's a much better source for figuring out which pieces you need instead of the parts sites. It's available through the Porsche Classic website. Look for the several hundred page PDF with line drawings, not their "online parts catalog".
The synchros in these transmissions are particularly not fond of a clutch that does not release completely.
I'd suggest you park the car until you fix this clutch issue, unless the transmission already needs to be rebuilt.
Lets see what do you need .
I suggest that you stop driving the car before you damage it and fix as many of the systems as you are able to,
as you could damage the investment you have made .
1 New Bosch Green wire .
NOTE get the Bosch part ONLY.there have been some supplies of bogus green wires made by URO.
these dont fit properly and can damage the distributor pickup coil as the connector has to be forced into the distributor to seat.
I just talked to 2 more people that had failed new URO green wires, even after their was noted that they had been fixed by the MFG
Important Take the KnN back to wherever you bought it and exchange it for a proper stock filter.
NOTE the new K n N filter will pass lots of microfine dust into your cylinders and rings and valve seats.
The factory filter will clean up the dirtiest air masses and remove every scoundrel thats trying to harm your intake system
For the clutch
1 Release arm bushing, use a dremel to open up the opening so its easier to install,
press it onto the ball first , then fit the release arm onto the cup.
NOTE Inspect the release arm to verify that your contact surfaces have one flat surface and one with a curved mating surface.
Also test fit the new TOB to the release arm verify proper fitment
1 Throw out bearing with new thrust collar
1 New correct guide tube for the TOB
1 Pilot bearing
1 Tube of sticky clutch grease,
1 New front and Rear disc
1 New pressure plate,
1 New Stub shaft, inspect the old one it might still be good
2 New trans mounts
1 New Greg Brown flex line from the sway bar link to the slave cylinder,
NOTE this will replace the hard line and the flex line you have now.
Note this upgraded part also makes bleeding the clutch the easiest thing to do .
Since your getting into it I would suggest that you replace the clutch MC and Clutch Slave and blue hose
NOTE cut down the MC piston so its 75MM long,
also cut off two winds of the new spring so it wont go into coil bind and shatter.
1 New heater control valve and short hose
Thank you for all of the advice, I'll probably start by trying to get under the car and see if I can see what's what. This is going to be a painful process I can tell, I'll document as much as possible as I go along. (as for the K&N filter, it's a heck of a lot better than the crusty thing I threw away.. and the fact that the egr hose wasn't even connected to the airbox which is below the filter allowing dirty air directly into the engine through that hole... I'm sure my engine is breathing a sigh of relief)
MrMerlin's list is good, but possibly expense. There is a good chance that much of your disengagement issue could be trapped air. These can be hard systems to bleed. There is a special technique which you can find here. Also, some of the new master cylinders do not work correctly on some cars. There is also documentation here about how to see and fix that. Another disengagement problem can be lubrication of the spline shaft, which requires the correct grease, which is cheap. I would not initially lean towards new discs since your problem is disengagement rather than slipping. Other than bleeding and lubrication for the spline shaft the best place to start is likely pulling the whole assembly down and inspecting everything. One of the easiest cars ever to pull the clutch on, although hard to get it working exactly right. Before I looked and new discs I would probably be looking at a new spline shaft, and possibly the hose to the slave.
So when you get the clutch out,
then you can inspect it and then decide what parts on that list you need.
from the picture the green wire is ready to be updated.
Note the release arm bushing is gone
FWIW every car that I work on that comes in with a kNn leaves with a factory filter.
Since yours looks unused I would return it or scuttle it, they really do let more dirt into your engine.
That's because you are "shopping" at the wrong sites.
These are the only two places you should be ordering parts from: https://928srus.com/ http://www.928intl.com/
The rest are just generic parts suppliers drop shipping parts from a warehouse. They don't really know anything about 928's.
Bare minimum you will probably need both bearings and the release arm bushing. Worst case scenario you'll need an intermediate disc and both clutch master / slave cylinders. Reality is probably somewhere in the middle.
Stop driving it. You are destroying the transmission.
A 78 I'm working on had similar symptoms as yours. Both the clutch master & slave needed to be serviced so I had them rebuilt by White Post Restorations: https://whitepost.com/
Once I had the clutch arm moving as intended, things were still hanging up, dropped the clutch I found this: https://rennlist.com/forums/928-foru...n-my-78-a.html
Both bearings shot and the release bearing housing damaged. The shaft was also bone dry, which is bad all by itself without the other issues.
Next topic, how to adjust the intermediate disc, I cheat with an inspection / adjustment cover. I put the unmodified cover back on once everything is working properly. https://rennlist.com/forums/928-foru...ch-owners.html
All good advice that I can't add to, other than to echo the recommendations that you pull the clutch assembly to determine exactly what parts you need, and replace all your old rubber lines.
Pulling the clutch assembly is not as daunting a job as you think, and posting photos here will remove the guesswork in determining what needs replacement.
There is a definite series of non intuitive steps.
One mandatory step is to depress clutch pedal or use come-along to deploy the clutch and install a shim at each of three places on press plate to facilitate removal. Otherwise, not enough clearance.
The shims are either thick gage coat hanger or little loops made from roofing nails or similar.
Must also bang out the three alignment pins.
Be very careful as the whole heavy apparatus can fall straight down and crush your head.
hi - welcome - the first thing i would look at is the actual clutch slave cylinder - and when i say look at that's exactly what i mean - raise the front of the car (support it solidly) and have someone press the pedal while you get underneath and watch the slave - there is an observation hole in the bell housing where you can see the slave rod engage the release lever - does it move enough to release the clutch? - i think the amount of movement for a fully pressed pedal is around 17mm - if it's not moving anywhere near that far your problem is in the hydraulics - could be air in system, bulging hoses, leaky master or slave, not enough fluid - if it is moving far enough you are probably looking at removing the clutch - as stated above this is one area where the porsche engineers got it right - pretty easy - no removing engine or tranny - good luck
Thank you all, this seriously is very good advice, I'm going to park it and get to work this weekend! I'll start with the basics then work my way up and I'll post pictures of everything I do here, thank you!
So when you get the clutch out,
then you can inspect it and then decide what parts on that list you need.
from the picture the green wire is ready to be updated.
Note the release arm bushing is gone
FWIW every car that I work on that comes in with a kNn leaves with a factory filter.
Since yours looks unused I would return it or scuttle it, they really do let more dirt into your engine.
I appreciate the advice on the air filter, but I'm really curious about this green wire you keep mentioning, the engine runs perfectly, in fact it starts on the first turn every time and seems to have all or most of its horses left, what is this green wire thing and should I really replace it if the engine is running solid?
10-18-2021, 06:01 PM
Serious 928S Clutch Advice Needed
