SharkSkin

Stan, I think he's looking to get it working for now, as opposed to trying to get it to 100%. I think the honeymoon has been over since he's had a taste of the 86 SC.

Tampa 928s

I know your correct about taking it apart, I am mentally trying to justify not removing the headers. I hope it's not the transmission and if I do all this it may still have that problem. Any one ready to fly in and help, weather will be nice next week. It gets a little old not having an extra pair of hands to help out.

Tampa 928s

Is there a parts list I should order for a rebuild? The clutch seems it must have been replaced in the past due to the travel of the fork per manual seems like there is a lot remaining.

SharkSkin

The reverse gear has no synchro on the early cars IIRC, so the test I mentioned above will tell the tale. There is not much that can go wrong shifting into reverse, other than a dragging clutch.

IIRC 928I has a clutch kit, all I had to add was the ball cup, the guide tube, and the stub shaft. I already had an IP ready to go in.

When I talked to Mark A about clutch parts he mentioned that they very rarely see friction disks that are worn out. Apparently the friction material is not the weak link. I went with new friction disks anyway, because what CAN wear out is the female spline on the disk. IMHO an excessively worn female spline can cause accelerated wear on the stub shaft. In any case -- talk to them. They help people put together kits all the time.

Tampa 928s

I hope nobody is having a pathetic evening like me and are working on there car.

I have the clutch pulled back "disengaged", and there is no gap on the T-bolts it's laying flat. Should I move it to create the gap or leave it alone? You can see the disks apart and shaft spins freely.

SharkSkin

Nope, that should be good. The only reason to pull it rearward from there is if you don't have enough gap for the rear disk. Also, when you release it the adjuster may get pushed forward by the pressure plate. That limits how far to the rear it can go -- any time it is too far to the rear it will get pushed forward under spring pressure from the pressure plate.

The important thing is the shaft spins freely.

Tampa 928s

I re-read the Post by SS and realized I need to release the clutch to measure the clearance. It looks like about .066 MM all the way around.

Landseer

When you replace the ball cup, the sequence is somewhat important for ease.

Put the white plastic piece onto the ball. Its possible to do this from under the car, using a long screwdriver for reach and a socket to keep from spliting the plastic piece with the end of the screwdriver.
Then, put the release arm partway onto the plastic piece. Actuation of the slave will push it into place.

Under what conditions do you have the rattle? When turning rear shaft (propellor shaft) or when turning the intermediate shaft? Chances are you need a new pilot bearing and throwout bearing at minimum.

Tampa 928s

When turning the rear shaft, but the pilot bearing has a cap the rests on the fork and is loose until under load. I am going to recheck it tomorrow.

Mrmerlin

there are 2 bearings in the clutch the Big fat one connected to the release fork is the throw out bearing the pilot bearing is tapped into the aft end of the crankshaft and the stub shaft runs in this smaller bearing.
The Throw out bearing TOB is the one thats running at engine speed all the time

SharkSkin

With the clutch engaged, is there a gap at point 6 in the diagram above? If not there is nothing more you can do. If there is a gap there, you can push the adjusters rearward to the point that the gap closes. To determine if that is necessary, try to figure out if, when the clutch is disengaged(pulled with strap), you have equal clearance for the front and rear disks. If you do, you're finished.

If there is a gap at point 6 with the clutch engaged and there is a smaller clearance for the rear disc when disengaged, you might benefit from moving the adjuster rearward.

BTW, with all new parts, the gap at point 5 with the clutch engaged is ~1.2mm on my car, and there is no gap at point 6. Wear should eventually widen this gap. Your observation of ~.66mm indicates to me that logically you ought to have some gap at point 6 with the clutch engaged.

Tampa 928s

You would never know I did a couple of clutches before on my 68 Vett. It was easy and never had a problem except for the stroker burning them out.
I'll do a little more poking around tomorrow, I have the bushing on its way. I maybe reading too much into this repair. The bushing was missing and the rattle most likely was the TOB assembly not resting on the fork. The car shifts great except for the occasional reverse and first

dprantl

Those springs that hold the T adjusters look really tired. On my '86 they broke off on one part of the pressure plate and the clutch could no longer be properly disengaged. When I took it all apart, they looked pretty much just like yours. Just a heads up.

Dan
'91 928GT S/C 475hp/460lb.ft

SharkSkin

That bearing is normally under some load unless the spring inside the slave cylinder is broken. It's pressure from that spring that normally keeps the release arm from flopping around. If the ball cup bushing is shot, that spring is extended more and doesn't hold the release arm in stable tension anymore.

This clutch has a lot more moving parts than the one in the vette. The only concern that I have*, seeing how far you've moved the pressure plate(compare where I have my assembly shims vs the same pins in your pix) is that you have moved the arm further to the rear than it normally goes. The closer you are to simulating the 17mm stroke length of the slave cylinder, the better you will be able to set the intermediate plate to the proper mid position between the flywheel and the pressure plate. If you move the arm too far, you may set the intermediate plate too far to the rear in your attempts to center it. Then, when it's only moving 17mm under the influence of the slave cylinder, there won't be enough clearance between the intermediate plate and the pressure plate.

I should tell you, before I touched my clutch I read everything there was to read about it, scrutinized threads and pics, even went through the motions with a strap like you're doing. And I never fully understood how the effing thing was supposed to work. The lightbulb finally went on when I moved the release arm with a prybar, watching those forks as I engaged and disengaged the clutch. Really, take a few minutes and do the same. Crawl under there and watch the forks as you operate the clutch. Then watch it from a different angle, and move the light around. Watch the disks as you operate the clutch.

* given your stated goals for the project

9x8

Once again I'm amazed by the mass of knowledge that is accumulated in this forum.
I had the same issue as the OP after I put the clutch back together in my 90 GT. The clutch fork seemed to have excessive back-to-forward free play and rattled somewhat unless I preloaded it by pressing clutch pedal. I was afraid that I had to tear it down again, but after reading the above post I'm pretty sure that I just have bad slave cylinder - it does not preload the arm correctly.