mcholdfast

I've got the Black Sea R&D rebuilt torque tube installed in the 89 GT and it seems to be working fine. Everything went back together easier than I expected but I do have a puzzling problem. Now that everything is back together, the clutch doesn't release until the very top of the pedal travel and it's not releasing completely as it slips when any amount of throttle is applied. When I install the slave cylinder, it's like the pin is too long. I can see it push the clutch arm back as I tighten the bolts on the cylinder and bring it in the final 1/2" or so. Any idea what would cause this? I seem to remember having the same issue with Woody's 5 speed S4 when we did the tb/wp and his slave cylinder had been unbolted to install the flywheel lock but I never heard what he did to fix it.

Lizard928

if the pin was too long this would help the problem.

However you probably got some air into the system. Also check to ensure that the pivot arm is on the ball cup bushing, and that the bushing is in good condition.

worf928

+1 what Colin wrote.

There is quite a bit of "pre-tension" on the slave cylinder push rod. If all the various bits and pieces of the clutch are back where they should be and there's no air in the system, then the clutch pretty much has to work.

So, check the top of the release arm then pressure bleed the clutch system. When the clutch hydraulics are disturbed (e.g. dropping the clutch) it is not unheard of, with old components, to get air into the system.

mcholdfast

Your comment about the pin makes me think I didn't describe the problem correctly. Normally when the clutch pedal is pressed, it pushes the arm with the pin. What's happening is the arm is being pushed by the pin without depressing the clutch pedal so that it's like the pedal is partially depressed when it's not. Would air in the system cause this? Could air get into the system just by unbolting the slave cylinder? Nothing else in the clutch hydraulics was touched.

Lizard928

So your clutch system is disengaging itself?

If that is the case ensure that the pedal is returning to the top and adjust the master actuation rod to remove any preload on the system.

worf928

Normally, the slave push rod DOES put non-trivial pressure on the release arm. The push rod has to be pressed 1/2" or more (IIRC) into the slave cylinder before it is "short enough" to seat on the release arm lower ball cup.

If the top of your release arm isn't seated correctly then the lower part of the arm may be closer to the slave cylinder and will therefore "push" harder on the slave's push rod.

One quick check: with the slave's push rod disengaged from the release arm, wiggle the release arm. It should be pretty "loose." If it doesn't move by several MM's freely then this is a sign that it is bound-up.

Possibly... *if* nothing is mis-aligned clutch-wise.

Yes.

Another quick check, if your cover is on and *if* your clutch friction disc isn't worn to the nubs....

Look directly and squarely into the inspection hole in the bottom of the bell housing cover. Can you see the bottom of the release arm through the hole? You shouldn't be able to see it at all if you are looking straight up through the hole.

Based upon your description, air probably isn't the problem. Something's "up" with the release arm.

mcholdfast

Yes, I can see the release arm through the hole. The hole for the pin is just about centered in the inspection hole. Time to drop the exhaust again and check the arm. We didn't remove the clutch but must have bumped the arm out of place while wrestling with the torque tube. I'll follow up soon with what I find.

cfc928gt

You can see the top of the release arm where it fits over the ball stud by removing the intake air box, much easier than dropping the exhaust.

worf928

What cfc wrote: check the arm from the top first. It'll either be a smoking gun or time for more head-scratching.

mcholdfast

I think maybe I had both problems. I took the cover off and checked the position of the arm. It looked right so I put the cover back on and noticed the arm is now much further back than it had been in relation to the inspection hole so I think that issue is solved just by taking it apart and putting it back together. Obviously it wasn't aligned correctly before.
Now that the arm is in the right position, I've got no clutch so I tried bleeding the slave but no luck yet. How far should the pin travel when the clutch pedal is pressed? The dinner bell is ringing so I'm going to pick up some brake fluid and try bleeding it completely tomorrow. Does the method in this thread work the best? It seems to be the simplest I've seen.

worf928

The operating travel of the slave's push rod is 10mm IIRC.

Can't help with the bleeding as I always use a pressure bleeder.

mcholdfast

Looks like I need to invest in a pressure bleeder also. The best deal is I find is this one on eBay. Do any of our 928 vendors sell them?

worf928

Yes. That link is the (IIRC) Motive pressure bleeder.

928 Specialists sells them - and I think for a lower price than that.

mcholdfast

I'm not finding it on their website. I'll send them an email.

worf928

Call.