Clutch Issue NEED Help

[wilson234]

I know there's a 964 dedicated forum, but not as many loyal followers, and I know may have done the upgrade to the cross shaft, so I present my dilemma here.

1989 964. I have the periodic clutch issues where the pedal goes down only half way. Clutch still is able to disengage because the engagement point is quite high on the 964. It feels like the pedal hits a stop about half way down the normal pedal movement. One shift normal, next shift half pedal. Then it just goes away typically after another shift or two.

When the clutch was exhibiting this half pedal issue, I examined the pedal box and didn't see any issuse, outside of not getting full range of motion. I disconnected the clutch master cylinder from the pedal linkage and the full range of motion was there (eliminates a potential clutch pedal box issue). I went ahead and replaced the master cylinder as I could see it was the original unit and figured I would start there. No change, still had the periodic half range of motion.

Question, before I take the time and cost to seperate the transmission to check out the cross shaft, my specific question to all of you who have does this is the mechanics of how the clutch fork operates.

Meaning, if the needle bearings on the cross shaft (964 has the updated unit with bearings on the transmission boss sides vs. on the fork itself) were causing this lock up binding, wouldnt the clutch fork have the ability to rotate independently? So if the shaft itself is locked up, the clutch fork can still rotate on the shaft since it has bushings. See attached photo of the updated cross shaft unit.

I've done lots of searching and uncovered folks that found wear on the cross shaft from needle bearings, but nothing to the point that it stopped the pedal half way through the range of motion. Just comments that their pedal had felt heavy.

My last option would replace the slave cylinder, as this is really the only mechanism left outside of the cross shaft.

Other than this periodic issue, there's no unusal noise or issue from the clutch, everything works properly.

Please help, this issue has really stumped me.

[johnsjmc]

Unless you know exactly how old the slave is I would replace it next. They wear out faster than the master. and can be done without dropping the trans.I,ve replaced mine twice in 5 yrs. I had an issue of a slightly dragging clutch (which seemed to come and go). Bleeding helped briefly and changing the slave helped a lot. I just dropped the trans and replaced the clutch ,and greased the input shaft splines to fix it properly.
I found nothing else wrong with the throwout mechanism. 1995 993

[wilson234]

Appreciate the feedback, I think I'll do the slave, if it works, it saves me a huge amount of time and effort. If not I at least know it's new.

Your indication of dragging clutch makes sense for the slave to start loosing it's ability to full extend the piston of the slave.

My issue, I can't explain, if the slave doesn't do it, I will dig into the cross shaft.

I was also thinking to pull the rubber cap off and attempt to grease or replace the outward facing needle bearing. Or maybe just spinning the cross shaft to possibly relocate the needle bearings and where it's binding on the shaft. Since this is also accessible from outside the transmission.

Anymore ideas????

[johnsjmc]

I am an experienced mechanic although my 993 is the first g50 911 I have worked on. Even though there are guys on Rennlist who have removed and replaced the crossshaft with the transaxle in the car I think it's nearly impossible after doing the clutch a couple weeks ago.I no longer have a lift since retiring and did the drop in my home garage with a floor jack and creeper.
Even with the engine out I dropped the bolt holding the cross shaft in twice while reassembling it(with a rag stuffed in the hole in case you drop it.) Then a magnet and try again. If you manage to pull the outer cap it might disturb the shaft enough that the inner will drop it's needles inside and then you HAVE to drop to get everything in again. My car has 111000 mi on the original clutch(dated 1994 on pressure plate). There was still some grease in the cross shaft caps but they are like miniature U joint caps. The shaft withdrawal pulls the needles out of place in the inner cap and they then probably will drop sideways preventing reinsertion.