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just an update, i shortened the rod, has been working well for the last 5 days. it still sticks every now and then, but engages well enough. I think the problem might have been that i was pressing the pedal in too deep. Is there such a thing?
It should not stick at all and your pedal should go all the way to the floor without issue. Like others including myself have said, don't go adjusting any linkages as you still have air in the system. @KevinGross gave you the best advise but it seemed like you ignored it. gl
It should not stick at all and your pedal should go all the way to the floor without issue. Like others including myself have said, don't go adjusting any linkages as you still have air in the system. @KevinGross gave you the best advise but it seemed like you ignored it. gl
I adjusted the linkage a small amount to account for the slack that's supposed to be there when you initially push the pedal.
As for air, i don't think it's air, at least not from the flush. I have a motive bleeder and used that, and it didn't help, i used a vacuum, and that didn't either, putting the butt in the air was better but not 100%. What T described, is the best so far, pushing the fork in slowly and then building pressure in the pedal. I haven't had to do a bleed since. in the last 5 days, pushing the pedal in and having it stick only happens when the weather is really cold, on first startups. I'm only replying to the threads so that people on the future have something to reference if they face the same thing. The car is driveable and you can feel when the clutch engages, it's working properly, but the pedal sticking every so often has me perplexed.
I adjusted the linkage a small amount to account for the slack that's supposed to be there when you initially push the pedal....
I suppose you and others may have different experiences idk. I had the same issue as you and was tempted to adjust the linkage. I was told not to as I hadn’t changed anything that would affect the adjustment. I had just changed master, slave and the rubber, blue & metal pipes and could not get all the air out. The problem was air in the system and it’s ususlly the problem in all cases that system hydraulics are opened up. The 944 clutch is particularly onerous as there are voids that can trap the air and make it difficult to evacuate all the air out of the system. Yes it’s a pain, but adjusting the linkages when nothing mechanical has been changed is just adding more problems plus, as you’ve found out, it doesn’t cure the issue.
After various attempts at bleeding what worked for me in getting that last bit of trapped air out was to pressurize the system with a Motive (I use mine dry) and while it’s pressurized bleed the clutch old school as if the Motive wasn’t hooked up. You’ll need another person to help slowly push the pedal down while you crank open the slave bleed screw, then close the bleed screw before your helper slowly releases the clutch pedal. Repeat several times until the pedal feels firm then disconnect your motive and you should be gtg.
Ive used this “double” method of bleeding a few times since and all worked well, I even use it for my brakes too, it’s become a habit.
After getting pedal, manually bleeding with the fork blocked through the inspection hole with a deep well socket seemed to work better. Light taps with a screw driver handle on both cylinders will help getting the tiny bubbles into one big bubble that will pass/bleed out
I suppose you and others may have different experiences idk. I had the same issue as you and was tempted to adjust the linkage. I was told not to as I hadn’t changed anything that would affect the adjustment. I had just changed master, slave and the rubber, blue & metal pipes and could not get all the air out. The problem was air in the system and it’s ususlly the problem in all cases that system hydraulics are opened up. The 944 clutch is particularly onerous as there are voids that can trap the air and make it difficult to evacuate all the air out of the system. Yes it’s a pain, but adjusting the linkages when nothing mechanical has been changed is just adding more problems plus, as you’ve found out, it doesn’t cure the issue.
After various attempts at bleeding what worked for me in getting that last bit of trapped air out was to pressurize the system with a Motive (I use mine dry) and while it’s pressurized bleed the clutch old school as if the Motive wasn’t hooked up. You’ll need another person to help slowly push the pedal down while you crank open the slave bleed screw, then close the bleed screw before your helper slowly releases the clutch pedal. Repeat several times until the pedal feels firm then disconnect your motive and you should be gtg.
Ive used this “double” method of bleeding a few times since and all worked well, I even use it for my brakes too, it’s become a habit.
Man I'm shocked that I didn't have this crazy hard time bleeding after my clutch / hydraulics work last year? I didn't raise one end or the other and just used the motive with about 15psi pressure. Sure, first time with the pressure only the pedal stayed down but then I had my son hop in and push the pedal a couple times while I quickly opened/closed the screw and... perfect.
Either I'm forgetting or beginner's luck. It just didn't seem that bad. I'm curious if the dealerships had all this trouble back in the day? I can't see them spending time lifting rear ends only... measuring with bubble levels.. having other techs jump in and out pumping this way and that... ...there's got to be something missing (?)
...pressurize the system with a Motive (I use mine dry) and while it’s pressurized bleed the clutch old school as if the Motive wasn’t hooked up. You’ll need another person to help slowly push the pedal down while you crank open the slave bleed screw, then close the bleed screw before your helper slowly releases the clutch pedal. Repeat several times until the pedal feels firm then disconnect your motive and you should be gtg...
Originally Posted by Dan Martinic
Man I'm shocked that I didn't have this crazy hard time bleeding after my clutch / hydraulics work last year? I didn't raise one end or the other and just used the motive with about 15psi pressure. Sure, first time with the pressure only the pedal stayed down but then I had my son hop in and push the pedal a couple times while I quickly opened/closed the screw and... perfect...
So, you basically did as I suggested in my post and it worked
hopefully, the last update, the pedal hasn't stuck in 2 weeks. I don't know if it was the last flush, or if this thing needed to work into a groove, but everything is working well now. Hopefully the last post
The Porsche 944 (1985 early one) clutch pedal autopsy. ( RHD UK )
The hydraulics were in good order
The mechanicals under the dash were another story.
The non airbag steering wheel was easy to remove. The driver's seat was moved as far back as
possible.
The plastic bearing on the push rod was non existent. This caused a lot of pedal play before
operating the master cylinder. Adjusting the push rod then caused the pedal to jam down if completely
floored.
During the 30+ years of life the pedal and push rod shaft had twisted out of parallel and the push
rod was now out of alignment with the master cylinder. The 8 mm hex along the push rod was now
riding on the washer within the master cylinder and had wedged enough to jam the pedal down.
Removing the clutch pedal assembly for repairs Looked impossible. ( Has anyone managed ? )
The first step was to make a phosphor bronze bush for the push rod. Because of the skew the
hole had to be skewed as well, in order to get the rod to center on the master cylinder.
A stiff bit of transparent plastic was mounted where the master cylinder fitted. A black line marked the center of the hole.
Precision alignment tool New bush Old bush Skewed pin
After a lot of fiddling, the rod was centered on the center line.
Using a lathe, the 8 mm hex was removed from the push rod in order to remove all possibility of
interference.
Finally a suitable washer was fitted to the shaft to retain the push rod in position and the rod was
set to approximately .5mm clearance.
The clutch pedal did not have any limit to movement so I will check if all of the travel is necessary
and possibly make a limiter. This might also reduce wear on the master cylinder !!!.
Some Pics included.
Drat, the handbrake lever is very flimsy and has been severely bent. Panel beating it and plating
and welding it up is next on the agenda. And so the restoration goes on!!
03-15-2019, 11:13 AM
