Clutch master cylinder X-post

[Vic Rattlehead]

Hi all. Also posting this in the 951/Turbo forums.

Recently started having clutch pedal issues. The pedal would only return halfway and sometimes even sink and get forced to the carpet (by the helper spring I'd imagine)

Before I get going I should say this is a UK car with the master cylinder on the right hand side including it's own separate reservoir. 1991 951

Going through the history, the car had a new slave cylinder 2 years ago. Checked the master cylinder reservoir and the fluid was black. I pulled the master and stripped it apart and the top most seal on the piston looked like it had been chewed by a mouse. I've rebuilt the cylinder with a repair kit, but can't get the pedal to pump up suffieciently.
Also bleeding the traditional way only yields small squirts and nothing much being taken from the reservoir. Reverse bleeding (with an oil squirt can and length of pipe) shows air coming up through the reservoir and the level fills up. But after a couple of pushes on the pedal (enough to drain what the squirt can has put in the master) it seems to not take anything or little from the main reservoir.

Question is, can anyone tell me the way the tapered seals on the master cylinder piston should fit? I originally thought they fitted as in example A. But on seeing this link.................
******** Parts Catalog
I decided to reverse the top most seal to how it's shown in B. Note neither arrangement has given proper results, although I've had better results with A.



Sorry, I should say that the right hand side (where the letters are) would be the pushrod side.

Thanks in advance everyone.

[Grandad#3]

Hi Vic, First off we do not rebuild the Master Cylinder, just the slave if it looks OK inside. The Fluid should be completely flushed to include the brakes. Fluid needs to be changed out every two years anyway per Porsche. The line going from the Master to the Slave could be clogged with foreign matter from the bad Master Cylinder seal. Go to clarks garage.com and click o "C" and look for Clutch.

http://www.clarks-garage.com/shop-manual/repair-procedure-index3.htm

Cheers,
Larry

[John_AZ]

Vic,
The picture from ******** has the cups as in your photo "B"



Next, this is a picture of my clutch MC changed Aug '09 and the cups position is the same as your photo "B"



The inside of my clutch MC was a thick paste of black/silver goop.

As Grandad#3 mentioned rebuilding is not recommended especially if the bore of the cylinder has pitting.

Flush the clutch lines and you may want to replace the rubber clutch hose as well because it deterioates and gets soft.

GL
John_AZ

1988 924S 61K+ 1987 924S 114K DD

[Vic Rattlehead]

Thanks for the replies guy's. Still had no success with the rebuilt master so I've bit the bullet and bought a new part. Will be changing over along with a new slave and flexi hose.

Hopefully that will clear things up.

Thanks again