replacing clutch slave cylinder

orange9mm · 05-09-2008, 06:17 PM

just wanted to share my experience with changing the clutch slave cylinder.

i had brake fluid loss that was hard to track down, eventually i noticed my clutch pedal sinking to floor after driving a bit. after a little investigating i found brake fluid leaking out the bottom hole in the clutch housing.

removing the cylinder is easy. you simply unbolt the fluid line ( 12mm ) and then unbolt the cylinder from the clutch housing ( 13mm ), the top bolt is a tight fit for the wrench and hand.

replacing the cylinder is easy too with one trick, first connect the fluid line and bleed the cylinder by pushing the rod in with the bleeder valve open then close the bleeder valve and let the rod out. do this a few times. then bolt the cylinder back on the car. if you don't bleed the cylinder you will find you have no clutch pedal pressure to properly bleed the rest of the clutch system.

cheers

orange9mm · 05-17-2008, 04:38 PM

after replacing the slave cylinder the clutch hose blew coming from the clutch master cylinder attaching to the hard line that goes to the slave cylinder. i am discovering that 30 year old parts are going to fail when something new is introduced to the any system on these cars. i replaced the brake master cylinder grommets and then the brake switches failed shortly there after.

Danglerb · 05-17-2008, 04:55 PM

WYAIT, while your already in there, words to live by with the 928.

ryanhoelzer · 05-22-2008, 09:20 PM

I had some issues with my clutch after replacing my timing belt. This tip on bleeding the slave helped but I still have some issues. Before the belt I had some rough shifting issues but it's worse now. Sometimes I can get it into gear no problem but sometimes I have to kill it and put it into gear and restart the engine. I have some rough shifting and some rough downshifting, but sometimes it's fine. I feel like I've bled it as much as I can. I do have some play in the clutch before it starts to engage. I haven't even looked at that yet but is there some adjustment?

82, 5 speed

Danglerb · 05-22-2008, 09:39 PM

Take this link for a page of tips on clutch bleeding. Seems like it can be tricky, but its not something you can let go, that sounds like misery.

http://www.google.com/search?hl=en&q=928+clutch+bleeding&btnG=Google+Search

ryanhoelzer · 05-22-2008, 10:54 PM

That's good info. It's the middle of the night so I'm not in front of it right now but I have a good inch of play in the pedal. It seems like a bubble but I wondered if there might be something else..

ryanhoelzer · 05-23-2008, 10:25 AM

Ran to the store this morning and broke the push rod on the pedal on the way home..

Upon further inspection the clutch pedal has been broken and welded and is bent.

Hopefully the new pedal and rod will be here next week and might solve my problems..

Danglerb · 05-23-2008, 10:31 AM

On of my cars had a broken pedal (arm or leg whatever its called), kinda odd for something like that to break on a Porsche, expensive too.

orange9mm · 05-24-2008, 08:49 AM

another spot that can cause shifting issues is the ball and cup socket for the shift linkage on the top of the torque tube. i have discovered that mine has fatigued and can pop out of the socket. when this happens you will have a very hard time getting into gears, reverse and first especially for me. the cup is plastic and after 30 years no longer holds the ball tight. if it has not been replaced it will soon need to be.

as far as clutch bleeding is concerned if you are only replacing the slave it is not hard it is when you replace/tinker the master cylinder. the master cylinder at the pedal sits at a angle and air tends to get tapped at the top. i have not had to mess with the master cylinder yet and i am crossing my finger that it is trouble free for at least year. i can't offered to replace everything at once. i am hoping for a piece mill restoration, praying the failures are spaced out so i can at least enjoy the car.

Danglerb · 05-24-2008, 10:18 AM

Quote:

Originally Posted by orange9mm

i can't offered to replace everything at once. i am hoping for a piece mill restoration, praying the failures are spaced out so i can at least enjoy the car.

It adds up fast, but I pay for labor, so its just the opposite for me, I can't afford paying a mechanic to take stuff apart twice to replace parts in the same area. A mechanic I know looks at it same as you though, he goes in VERY careful not to disturb wires or hoses and fixes just whats broke.

orange9mm · 05-24-2008, 02:57 PM

so far i have done the all work on the car, besides alignment. if i see something that clearly looks old then i will replace it. but in the case of my clutch hose/line i had no idea, the line disappears in to la la land, the part of the line that turns into hose was not visible from under the car ( i also assumed the whole line was metal doh ). all hoses should be replaced on something of this vintage. so far i have replaced all vacuum hoses, brake lines, and now this clutch hose. the blue hose from the brake cylinder to the clutch pedal is new already. i am now going to go over the diagrams looking for hoses. fuel lines are coming to mind.

ryanhoelzer · 06-02-2008, 10:15 AM

So I got a pedal assembly and put it in and the clutch was very, very hard. Actually wasn't really giving much at all. I pushed fairly hard and popped something. I definitely lost fluid from the system. Did I blow the clutch MC or just pop a line? I've read some stuff on replacing the cylinder but haven't started removing anything yet..

orange9mm · 06-02-2008, 11:25 AM

where is the fluid loss going?

if it is under your pedal in the car cabin then it is the clutch master cylinder.

if it is in the clutch housing, leaking out the view hole at the bottom of the clutch housing, then it is the slave.

if it is running down your firewall then it is the blue hose from the brake reservoir/cylinder to the clutch pedal.

if it is running/leaking down from the lower back of the engine not firewall, trace the hard line from the slave up and see if the leak is coming from there. that is the hose i blew, in between the clutch pedal and the slave cylinder. when i blew the hose i heard a audible pop and the pedal drop to the floor. the fluid was leaking on the back of the engine so i got smoke from the fluid burning.

ryanhoelzer · 01:58 PM

I started tearing it down and the rubber section between the master and slave cylinder had a blowout. I think what caused it was the slave. When I took it out the piston was all the way extended and had actually pushed the rubber out and tore it. The rod itself has a knick taken out of it even. I pushed the piston back and it squirted fluid out the line connector but I'm questioning it. I'm guessing this happened when I broke the pedal? Like it was stuck extended? I think I'm gonna replace the slave and the rubber hose and cross my fingers on the master. The fact that it blew out the hose makes me think the master should be good?

edit: I went ahead and ordered the blue hose, the lower hose, and a slave cylinder. I figure I'll try my old one and see if it works and I can return the new one or keep it for inventory..

ryanhoelzer · 07-05-2008, 02:51 PM

I ended up just using the new slave cylinder and everything's great. When I compared the new one to the old one the old one wasn't traveling like it should so I just used the new one..

Danglerb · 07-05-2008, 04:08 PM

I've heard that some get a ridge from being in the same spot a long time. For $80 or whatever a new one costs, its not worth keeping an old one with even the slightest issue.