Clutch master/slave replacement
Thread Starter
Drifting
Joined: Dec 2004
Posts: 2,235
Likes: 2
From: Atlanta
following up
Just to follow up, today was the first chance I had to get back in the garage and finish things. I got everything installed again, pedal cluster back together and hooked up the power bleeder. Bled all four brakes and then tried bleeding the clutch at the slave and got a lot of air out there, but it still wasn't right. Then I followed others' suggestions to burp the master from the footwell and once I did that the clutch was PERFECT. Wow what a difference the new everything makes! The clutch has NEVER felt like this, absolutely a revelation. FWIW here's a quick primer on burping the master, really easy once you figure it out. Takes a total of 5-10 minutes max.
I can't begin to describe just how much better the clutch is after doing all this. It was a lot of work, but so much better to drive now...at least for a little bit until I had another problem. After sitting for the past three weeks the battery was dead and ignoring advice to the contrary I jumped it at the battery because the post under the hood is not in good shape. Worked fine and I drove around the block a couple times. Then a little while later I went to start it again and nothing, battery just didn't get enough charge. So I figured it was fine and I tried to jump it again...CRAP. I have dash lights and the fuel pump is running, but the starter doesn't even click. I think I blew something.
Off to search and figure out the next problem.
[edit] it was the Clifford alarm, tripped it when I jumped it...oops. Now I'm driving!
- Remove the clip from the pin on the pedal
- slide the end of the pushrod off the pin and pull the pushrod out
- remove the rubber bellows
- put the pushrod back in the master and back on the pin - this will keep the "guts" of the master in place while you remove the snap ring
- using the snap ring pliers, pop the ring out, the pushrod will not move
- hold the pushrod tight and slide it back off the pin
- slowly let it out, no more than 1/2" until you see the seal - I actually heard the air come out when I did this
- push the pushrod back in and slide it back on the pin
- pop the snap ring back in
- slide the pushrod off the pin and pull it out of the master completely
- put the bellows back on
- put the pushrod back in the master, slide it on the pin and clip it down
I can't begin to describe just how much better the clutch is after doing all this. It was a lot of work, but so much better to drive now...at least for a little bit until I had another problem. After sitting for the past three weeks the battery was dead and ignoring advice to the contrary I jumped it at the battery because the post under the hood is not in good shape. Worked fine and I drove around the block a couple times. Then a little while later I went to start it again and nothing, battery just didn't get enough charge. So I figured it was fine and I tried to jump it again...CRAP. I have dash lights and the fuel pump is running, but the starter doesn't even click. I think I blew something.
Off to search and figure out the next problem.
[edit] it was the Clifford alarm, tripped it when I jumped it...oops. Now I'm driving!
Last edited by shmark; Mar 29, 2008 at 04:45 PM.
Thread Starter
Drifting
Joined: Dec 2004
Posts: 2,235
Likes: 2
From: Atlanta
brake booster removal
One more thing, just because it took me a while to really figure this out. Removing the brake booster is a pain the ****, but if I ever do it again it will be easy. Reading posts on this site as well as the manual lead me to the process, but I needed the "Booster for Dummies" primer. So here it is.
Hope that helps someone. Being a computer guy, I needed the step-by-step instructions to get it done and it took me a lot more times back and forth in the footwell to figure it all out!
- Remove the fluid reservoir, it just pulls out of the brake master cylinder
- disconnect all lines from the brake master and remove the master cylinder - the two electrical connections just pull off
- it helps to completely remove the hard line connected to the end of the master, going down to one of the two pressure regulators
- remove the forward pressure regulator, just one bolt and the hard line you just removed
- I just unbolted the rearward pressure regulator, left it in place and disconnected the hard line
- pull the vacuum connector off the face of the brake booster...it just pulls out but you have to pull HARD
- have someone push the brake pedal to the floor and hold it (my wife was a trooper)
- using a pair of long-nosed vice grips, grab the brake pushrod as it is fully extended from the center of the booster and clamp it in place
- now dive into the footwell (wife is out of the car now) and remove the clip and washer from the pin at the end of the pedal/pushrod
- push the pin through and then push the pushrod the opposite direction and it will come off the pin
- loosen the jam nut and then unscrew the end from the pushrod...almost all the way out, but leave it engaged with the first couple threads
- put it back on the pin on the pedal
- have wife hold the pedal in again, this will push the piston in even further
- now back in the engine bay, re-clamp the vice grips as the rod will have come out even further
- now you're ready to unbolt - dive back in the footwell and remove the four nuts holding the booster in place
- now back in the engine bay, carefully pull the booster forward and then roll/tilt towards the engine
- after playing around and applying suitable swearing, the booster will be out!
in - installation is the reverse
Hope that helps someone. Being a computer guy, I needed the step-by-step instructions to get it done and it took me a lot more times back and forth in the footwell to figure it all out!
Team Owner
Joined: May 2004
Posts: 31,234
Likes: 4,220
From: Philly PA
For anyone following this see post 17
I think this is the best way to work on the clutch hydros. If you do it this way you dont need to remove anything but the clutch hydro parts and the starter.
Mark glad you got things working, but there may still be air in your clutch system due to the convoluted line routing. You can still follow post 17 if you have any doubts, no need to remove the brake booster, Stan
I think this is the best way to work on the clutch hydros. If you do it this way you dont need to remove anything but the clutch hydro parts and the starter.
Mark glad you got things working, but there may still be air in your clutch system due to the convoluted line routing. You can still follow post 17 if you have any doubts, no need to remove the brake booster, Stan
Thread Starter
Drifting
Joined: Dec 2004
Posts: 2,235
Likes: 2
From: Atlanta
I think I agree with you. 
After putting some thought into it, it's really difficult to fill the clutch system fully from the reservoir because of the way the clutch master isolates it. The thing that did it for me was keeping the power bleeder connected the whole time, even when I bled the master directly. Filling it prior to installation will ensure it's completely full.
After putting some thought into it, it's really difficult to fill the clutch system fully from the reservoir because of the way the clutch master isolates it. The thing that did it for me was keeping the power bleeder connected the whole time, even when I bled the master directly. Filling it prior to installation will ensure it's completely full.
Instructor
Joined: Sep 2002
Posts: 131
Likes: 0
From: Sardis B.C. Canada
I read all the posts and would like to add something that I did on my racecar that made clutch bleeding alot easier. By carefull sighting and an exploratory 1/8 hole, I drilled a hole from the inside of the fender well that lines up with the hard line out on the master cylinder. Using a" unibit or step drill" I went as large as possible untill the bit would hit the mc then widened the hole with a die grinder to accept a line wrench that fits on the mc hard line nut [12mm?]. I then just made a small plate that covers the hole so no debris and water can get in , used a couple of self tappers and done. This way you can just crack the nut at the master when the slave is installed and the air will weep out at he fitting which just happens to be the highest point. Works for me, Porsche should have had an access plate there from the beginning.
Darrin.
79 5 speed street
79 racecar
A bunch of parts cars.
Darrin.
79 5 speed street
79 racecar
A bunch of parts cars.
Team Owner
Joined: May 2004
Posts: 31,234
Likes: 4,220
From: Philly PA
we have a had a few of these modified cars in the shop. Even with this setup still had some air
Still the best way to eliminate all of the air is by following post 17.
It is really easy and once its done you wont ever lose the circuit unless the master or slave fail, but then again if you replace the whole system then you should be a good to go for atleast 5 years or more
Still the best way to eliminate all of the air is by following post 17.
It is really easy and once its done you wont ever lose the circuit unless the master or slave fail, but then again if you replace the whole system then you should be a good to go for atleast 5 years or more
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Drifting
Joined: Nov 2001
Posts: 2,233
Likes: 1
From: zürich, switzerland
About the approach of burping the master.
Strangely the hard part was to get the piston back in ( I wonder why? ) - I had to use both hands on the pushrod to get it down to the point where the little bolt thingy would go into the hole in the pushrod.
I assumed that all I was doing was pushing fluid back into the reservoir which should be easy to do?
The resistance was uniform; I mean it was not like the piston passed the entry hole & then got harder to push.
Also the piston really wanted to jump out of the M/C after I released the push rod - I wonder where this pressure comes from?
Anybody know?
Marton
Strangely the hard part was to get the piston back in ( I wonder why? ) - I had to use both hands on the pushrod to get it down to the point where the little bolt thingy would go into the hole in the pushrod.
I assumed that all I was doing was pushing fluid back into the reservoir which should be easy to do?
The resistance was uniform; I mean it was not like the piston passed the entry hole & then got harder to push.
Also the piston really wanted to jump out of the M/C after I released the push rod - I wonder where this pressure comes from?
Anybody know?
Marton
Thread Starter
Drifting
Joined: Dec 2004
Posts: 2,235
Likes: 2
From: Atlanta
It's pressure from the slave. The slave piston compresses a bit when installed so it's constantly under some load. Pulling the guts from the master allows this "pre-load" to push back, forcing the master pushrod out. It shouldn't be a lot, no more than when installing the slave. I noticed it push, but I expected it and held it tightly, only letting it out as far as I wanted.
Turns out I still have some air in the line.
I have absolutely no desire to cut my brand-new blue hose but I might be looking at doing just that and taking Stan's advice to bench bleed it. I'm going to bleed it traditionally tonight, hopefully ready for a local show on Saturday and then seeing what else I'll have to do.
Turns out I still have some air in the line.
I have absolutely no desire to cut my brand-new blue hose but I might be looking at doing just that and taking Stan's advice to bench bleed it. I'm going to bleed it traditionally tonight, hopefully ready for a local show on Saturday and then seeing what else I'll have to do.
Drifting
Joined: Nov 2001
Posts: 2,233
Likes: 1
From: zürich, switzerland
HTML Code:
The slave piston compresses a bit when installed
about
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Turns out I still have some air in the line.
I thought about taking it all out as suggested but how do you check all the air is out before you stick it back in.
I don't want to do all that work to find no improvement
Marton
Last edited by marton; Apr 2, 2008 at 02:46 PM. Reason: finger trouble
Thread Starter
Drifting
Joined: Dec 2004
Posts: 2,235
Likes: 2
From: Atlanta
I don't think it will be that bad, now that I know how it all comes apart. With the hard line attached, it will actually help to hold the master in place while bolting it back down. Depends on how ambitious I feel, but I'm going to get some air out tonight so I can drive to the show and then probably bench bleed Saturday. I'll time it and see how long it takes.
Drifting
Joined: Nov 2001
Posts: 2,233
Likes: 1
From: zürich, switzerland
About
On second thoughts why does it not push fluid up into the reservoir instead of puttung pressure on the M/C piston?
Marton
HTML Code:
The slave piston compresses a bit when installed so it's constantly under some load
Marton
Team Owner
Joined: May 2004
Posts: 31,234
Likes: 4,220
From: Philly PA
if you can get a helper to hold the Master cylinder in place while you install the holding screws this helps A lot.
All of the air will come out if you hold the slave higher than the master and tap on it a few times you can see the air coming out of the slave cylinder bleeder while its on the bench. Really this is the best way to fix your hydro system.
Mark for you you will need a sharp razor blade to cut the blue hose off just under the nipple of the resivour, have a rag handy to catch the dripings then you carefully cut off the rest from the resivour , plug the hose with a bolt to prevent contamination and fluid spray
All of the air will come out if you hold the slave higher than the master and tap on it a few times you can see the air coming out of the slave cylinder bleeder while its on the bench. Really this is the best way to fix your hydro system.
Mark for you you will need a sharp razor blade to cut the blue hose off just under the nipple of the resivour, have a rag handy to catch the dripings then you carefully cut off the rest from the resivour , plug the hose with a bolt to prevent contamination and fluid spray
Burning Brakes
Joined: Sep 2003
Posts: 1,107
Likes: 12
From: Baton Rouge, LA
The clutch fluid should gravity drain from the slave bleeder unless the pre-load is incorrect. No gravity drain is a good indication that the ports at the master are blocked fro too much pre-load.
The pre-load is set at the pedal rod, not the slave. Depending on the model year, the pedal rod requires either clearance at the master piston or a pre-load of one turn. Too much pre-load will restrict the ports on the master which allow the fluid to flow back and forth through the master from the reservoir.
You can bleed with a power bleeder or by the "pedal up/ pedal down method (which will take longer).
After bleeding, the fluid must be forced back through the master to remove any air trapped within the master. To do this:
- Remove the rod from the pedal - this removes any pre-load and makes the next step easier.
- Unbolt the slave and (with bleeder closed) force the piston all the way in. Hold and slowly release -- then repeat several times.
- This forces the air back up to the reservoir. And there will almost always be air which needs to be forced back even after pressure bleeding.
- Button back up and give it a test.
The pre-load is set at the pedal rod, not the slave. Depending on the model year, the pedal rod requires either clearance at the master piston or a pre-load of one turn. Too much pre-load will restrict the ports on the master which allow the fluid to flow back and forth through the master from the reservoir.
You can bleed with a power bleeder or by the "pedal up/ pedal down method (which will take longer).
After bleeding, the fluid must be forced back through the master to remove any air trapped within the master. To do this:
- Remove the rod from the pedal - this removes any pre-load and makes the next step easier.
- Unbolt the slave and (with bleeder closed) force the piston all the way in. Hold and slowly release -- then repeat several times.
- This forces the air back up to the reservoir. And there will almost always be air which needs to be forced back even after pressure bleeding.
- Button back up and give it a test.