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Replacing Clutch Master and Slave Cylinders

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BASS

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Ok, it looks like my clutch master cylinder is shot (i.e. no more clutch pedal feel and I cannot shift the car at all from a dead stop). I plan on replacing the clutch master and slave cylinders at the same time, and was wondering if this is a straight-easy job to do? Im going to order the ones from Moss for my 1500...I figured that since I replaced the brake switch myself, this job wouldnt be any harder..

I know the tricky part will be bleeding it, but other than that, is there any hidden tricks I need to know before replacing them or is it a straight remove and replace job?? Thanks
 
"BASS" -

I had the same issue -- it was the slave clutch cylinder. Easy & Cheap. Helps immensly if you can get the car in the air.

Geo
 
Not sure what car you have, but consider modifing the clutch slave so you can bleed it from above. I will see if I can find that link. It puts the bleeder where you can reach it. Maybe someone else can find the information also.
 
When I bought my 5 speed from Paul A. I also ordered a flex hose line for the clutch slave. With it I was able to hold the slave above the master and bleeding was a snap. If you get a flex line you will have no problem with the bleeding.
 
I followed Duncan's advice and it couldn't be easier.

Install the slave, the hose, connect to uninstalled master cylinder. Fill, and gently rock the master to allow the bubbles to escape. It will take about 2 minutes. Then install Master Cylinder in frame. I can't even begin to describe how much easier it is this way.
 
The 1500 clutch can be a pain to bleed. Whether you do it by the book or with a Mityvac, there's an air bubble that will get trapped at the peak of the hose. Once you bleed it, stomp hard and fast on the clutch a few times, and that should move the air bubble out. You might have to bleed once more in case the bubble went to the slave cylinder.

One quirk I found with the slave is the dust boot makes a tight seal with the pushrod, so when you shove the slave in place the pushrod acts like a piston and builds up some air pressure inside the dust boot. Once you work the clutch a few times, that air pocket burps its way into the slave cylinder and you'll have to bleed it. Guess how I know :blush:. I had to remove the slave briefly, and figured I wouldn't need to bleed it since I didn't open the lines. Well, the clutch worked fine - twice.
 
sparkydave said:
The 1500 clutch can be a pain to bleed. Whether you do it by the book or with a Mityvac, there's an air bubble that will get trapped at the peak of the hose.
Click to expand...

which is why it is so much better to bleed with the MC off the car
 
JPSmit said:
which is why it is so much better to bleed with the MC off the car
Click to expand...

I was about to question how that was easier, but in the event of replacing the master cylinder, then yes, it would certainly be easier to do that before bolting the master in. :smile:
 
If you can thread the slave cylinder up from below while still connected to the hose, you can hold the slave outside of the car and bleed it, while you sit in the driver's seat. Putting the bleeder at the highest point in the circuit makes things MUCH easier.

With the slave in place, you can pop off the access plug on the side of the transmission tunnel, and reach the bleeder screw with a 12" wobbly socket extension, also from the driver's seat.

Edit: ...I <span style="font-style: italic">think </span>the '79 still has the access plug on the tunnel.
 
Ok, I lifted the car up today, and removed the slave cylinder. I noticed the rubber diaphragm had a big tear in it (this is the rubber piece that connects into the end of the cylinder and the pushrod slides into)..I guess this is the dust cap? Was this the cause why I have zero clutch pedal feel? Or maybe the slave cylinder itself is bad (the piston was not able to move and retract freely when I pushed on it)..

If so, it looks like ill just replace the slave cylinder for now. The one bolt to remove the master cylinder looks like its IMPOSSIBLE to get to (the one on the bottom)! When I pushed on the clutch pedal after I removed the slave, alot of fluid shot out of the tube, so im guessing the master is still ok...
 
You can rebuild the slave easy enough (if it's like the early ones) Last time I did one I didn't even take it off the car, did it from underneath, all it is is a piston, seal and retaining clip, dust boot. If the bore inside is pitted and rough then that may not bring it back but rebuilding is easy.
I put a bend in a cheap wrench so I could turn the bleeder through the access hole in the passenger footwell. I also put a speed bleeder type bleeder on it so I can just sit in the driver's seat and pump the clutch and it bleeds itself.
I've also read some guys will cut a slot in one of the slave's mounting ears. so they can remove the whole thing (with the pipe still attached) to hold it at a better angle for bleeding then bolt it back on without too much fuss.
 
Ok, im about to order a new slave cylinder..Is the Classic Gold one the Moss sells OK? Or, should I go with the ones I see listed on ebay (i.e. from Pat's MG and Triumph Parts)??
 
I replaced the slave cylinder on my car last fall, found the best deal from Little British Car Company. They're all basically the same cylinder, so doesn't hurt to get the best price, check around and compare.
As far as replacing both the master and slave, check the fluid resevoir, if it's empty the problem is most likey the slave cylinder, if the fluid resevoir is full then the slave is probably ok and the master cylinder is bad. It's not a bad idea to replace both, but if you're like me and watching my money it helps to identify which item is the cause of the problem.
Oh, one other hint, because of the way the slave cylinder is mounted you'll get better results bleeding if you jack up the rear of the car instead of the front. You want the bleeder port end highest.
 
I've rebuilt several with success but this last one the bore was pitted and rough and beyond honing out. I would certainly get a kit and have it and if it won't rebuild you're only out some time and $13 (the cost of a rebuild kit).
 
Hmm, the reservoir is full, and I thought that since the reservoir was full and the fact that the fluid shoots out the tube (where it plugs into the slave cylinder), that the master cylinder is OK?

Also, it looks Impossible to get to the second bolt that secures the master cylinder down to the car (i.e. there is no room for a wrench or socket to get in there because the edge of the pedal box frame is in the way)..I tried to see if I could get an open-end wrench in there, but there is not enough room..How would I go about getting a tool to reach that bolt??
 
Not necessarily, without any resistance the master cylinder should pump fine, it's when there is resistance that the seals fail and bypass fluid. Removing the mounting bolts is one of those nasty jobs on a Spridget. I've had reasonable luck using a long extension and a wobble socket to hold the bolt while loosening it from the front side, but it's tough. The easiest way in the long run may be just to remove the entire pedal box from the car. That will mean that you have to rebleed your brakes as well though. Sometimes you can just loosen the mounting screws enough to lift the box and get some clearance for a tool.
 
Rebuilding the clutch master is certainly something you could try. The cylinder is pretty straight forward, no hidden snap rings like the dual brake cylinder so an inexpensive kit would be worth the time. If the bore is too pitted when you get it torn down then you're not out much except for the price of the kit and if you get that from your local auto parts store you could probably return that if it's unopened. Same for the slave cylinder. If you can afford to wait a few days, go ahead and inspect them for pitting, you might be able to rebuild one or both and save a lot of money over replacement.
 
BASS said:
Also, it looks Impossible to get to the second bolt that secures the master cylinder down to the car (i.e. there is no room for a wrench or socket to get in there because the edge of the pedal box frame is in the way)..I tried to see if I could get an open-end wrench in there, but there is not enough room..How would I go about getting a tool to reach that bolt??
Click to expand...

seems to me that I used a 1/4 in socket plus the adapter to get it on the 3/9 wrench with an extension was a narrow enough wall to get past the edge
 
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