Several weeks ago my slave cylinder leaked out overnight. I noticed a low pedal in the morning, and looking under the car there was a good sized puddle on the driveway. I was able to top off the master, and after many pumps pressure came back up and I was able to drive the car without issue. Once in the garage, I crawled under the car, removed the pushrod and pulled the slave piston out. I wiped the inside, checked the piston and seal, and all looked good. Put it back together, bled it, and it worked for about a week, then after another overnight it had leaked out again.
This time, after getting it back to the garage, I removed the slave. This was a replacement from Moss Motors, maybe three years old now, and it looks exactly like the older one I pulled out when I replaced my clutch. I had replaced it because I needed a new pushrod as the PO had cut and welded the pushrod that was in the car (he had also installed the clutch plate in backward!), so I ordered a slave and an adjustable pushrod to be sure it would work. I cleaned the bore using a green 3M Scotch pad wrapped around a wire brush and chucked in my drill, using brake fluid as a lubricant. The piston and seal were cleaned up and lubed with brake fluid. I tested the "rebuild" using compressed air and puller as shown, backing the piston out with the puller so I could see whether it would leak at different points in the piston travel. It passed my test, and I reinstalled it and it's been fine ever since.
I have since "rebuilt" the old one, and it works just as well, although the piston seems to slide easier than the new one did, possibly due to the age of the seal. The seal was hard after sitting essentially dry for the past years on the shelf, so I dropped it in a baggie of brake fluid for a few weeks before I rebuilt it and took these pictures. But with 80psi of air behind it, it didn't leak a bit.
The photo of the cleaned bore is with brake fluid on it. Just thought I'd share my experience, and does anyone know if replacement seals are available anywhere? I couldn't find rebuild kits for these. Aside from cracks or corrosion, with a new spring and seal these would be very easy to rebuild.
1974 TR6 CF24871UO. Dual Weber MCHH carbs.
Slave cylinder leaked dry overnight
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