Clutch Release (slave) Cylinder Advice

[Mickly]

Like peeling the layers away of a bad onion (1994 Triumph Trophy) I found evidence that the Clutch Release (slave) cylinder has sprung a leak.

Having disassembled it with the intention of replacing the seal, I have found a witness mark within the cylinder created by the bike being unused for 3 years (see photo) I can hardly feel it with my finger nail, would a quick wipe round with 1200 grit wet and dry to remove it be ok or am I looking at a complete (expensive) replacement?

P.S. if you ever do this, ferchrists sake be careful, I used a bicycle pump to pressurise the piston out, because it was slightly stuck it suddenly flew out at quite a rate, luckily I had it wrapped in rags.

[TimR]

soak in brake and clutch cleaner ...

remove as much of larger deposits you can with a non metallic scraper or even a soft wire brush ( brass )

then use fine grit paper to hone .

as the seal sits on piston it will give a bit more tolerance to seal if minutely oversized but don't gouge or heavily mark the faces .

and agree with piston popping ...

seen fingers split open on brake calipers where trapped between piston and caliper .

[Mickly]

Ta for the advice, I’ll do that and replace the seal.

Won’t know if it works until everything is all together.

[fredc]

one of these https://www.ebay.co.uk/itm/Brake-Cylinder-Hone/221872747430?hash=item33a8a573a6:g:AB4AAOSw~gRV6FAJ would be better than grit paper

[fastbob]

I wouldn't worry about it , in theory there's no metal to metal contact , just contact between the piston and the seal so a little discolouration makes no odds . If you do want to polish it use 2500 grit paper dipped in a bit of light oil . If the surface of the piston is a bit ropey you can get a pattern replacement kit .