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I have a seized front piston - well, I can pump it out but it refuses to go back, leaving a couple of mm proud. I also have to force the lever to get it moving each time. I've tried dripping on brake fluid, WD 40 etc but it just refuses to go back.
I wanted to avoid removing the piston as I haven't the foggiest how to get it all back in again - do you just shove the piston back in after cleaning it? How do you replace the seals? Inevitably this is going to involve bleeding I suppose....
Also, when will someone sell a brake that doesn't bind and jam?!!
hmmm...I've just ordered some replacement pistons for my old style minis...you got me wondering now how I'll get them in!
If you have the ally pistons like mine (rather than phenolic) apparently they can corrode into the caliper.
I am afraid you need to take the piston out and clean corrosion off. You might get away without a new seal but might not. Get some seals and strip an rebuild - then bleed thru - its not difficult.
Metal pistons? Polish it up with fine wet and dry or emery paper lubricated with light oil. Phenolic (plastic pistons) obviously don't corrode but can get dirt baked on.
Its a fiddle and a faff but not intrinsically difficult to strip and rebuild. Get some red rubber grease to lube the pistons / seals on reassembly.
I've just ordered the phenolics from crc...fiver each.
Apparently they improve the brakes no end...we'll see 🙂
I just had the same problem on my M4's.
I put cable ties around the 3 pistons i don't want moving.
I then gently squeezed the sticky one out. Rubbed some 5.1 around with a cotton bud then eased it back in.
Repeated this a couple of times. Seems to have worked so far.
Its a bit of a faff but saves a complete strip-which i may consider getting someone else to do!
But a brake bleed itself, thats simple enough.
Thanks for the various tips, guys.
I'll, er, think about what to do!