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I recently replaced the stuck pistons and seals in my rear brake. Getting out the piston from the non hose side a an absolute nightmare. It was stuck fast and I ended up drilling it out.
I need to sort out my front brake and want to avoid repeating the problems I had before, is there any easy way of removing a stuck piston?
Replace them one at a time.Hold one piston in and pump the other out with the lever.Replace it with new seal,bleed and repeat for the remaining one.Its a PITA but the only way to do it and not damage them.
How do you hold one piston in, just clamp it with pliers?
Annoying that there isn't an access hole behind the piston, plugged with a little screw that could be removed so that you could push the piston out from behind
I usually use the ring end of a ring spanner,you can lever it off the the caliper and still get it to clear the other piston.
My technique - split the caliper, use a shock pump with a marzocchi adapter (its fits quite neatly into caliper holes). And pump til the piston pops out. On one side of the caliper you'll need to cover one hole with your thumb or air will escape.
THE BIG HEALTH & SAFETY WARNING - make sure the caliper and piston is pointed away from you and ideally have it inside a shopping bag or similar. It will fly out at some speed and do real damage to anything (or anyone) in its way. My kitchen cupboard door still has scars from an impact! I've done it this way penty of times.
I've done the airline thing to get master pisons out of stoker lever bodies......one embedded itself in the ceiling!!!
I'd read about using air pressure but couldn't work out how to do this on the side with two holes. Can you really hold the pressure in with your thumb?
Yes, usually can cover hole with thumb while pumping with other hand (ooh er). Only once has piston been so seized I've needed the GF to pump while I use both thumbs to press down on the hole (woof) :lol:.
If you don't have a Marzocchi adapter you might be able to use one of those conical plastic thingies you get for blowing up small inflatable matresses, beach balls, and the like (top one [url= http://is.gd/8yr9Jj ]here[/url]). They wedge into the threads tightly enough to get the pistons out of my Juicys with a track pump. You do the non-hose side first, then split the caliper, and put your thumb over the hole to get the hose-side one out. Make sure you cover the caliper with a rag to avoid spraying DOT everywhere or hitting yourself in the face with a high-velocity piston...
I read a lot about Avid pistons sticking and was told to use Castrol red rubber grease on them. They have been fine so far, and I used the same method as bri-72 to get the pistons out.
Of course I did this as a preventative ,so didn't have to get seized pistons out 🙄