rear caliper piston stuck

[Banshee_370]

i cant get one of the rear pistons out of the caliper, tried heat, compressed air, pumping the pedal. its flush and i cant even get a channel lock on it.

any ideas?

[red88r]

I had to put the other piston back in before to try and get the stuck one out. I just rebuilt a few of them-never had to use heat though. Also you can hook the brake line back up and use the brake pedal. Another handy thing is a pentetrating lube called PB Blaster. I use it at work and it is some great stuff-way better than WD-40 for almost everything.

[Banshee_370]

put the other piston in already, tried with the pedal no luck

[Saul76]

Just put the other piston in - hold it in place with a c-clamp .... thread the end of your grease gun into where the banjo bolt goes and pump it full of grease. It will come right out.

Pumping grease into the caliper will free any stuck piston. Just get the correct size adapter for yor grease gun to thread into the banjo bolt threads of the caliper & you're all set.

[Banshee_370]

and how do you get the grease out of the caliper after?

[Swiper77]

Solvent eg: Brakleen or lacquer thinner, mineral spirits all work well.




Originally posted by Banshee_370
and how do you get the grease out of the caliper after?

[Banshee_370]

hooked up my air grease gun to the bleeder valve...withing 3 minutes it popped free. great tip thanks so much. went at it with break cleaner and a small pick with some compressed air.

[Saul76]

Originally posted by Banshee_370
hooked up my air grease gun to the bleeder valve...withing 3 minutes it popped free. great tip thanks so much. went at it with break cleaner and a small pick with some compressed air.

Excellent. VERY glad to hear that! Feels good to pick up tip's here and there and be able to pass them on to fellow riders.

Now that you have them out really go through the caliper and get that sucker working like new.

When you pull the rubber seals out - something I like to do personally - is take a small propane or butane torch and play the flame lightly inside the caliper, not enough that it gets super hot but enough that it kinda cooks the corrosion - then the corrosion turns to dust and you can just scrape it away.

I've bought used calipers and when I took them apart and got the seized pistons out, removed the rubber seal they were CAKED with corrosion in the slots where the seals are installed. This pushes the seals 'out' enough to cause your pistons to stick and not travel free.

Spend 20 minutes cleaning up the corrosion - reinstall and it's like a new caliper again.

Take care & happy riding!