Stubborn caliper piston

gammaguy21

gammaguy21

Well-known member
I'm rebuilding a seized caliper I got from the UK.
I've tried using compressed air. And I've tried using a caliper piston removal tool.
I've got three of the four pistons out... but there is one really stubborn one.
I haven't had luck using either method. The piston is stuck almost all the way in with 1mm, maybe 2mm showing.

Any body have a method or suggestion to get the seized piston out?
Here's a pics for a visual :

20140427_221935_zps30klubl4.jpg
 
Does it move at all? Can you put the other piston back in, clamp it in place, then use compressed air to push out the stuck piston?

If it's rusted, I'd apply a liberal amount of penetrant oil first. Maybe use a c-clamp to push it in a bit to free it. Do that very gently.
 
Thanks for the suggestions guys.
mroberto - gonna give what you suggested a shot. A friend mentioned that I just need to break the seal by either twisting the piston or pushing it back in. Pushed it back in with a c-clamp last night.
Have visitors over, so not able to use the compressor (guest room is right above), so I'll re-assemble and try compressed air again and if that doesn't work, maybe I'll try with fluid.

thanks.
 
What you use is a grease gun and zerk in place of the bleed nipple, grease gun will make up to 5000 psi, and a mess, but it will get it out
 
Soak a bit in vinegar to get rust out.
Use penetrant oil.
Push it in a bit with clamp as mentioned.
Then use compressed air. Make sure you put a block of wood to stop it
 
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