Haase brake rebuild....stuck pistons

I’m doing my first brake rebuild and I need some tips. These Haase brakes are a 2 piston caliper. The larger came out no issues, but these smaller ones won’t budge.

I’ve tried to wedge stuff in there too get it to rotate. Air compressor got the larger ones.

I had then used a vice grip to hold the larger in and using air again but no luck.

Any tips fellas?.

Some ideas…

If the master cylinder works, you could try putting the big piston in again and try to force the small one out hydraulically.

You could try heating the caliper body.

Another thing to try, perhaps as a last resort is drill the back of the caliper, drive the piston out with a drift and re-seal the hole with a tapered plug.

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Similar to what James is saying. I would put the larger piston back in and clamp that one so it doesn’t move. Use air pressure to force the smaller one out. You could also try to find something that will fit tight on the inside of the smaller piston like a bolt that will give you the ability to pull on it as you are doing the pressure method.

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Maybe try the old block of wood trick? Put the caliper completely back together without the pads. Cut up a block of wood that fits where the pads go, but is wide enough that it wont let the pistons pop out past their seals. Apply air pressure and they should pop out into the block of wood, but still stay in place to maintain the seal so the stuck one still gets pressure. Should have enough to grab and wiggle them out by hand.

For nasty ones, I rigged up a -3 to air chuck fitting with a small regulator. Keep turning up the pressure until all 4 pop out into the block, sometimes just leave it pressured and walk away for a bit… The “pop” will let you know its ready.

He’s already tried air pressure it looks like.

Thanks for all the tips! I got them out. I ended up getting access thru the bleeder screw. Worked perfectly!

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