Seized Brake pistons?

[TwistedRoot]

Looking for tips. Pistons are seized in my project bike. Wont budge. Soaked WD40 overnite. Still stuck. Tried compressed air, and gentle prying. Not moving. Thinking about getting some PB blaster...and maybe a little heat but don't want to melt the seals inside. Thoughts? TIA.

[ericr]

You can use a grease gun. Plug the banjo fitting with a bolt, find a zerk to replace the bleeder, and pump away.

[bufftester]

+1 on the grease gun. Heat will also help, you'll want to replace all those seals anyway. You could also try spraying some PB blaster inside the caliper to soak the back side of the pistons.

[KDXGarage]

If the pistons won't move, then you need to replace the seals too.

boiling water poured over it might help to expand the caliper metal a touch

Otherwise, the grease gun sounds like it is a good idea.

The pistons may be damaged or the bore damaged preventing movement.

[TwistedRoot]

Thanks all. Im soaking them in some PB overnite. Hopefully that does it.

[KDXGarage]

How many pounds of pressure did you use on the air gun?

[doakley]

You might try rapping the caliper body with a plastic hammer every so often to help the PB Blaster along. Rap NOT Brap! It may take longer than you think to penetrate. A heat gun may help as those seals have to be history anyway.

[TwistedRoot]

One of the pistons came out after the soak last nite. But the other just would not move. I got impatient and drilled a 5/64" bit in the center and used a drywall screw about 1/4" deep. Gripped it and rapped it with rubber mallet and it FINALLY broke loose. That piston was really crisp and cracked easily so had to order a new one.

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