Brake piston removal tricks.

[Steve Webb]

Has anyone got any special tricks for removing seized brake caliper pistons.

I've read all the usual tricks, heat, air hose, physical violence, but do you guys have any other tricks?
The pistons are all being replaced so no worries about damaging them.

Cheers

[Billy_Bear]

We use heat and physical violence.. Did you heat the piston complete to glow?
Sometimes is the problem that the piston canted in the hole. You must press it a littlebit back.. Heat it a few times and use oil spray. I think this is the only way, befor buy new ones..

Best regards

[AlfaJack]

Heat and a fight - stand back when it pops!
Is it a single pot caliper?

[Steve Webb]

In the end very little physical violence was needed.

The calipers were first split (Twin pot calipers) and left cooking in the electrolysis rust removal tank for a few days each.

Then they were washed off and dried and the pistons were given a good soak of release fluid front and back.

The pistons were then hammered (gently ;) ) back a touch to break any seal that the rust may have developed.

Calipers back together and a pry-bar jammed in the caliper between the 2 pistons so neither can pop fully out. Air hose pressed into where the brake pipe goes and apply pressure.
One piston moves fine, the other needs to be tapped with a hammer at the same time as the air to make it move.
More release fluid, move the pistons back in, and repeat.
Continue until with a pair of molegrips you can twist and pull the pistons clear.

All 4 pistons have a little corrosion around the outer lip, the area past the seal, so I'll get a complete rebuild kit including all seals and 4 new pistons.

[Steve Webb]

Managed to get the rear calipers stripped last night, a lot easier just winding them out.

While the front calipers seem easy to pick parts up for, the rears are a little more tricky, the rebuild kits I've seen only seem to contain some of the seals, not the ones for for the handbrake adjustment nor the ones between the caliper halves.

As I was searching out the parts I found what look like exchange calipers on www.brakeparts.co.uk for a little over double the cost of the parts needed to rebuild.
New calipers for £62.74 (+Vat no doubt) can't be moaned at.

I'll still rebuild the front ones though.