Seized Brake caliper pistons.

min200 · Aug 19, 2016

OK then I have fitted new discs and brake pads to the Disco 1 only to find that now the inner brake caliper pistons on the nearside have seized in place fully pushed back.

What's the best way to free them up again? I am kind of stuck here with it so any suggestions appreciated.

simonlap · Aug 19, 2016

Put a piece of wood between the pistons (leaving room for stuck one to come most of the way out) and apply compressed air into the stuck side. If it does not free it up at 100 psi then it will need some serious heat and pulling force. Dont get you fingers in the way, piston should come out like a cannon ball.

Flossie · Aug 19, 2016

That normally happens if you don't clean the cack off the exposed piston surface. If you find its rust and not cack then they are toast imho. If you prise out the wiper seal and the steel ring that may reduce the friction holding the pistons in so they will come out again. I had the same on my 110 and rebuilt the calipers with new pistons and seals , they aren't expensive really. Stainless piston kits are a bit dearer but still reasonable so I've used them instead.
Think it was £42? To do both front 4 pots and £25? To do both 2 pot rears.
New calipers for mine were quite cheap as well but come with steel chromed pistons and I fancied going stainless so rebuilt mine instead.

wammers · Aug 19, 2016

simonlap said:
Put a piece of wood between the pistons (leaving room for stuck one to come most of the way out) and apply compressed air into the stuck side. If it does not free it up at 100 psi then it will need some serious heat and pulling force. Dont get you fingers in the way, piston should come out like a cannon ball.

The brake pressure is a lot more than 100 PSI, if the pedal pressure won't shift it airline has no chance.

Flossie · Aug 19, 2016

wammers said:
The brake pressure is a lot more than 100 PSI, if the pedal pressure won't shift it airline has no chance.

Agreed, if pedal pressure won't shift them they are toast.
Like I said, mine were the same and to get the old ones out I split the calipers and welded a bar to the inside of the piston , bar clamped in big vice and levered the caliper off the piston, two came out ok with this method but one was a swine but came out with perseverance.
The other 9 popped out with 10 bar of air.

Brown · Aug 19, 2016

When I did mine some of them were very well stuck in. As I was going to replace the pistons anyway I chiselled them round to get them shifted and then prized them out:

Some of them got a bit chewed up.

Flossie · Aug 19, 2016

Yeah, I had to do the same but even that didn't work on 3 of them, that's when I did the welded bar thing.

min200 · Aug 20, 2016

Well thanks for all of the advice folks

I decided that I was going down the lazy route and bought a new unit complete for what they cost. Fitted in 30 minutes and I now have proper brakes once again

Seized Brake caliper pistons.

min200

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simonlap

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Flossie

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wammers

No longer with us, RIP

Flossie

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Brown

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Flossie

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min200

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