Bloody Caliper piston stuck? Advice?

[Danny S]

I was trying to change the pads on my Vauxhall Corsa last night, but the caliper piston will not budge backwards.

We've tried brute force, as simple Yorkshire males that's the first thing me and my dad tried. But that didn't work.

Does anyone have any advice on what to try? Or does the caliper need to be bled before it will return?

Cheers
Dan

[TonyHetherington]

Did you un screw the cap from the fluid reservoir under the bonnet?

[_rubinho_]

Front or rear caliper? If it's a rear you might need to wind the piston back in as it'll be on a threaded shaft. There are specialist tools or you can use some pliers to twist the piston using the recesses on the face. It's hard work!

When I got one stuck once I took it to a local garage and they wound it back for me in 2 minutes for free.

[Danny S]

_rubinho_ said:

Front or rear caliper? If it's a rear you might need to wind the piston back in as it'll be on a threaded shaft. There are specialist tools or you can use some pliers to twist the piston using the recesses on the face. It's hard work!

When I got one stuck once I took it to a local garage and they wound it back for me in 2 minutes for free.

I might have to take it to a garage then, theres one nearish to work that i think i can trust!

TonyHetherington said:

Did you un screw the cap from the fluid reservoir under the bonnet?

Yup

[Danny S]

What's a good/bad price for both the front 2 pads replacing at a garage, if i supply the pads?

[eltax91]

Danny S said:

What's a good/bad price for both the front 2 pads replacing at a garage, if i supply the pads?

So, it's fronts then, not rears? It's unlikely that the fronts have a threaded piston, I've never seen any. If it won't go back then it sounds like it's seized, might even be a new caliper job if that's the case. Were the brakes OK before the pad change, by that I mean were they sticking or getting hot? Was the car pulling to one side to indicate the piston might be seized?

When you say you have used brute force, what sort of leverage did you have? I used a simple spreader tool that I bought from machine mart which is great for front pistons. You need a more specialist one (still on £20 in halfords) for the threaded rear types

[_rubinho_]

Danny S said:

What's a good/bad price for both the front 2 pads replacing at a garage, if i supply the pads?

Shouldn't be more than an hour's labour. £50 at a local place maybe and more at a dealer.

[Danny S]

eltax91 said:

Danny S said:

What's a good/bad price for both the front 2 pads replacing at a garage, if i supply the pads?

So, it's fronts then, not rears? It's unlikely that the fronts have a threaded piston, I've never seen any. If it won't go back then it sounds like it's seized, might even be a new caliper job if that's the case. Were the brakes OK before the pad change, by that I mean were they sticking or getting hot? Was the car pulling to one side to indicate the piston might be seized?

When you say you have used brute force, what sort of leverage did you have? I used a simple spreader tool that I bought from machine mart which is great for front pistons. You need a more specialist one (still on £20 in halfords) for the threaded rear types

Sorry forgot to reply - it is the fronts yes. And the piston goes forth no problem (Got my dad to test this, not sure how think he just watched it compress as i pumped the foot brake)

We had about 30cm long pipe grips which to be fair was struggling for grip

Is it possible that the piston would not compress as all the pressure was on one side?

Edited by Danny S on Tuesday 10th August 09:24

[Martin F]

If you are really stuck you can open the bleed nipple to help relieve pressure in the caliper.

But you will definitely need to bleed the brakes afterwards.

[Big Rod]

Use a large 'G' clamp to push the piston back in.

If that doesn't work, it sounds like you need a new piston and/or caliper.

Might be worth pushing the piston out to have a look at the bore/piston wall for corrosion/debris.

[Ozzie Osmond]

Big Rod said:

Use a large 'G' clamp to push the piston back in.

If that doesn't work, it sounds like you need a new piston and/or caliper.

Might be worth pushing the piston out to have a look at the bore/piston wall for corrosion/debris.

^^^^^^^ Yes, that's the way I do it.

[Gad-Westy]

I've had some success in the past by pumping the piston until it's almost right out and then cleaning with brake cleaner and smearing grease onto the face. Then push it back in. And then repeating process until it goes in freely. Turning it a little as it goes in will help. If it's really stuck, you may need to push the piston fully out and clean the outer face with some fine emery tape. You'll need to replace and bleed the brake fluid afterwards though.

[balls-out]

Ozzie Osmond said:

Big Rod said:

Use a large 'G' clamp to push the piston back in.

If that doesn't work, it sounds like you need a new piston and/or caliper.

Might be worth pushing the piston out to have a look at the bore/piston wall for corrosion/debris.

^^^^^^^ Yes, that's the way I do it.

I would NOT just force the pistons back. The outsides are probably covered with grit (or is there a boot to keep things clean?). You don't want grit grinding into the bores of the caliper, nor the seal.

These are your brakes, so take them seriously! I would get the calipers off the car. Pull the pistons and give everyting a clean up and then put them back together again. There is nothing hi-tech going on, so its not difficult.
Don't forget to clamp the hoses before you discconnect, or you will have a lot of fluid on the floor and a bigger job to bleed all that air out after.
Other tip is to remove the lid of the fluid reservoir and then seal the hole with a layer of clingfilm and them out the lid back over the top. This will form a seal and prevent fluid pouring out - just drip instead.

The easiest way to get the pistons out is using a tire pump into the brake pipe hole. GENTLE pressure on the foot tyre pump and the piston will ping out. Clean it and put it back. Then hold that piston in (cable tie) and repeat and another will pop out. Repeat for as many pistons are you have - I assume you aren't running 6 pots!

Edited by balls-out on Tuesday 10th August 10:32

[balls-out]

_rubinho_ said:

Danny S said:

What's a good/bad price for both the front 2 pads replacing at a garage, if i supply the pads?

Shouldn't be more than an hour's labour. £50 at a local place maybe and more at a dealer.

I think £50 is assuming that all is well and things don't need to be sorted properly.
You shouldn't need to FORCE a caliper back in - it should go fairly easily, so you probably need more than just new pads dropped in. Any garage should be well careful with brake - particularly given the legal actions that fly at the moment. If a caliper is siezed then one hour isn't long enought to sort it all out and bleed everything.

Edited by balls-out on Tuesday 10th August 10:30

[balls-out]

Danny S said:

Is it possible that the piston would not compress as all the pressure was on one side?

Just re-read this.
Yes if the pressure is not central you may be find that the piston gets stuck.
The way I do it is put the OLD pad back in and use a screw driver to gently lever, with the end of the blade in the middle of the old pad and the fulcrum against the edge of the disc. It will knacker your old pads (but who cares) and unless you get very carried away it won't dammage the disk.

I think you can tell I'm bored at work ?

Edited by balls-out on Tuesday 10th August 10:40

[Danny S]

balls-out said:

Danny S said:

Is it possible that the piston would not compress as all the pressure was on one side?

Just re-read this.
Yes if the pressure is not central you may be find that the piston gets stuck.
The way I do it is put the OLD pad back in and use a screw driver to gently lever, with the end of the blade in the middle of the old pad and the fulcrum against the edge of the disc. It will knacker your old pads (but who cares) and unless you get very carried away it won't dammage the disk.

I think you can tell I'm bored at work ?

Edited by balls-out on Tuesday 10th August 10:40

I did actually begin to do this last night, but then it hit me that if infact the piston didn't retract then i would have knackered pads that i would need to put back in :|

And its just the 1 piston, i don't have fancy brakes lol! Its only a corsa :0

[jeff m]

Stuck piston is very often a small peice of the inside of a brake line lodged inside preventing the fluid flowing back.
Very difficult to remove without doing the job properly.
You could try removing the bleed nipple and giving it a slow pump on the pedal.
If you get a foreign object come out,change the brake hose and re bleed.
(and drive accordingly)
If it was locked for a while you could have a warped disc fron excess heat etc.