My rear break was binding on the disk after fitting new pads so i decided to take a look at it, i took off the wheel and took the pads out and presses the brake peddle only one piston moved so after spraying them with WD40 and pressing the brake peddle 100 time to work the wd40 in the one piston had moved right out so i push the piston back in with a bit of force now i am stuck when i press the brake now nothing happens with either piston so i have no rear brakes

will the brake need bleeding now or will i have to take the calliper apart?

it would be helpful if anyone could give me any diagrams or links on taking it apart if this is the case

Never use WD40 to lubricate brake seals. It is OK to loosen things up for dismantling but it must be quickly and thoroughly removed with detergent or brake cleaner.

The probable cause of your problem is corrosion on the piston, corrosion in the bore or seal grooves and old brake fluid. The hard to see side of seal groove usually most corroded

Thorough strip and clean is remedy. Dental inspection mirror is useful to check seal, grooves. Look back over previous posts for more info.

Never use WD40 to lubricate brake seals. It is OK to loosen things up for dismantling but it must be quickly and thoroughly removed with detergent or brake cleaner.

The probable cause of your problem is corrosion on the piston, corrosion in the bore or seal grooves and old brake fluid. The hard to see side of seal groove usually most corroded

Thorough strip and clean is remedy. Dental inspection mirror is useful to check seal, grooves. Look back over previous posts for more info.

I have google searched for diagrams and been on YouTube for videos on how to strip the brake down and can't find anything

So i have took the caliper off undone the 2 bolts but can i hell as get the two pistons things out off the calliper dose anyone have any ideas?

Cheers

Edited November 15, 201411 yr by gasgas694

There are only two things that should be used to clean the hydraulic parts of a braking system one is brake fluid and the other is a combination of soap and water. If you go the soap and water direction you will need to make sure all pieces are water free before re-assembly.There are special types of lubricant that may help with re-assembly.Brake/contact cleaner should never be used on any hydraulic parts of the brake system, they are good for cleaning pads, shoes, discs, and drums.

There are only two things that should be used to clean the hydraulic parts of a braking system one is brake fluid and the other is a combination of soap and water. If you go the soap and water direction you will need to make sure all pieces are water free before re-assembly.There are special types of lubricant that may help with re-assembly.Brake/contact cleaner should never be used on any hydraulic parts of the brake system, they are good for cleaning pads, shoes, discs, and drums.

thanks for the advice about cleaning

do you have any advice on how to remover the pistons?

I always use compressed air to shift them. There is definitely a video on you tube on how to strip and rebuild calipers.

Blow them out with compressed air but first wrap the calliper and air nozzle in a towel or similar or the piston could fly anywhere and you could get a brake fluid shower.

If air will not shift them you need to make up a fitting with a grease nipple and pump them out with a grease gun.

Blow them out with compressed air but first wrap the calliper and air nozzle in a towel or similar or the piston could fly anywhere and you could get a brake fluid shower.

If air will not shift them you need to make up a fitting with a grease nipple and pump them out with a grease gun.

Thanks for the advice,

The stage i am at now is i have managed to free the Pistons but they are all marked from where I had the grips on them so I want to change them, so I have pumped them out so both faces of the piston are touching each other

So how do I go about taking them out do I change one at a time and bleed the brakes after each piston or with them both pushed out if I was to split the caliper will they just pull out?

I use a

to hold one of the pistons, than use the brake to start moving the other etc. than it will come free and you can clean the sides of the pistons a bit. (i would not press them out totally)

I can offcource explain that you didn't had to damage them, but well, you did. I would now dismantel them and take them appart totally and replace the seals. Since you already damaged them, better fix it now for the long run.

Edited November 17, 201411 yr by crazybond700

https://www.youtube.com/watch?v=FcQq4U5ALyk

old model bike but the principle is the same

you can buy a kit which contains new seals & pistons

Edited November 17, 201411 yr by perce

You can't sort this properly without splitting the calliper and thoroughly cleaning the seal groves, see my previous post, It sounds as if you may have to replace the pistons as you have marked them with grips. Do not push them back in or you could trash the bores / calliper as well. You will probably now need new pistons and seals.

Never use grips on pistons. If all is correct they should ease in with light finger pressure.

OMG, you put grips onthe pistons !! Sometimes I think it just might be best to take the bike to somebody that knows what they are doing!