Stuck Brake pistons.

[Shillz]

After admitting defeat at getting these brake pistons to go back in, I've come to you guys to beg for help.

I have tried A g clamp and no difference, they have also been reasonably well cleaned. What should my next step be to get the system working again.

( i started this thinking it would be a simple job to clean the callipers out after winter, but after getting the pistons stuck I am doubting myself a little...)

[fatpies]

Did you take out the seals and clean those too? If you did it should be no more than your thumbs on your palm to push them back in.
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"It's easy to attack and destroy an act of creation. It's a lot more difficult to perform one"

[Matt B]

Yep, sounds like knackered seals to me, especially if you have been mashing them with a g-clamp! If they have come out past the pressure seal and you tried to force them in at an angle its game over.

As said, pistons should take no more than thumb pressure to push in.
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stinkwheel: He had an animated .gif of a cat performing fellatio. It's not socially acceptable. It can have real life adverse effects on other people.

[Shillz]

Don't think I can access any seals, the pistons are just stuck out, I can't remove them or force them back into where they're supposed to be.

[Matt B]

Pistons need to be removed for you to see the seals. Some calipers split in half (2 bolts normally) to let you get the pistons out. Hard to tell from your photo and not knowing what bike it is.
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stinkwheel: He had an animated .gif of a cat performing fellatio. It's not socially acceptable. It can have real life adverse effects on other people.

[Shillz]

There is no way of splitting the calliper up any further, the bike is a cbf 250. Single front disc.

[Matt B]

Then they should just pull out through the curved cutouts, although I have never stripped that particular caliper.
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stinkwheel: He had an animated .gif of a cat performing fellatio. It's not socially acceptable. It can have real life adverse effects on other people.

[Shillz]

I will persevere with that, however having tried already I'm doubtful. Trying to avoid taking it to the garage, being a student on a budget excludes that dream.

Thanks for your help so far, but is there some technique I should be using to remove the pistons or is it just brute force?

[jeddy11]

its best if they were still conected then you can just pull the brake lever until one is nearly popped out then brace that with some wood and keep pumping untill the other one falls out then they should just need tweaking out...

If you try to grip those pistons with pliers or pump grips etc your likely to damage them unless you can find someone with a pair of internal piston pliers..

hope that helps a little
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[c_dug]

The trick is to pop them as far as you can while the system is all connected up, letting the hydraulic pressure do the work for you. I had a similar issue with my CBR when I rebuilt the front brakes and ended up scratching the buggery out of a piston when getting it out.
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I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock.

[Islander]

[Shillz]

Well bank holiday monday's job is sorted. Will report back, thanks guys.

[trisers]

[trisers]

Incidentally...i used various things of increasingly thinner size to wedge the piston that was coming out first and found they all move so the face of them is nearly level with the face of the opposite (cut-out) side of the caliper. In fact my steel rule which is only about 1mm thick was enough to stop the pistons popping out but got them all to the point that they could just be worked out by hand