Can't push the rear brake pistons back in

[linssen]

I've just removed the rear brake pads for a bit of an inspection and clean up, and now I can't get them back on: the pistons aren't leaving enough room to get the pads back over the disc.

I can push the pistons back one at a time with a bit of pressure, but as you push one, the other pops out. I can't seem to apply enough pressure to push both back simultaneously and give enough room for the pads.

Can anyone offer any advice?

 

[(RIP) Miff]

Remove the master cylinder cap.

Use the old pads to help press both pistons back in.

 

[linssen]

Remove the master cylinder cap.

Forgive the ignorance, you mean under the heel plate on the master cylinder itself?

 

[Mr K]

Forgive the ignorance, you mean under the heel plate on the master cylinder itself?

He means the fluid reservoir, where you would top-up the fluid.

 

[linssen]

He means the fluid reservoir, where you would top-up the fluid.

No joy: I've applied a lot of pressure there and they're not moving one mil. They'll happily move on their own though. Any other thoughts?

 

[cookie]

is the master cylinder reservoir full?

 

[linssen]

It's smack bang in the middle of min / max.

 

[OldCroc]

Looking at the corrosion in the photos I would guess that the pistons are seized....... Probably need to strip the calipers.
OldCroc

 

[LOLGEOFF]

Try levering one side enough to put one pad in and then lever the other side and put the other one in. I would suggest slackening the bleed nipple off a bit, to relieve the pressure, but that may be a little too advanced yet.

 

[linssen]

Thanks all, loosening the bleed nipple gave me enough space to get the pads back on. They're still really stiff though and I'm unsure whether it's the pistons, the pedal or what.

Probably best I ride it gently over to the dealer and let them charge me through the nose.

 

[Popell]

If you can, make sure that you apply leverage to both sides of the piston ie at 12 and 6 oclock, this stops the piston going askew and locking in the bore, use something to protect the piston faces and try with 2 small levers or old screwdrivers.
Pistons should not be stiff, sounds like they are sh*tted up, lots of cleaner, an old toothbrush and keep working them in and out, makes a massive difference (at least it did to the R1 brakes)
Having said that, if you lack mechanical confidence/competence, it may be good to remember that brakes are generally seen as a benefit when looking to reduce your speed, and it may be best to seek out a workshop and watch them do the job this time

 

[Greg Masters]

Make sure that the pedal arrangement is adjusted so that there is a little slack in the master-cylinder push-rod when the pedal is released.

It sounds to me like the master-cylinder is still in 'pressure' mode and that you haven't released the piston far enough to uncover the hole for the fluid to move back to the reservoir.

Greg