Brake caliper

You're going to need to dismantle and replace seals as part of re-commissioning. It helps to have the pistons free first. The pistons are also likely to need replacement. Caliper bodies are usually OK unless they've worn from chattering pads.

Are they both stuck ? I'd suggest removing the front wheel and pumping on the lever. When one piston begins to move, put a wedge in the aperture and allow the other piston to be pumped.

If they're still seized, the outside one can be carefully drifted inwards to free it after removal of the blanking plug. The inside one is more of a problem. I've had some success in the past by jamming a short nut and bolt inside the open piston cup and turning it in order to free it.

An airline is often the easiest way to push the inside piston right out - do put a rag over it though as it van come out with quite a bang.

Ok the way i do it has neaver failed me yet

take the caliper off the bike take the pads out pu a piece of metal plate in the slot where the pads were

then screw a grease nipple into the bleed hole pnd pump up with a grease gun.

clean the grease out after the pistons are out.

its allwaws the inner one thats hard ro remove some people drill a hole in the back of the caliper .

Have just dismantled a seriously seized caliper I picked up at Kempton autojumble two weeks ago.

Forremoval ofsteel endblanking plug,which wastotallystuck , put in oven for15 minsat 200 degrees C , left to cool then it freed easily withpeg spanner (steel end plug and alloy caliper expandby different amounts breaking the seizure).

Outside piston was very tight but eventually budged with leverage firstly on its brake pad and then afterremoving padcould befurther pushed out with a suitably shaped lever. Inside piston was really seized solid so drilled it carefully in the middle (avoiding drill bit running though into caliper housing) then made a puller from a long thin bolt , filing down the head leaving just a small lip to hook onto piston , tightened up puller nut andout pistoncame.Despite all this brute force , caliper bore was unscored and after a clean up with very, veryfine emeryis as good asnew.

Previously roger_johnson wrote:

You could also try, plenty of WD40 the hit the back of the caliper hard with a hide mallet a few times and due to equal and opposite reactions the piston will often come out. worked for me several times!

My Commando has not been registered since 2000 and the pistons in the brake caliper are seized. Any tricks to free them off?

Iuse a spare stainless mirror stemfor removing the outer piston, the curve in the stem is perfect for levering against the inner body of the caliper, and will ease out the outer piston.

To pull out the inner piston: take a bolt with a nut, and wind itout to wedge it in the piston. You're going to replace the seals anyway, so then heat the caliper body inthe oven and pull out using awire coathhanger or similar wound around the bolt.

Regards

Mike