protonn

Hey people

I have on my bike a couple year old Formula racing hydraulic disc brakes.

On the rear brake one of the pistons is completely stuck.

I removed the pads and tried to press the lever but only one piston is coming out - even if I try to apply pressure on the functioning piston.


Couldn't find any explanations for how to tackle this issue.


Any help?

Thanks

masonv45

I've experienced this on motorcycles. There were 2 solutions. Maybe one can be adapted to your situation.

1. Remove the caliper and block the moving piston and the hydraulic line inlet. Attach a grease gun to the bleed nipple at the caliper. The grease gun can apply much more pressure than the hydraulic lever.

2. Remove the caliper and block the moving piston. Place a rag over the stuck piston to prevent it from shooting across the garage. Using the rubber tip from a compressed air line, shoot air into the hydraulic inlet ... gradually increasing air compression after every attempt until the stuck piston is freed.

grumpus

Try pushing the stuck piston back with a pry bar,then yank on the brake lever to see if it moves. If you're lucky you can repeat until it loosens up.

probe1957

My unqualified opinion would be to replace the caliper. I wouldn't want to risk freeing the piston up, only to have it lock up again on a downhill after touching the brakes to navigate a curve.