Brake piston issue

[thorns]

Last ride my front brake was pretty much non existent, no matter how hard I yank on it, it just wouldn't really stop, which if you've ridden with brembo brakes, you know they are usually a light single finger pull for all the brakes you'd ever need (motocross bike not road bike just to clarify).

Just pulled the pads out to inspect those, but they look fine, still heaps of meat left on them.

Noticed however when I pump the lever when the pads are out, only one piston is coming out. The second one wiggles a little bit but wont actually push out. If I put a piece of timber between the good piston and caliper, and pump the lever, then the second one will come out, which tell me its not seized.

Have bled the brakes, and still have plenty of fluid in there it seems.

What should I check next? Should I drain out all the brake fluid and start over again with fresh fluid?

[jellywrestler]

Last ride my front brake was pretty much non existent, no matter how hard I yank on it, it just wouldn't really stop, which if you've ridden with brembo brakes, you know they are usually a light single finger pull for all the brakes you'd ever need (motocross bike not road bike just to clarify).

Just pulled the pads out to inspect those, but they look fine, still heaps of meat left on them.

Noticed however when I pump the lever when the pads are out, only one piston is coming out. The second one wiggles a little bit but wont actually push out. If I put a piece of timber between the good piston and caliper, and pump the lever, then the second one will come out, which tell me its not seized.

Have bled the brakes, and still have plenty of fluid in there it seems.

What should I check next? Should I drain out all the brake fluid and start over again with fresh fluid?
pump the pistons out and give them a clean, seals should be fine just all needs good cleaning, reassemble using brake fluid. pull the master cylinder apart and get the old fluid out, remove the piston assembly disassemble and clean make sure there's no shit inside the resevior, it could be a bit of grit getting into the return hole. reassemble after holding the brake line up and draining all the fluid out of that, then bleed and it should be all good. if there's one issue it's time for a full service.

[husaberg]

pump the pistons out and give them a clean, seals should be fine just all needs good cleaning, reassemble using brake fluid. pull the master cylinder apart and get the old fluid out, remove the piston assembly disassemble and clean make sure there's no shit inside the resevior, it could be a bit of grit getting into the return hole. reassemble after holding the brake line up and draining all the fluid out of that, then bleed and it should be all good. if there's one issue it's time for a full service.

What he said plus make up a syringe with a pipe to fit onto the caliper bleed nipple and bleed it from the bottom to the top by pushing in and up clean fluid you will also be able to push air into the syringe.
Get the syringe from a vet they have nice large ones. you will find this to be both easier and faster.

[Premature Accelerato]

A word of warning. Keep the likes of kerosene away from your calipers. Kero etc will bugger the seals for good. I just use brake fluid to clean everything.

[Shaun Harris]

What he said plus make up a syringe with a pipe to fit onto the caliper bleed nipple and bleed it from the bottom to the top by pushing in and up clean fluid you will also be able to push air into the syringe.
Get the syringe from a vet they have nice large ones. you will find this to be both easier and faster.


That is the very best way to bleed brakes as far as I am concerned also

[nzspokes]

That is the very best way to bleed brakes as far as I am concerned also

+1, this is how I train new mechanics to do it. Easy and quick.

[Shaun Harris]

+1, this is how I train new mechanics to do it. Easy and quick.


Always makes me laugh when I see people starting there bleeding process from the calipers instead of the master cylinder being up top where in theory the air is! So effectively, they are pushing the air back through the lines to the calipers, and never bleed them enough to make all the air travel completely through and out.