[randomtask]

So I had to replace my rear brake caliper and now my brake isn't working. I first bled it with a mighty-vac and fluid is definitely going through the system but I couldn't get any pressure on the pedal or movement of the piston. Then I tried bleeding it the old fashioned way and fluid still passed through the whole system, reservoir to caliper bleep nipple, but no brake pressure at the pedal.

Next I pulled the caliper off and took it apart to check if the piston was seized. I was able to push both pistons down into their holes without too much trouble. I'm going to fire up my air compressor next to remove/clean the pistons just in case but I don't have a good feeling that's going to help.

Any ideas what else I can try to get pressure back in my rear brake? I pumped the crap out of it when bleeding but never got any pressure, fluid put the other end, but no pressure.

 

[Dukaki848]

Rear brake caliper has to be bled when it's removed from the bracket. The bleeder needs to be on top when bleeding or it doesn't get all the air out.

 

[pat1098]

This has troubled many in the past.

Essentially, you need to be pumping the fluid consistently uphill. So you need to pump (slowly!) the fluid with the hose disconnected from the caliper, and angled 'uphill'.

When fluid arrives at the open end, reconnect it to the caliper, which should have as much fluid in it as you can manage. All this done with the hose running uphill, and the caliper up around the level of the seat.

Once the caliper is connected, it needs to have a piece of flat material the same thickness as the disc (5mm) placed between the pads, and clamped to the bike.

This then supports the caliper so the bleed nipple can be 'worked'. Make sure the bleeder is the highest point in the system.

You are now ready to bleed the system, SLOWLY and CAREFULLY. Avoid quick movements of the pedal.

Once you have eliminated the air from the system, remount the caliper.

 

[randomtask]

Thanks guys, problem solved. I think my brake works even better now than it did before - I had to hold the rear brake AND sit on the bike before when torquing the rear wheel nut. This time the rear brake was sufficient on its own.

Why isn't this procedure in the service manual? As common an issue as this, it ought to be there.

Anyway, thanks again