Back brake rubbing after caliper clean.

Struggling to figure this out so...

I removed & cleaned the callipers off my bike taking the opportunity to fit braided lines at the same time. Front brakes are fine & dandy but not the back one.

First time I fitted it you could hear it rubbing but when it pressed the pedal it completely locked up. Brake fluid drained & caliper was still clamped to the disc. Took the caliper apart again & renewed the seals (yeah should have done that in the first place but they looked ok) & used some rrg to help the pistons slide.

Second time I fitted it didn't lock up but it was rubbing still.

Taken off again & checked it out, I had the anti squeal shims on the wrong sides compared to the pic in Haynes so changed them round & guess what still rubbing (not locking up tho)

Pedal movement seems quite small too, about 1cm to fully on.

All I can think of is that the pads aren't seated as they were before so they need to bed in again?

Any ideas? I've done nothing but pump that brake lever all night agghhhh

When I did mine back in November, the front was rubbing, I re-bled the line (reusing the new fluid) but made sure to leave some travel (Perhaps about 3-5cm) in the lever before it applied the brake, my guessing is this created more suction for the pistons to go back in as there was room for the lever to return. But it might have been something else. When it comes to brakes and such so much baffles me...

[andrewsmith]

Is the pressure on the lever constant?

It sounds like the caliper is binding

[Sid Squid]

Are you sure that you correctly cleaned the seal grooves? You must make sure they're completely clear and square or the seals will deform when fitted and the pistons will not retract.

Also make sure that the fluid way between the caliper halves is clear As the caliper is underslung, those drillings often get sludged up, causing the inner piston to not retract,

Thanks Sid

Originally Posted by Sid Squid

Are you sure that you correctly cleaned the seal grooves? You must make sure they're completely clear and square or the seals will deform when fitted and the pistons will not retract.

There was what just looked like discolouration but i'll give them another go over to make sure they are perfectly clean. Whats good for removing any residue?

Originally Posted by Sid Squid

Also make sure that the fluid way between the caliper halves is clear As the caliper is underslung, those drillings often get sludged up, causing the inner piston to not retract,

This bit looked all good, the caliper wasn't in a very good state externally but internals were all nice & clean.

Originally Posted by andrewsmith

Is the pressure on the lever constant?

I don't get what you mean? The lever moves what seems to me to be less than it did (about 1cm) then is solid as the fluid is fully compressed. The lever does reset itself.

[andrewsmith]

Originally Posted by HoL

I don't get what you mean? The lever moves what seems to me to be less than it did (about 1cm) then is solid as the fluid is fully compressed. The lever does reset itself.

When you press the lever does the resistance stay the same through the full movement

Originally Posted by andrewsmith

When you press the lever does the resistance stay the same through the full movement

It tightens up at the end - but thats what brakes do isn't it?

Thinking about it, it probably feels a bit firmer than just the resistance of the spring then goes solid quite sharply, like i said it only moves about 1cm though. It's a bit funny using my hand instead of my foot so difficult to compare the difference.

I think I see were you're going with this. Everything points to the pistons stuck in the caliper doesn't it?

Looks like they're coming off again tonight. I'm so glad I built a shed to do this in!

[andrewsmith]

Originally Posted by HoL

It tightens up at the end - but thats what brakes do isn't it?

Thinking about it, it probably feels a bit firmer than just the resistance of the spring then goes solid quite sharply, like i said it only moves about 1cm though. It's a bit funny using my hand instead of my foot so difficult to compare the difference.

I think I see were you're going with this. Everything points to the pistons stuck in the caliper doesn't it?

Looks like they're coming off again tonight. I'm so glad I built a shed to do this in!

The travel's fine

Does sound like it needs cleaned and stripped

Originally Posted by andrewsmith

The travel's fine

Does sound like it needs cleaned and stripped

A good soak in brake cleaner to remove any gubbins?