problem with rear brake

[Spike]

Hi guys need some advice, never had this before.
I seperated the bike a few weeks ago to do the clutch so had to diconect the rear brake lines from the servo, so refitted them and bled the brakes, mine is the newer servo so bleeding the brakes is just like doing them on a normal bike so I got told from a veryu informative member on here.

Anyways takes the bike out and front brakes are fine bu t the rear brake was not there, it worked when pressed right down, so thought mmm brakes are notr bled properly, brings it home and bleeds the rear brake again, no air bubbles come out and went through nearly 1.3 of a litre of brake fluid to make sure.

took the bike out again and same again only this time the odd time the rear brake pedal was solid like it used to be, then when released and re applied it was soft again.

What would be causing this, I have no lights come on on the dash and the front brake is fine. same as it always is.

spike

 

[Pukmeister]

You could have worn seals in the rear master cylinder, allowing fluid to pass rather than be forced under pressure.

If you press hard and sudden, does the rear brake work?

If so, try it again slowly and see if the brakes are softer.

If they are then I would strongly suspect the seals are worn. You could also have a tiny amount of air trapped in there somewhere, brakes are best bled with a "Mityvac" vacuum pump or similar to pull the fluid through and remove any air.

 

[Spike]

Went out and tested your theory and I pressed hard and fast and the lever had a little more resistance but still went down easily.
The brake works just the lever goes further down than it used to when I got the bike, going to get a new set of rear pads as they are ready for changing and see if that makes a differnce, could be that the pads are worn just a little too much.

will keep you informed.

thanks again

spike

 

[mickyg10]

bmw

hi guys i had my back pads replaced at bmw vines and the same thing has happen to me. i have had to press really hard to make the bike slow down. BMW vines said you may need to bleed the brakes ie take off the tank and about 90quid. contacted bmw direct they said dont need to bleed the brakes but could not tell me what was wrong.

 

[Pukmeister]

Check that your rear caliper is floating properly on its pins. If it has partially seized, it could take more pedal travel to get the desired braking effect, along with wearing out one pad more rapidly than the other and also warping the rear disk sideways.

 

[Spike]

Good call mate i will check that out and let you know, got some pads on the way so will do it all in one hit.

spike