Rear brake problem !

I cant figure out why my rear brake isnt working. I push down on the lever and nothing happens at all, there is no brake there what so ever. I have had it bled a few times and also changed the master cylinder which has made no difference. The garage i use has told me there is definately no leaks and no air in the system. when the rear brake caliper is off the bike they said the brake is pushing the pads together nicely but when fitted to the bike its not grabbing hold of the disc.
Also, i was riding along the other day and i heard a loud twang come from the back end of the bike, i looked down and couldnt see anything wrong, i tried my rear brake and it was working perfectly ! A few minutes later i heard it happen again and the brake stopped working again ! :confused
Has anyone else had this problem or can anyone give me a clue what might be wrong 'cos the garage i use has given up and doesnt want to know anymore.

Air in the system......if you do a search there will be lots of info......you have to take the caliper off and hold it high up as you bleed....etc...etc

Also....tie wrap the lever down over night makes a big difference

RYE said:

I cant figure out why my rear brake isnt working. I push down on the lever and nothing happens at all, there is no brake there what so ever. I have had it bled a few times and also changed the master cylinder which has made no difference. The garage i use has told me there is definately no leaks and no air in the system. when the rear brake caliper is off the bike they said the brake is pushing the pads together nicely but when fitted to the bike its not grabbing hold of the disc.
Also, i was riding along the other day and i heard a loud twang come from the back end of the bike, i looked down and couldnt see anything wrong, i tried my rear brake and it was working perfectly ! A few minutes later i heard it happen again and the brake stopped working again ! :confused
Has anyone else had this problem or can anyone give me a clue what might be wrong 'cos the garage i use has given up and doesnt want to know anymore.

Click to expand...

I would go back to basics and do it all again yourself so you know it's right.

Firstly adjust the pushrod on the mc for about 5mm of play before it engages the piston. If you have too much the brake won't come on and too little and it will drag and lock on.

then remove the caliper and raise it up as high as you can get it with bleed nipple uppermost and bleed it. Then rotate the caliper a bit and give it a tap and bleed again as air gets trapped easily. Pads should be pushed right back with something between them to hold them there.

It can take a lot of bleeding to get all the air out and somethimes a syringe is needed to add pressure to force the air out.
If it's bled with the caliper still attached it will never work as the air just won't come out.

If you have not had the updated fluid res then the pipe mount on the res and the M/c needs drilling out to 4.5mm to aid air rising to the M/c or you can buy the updated parts from Aprilia. Same goes for the clutch

Hopefully then you will have a working brake.

Southern Cross upgraded my M/Cyl by drilling out the holes to raise it or something whilst the belly pan was off... took about 5mins... free of charge too... there good lads !! :biggrin