locking rear brake

[steve]

Hi Guys
Have had a 620i monster for about 4 years now and use it every day for work.
I have had a persistant problem with the rear brake seizing up when used during filtering it seems to get hot them seize solid, there seems to be some sort of hydrolic lock that only
freeing up when the caliper cools. have had a new caliper and master cylinder, but the problem persists. any ideas please. :Furious:

regards Steve

[Half Pint]

i had this problem on a trip round scotland last year... it turned out to be my master cyclinder.

although i would not rule out the the caliper.

try and bleed the brake through without using a bleed kit to see if the master cyclinder is the fault (by the pressure when bleeding)

don't worry they are cheap enough brand new actually

[Gilps]

Make sure there is enough free play in the pedal. Adjust the pin that goes in to the slave cylinder. The heat from the brake can cause the fluid to expand and without enough free play the pads don't come back from the disc, things get even hotter, then the brakes just lock up until it cools down.

[steve]

bike going in for tyers this weekend, will get them to bleed it for me. Tried to bleed it before when changed the pads but had problems then. the pistons would not go in unless i undo the bleed niple. after which i could not get the fluid to pump through the system, one of those ducati quirks i supose.
what i need is a nice garage so i can play with it properly

Thanks steve

[Nickj]

the pistons would not go in unless i undo the bleed niple. after which i could not get the fluid to pump through the system

You doing the normal kind of thing?
Set up the free play in the arm that rams into the master cylinder first.
Loosen off the bleed nipple then tighten back but not too tight.
Push down brake pedal.
Hold down pedal and loosen nipple to let pressure off.
Retighten nipple then release pedal slowly.
Repeat until fluid comes out with (a) no bubbles in it and (b) clean.
Never had a problem with this.

I've never used one of the suck out the fluid devices so not a clue what you'd do with them.