Rear brake 996
 

I am at a loss as to what caused this, Was out on thé local track this morning had done a few laps with no problems, Tyres had just warmed up nicely, was on my way down the back straight coming up to a left hander, now i am not sure if i touched the back brake leaver or not ( i dont normaly acvtualy think about it) anyway back wheel locks up solid leaving a nice strip of rubber on the track i clutch in thinking its an engine problem thats locked the back end, but back wheel is still locked on solid stop in a cloud of smoke the rear disc is actualy smoking.

We get the bike off the track and back to the pit lane, up on the padock stand and the wheel turns freely brake leaver depresses and returns as normal.

So does anyone know what could have caused the lock up and what i should be checking for ??

Had the same thing a couple of years back.
Turned out the pushrod wasn't returning far enough in the master cylinder and therefor not releasing the pressure in the calliper. As the pads rubed the disc it heated the system, expanding the fluid therefor applying more and more pressure on the brake. Allowed it to cool and all was back to normal... until the next time!

A twist of the adjuster bolt allowing the rod to return a little further and not had the problem since.

Credit goes to Nelly for finding and resolving that for me.

Hello Bionicle

maybe worth taking the caliper off and giving the piston a good clean.
Put a small block of wood between the pistons, so they don't pop out
and clean then apply break slowly you will see the piston bite the wood.
Open them up again and repeat. (check fluid level)

Maybe possible the pistons have locked as they dont tend to get much use on a Duc,

bloody scarey for you I bet. . . .


TopiToo

Hmmmmmmmm, just had the opposite problem, fine all day on the track then in the penultimate session the rear brake pedal went away completely as if the fluid had boiled.

Removed the caliper turned it so the bleed niple was at the top, bled it, no better, had to resort to winding the rod out to take up all the free travel:confused:

Ray.

Thanks for the advice, It was a bit of a shake up, but fortunate that it was on the straight that it happend and i had already started to slow down, but is sure puts the wind up you :(

Bionicle,
I had the same thing happen last year not on a track but every time i went out on the bike brake disc got really hot and the rear brake started binding up. When i took the master cylinder apart inside there is a PTFE bush that the piston slides up and down in, problem was the PTFE bush had gone oval and the piston wasnt sliding up and down properly. so i made a new bush out of brass and have had the best brake i have ever had on the duke for over a year now and it has never needed bleeding since.

Stu

My rear brake went tits up at LLandow 2 weeks ago and I just thought the fluid had boiled but last Sunday the rear pads were binding badly.

So tonight i removed the master cylender tonight and cleaned up piston as it had some rust on it and all is fine now !!!

The bit that cheesed me off was it was a new master cyl last year !!

Age