Bull 150 rear brake lockup problem

[Dusman]

Hi guys,

Question: have any of you had problems with your rear disc brake locking up due to part of the linkage to the brake foot pedal touching the exhaust and overheating the brake’s hydraulic mechanism?

I figured this would be a problem when I was looking over the bike. What a junky design!

Anyways, I thought of a modification I could do to the exhaust that simply put another piece of hard plastic behind the heat shield piece that attaches the exhaust pipe to the rear frame. This would keep the pipe off of the linkage mechanism and prevent the problem (maybe).

Any other ideas?

Thanks a bunch!

[FLASHLIGHTBOY]

this should not be a oproblem.... do you have the adjustment to tight>>> loosen the linkage to allow for more play or free play in the rear brake setup.... not a design problem...

[Dusman]

Originally Posted by FLASHLIGHTBOY

this should not be a oproblem.... do you have the adjustment to tight>>> loosen the linkage to allow for more play or free play in the rear brake setup.... not a design problem...

Thanks for responding. I didn't try that, but this is the modification I did to fix it:

[Dusman]

Originally Posted by FLASHLIGHTBOY

this should not be a oproblem.... do you have the adjustment to tight>>> loosen the linkage to allow for more play or free play in the rear brake setup.... not a design problem...

I thought I had fixed it, but nope. After my daughter rode it tonight for 30 minutes the rear brake completely seized, started smoking, and the little plastic piece melted off the rear-bottom part of the disc brake housing. The brake works fine when initially riding. I just don’t get it.

[FLASHLIGHTBOY]

a lot are close... I guess you can either get a muffler shop to bend the pipe away... or put a heat shield over it.. I can not see heat causing it to swell up the brake fluid???? the rear disc brake should be floating and a small gap between the rotor and pads... if you let it cool down does it get back to normal ??? I know when I sell a rear brake assembly I have to make sure the people check the rear spacer gap on th e back.. between the mount and calipher.. let us know if the brake return to working when cooled down..

[zackattack91]

Yeah they really don't take into account how hot the exhaust pipes and mufflers get in these things.

[Dusman]

Originally Posted by FLASHLIGHTBOY

a lot are close... I guess you can either get a muffler shop to bend the pipe away... or put a heat shield over it.. I can not see heat causing it to swell up the brake fluid???? the rear disc brake should be floating and a small gap between the rotor and pads... if you let it cool down does it get back to normal ??? I know when I sell a rear brake assembly I have to make sure the people check the rear spacer gap on th e back.. between the mount and calipher.. let us know if the brake return to working when cooled down..

It does seem to work normally, but when I elevate the wheels off the ground the wheels move but they stop quickly. How loose should those wheels be? You have the chain assembly and the mild drag from that. But according to you, these should be freely flowing.

How do I loosen the brake pads or create that gap?

Also, I’m wondering if the master cylinder is fried due to being indirectly heated up previously by the exhaust contacting the linkage arm?

Any ideas are appreciated. Thanks for your help!

[Dusman]

Originally Posted by zackattack91

Yeah they really don't take into account how hot the exhaust pipes and mufflers get in these things.

Yes, I don’t understand why they designed it like that.