300ex Rear Brake system?

My rear brake caliper on my 300ex is completely screwed up on my quad. Acually my whole rear brake system is screwed. Is there any other quads rear brake system that i could put on my 300ex to make the back brakes a lil better?:confused:

[SNIPA]

My brakes rear caliper was not working either..Take your caliper off and disassemble it. I bet it is a seal. That is what the prob was on mine. They are real easy to take apart and seals are cheap. If you need a schematic of the caliper go to www.ronnies.com and look at the micro finch.
Hope this helps!!!