grabbing brake

[Hogwylde]

A friend of mine has a problem with the rear brake on his KX grabbing. He's getting frustrated with it because if he just barely touches it, the rear wheel locks and if he's not on the clutch, it kills the bike. I know he's got sintered pads and what looks like an aftermarked rotor. I've though of maybe switching to organic pads. Not sure if this will fix his problem though. Anyone else have any ideas how to soften this brake up a little so it's not so grabby?

 

[marcusgunby]

Is it a over size rotor as well?? as normally KX brakes are not that strong.

 

[Hogwylde]

nope, standard size rotor.

one thing that we have done already that has helped.....cracking the bleeder screw and letting in a little air. at least it doesn't lockup like it did, but it's still overly sensitive. I have an identical bike and we can't figure out why his is so touchy and mines not.....except for that aftermarked rotor.

 

[motometal]

is there any possibility the rotor and or pads are contaminated with oil/etc? that could make it grab. I don't like the idea of letting air into the system.

 

[rc331]

I agree with motometal, I don't like the idea of air in the system either.
How about the linkage between the brake pedal and master cylinder? could it simply be set up way too tight?

 

[rc331]

Thinking about it now, playing with the linkage and pedal height really shouldnt make the brake grabby. Maybe it is the sintered pads.

 

[biffpk]

Try removing and cleaning the master cyl. there could be a piece of crud pluging the very small return hole. this means dissasembly of the cyl. It is not difficult, just requires a snap ring plyers

 

[RM_guy]

Grease on the pads will make it grab. The problem is, once it's there you may never get all of it off. You can try cleaning them with brake cleaner but might just have to try new pads.

 

[ps2112]

I have this exact same problem and thought it was just my heavy foot. Please let me know what you find out!