Hm, didn't know we had a 'tech' area! I already posted this in the 929 section, but maybe I can get more help here too![/align][/align]Hey. My buddy called me today and said while on the way home, his brakes suddenly locked up on him, to the point that the tires wouldn't roll, it was stuck where he was stopped. I went out to save him... all we could do for now was take a flat-blade screwdriver and pry the brake pads off the rotors so he could cruise it home. I thought only the front brake pad was locked up, but after he rode it home, he said both brakes were worthless, didn't do anything... he had to slow down/stop with him feet.

What would cause this? I checked both of his brake fluid resevors and neither were empy. They did appear 'low'... they both were only full to the 'lower' point, would it cause the brakes to lock up if it's not all the way to the 'upper' point? The lines and such didn't appear to be disconnected anywhere. After getting the bike home, we could pull the brake lever a few times and the pads would clamp down on the rotor again... but won't release off the rotor.[/align]

 

It sounds like there's a problem with his brake master cylinder... or maybe he's got a collapsed line? The line could look fine on the outside, but have collapsed on the inside.

 

Any recommendations to fix this problem... if it is the brake master or something?

 

If it's the lines, they'll need replacing. If it's the master cylinder, again, it'll have to be replaced. The thing that's getting me is, you're saying it did it to the front AND the rear? That seems really fishy that "all of a sudden" both front, and back brakes go to junk.... especially since they're not linked in any way. Is your buddy SURE that NOTHING has been added, poured in, whatever... to his brake resevoirs? Did he recently add fluid? Anything?

 

I told him to lay off the front brake on the way home(since we had just pryed the pad off the rotor), so I told him to use his rear brake to stop. He saidthe rear brakewasn't really doing a thing... said it was BARELY trying to stop him, but not nearly quick enough, so he was shoe brakin it.

He hasn't touched the fluids on this bike since he got it a few months ago. He bought it in middle of winter and kept saying he was waiting till riding season to give it a tune-up.

 

Does he have the wrong brake fluid in there? That stuff has to have room to expand. DOT3 is not good enough. Any recent work to the bike?

 

He bought the bike in like... November/Early December. It ran fine when he got it, he rode with us on nice days, but he's never had any brake problems. Only thing I know of that he's done to it is mirrors and slip-on. He said today is the first time he's ever experience a problem like this.

When I got there, the bike was on a down-hill slope in neutral, but the bike would not roll at all, even if I tried to force it to roll down the hill... the front brake was absolutely locked up. The lever felt 'loose', I initially thought the lever somehow became disconnected. So after getting the pads to release the rotor, he rode it back to his house where we played with it for a few. I pulled the front lever a few times and the pads clamped down, but not releasing... lever still feels loose.

Are the 'bleed' valves easy to get to on bikes? Cars it's no problems, but I've never looked at bike brakes. I'll have him get some DOT4(not DOT3 like cars right?) brake fluid and I guess we'll change the brake fluid.

 

Lol, I guess that would be a no to recent work, ha.

 

We posted at the same time. There may be air in the rear if he moved the rear master out of the way for a slip-on. It is possible it was tilted sideways and air may have entered. As for the front brakes, there are several possibilities. It kind of sounds like stuck pistons at the moment, but it is hard to diagnose without being there.

 

The slip-on took like 4 seconds to do, nothing was 'interfered with' or 'moved'. A stuck piston!? Wha!?