Brakes Locking Up

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. 

quote:

ORIGINAL: Lrn2Go

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 said the rear brake wasn'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.

quote:

ORIGINAL: Tacoma25

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!?

If the resevoir is low (& chances are its been topped up) then I suspect that your friends brakes are down to the metal, which can make them overheat, expand the piston & bind themselves to the disc.
As for the rear brake (which wears faster than the two front pads) is probably in a similiar state, with little or no meat left on em. The rear brake always feels weak when you don't use them in tandem with the front.
Either way, he needs to pull his finger out & get stuck into some brake maintenance, new pads & fluid. With a bit of luck this could be the only problem.

I have no idea what shape the pads are in, but my buddy called me a little bit ago.  He said both the front and rear ARE locked up.

What Tacoma was referring to with the stuck piston is the thing that pushes on the brake pad. The piston is generally an aluminum cylinder. The brake fluid fills in behind the caliper piston and forces it outward, pushing the pad onto the rotor. In older bikes what will happen is moisture will get into the brake fluid and corrode the piston. Then when it moves in and out it'll get hung up because the aluminum will become pitted.

My diagnosis? I agree with Pacemaker. What probably is going on is that the pads have been worn so far down that the piston overextended itself and became unseated or seated crooked inside the caliper. I'd take the calipers apart, pump the lever until the piston pops out. Inspect the pistons and look at the brake pads. My guess is the pads are shot. Just pop the piston back in and bleed the brakes.

... Dunno how I got recommended for this job.  We had the 60degree day today... but no, the bike has to be fixed when there's a high of 37degree's tomorrow.
 
I guess I will pop off each caliper and take a look at the pads and see what kinda action I can get out of'em tomorrow.  I have spare 954 pads, hopefully they'll fit his bike so I can get this over with.

929 and 954 pads are the same.

I went over to his house tonight and looked the bike over while there.  The pads are in okay shape, not worn down to metal or anything, no wear on the rotors.  Yes, both front and rear pads are locked up.  I released the valves on each caliper and loosened the pads up... brake fluid immediately oozes out, so it's getting juice.  Seems like it's a bad brake line, but front and rear went out at same time?