Front brake won't release ******URGENT NEEDS TO BE FIXED ASAP****

[tussey]

When the front wheel was off the brake lever was squeezed. I didn't have trouble getting the pistons back (used a QuickGrip to compress them) but the brakes are not behaving the same now. Got the bike all back together and the front brakes are clamped down.

Spent about 10 minutes bleeding the front brake and air bubbles kept coming out. Eventually I gave up because I wasn't sure if what I was doing was helping so my question is.

1) What would cause the front brake to not release?

2) Should I just keep bleeding it or do I need to tear the whole front brake apart and rebuild?

Thanks.

[bobthebiker]

keep bleeding em.  while you're at it, top off the fluid up in the reservoir.     air doesnt help brakes work right, as you know.

[CndnMax]

Remember to close the bleeder before releasing the lever or your gona be doing work for nothing 

[gsJack]

If you open the bleeder screw and try to spin the wheel and it's binding, it's not a hydraulic or air problem, it's a mechanical problem.  Most likely a piston binding from pushing dirt back into the seals.

I had pistons binding a couple times so when replacing pads now I always pop out the pistons and clean them up like new and put them back in lubed with brake fluid and then bleed the system.  Good as new every time now.

Another posibility is the outer wiper seal is twisted and binding the piston caused by the same dirty piston problem.  When those get a bit old and are twisting, I just throw them away.  They are there to keep the dirt out and wipe the dirt off the piston when it's pushed back in.  Don't need them since I put the pistons back in clean every time now.  Those wipers will wipe off the brake dust but they don't touch the hardened crud that builds up on the pistons.  After the job is done the pistons only move out from the seals as the pads wear down.

[tussey]

Well I seemed to have fixed it. I took the caliper off, and used QuickGrips (a mechanical vice) to squeeze the pistons back in. Then I remounted the caliper and squeezed it a few times and it no longer sticks...for now. I plan on rebuilding the whole system soon. I've never taken the calipers apart so I don't know what needs to be replaced. Are there kits available?


Also I don't really understand how the brakes work. What makes the pistons come back in when I let off the lever? Why wouldn't they just stay clamped down?

[yamahonkawazuki]

mostly a prnciple of hydraulics. anbd btw WELCOME BACK jack , lol i know its a bit late, but hey