Author Topic: rear brake lockup (Read 2590 times)

bgrundy · « **on:** July 15, 2007, 09:44:17 PM »

Okay, so I just replaced my rear tire. I put the wheel back on, bleed the rear brake (done it a thousand times), leaving the brake fluid level 1/2 way between full and low markers...and go for a short ride.

About 5 miles into the ride the bike drags to a halt (feels like it's stalling) in the middle of a country road. ABRUPT halt. And I can't get it to the side of the road. Come to find out the rear brake is seized up.

I break out an 8mm wrench and open the rear bleed nipple (heh-heh, he said "nipple") with a rag handy, and out spurts a little fluid. the rear wheel spins now. I bleed a little more and hop on and boogey home.

What, in the wide wide world of sports, would cause this? Never happened before in 20 odd years of riding and bleeding brakes. Fluid was not overfilled. Rear brake pads just seized....thoughts?

<edit> Bah! this was supposed to go in mechanical/technical...not general motorcycle. Sorry

StangMATA · « **Reply #1 on:** July 15, 2007, 10:44:11 PM »

Did you hit the brake when it snagged and drug you to a stop? Could have been a piece of gunk or dirt in the caliper that stuck it open. May have been an air bubble that you missed that just screwed with your brake system....or it's a fluke that you will never find the answer to.

bgrundy · « **Reply #2 on:** July 16, 2007, 01:09:00 AM »

Quote from: "StangMATA"

Did you hit the brake when it snagged and drug you to a stop?

Not that I recall... I was actually headed uphill when it started to seize. So I was not touching the brake at all (IIRC).

It's the "maybe this is a fluke" part that has me worried. I'd hate to have that happen again in a 70mph turn...

Red01 · « **Reply #3 on:** July 16, 2007, 09:25:57 AM »

I'd run the brake thru several cycles and see if the caliper pistons are hanging up at all, if they're not, then I'd chalk it up to a fluke.

Bob Holland · « **Reply #4 on:** July 16, 2007, 11:00:54 AM »

I have had this happen. Check your brake disc and see how hot it is after it locks up. Mine was to hot to touch. After I bleed the air from the line, it was OK.

pmackie · « **Reply #5 on:** July 16, 2007, 12:56:53 PM »

AS BHolland said, it is possible that you still have/had some air in the lines. As it warmed up on your ride, the air started to expand and applied the brakes. As the brakes started to drag, the heat went up and the situation got worse until the rear brake locked.

Do a carefull re-bleed of the brakes. Remember that there are two bleeders on the rear caliper.