ASK THE MXPERTS: MY REAR BRAKE LOCKED-UP SOLID
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My rear brake locked up on the farthest part of the track from the pits. The rear wheel wouldn’t turn. The bike wouldn’t roll, and I was stuck out back. What could I have done to get back to the pits?
If you had a 10mm wrench, you could have adjusted the pedal play at the rear brake master cylinder to allow the hydraulic plunger to release pressure on the caliper, but no one carries a 10mm wrench with them while racing. The brakes will release themselves once they cool down, but this could take up to 30 minutes. In the heat of battle, the MXA wrecking crew has been known to grab a fire hose from a track worker and spray the brake system with cold water. This speeds up the cooling process significantly — with a small risk of cracking the sizzling hot rotor; however, this only works if your bike stops within fire hose or sprinkler head range. Normally, one of your friends will ride out to look for you and you can send him back to bring you the proper tools. Then, work with the brake pedal to release the pressure or, in a pinch, crack the bleeder valve open to let some fluid out. Be careful riding back to the pits, because you probably won’t have any rear brake. And if you try to use the rear brakes, they might heat back up again. Once in the pits, bleed the rear brake completely and add new fluid. The brake pad will be glazed and should also be replaced.