BRAKE HEAT MYSTERY: MR. KNOW-IT-ALL

BRAKE TIME
Dear Mr. Know-It-All,
Should I beg for you to impart some of your great dirt bike knowledge? The way readers had to beg for a response from Rondo Talbot in the mid-’70s? I have a Husky, a KTM, and a new GasGas. When braking, I start using both brakes, but release the rear first while repositioning my feet for corner entry. I am positive I am not dragging the rear brake through the corners. I am positive I am braking harder with the front brake entering corners. And yet, after riding either trails or the MX track, my front rotor is only warm, and the front master cylinder is cool. The rear rotor is always scalding hot, and the rear master cylinder is also hot. Is there something inherent in dirt bike design where the front brake system is better cooled?
Please enlighten me.
John Barnhart
via [email protected]

Two things here, Johnny boy. The front rotor is much larger (260mm), while the rear is 220mm, so it will naturally dissipate heat with more alacrity. Second, the only way that your rear rotor heats up dramatically is by friction, and I mean friction caused by engaging the pads to contact the spinning rotor. I have witnessed riders who have not put enough play into their rear brake pedal and the pads drag. But, the most common cause is brake dragging. In the woods, this is a natural habit for just about every single competent enduro pilot I have known—from Dick Burleson to Randy Hawkins to Mike Lafferty.
My words of sage are as follows: change your rear brake fluid often. This helps fight chronic brake fade. Keep fresh pads in place. With more pad material, you will have less heat buildup. There are several companies, such as SRT and Works Connection, who offer cooling devices for the rear caliper and extended reservoirs for additional brake fluid—get them. Over and out.

If you don’t mind displaying your ignorance for the world to see, who are we to deny the opportunity?
Send evidence of your failures to
[email protected] or Mr. Know-It-All
Dirt Bike, P.O. Box 957, Valencia, CA 91380-9057