Brake rubbing: why it happens
Page 2: Brake rubbing: The causes
The problem can also be caused by loose wheel guide parts in the brake area or even by excessive wheel imbalance. Even with different thicknesses, it can be worthwhile turning off expensive discs or grinding them in again at the same time. However, you must still make the entire brake system operational again and repair the periphery of the brake, otherwise a) this will reliably happen again after a while and b) stiff or even blocked parts on the brake caliper or loose wheel guide parts are potentially life-threatening.
(Image: Clemens Gleich)
Brake disk warped due to frictional heat
"Warped brake disk" is the most common diagnosis I have come across in conversations and the one I have encountered least often in practice. With this problem, the brake disk deforms so much under the effect of enormous heat that it becomes slightly wavy (beyond the normal "shielding", if you want to google it). In my experience, it's hard to miss this because it sounds downright cracking under braking. I remember testing the Buell 1125 R on a hot Spanish racetrack with a very long start-finish straight. Depending on the severity of the rider, after more or less laps at the end of this straight, there was a real crash, and then you drove into the pit lane, parked the thing to cool down and drove on with another test machine.
(Image: Clemens Gleich)
Our colleague Sebastian Bauer had a similar experience when testing the Mercedes-Benz SL in an AMG configuration, which tempted him to speed (not that he needed to be tempted). In both cases, this was a design problem. The Buell's single-disc brakes were not sufficient on the hot racetrack (racing teams therefore converted them to double discs); the SL was simply not built for Sebastian's riding style. The discs of both cars returned to their straight shape when they cooled down and could continue to be used normally. In such a case, you can slow down or upgrade the brakes like the Buell race teams.
(Image: Clemens Gleich)
However, this can also happen if you experiment with the pads. Then the problem temperature sometimes moves into areas that occur in everyday life, for example my steep highway descent, where I have to brake from highway speed to about 70 km/h for the downhill curve. If something like this comes out of the braking experiment, it has failed, and you have to move on to the next experiment or go back to the tried and tested. If this happens to you in many vehicles off the racetrack, it is often due to standing around on the brakes for too long, which leads to the accumulation of heat. It is better to brake shorter and harder. This ensures that the brake system gets rid of the heat before it causes problems.
(cgl)