Warped Brake Disc - Affecting brake performance?

Hi Everyone,

For a while now, my brake rotor has had a slight warp in it. When rotating the axle you can see the disc sway roughly ~1.5 to 2mm either-side from its center position between the brake calipers. Do you think this could be affecting the braking performance of my kart?

When on a hot lap (warm tyres, grippy track) I really have to stamp the brakes to get the tyres to lock. I only recently bled my brakes, so there shouldn’t be air in the lines, and my calipers have still got a reasonable amount of wear left on them, however have not been replaced in the last 2 years (the kart has not had much use).

I will take the calipers off and have a look for any potential grease, maybe thats the solution?


If you have firm pedal feel then I would assume you have glazed pads/rotor. That happens over time and gets sped up when you overheat the brakes. You can try to remove the glaze by taking the pads out, setting some mild sandpaper (like 320) on a flat surface, and then running the pads over the sandpaper until the surface looks uniform and dull. It shouldn’t take much. Next will be to surface the rotor (or simply replace if the warp/bend is that bad). I would take some red scotchbrite pad and scuff perpendicular to the rotation of the rotor, while spinning the axle. This may take a decent while but you want to take the shine off the rotor without overly scratching the surface.

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My opinion is: unless it’s a floating setup and your eye is getting tricked by it, then 2mm of sway is way too much of a warp. A replacement disc is usually cheap enough, I would get a new one along with new pads.

When you do replace it, I would also flush the system with new fluid. If you overcooked, you could have torched the oil too, by the caliper. So it’s wise to flush it.

Do you know what could have caused it? Disc not centered to caliper? Driver habit?

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Okay Thanks for that, I think I’ll try the sandpaper and scotchbrite first and see if I get any improvement with the brakes.

The warp is not overly bad, looking at the rotor again yesterday I probably exaggerated how much warp it had. Id say its 1.5mm of overall movement.

If the problem still persists, I’ll have to look into a set of new pads and probably a rotor.

Thanks for the help, will update on how I go…:+1::call_me_hand:

I was caught in a decent shunt last year, and the axle was knocked out of position. I think when it shifted over the rotor could have been pushed against the calipers and bent that way?

The rotor has not been replaced since I bought the kart fairly new from a friend, so there’s a good chance it has glazed over time. The pads were replaced around this time last year, but I haven’t checked them in a while. So those two things could be contributing.

I only replaced the fluid not long ago, after I noticed a warp in the disc. It shouldn’t have cooked since then I wouldn’t think.