Burning through rotors? Blame the calipers.

Dear Car Talk

Dear Car Talk | May 01, 2004

Dear Tom and Ray:

I own a 1990 Mazda 626 and had the brakes and rotors replaced last September. Two months later, the rotors were warped again and had to be replaced. Four months after that, I had the same situation. Can you explain why new rotors warp so quickly? We did not have this problem during the first 13 years we owned this car. -- Ken

TOM: To quote Shakespeare, the problem, dear Ken, is not in our rotors, but in our calipers. He said something like that, didn't he?

RAY: If one of your calipers is sticking -- holding a brake in the "on" position, even when your foot is not on the brake pedal -- that would heat up a rotor and cause it to warp prematurely.

TOM: We always check the calipers when we do a brake job, to make sure that both the pistons and the slides are moving freely. I mean, why miss an opportunity to sell a customer a caliper? But the guys who did your brake job might have missed one. You could also have a faulty power-brake booster that's applying the brakes even when you're not. Or a restricted rubber brake hose that's acting like a check valve and creating the same effect.

RAY: So, those are the things I'd ask the mechanic to look for, Ken. There's no reason why new rotors -- even cheap ones -- should warp after only a few months unless there's something else in play.

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