Not All Aftermarket Parts are Created Equal -- Especially Rotors

Dear Car Talk:

Ihave

a 2013 Kia Optima with

144,000 miles on it. It runs great, and I’ve only had one problem with it.

It went 98,000 before the front brakes were replaced. Since then, I’ve driven it another 46,000 miles, and I’m on my third set of rotors. They keep warping.

Now they’re starting to warp again just 8,000 miles after they were last replaced. Any reason you can give me why? The brake shop has replaced the rotors three times at no cost to me. -- Mike

Well, tell them to get ready for number four, Mike. I can think of four possible reasons when your rotors are warping so quickly.

One is that you have a teenage son who recently got his driver’s license.

Possibility two is that you’ve got a sticky caliper. The caliper is what pushes the brake pads together and squeezes them against the rotor. I would hope the brake shop would have checked for sticky calipers. But if one or both of your front calipers aren’t always releasing when they should or aren’t releasing completely, you’d effectively be driving around with your brakes always applied. That would overheat the rotors and make them warp pretty quickly.

If the calipers are good, another possibility is that your power brake booster is faulty. The brake booster multiplies the force applied by your foot on the brake pedal. It’s the power in power brakes. And if the booster is failing, it could be applying brake pressure even when your foot’s not on the pedal. If it’s the booster, it would tend to get worse the longer you drive -the more times you apply the brakes. Like a sticky caliper, that would be like resting your foot on the brake pedal, which would cause the rotors to heat up and warp.

The final possibility is that the brake shop is just using cheap rotors. Not all rotors are created equal. Based on many years of experience -- and many unhappy customers coming back to complain -- we have learned which aftermarket brake parts we can trust and which we can’t. And if we can’t get aftermarket rotors that we trust for a particular car, we’ll get the original equipment rotors from the dealer. We’ve just learned over the years that the original equipment rotors always perform well -- so we’ll often just go right to those, even though they’re more expensive. The fact that the brake shop keeps giving you free rotors without complaint indicates that either they’re saints or they’re getting them real cheap. So, if your brake booster and calipers check out, I’d ask them to get you a set of OEM (original equipment manufacturer) rotors from the nearest

Kia dealer.

Offer to pay for the rotors yourself if they’ll do the installation. That seems fair. You’ll get many more miles out of your rotors (you got 98,000 out of your first set), and they won’t have to go hide in the men’s room every time they see you driving back in, Mike.