Purchased a 2001 cl/s with 40,000 miles and a known brake problem (warped rotors). Car was serviced regularly at an Acura dealership by original owner. Are warped rotors covered by the warranty? How does a technician determine if warped rotors need resurfacing or just need to be turned?

 

The Acura warranty does not cover brake pads or linings, which means rotors in this case. The diagnosis of "warped" rotors can be somewhat of an enigma, as most times when you feel a vibration or pulsation while braking, it is not really because the rotors have actually warped - its almost always an uneven buildup of brake pad material that has occurred on the rotor.

This uneven buildup or transfer of pad material feels like a warped disc, but the discs actually distorting is extremely rare for any vehicle, not just Acuras/Hondas. If you have deep enough groves worn into the rotor, a tech will likely "turn" them which means cutting several thousandths or more of material off the surface of the rotor and rendering them perfectly flat again. If the surface defects are very slight, a mild sanding with GARNET sandpaper may be enough to eliminate this warped sensation. (Do not use aluminum oxide based sandpaper as the abrasive material will cause a chemical reaction with the cast iron rotor and create troublesome deposits on the surface and magnify the warped sensation!) Turning of the rotors is not desirable because brakes turn motion energy into heat, and the rotor absorbs this heat. The more mass a rotor has, the more heat it can absorb and the better the braking system works. Turning the rotors removes mass from the rotor and actually decreases the efficiency of the brakes on your car. This is why many manufacturers suggest new rotors only with a new set of pads.

There is a really good "whitepaper" article on the StopTech website that explains a lot about the myth of warped rotors and bedding-in brake pads. You should check it out. Bottom line is that no concern with the pads or the rotors is covered under warranty unless it is something like the entire pad crumbling and falling off or the rotor fracturing due to a casting defect. Comfort issues like "warped" rotors can usually be eliminated by doing a rebedding of the pads per the StopTech website instructions. You can find this info from other places as well by googling brake pad bedding procedure or the like.

Hope this helps!

 

Thanks for your reply...very helpful.

 

You're welcome. I have rebedded the pads on my Audi when I started to get a lot of vibration and pulsation through the brake pedal. It really does work with eliminating the warped sensation, but it is hard sometimes to do the procedure properly (letting the brakes cool naturally without having the pads bake on the rotors, like at a stoplight). At first when you do it, it seems extremely abusive (the higher performance the pads, the more "abuse" you have to give it to eliminate or even-out the pad material buildup) but it really works. Obviously, this causes more wear on the pads, but in the long run its cheaper than having the rotors turned.

There are many high performance aftermarket pad suppliers out there who make pads with higher coefficients of friction and that will hold up to higher temps (which equals more aggressive braking) before experiencing total fade. OEM pads are usually designed for low noise, but this usually makes them not able to withstand really high temps. Aggressive pads will usually produce some squeal during city driving and most people will trade off performance for low/no noise.

 

warping can be checked very easily, when the auto tch puts the rotor on the resurfacing machine and ready to cut first they let it spin on the machine to check for wobble in the rotor(warpage) very easy