Front Or Rear - Warped Rotor Diagnosis

[99 C4]

I get vibrations when braking at higher speeds, primarily felt in the pedal and the seat. I'm getting ready to change my rear rotors and pads, but I just wanted to make sure that I don't misdiagnose and change the rear for no reason. If it was the front's that were warped, then I should feel the vibrations primarily in the steering weel, right?.

[Loren]

A good read...

The "Warped" Brake Disc and Other Myths of the Braking System

[JimB]

The first time I read that article a couple of years ago it made perfect sense to me. I could never buy into the idea that heat behind the pads would actually warp the rotors. Either way, whether the vibration is caused by warping or deposits, I would have a hard time imagining it happening on the rear rotors. Our car's brakes are very biased to the front. We actually run higher friction (Pagid Blacks) pads in back and lower friction (Pagid Oranges) pads in front of our 996 race car to shift the bias to the rear. That doesn't mean that the problem isn't in the rear pads or rotors but I would be surprised if it's what we traditionally thought of as warped rotors.

When you have the rotors changed, make sure they give your suspension and wheel bearings a good going over. A loose bushing/bolt or a bad bearing could also cause a vibration. As long as they have the car up on the rack it shouldn't cost anything to do a good inspection.

Jim

[99 C4]

Thanks for the tips and the info.