Replacing Rotors

Servicing disc brakes is normally a lot easier than working on drums. Rotors and calipers have fewer, larger parts than the average drum-brake system, so the average-skilled do-it-yourselfer can usually perform routine disc maintenance.

Rough Rotors Although rotors routinely last longer than pads, they should still be checked at every regularly scheduled tire rotation.
Replacing disc-brake pads is a story unto itself. This time the focus is on the inner surfaces of the disc-brake friction equation—the rotors. Although rotors routinely last longer than pads, they should still be checked at every regularly scheduled tire rotation. Over time, the friction that causes the car to stop will wear down the rotor's outer surfaces. Another possible rotor-destroyer is pads that are allowed to wear down to their metal rivets, which then cut grooves into the discs. Run your fingers across the rotor's contact area to feel for irregularities.


Also, rotors that are allowed to overheat for extended periods of time can warp. This can cause the car to feel like the tires are horribly out of balance during braking.


Most rotors have the minimum-thickness specification cast somewhere on their inner, non-friction area. Do-it-yourselfers can use a micrometer to determine if the rotor has enough meat or should be replaced. Run-out, or warping, can be checked with a dial indicator. It's even easier to have in-use rotors resurfaced on a brake lathe when changing the pads. Reputable mechanics will alert you to any problems and flat-out refuse to "turn" the rotors if they're too worn.

Installation Tips
> Wear a filtering mask when working on brakes—brake dust can contain asbestos.