Brake Pulsation: What Causes it. How to Fix It

Brakes rely on friction, lots of it, to convert movement into heat. That heat is absorbed and dissipated by the brake rotor or drum. But not all rotors and drums are created equal. The market is flooded with economy rotors from China. These low cost rotors are made from poor quality materials and are actually thinner than brand new rotors from name-brand manufacturers. In addition, the cooling fins often do not match the fin patterns designed by the car’s manufacturer. Less efficient cooling fins and thinner friction surfaces contribute greatly to rotor warp. It’s the warp in the rotor that produces brake pedal pulsation.

What can you do to correct the problem?

1) Insist on name brand quality rotors that are B.E.E.P. certified by the Brake Manufacturer’s Council, or independently certified by D3EA/Greening Laboratories. These rotors cost more than the economy imports, but are FAR superior in every respect.

2) Most car manufacturers NO LONGER recommend machining rotors!!! They are thin enough when they come out of the factory. If they are not grooved, the current advice is to re-use them or replace them. Goodbye brake lathe.

3) Clean the mounting surface. Rust on the wheel bearing hub can cock the rotor enough to cause uneven wear and warping. Clean the surface with a wire brush and apply anti-seize compound to prevent the return of rust.

4) Use a TORQUE wrench to tighten the lug nuts. Yes, you read that right. Uneven torque of the lug nuts also causes the rotor to cock slightly, causing warp. Remember it only takes .0015” of warp to cause brake pedal pulsation. So invest in a good quality torque wrench and tighten lug nuts in a star pattern. Tightening is a two-step process. Tighten all lugs to 50% of the stated torque. Then tighten a second time to the full torque.

Best brands to use: Raybestos, Wagner, NAPA/United, Bendix, Carquest

©, Rick Muscoplat

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