An uneven rotor surface is the most common cause of pulsation that drivers feel in their brake pedal while braking. Tomorrow's Technician explains that the surface of brake rotors, sometimes called brake discs, should not vary any more than 0.001 inches around the entire rotor. This means that even the slightest variation in the surface of a rotor or disc is felt by drivers when braking.
The brake pad that is activated when drivers press down on a vehicle's brake pedal performs a clamping motion on the rotor or disc of each wheel. Cars that have uneven rotors wear down brake pads much more quickly and may cause long-term damage from excessive friction and vibration of the entire braking system. Drivers who feel pulsating in their vehicle should ask a mechanic to look at the brake system, including rotors and pads. Sometimes addressing these components alone is not enough to completely stop brake pulsing, and mechanics may need to look for rust accumulation in the wheel studs of the vehicle. A final cause of pulsating brakes may be improperly set torque for lug nuts. If pulsating occurs after a recent auto repair, such as new tires or brakes, drivers should consider taking their vehicle to a mechanic that specializes in caring for their model of vehicle.