During a normal non-ABS stop the brake pedal pulsates/vibrates. What is likely at fault?

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Multiple Choice

During a normal non-ABS stop the brake pedal pulsates/vibrates. What is likely at fault?

When you press the brake, the pad should grip a smooth, true rotor. If the rotor has excessive thickness variation (or warping), the contact between pad and rotor changes as the wheel turns. This causes the braking force to rise and fall slightly with each rotation, which you feel as a pulsating or vibrating brake pedal during a normal stop. The system itself is fine; the rotor surface isn’t delivering a consistent bite. Other possibilities don’t match the symptom as well. Worn brake pads can reduce braking effectiveness or cause noise, but they don’t typically produce a repeating pedal vibration on a normal stop. A faulty master cylinder changes how the pedal feels (spongy or hard) or the braking pressure, not the repeating vibration. Air in the lines causes a spongy pedal, not a pulsing one.

When you press the brake, the pad should grip a smooth, true rotor. If the rotor has excessive thickness variation (or warping), the contact between pad and rotor changes as the wheel turns. This causes the braking force to rise and fall slightly with each rotation, which you feel as a pulsating or vibrating brake pedal during a normal stop. The system itself is fine; the rotor surface isn’t delivering a consistent bite.

Other possibilities don’t match the symptom as well. Worn brake pads can reduce braking effectiveness or cause noise, but they don’t typically produce a repeating pedal vibration on a normal stop. A faulty master cylinder changes how the pedal feels (spongy or hard) or the braking pressure, not the repeating vibration. Air in the lines causes a spongy pedal, not a pulsing one.

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