When does a pulsation in the brakes typically occur?

A pulsation in the brakes typically occurs when there is thickness variation around the rotor braking surface. This variation can lead to an uneven surface area for the brake pads to make contact with the rotor. As the brake pads press against the rotor, any inconsistencies in thickness result in a change in braking force that can be felt as a vibration or pulsation through the brake pedal. This is often a sign that the rotor is out of specification and may need resurfacing or replacement to restore even contact.

Other factors, such as low brake fluid, high rotor temperatures, or worn brake shoes, can lead to different issues, but they do not directly cause pulsation in the brake pedal in the same manner as thickness variation does. Addressing the thickness issue is crucial for maintaining smooth and effective braking performance.