If your vehicle is showing brake pedal pulses or vibrates under normal braking, here are the most likely causes and the parts you'll need to fix each one.
Over time, heat and wear can cause brake rotors to develop uneven thickness or warp. As the brake pads squeeze the uneven spinning rotor, they bounce over the high spots, pushing hydraulic fluid back up the lines and causing the pedal to pulse.
If the wheel hub is not thoroughly cleaned with a wire brush before installing a new brake rotor, the rotor will sit slightly crooked. This creates 'lateral runout', causing the rotor to wobble and pulse the pedal almost immediately after a brake job.
If lug nuts are tightened unevenly or over-tightened with an impact wrench rather than a torque wrench, the uneven clamping force can actually distort the brake rotor hat, leading to pulsation.
If a brake caliper or its slide pins seize up, the brake pads will constantly drag against the rotor. This generates extreme heat, rapidly warping the rotor and causing pedal pulsation.
While not the direct cause of the pulsation, worn suspension bushings will amplify minor rotor imperfections. A slight rotor warp that would normally be unnoticeable will feel like a severe shudder in the pedal and steering wheel.
A failing wheel bearing allows the entire hub assembly to wobble as you drive. This wobble pushes the brake rotor back and forth against the pads, which translates into a pulsing brake pedal.