The dashboard, steering wheel, and seats vibrate abruptly upon braking. A pulsation is felt on the brake pedal at the same frequency as this vibration. Although the frequency is similar to that of body shake, the amplitude of this vibration is greater. It occurs mostly when you apply the brakes while driving at intermediate to high speeds.
Excessive runout of disc brake rotors
Different thicknesses of disc rotors
Excessive runout of brake drums
Runout of rear axle shaft flange
1.Any runout of the disc brake rotors or drums causes the disc pads or shoes to vibrate when the brakes are applied.
2.These vibrations are then transmitted through the hydraulic system, causing the brake pedal to pulsate.
3.The disc brake rotors are also caused to vibrate simultaneously, causing the steering knuckles and axle shafts (or hubs) to shake both vertically and in the fore-and-aft direction.
4.These vibrations of the axle shafts are transmitted through the suspension to the body, causing the body to resonate and thus amplifying the vibrations. These vibrations are similar to body shake.
When a wheel having excessive runout is mounted with lugnuts onto the brake drum, it may cause the shoe-contacting surface of the drum to deform.