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FAQ's
ANSWER:
A pulsation in the brake pedal, that may also make the vehicle shudder
or jerk when stopping, is usually caused by a warped brake rotor or
out-of-round brake drum. (Usually rotors.) It can also be caused by bent
axle shafts, loose or worn wheel bearings or loose brake parts.
Often you can visibly see signs of a warped brake rotor. If the rotor has
a bluish tint to it or has discolored patches on it they are signs the
rotor is warped. Resurfacing the rotor will usually eliminate the
pulsation, but sometimes only temporarily. The rotor may have suffered
metallurgical changes that cause hard spots to form below the brake
surface, which reappear a few thousand miles later as the rotor wears. GM
and others now recommend replacing warped brake rotors rather than
resurfacing for this reason.
Most experts agree that overtorquing or unevenly torquing the wheels
lug-nuts will cause a brake rotor to warp. When changing a tire you should
use a torque wrench or torque limiting socket on an impact wrench to
tighten the lug-nuts.
Sometimes defects in the rotor casting ,such as thick and thin spots in
the rotors surface, will cause uneven heat transfer leading to warp-age.
Hard spots in the metal by casting impurities is another cause.
Unfortunately all you can do is replace the defective rotor.
Overheating of the brake rotor will also cause it to warp. Overheating can
be caused by sticking calipers and hardware or abuse by the driver of the
car. Riding the brake pedal will cause the brake pads to constantly be in
contact with the brake rotor, causing excessive heat. Being impatient and
racing from light to light and slamming on the brakes when you get there
will also cause excessive heat build up. If you drive this way you will
always be doing costly and premature brake repairs.
