A knocking sound when applying the brakes could indicate different problems, such as loose calipers, bad shock absorbers, worn constant velocity joints and failing tie rods. There are telltale signs that help identify the actual source of the problem.
The culprit could be bad tie rods if the knocking sound is accompanied by a loose or wobbly steering wheel when brakes are applied. Tie rods keep the front tires running in the same direction, and are connected to the wheels by an articulating bearing, which pivots to allow an arc-shape movement of the front wheels.
Worn out tie rod ends can cause the front wheels to shake or wobble and emit a hard knocking sound when brakes are applied, especially while driving at high speeds. This situation is extremely dangerous and the damaged components must immediately be replaced by a qualified mechanic, reports Driverside.com.
Clunking and knocking sounds can also be the result of the nuts and bolts holding the brake calipers being loose. Vibrations can cause brake bindings to come loose overtime, which leads to damaged components, according to AG Auto Corporation. This situation is typically indicated by a jerking reaction and a knocking sound when the driver is trying to stop the vehicle.