Control Arm Bushings
Control arm bushings are considered torsion bushings. This is because they allow for the twisting action needed as the control arm moves up and down over bumps in the road.
They’re rubber bonded to two thick metal plates or washers. One of these plates is attached to the frame and the other attached to the control arm. Because they’re located between the frame and the control arm, they cushion and help prevent vibrations from transferring to the chassis.
When worn, a clunking sound can be heard and felt that’s more pronounced as the vehicle accelerates and disappears as the vehicle reaches cruising speeds. The vehicle may begin to wander as alignment angles shift from this excessive looseness and play. A shimmy will develop, and a vibration in the wheel can be felt.
Sometimes the ball joint is integral to the control arm, and a problem ball joint requires replacement of the entire control arm. When worn, a special C-clamp or a press with the appropriate adaptors are used to remove and replace these bushings.
Typically control arms are tightened on the ground. Failing to do so can result in premature bushing failure. Because removing the control arm disrupts the alignment, a wheel alignment is performed after the replacement is complete.