A control arm is a bar that has a pivot at both ends. Your car has several, including the upper control arm and the lower control arm, which are arranged to form the letter A. Control arms are part of the suspension system. They attach suspension members to the chassis and manage the motion of the wheels so that it synchronizes with that of the body of the car. They work with bushings, which are cylindrical linings that reduce friction and restrain the auto parts from going every which way.