2 Pcs Suspension for Ford Expedition 2002 Rear Lower Trailing Control Arms Kit 39920138Introductions: The control arms are perpendicular to the axis of the vehicle, in automotive suspension, a control arm is a hinged suspension link between the chassis and the suspension upright or hub that carries the wheel. Control arms allow wheels to move up and down while preventing forward and rearward movement. They are typically equipped with bushings on the frame side of the vehicle and a ball joint on the wheel side of the vehicle that allow