A torsion bar is a long metal element in an automobile suspension that has one end held rigidly to the frame end and the other twisted and connected to the axle and that acts as a spring. As the wheel passes over a bump the bar twists. It returns to its original position when the bump is passed and restores the car to its normal drive height.Manufacturers change the torsion bar or key to adjust the ride height, usually to compensate for engine weight. While the ride height may be adjusted by turning the adjuster bolts on the stock torsion key, rotating the stock key too far can bend the adjusting bolt and place the shock piston outside its standard travel.