So, what are these bars supposed to do? When properly adjusted, they will eliminate axle wrapup. Axle wrapup occurs when your car is launched hard, e.g., the start of a drag race. As the wheels turn forward, the axle housing will want to rotate in the opposite direction. When the spring has wrapped up as far as it can, the energy in the spring forces it to return to its normal location. This occurs violently, and the force of the returning spring can force the car upward, unloading the weight of the car off the tires. When the weight of the car is off the tires, they will spin. The diagram illustrates axle wrapup.