It is the lateral distance between the wheel and the instantaneous centre A. The shorter the swinging arm length, the greater the change in track during suspension movement and the greater the camber change during bump (wheel moving up in relation to the chassis). However, if the swing arm is too short, the system starts to act like a swing axle with resulting jacking forces. Generally, a swinging arm length of 2.5 - 3.8 meters is considered optimum.