A calibration fixture for use during a calibration procedure of a machine vision vehicle wheel alignment system. The calibration fixture consists of a pair of support legs, and a rotating transverse bar supported within an outer support tube secured between the support legs. The rotating transverse bar is supported within the outer support tube by a pair of annular bearings adjacent each end of the outer support tube, and is isolated from external influences which may result in deflection or distortion. A hub for receiving a sensor or optical target is secured to each end of the rotating transverse bar, such that optical targets mounted to each hub are maintained in axial alignment at opposite ends of the rotating transverse bar.