Abstract: In an automotive vehicle wheel alignment system, a rim clamp is attached onto the rim of a wheel and a head unit is connected to the rim clamp. The rim clamp includes a spindle having circumferential grooves. The head unit includes a spindle-receiving sleeve with a spring loaded plunger and a set screw adapted for being received by the grooves in the spindle. The set screw tightens the head unit on the spindle of the rim clamp. The spring loaded plunger and groove allow the head unit to rotate with respect to the wheel without loss of registration in the axial direction between the head unit and the wheel.