The rotor of a rotary position sensor mounts directly upon the rotary shaft to be sensed. The rotor prior to installation is retained in position by a pair of small protrusions extending from the rotor that cooperatively engage a pair of small indentations formed in a pair of supporting arms. During the installation process, the rotor is slipped onto the shaft and the protrusions are released from the engaged position. During operation of the position sensor, the rotor is free from direct contact with either the supporting arms or any other stationary part of the position sensor. Only the contactors engage the stationary components. This design eliminates the need for bearings and return springs prevalent in the prior art.