Spindle motor including magnetic element for pre-loading a ball bearing set

A spindle motor for use in a disk drive includes a spindle motor base and a motor shaft. The motor shaft has a central axis. The spindle motor includes a spindle motor hub rotatably coupled to the spindle motor base, the spindle motor hub including a central magnetic metal portion disposed adjacent a distal end of the motor shaft. The spindle motor includes a ball bearing set disposed between and in mechanical communication with the spindle motor hub and the motor shaft for rotatably coupling the spindle motor hub to the spindle motor base. The spindle motor includes a shaft magnetic element attached to the motor shaft at the distal end adjacent the central magnetic metal portion, the shaft magnetic element being sized and configured to apply an attractive magnetic force to the central magnetic metal portion in a direction along the central axis for pre-loading the ball bearing set.