The controllable suspension system includes a strut with a magnetorheological fluid damper. The magnetorheological fluid damper includes a longitudinal damper tubular housing having a longitudinally extending axis and an inner wall for containing magnetorheological fluid. The damper includes a piston head movable within the damper tubular housing along a longitudinal length the housing, with the damper piston head providing a first upper variable volume magnetorheological fluid chamber and a second lower variable volume magnetorheological fluid chamber, with a fluid flow gap between the upper and lower fluid chambers, the damper piston having a longitudinal piston rod for supporting the piston head within the housing, with the piston supported within the housing with a piston rod bearing assembly disposed between the housing and the rod, with the piston rod bearing assembly having a piston rod bearing seal interface.