A passive seat belt system includes a continuous loop of seat belt having one end connected to the vehicle body generally adjacent the shoulder of the occupant and the other end attached to the vehicle floor outboard the seat. A retractor is associated with at least one end of the belt for extending and retracting the belt. A continuous tubular track has an outboard end mounted on the roof rail generally adjacent the shoulder of the seated occupant and extends longitudinally along the roof rail, vertically along the windshield pillar, transversely along the instrument panel structure, and longitudinally along the vehicle body centerline to an inboard end located generally adjacent the inboard hip of the seated occupant. A continuous flexible helical screw is rotatably supported within the tubular track and threadedly engages a belt carriage mounted within the tubular track. The belt carriage has a belt loop extending through a continuous slot of the tubular track and slidably receives the belt. A reversible motor rotates the helical screw to move the belt loop between the outboard end of the track where the belt is retracted and stowed outboard the vehicle seat and the inboard end of the track where the lap and shoulder belts are disposed in the occupant restraining positions.