Seat belt retractor and torsion bar providing secondary load limiting

A torsion bar, constructed in accordance with the teachings of the present invention, an elongated bar has a first end, a second end, and a mid-section between the first and second ends. The first end of the elongated bar has a material void. The first end preferably has a diameter substantially equal to a diameter of the mid-section. In one design, the material void is a slot extending longitudinally, and the first end may also define a plurality of circumferentially spaced slots extending longitudinally. In another design, the material void is a bore extending longitudinally, and the first end may also define a plurality of slots extending longitudinally and extending from the bore through an exterior surface of the elongated bar to leave a plurality of fingers at the first end. In these designs and other, the torsion bar and the material void may be cold forged, thereby eliminating a second forming step. The torsion bar may also include a plurality of circumferentially spaced ribs extending longitudinally from the first end to the second end.