A fold down seat back has a lumbar support device in it. A traction cable is operatively engaged at one end with the lumbar support device to actuate it. The fold down seat back includes a rotating cable tension unit and a fixed torsion bar. The rotating member moves relative to the fixed member when said fold down seat back is folded down. The traction cable is comprised of a sleeve having a first end and a second end and a wire having a first end and a second end. The wire is disposed to slide axially through the sleeve. The first sleeve end is attached to the rotating cable tension unit. The wire end is attached to the fixed torsion bar. The wire end may be attached to the torsion rod with a pulley. These attachments of the sleeve end and the wire end cause the wire to be drawn axially through the sleeve when the seat back is folded up, extending a lumbar support, and cause the wire to be relaxed when the seat back is folded down, flattening the lumbar support.