Abstract: A seat belt retractor includes a reel rotatably mounted on the frame side walls and having toothed plates disposed adjacent to the side walls and a belt wound on the reel to a diameter greater than the toothed plates. A lock bar extending between the side walls is movable from a rest position spaced away from the toothed plates to a locking position engaging one of the sprocket teeth subsequent to the unwinding of sufficient belt from the reel to decrease the belt diameter to a diameter less than the diameter of the sprocket teeth. A sensor pawl eccentrically mounted on the reel flies out into engagement with inside clutch teeth of an annular clutch member, an annular split clutch ring encircles the outer surface of the annular clutch member and has an actuating arm which actuates the lock bar. The split clutch ring has fingers which seat into teeth provided on the outer surface annular clutch member.