Torsional vibration damper having helical torsion springs

A torsional vibration damper (1) has an input assembly (2,6,7) and a reactor plate (25) with coil springs (40) circumferentially spaced about a center axis of the damper to absorb vibration between the input assembly and reactor plate. Each coil spring (40) includes a plurality of active coils (50) and partial end coils (44). The active coils have a pitch greater than the diameter (d) of the wire (11) and the partial end coils have a pitch equal to the diameter of the wire. A flattened arcuate surface (42) is formed on the partial end coil which spans less than a full coil turn. A distal tip (46) of the end coil has a thickness that is a fraction of the diameter of the wire that is inversely proportional to the amount of arcuate flattened surface of the end coil section. The gap (66) between the tip and the adjacent coil is also inversely proportional to the amount of arcuate spanning surface of the end coil section.