Helical compression spring for a vehicle suspension

The present invention is directed to a helical compression spring which is mounted on a vehicle body to be compressed between an upper seat and a lower seat. The spring has a coil axis that is substantially curved at a predetermined radius of curvature in an unloaded state of the spring. A pitch of a lower end coil of the spring is set to tilt the end plane of the lower end coil at a first predetermined angle to the lower seat in the direction for shortening the longitudinal length of the spring at the inside of the curvature, and/or a pitch of an upper end coil is set to tilt the end plane of the upper end coil at a second predetermined angle to the upper seat in the direction for shortening the longitudinal length of the spring at the outside of the curvature. The coil axis of the spring may be substantially curved in accordance with at least two radiuses of curvature in the unloaded state of the spring. Or, the coil axis may comprise a plurality of rectilinear lines connected to be substantially curved at the predetermined radius of curvature in the unloaded state of the spring.