The rear coil spring is a device that compensates irregularities of a road surface of a rear side. Its kit maintains a vehicle’s suspension system at a defined height and supports excess weight without sagging. Its function is pretty essential in order to provide comfort, handling and the weight carrying capacity of a modern car. As the driver increases the vehicle speed, the rear spring starts to absorb the impact of irregularities of the road surface. The conversion is very simple as it reduces the effects. In a bid to do so, a stiff rate is needed to remain axles and wheels in contact as per the terrain. This the reason why high performing cars uses stiffer suspension system when compared to the regular vehicles.