XRAY 4S Spring Set Progressive C=2.5-2.8 (2)

XRAY_4S Spring Chart.pdf

The main advantage and benefit of progressive springs is that as the car initially enters the corner they work like a C2.5 spring to provide maximum traction. At the same time, when the chassis begins to roll, in the middle of the corner, the spring rate progressively increases until it works like a C2.8 which allows the car to maintain maximum cornering speed. 

The 4S springs, like all the other XRAY springs, are manually measured, selected and matched into pairs to guarantee precisely equal length and damping characteristics.