Abstract
This paper investigates spring surging phenomenon & its effect on vehicle vibration. There are several factors affecting vibration of spring pitch. To describe this vibration, spring should be modeled as continuous element and vehicle body, S/ABS, tire &every suspension arms should be investigated. Since spring of suspension parts accumulates elastic potential energy from the road input and transfers it to the strut housing with little internal damping, resonance of spring will be serious problem if there is no damping part for spring surging. This paper summarizes effective static & dynamic analogy method to transform spring vibration that has harmonic modes into rod vibration and show the analytic procedure to investigate vibration of spring excited by the road input through tire.