The identification and reduction of sound sources in car wheel suspensions is one of today's major issues in the Automotive industry. The last five years a lot of effort has been spent identifying shock absorber noise. These investigations have now been extended towards complete suspensions. Due to its strong nonlinear characteristic, the shock absorber generates high frequency vibrations (100-900 Hz). First, the relationship between the structure borne noise and the damper behavior needs to be defined by means of a vehicle evaluation. Next the components that need to be modified are identified by comparing time-domain simulations and measurements. To deal with full suspension noise source identification and reduction some specific time-frequency techniques are applied. Additionally, some new techniques such as the 3D coherence function are proposed. Because of the transient character of suspension components, these techniques can give some insight into operating mechanisms and reduction potential of car wheel suspensions.