Abstract: An apparatus for testing the wheel suspension of a vehicle in the frequency domain, in particular the shock absorbing element of said suspension, comprises a measuring plate, a mechanism for oscillating the measuring plate with a frequency varying in a predetermined range, for example from 0-25 Hz, a measuring device for measuring the vertical forces exerted by a tire of the vehicle on the measuring plate, a memory for storing the measured force values and a logic circuit for processing the measured force values. The apparatus stores both the frequency values corresponding to the measured force values and a mathematical model of a linear second order mass spring system formed by the unsprung mass, the tire and the shock absorbing element, and determines the minimum force value and corresponding frequency value from the stored measured force values and corresponding frequency values.