Because of the noise and temperature drift, the raw test data must be pre-processed before any calculation and analysis. The preprocessing includes: (1) spike elimination, (2) band pass filter, and (3) calibration. The strain of right front spring tower and deformation of the spring damper is to be analyzed .Fig. 5a–d shows the time history of spring tower strain and coil spring displacement under the first two tests and Fig. 5e and f shows the level crossing counting curves of the strain and displacement.