High amplitude level of steering wheel vibration is observed during idle running tractor validation tests. It is found that the tractor’s platform firewall area’s lateral mode is close to 1.5th order excitation frequency of
three cylinder engine and this resonance has contributed to high y-direction vibrations at idle condition. In order to comply with the requirements of ISO 5349 Measurement and evaluation of human exposure to handtransmitted vibration and to satisfy the comfort level by investigation of human subjective response, decreasing the magnitude of vibration is taken as a target. To achieve this target, three iterations are evaluated by comparison of modal frequency response plots. Increasing the lateral stiffness of the firewall area is main purpose. The validation of chosen iteration by finite element model is made through vibration testing and
subjective comparisons.