This paper presents the modeling and validation of front and rear suspension systems in (4x4) trucks utilizing ADAMS software, focusing on leaf spring mechanisms essential for supporting light, medium, and heavy loads. The validation process compares the vertical stiffness of the multi-leaf spring in the front suspension and the dual-rate helper in the rear suspension which consists of main and auxiliary taper-type leaf springs. The stiffness values obtained from ADAMS simulations using the 'Parallel Wheel Travel' test are compared against those calculated analytically via beam theory and with reference values provided in engineering drawings. The comparative analysis indicates that the errors are within an acceptable range. Therefore, it is concluded that the suspension models are validated and can be used for full truck simulation.