Abstract:According to the nonlinear theory, the bifurcation characteristics of front wheel selfexcited shimmy of some motor vehicle with nonindependent suspension were studied. Computer programs were carried out to calculate the range of selfexcited shimmy speed of the motor vehicle with MATLAB when Hopf bifurcation took place. Various bifurcation diagrams indicating the relationship between angle amplitudes of right tire and vehicle speed were presented. And the influences of different parameters on selfexcited shimmy were analyzed. Numerical simulation results have indicated that the increase and decrease of the structural parameters of steering mechanism and tire parameters can restrain the selfexcited shimmy. With the change of some parameters, the vehicle speeds relating to the tire maximum angle amplitude of the selfexcited shimmy change correspondingly. The steering stiffness, tire cornering stiffness and pneumatic trail show greater impact on the amplitude of selfexcited shimmy.