Two-degree-of-freedom vibro-impact model with clearance nonlinearity of torsional vibration is presented in this paper. Clearance in coupling in any rotating machinery can exhibit chaotic and multiple periodic phenomena. Coupling inertia also contributes to change the vibration characteristic significantly. In this paper, coupling effects, from a small inertia to large inertia compare to rotor, have been investigated for a wide frequency zone by simulation and some experiments focusing on resonance and bifurcation diagrams. As the spring in the clearance usually possesses quite low stiffness compared to shaft stiffness, symmetric and asymmetric characteristics can be exhibited. The results found are noticeably different from each other for the symmetric and asymmetric conditions. The presence of vibro-impact due to clearance can cause periodic, multiple periodic and chaotic motions.