The purpose of this paper is to investigate experimental responses of a preloaded vibroimpact Hertzian contact to an order 2 superharmonic excitation. A test rig is used, corresponding to a double sphere–plane contact preloaded by the weight of a moving body. Typical response curves are obtained under the superharmonic excitation. The Hertzian nonlinearity constitutes the precursor of vibroimpacts established over a wide frequency range. This behavior can be related to the existence of a transcritical bifurcation. In conjuction with the experiments, numerical results lead to the same conclusion. In particular, the threshold level of the excitation necessary to induce vibroimpact is confirmed.