A generator module for a vehicle includes a housing arranged for fixing to a combustion engine, a generator arranged in the housing, a shaft, a spring, circumscribing the shaft, and a cup, circumscribing the spring. The generator has a stator, fixed to the housing, and a rotor, rotatable within the housing and including a rotor carrier. The shaft is fixed to the rotor carrier and the cup has an annular flange disposed axially between the spring and the housing. In an example embodiment, the housing has a pump housing for a cooling pump and the cup contacts the spring and the pump housing before the generator module is installed in the vehicle. In an example embodiment, the housing and the rotor carrier have complementary conical surfaces, and the spring is arranged to urge the complementary conical surfaces into contact.