Abstract: A reinforcing unit for a longitudinal bearer of a body structure of a passenger motor vehicle which serves for the supported mounting of a transversely arranged auxiliary bearer for the support of a lower wheel guide member, for the fastening of a steering mechanism and for the mounting of drive aggregates or parts of the force transmission. Within the offset area of each longitudinal bearer, a form-rigid body is formed composed of several shell-like shaped elements and closure panels. The form-rigid body is constructed at least partially as box profile and forms together with the U-profile-shaped longitudinal bearer a fixedly connected structural unit with an abutment surface for the fastening of the auxiliary bearer.