The suspension thrust bearing device for a motor vehicle comprises a rolling bearing forming a thrust bearing and provided with an upper ring, with a lower ring and with at least one row of rolling elements arranged between the rings, a bearing cap in contact with the upper ring, and a support cap in contact with the lower ring and forming a bearing means for a suspension spring. At least one of the caps comprises a body made of synthetic material and an insert covered at least in part by the body. The insert comprises stiffening ribs in order to reinforce the mechanical strength of the cap with respect to the axial loads resulting from the forces exerted by the suspension spring.