Abstract: A ball joint, and in particular a motor vehicle steering or suspension ball joint, which includes a pivot with a spherical head, a ball joint case with a housing for receiving the pivot head and a case housing, and a plastic bearing interposed between the pivot head and the case housing. The ball joint bearing includes a cup molded in one single piece, closed at a base, and having a molded inner spherical surface extending over more than one hemisphere. A circular orifice with a diameter smaller than the spherical inner surface diameter, opposite the base, is also provided as are several rupture zones distributed on the periphery of the opening part and shaped so as to be subjected to a predefined rupture into two sections when the opening part first expands and to enable, after the head has been inserted in the bearing, an elastic tightening of the opening part with accurate repositioning of the two sections of each rupture zone around the head.