Abstract: Disclosed is an inverted cup-shaped cover of deformable material to be fitted over an open socket housing end of a pivotal ball joint assembly. The cover has a pair of opposite end openings, one of which is considerably smaller in diameter than the other and receives therethrough in sealed relationship the shank of a ball stud protruding from the housing through an open end thereof. The cover has a gently curved longitudinal sectional configuration and is flared toward its other end opening at which it is fitted over the open end of the housing. A ring is embedded in the flared portion of the cover and has an inner circumferential edge exposed toward the interior of the cover. This inner edge is sharp-angled and has a diameter slightly smaller than the maximum diameter of the housing at the open end thereof. This ring is formed of resilient material, for example, spring steel.