Moog K6539 Ball Joint Problem Solver powdered metal gusher bearing design enables grease to flow through the bearing to the stud for reduced friction and enhanced strength and stability. Moog engineered steel composition results in a stronger component Full ball metal stud provides 36 degrees of smooth, consistent, rotational movement resulting in more responsive steering. Belleville washer preload provides lower torque and stud articulation with minimal axial clearance. Greaseable socket design allows new lubricant to flush contaminants from the assembly, reducing corrosion and wear Loose or worn chassis parts can lead to premature tire wear