This ball joint connects the steering rod to the steering knuckle, translating rotational input from the steering gear into angular movement of the wheel assembly. It is the pivot point that allows the wheel to turn while accommodating suspension travel. Wear in the joint produces free play at the steering wheel, causing imprecise directional control and uneven tire wear. The manufacturer machines the ball stud and socket to the same clearance as the original assembly, so no shimming or adapter sleeves are required during installation. Torque the retaining nut to specification on reinstall.