This ball joint connects the steering linkage to the front axle knuckle, converting rotational input from the steering gear into angular movement of the wheel hub. It sits at the pivot point between the tie rod and the steering arm, allowing the wheel to turn while transmitting lateral forces. Wear in the ball socket produces free play that causes wandering steering and uneven tire wear. The joint is manufactured to the same stud taper and housing bore dimensions as the original assembly, so it seats without shimming. On installation, tighten the castellated nut to the specified torque and install a new cotter pin.