This ball joint connects the steering linkage to the front axle knuckle, allowing the wheel hub to pivot while transmitting lateral and vertical loads. It sits at the outer end of the tie rod or drag link, where its spherical bearing accommodates the angular movement required during steering. Wear in the joint produces free play that manifests as steering wander and uneven tire wear. The manufacturer machines the ball stud and socket to the original geometry, so the taper and thread match the host knuckle without requiring shims or adapters. On installation, tighten the retaining nut to the specified torque and fit a new cotter pin.