This ball joint connects the front axle steering linkage to the wheel hub carrier, allowing the steering knuckle to pivot while transmitting lateral loads from the wheels to the chassis. It sits at the outer end of the tie rod or drag link, where it articulates through the full steering arc. Wear in the joint produces free play that manifests as wandering steering, uneven tire wear, and a clunk when turning. The original part is machined to the same taper and thread dimensions as the housing bore, so the taper seats fully without shimming and the castle nut torques to specification without binding. On installation, clean the taper bore and replace the cotter pin.