This bushing fits between the connecting rod and the crankshaft journal, providing a replaceable wear surface for the big-end bearing bore. It sits in the upper end of the connecting rod and rotates with the crankshaft, maintaining the correct clearance between the rod and the journal. As the bushing wears, clearance increases, leading to a knocking sound from the crankcase and a drop in oil pressure at the rod bearing. The bushing is machined to the same bore tolerance as the original assembly, so no additional shimming or line boring is required during installation. On reinstall, lubricate the bushing bore and torque the connecting rod cap bolts to specification.