Rear Upper Knuckle Bush – a rubber-to-metal bush that forms the upper pivot mounting between the rear knuckle and the radius arm in the independent rear suspension.

The rear knuckle carries the wheel hub and locates it within the suspension; this bush provides the compliant upper pivot, absorbing road shock and maintaining wheel geometry under load and braking. A worn or perished bush allows excess movement, causing knocking, imprecise handling and uneven tyre wear.