F-450 and F-550
The rear hub (1109) is supported or floats on the axle spindle on two opposing tapered roller bearings. A rear hub seal is installed behind the inner rear wheel bearing to prevent rear axle lubricant from leaking onto the rotor. The rear hub is retained on the spindle by a ratcheting hub nut tabbed to a slot on the spindle.
The rear wheel bearings are packed with a lithium base grease, Premium Long-Life Grease XG-1-C or equivalent meeting Ford specification ESA-M1C75-B, to provide initial lubrication until axle lubricant flows into the rear hubs and the inner rear wheel bearings during vehicle operation.