Rear Axle - 248RBI: Overview
DESCRIPTIONThe 248 Rear Beam-design Iron (RBI) axle housing consists of an iron center casting (differential housing) with axle shaft tubes extending from either side. The tubes are pressed in to form a one-piece axle housing.
The integral type housing, hypoid gear design has the centerline of the pinion set below the centerline of the ring gear.
The axles are equipped with full-floating axle shafts, meaning that loads are supported by the axle housing tubes. The full-float axle shafts are retained by bolts attached to the hub. The hub rides on two bearings at the outboard end of the axle tube. The axle shafts can be removed without disturbing or removing the wheel bearings. The wheel bearings are opposed tapered roller bearings and are contained in the hub assembly.
The removable, stamped steel cover provides a means for inspection and service without removing the complete axle from the vehicle. A small, stamped metal axle gear ratio identification tag is attached to the housing cover via one of the cover bolts. This tag also identifies the number of ring and pinion teeth.
The rear wheel anti-lock (RWAL) brake speed sensor is attached to the top, forward exterior of the differential housing. A seal is located between the sensor and the wire harness connector. The seal must be in place when the wire connector is connected to the sensor. The RWAL brake exciter ring is press-fitted onto the differential case against the ring gear flange.
The differential case is a one-piece design. The differential pinion mate shaft is retained with a roll pin. Differential bearing preload and ring gear backlash are adjusted by the use of shims located between the differential bearing cones and case. Pinion bearing preload is set and maintained by the use of a collapsible spacer.
Axles equipped with a Trac-Lok differential are optional. A Trac-lok differential has a one-piece differential case and the same internal components as a standard differential plus two clutch disc packs.
OPERATION
The axle receives power from the transmission through the rear propeller shaft. The rear propeller shaft is connected to the pinion gear which rotates the differential through the gear mesh with the ring gear bolted to the differential case. The engine power is transmitted to the axle shafts through the pinion mate and side gears. The side gears are splined to the axle shafts.