Because of the many changes that have been made in the rear axle assembly since the beginning of 1955 production, the following information was prepared to describe the initial rear axle changes and subsequent changes made up until present production. Following the recap of these changes will be detailed service procedures and information pertaining to interchangeability of new parts with past model rear axle assemblies.

Since the beginning of 1955 production changes in the rear axle assembly consisted of the following:

  1. One new Departure double row radial thrust ball bearing (front) and one new Hyatt roller bearing (rear) used with a longer lock sleeve and wider spacer. See Figure 30.
    1955 Buick Rear Axle - Exploded View

    1955 Buick Rear Axle – Exploded View

The load angle of the double row ball bearing has been changed whereby the thrust on each row of balls is placed closer to the bearing center. This design permits slight variation in alignment under load to be absorbed without causing excessive cramping load on the bearing. The end shield has also been eliminated from this bearing as it is no longer required; however, the oil seal has been redesigned to set flush with the bearing end to provide an effective seal.

The rear bearing is a single radial roller bearing which replaces two roller bearings of the previous design. The new type single roller bearing is longer than that of the previous design and provides greater life factor, while allowing for slight alignment variation under load without end-pinch on rollers.

The new roller spacer and lock sleeve places the rear bearing deeper into the carrier bore to provide more bearing support. Dimensional changes in lock sleeve (longer) and roller spacer (wider) compensate for the elimination of one bearing.

  1. Improved lubrication within the axle is provided by relocation and enlarged feed holes to the pinion bearings and a revised gear channel shape in the rear cover which redirects more oil to the differential side bearings. A rear axle vent used in 1954 is continued for 1955. It is located on top of left arm of housing just inside of rear spring seat and it prevents build-up of pressure within the axle and decreases the possibility of oil leakage.
  2. At the time the above changes were made the ring gear was riveted to the differential case; however, since then a bolted type ring gear, which is attached to the differential case with twelve (12) special alloy steel bolts, has gone into production. In this design the ring gear attaching bolts are threaded directly into the ring gear web for maximum holding power and provide a bond between case and ring gear of approximately 100,000 pounds of clamping force which causes the case flange and ring gear to function as one unit, mutually supporting against deflections under load taking the driving force directly from gear to case by friction rather than through a shearing force on the rivets.
  3. Following the bolted ring gear into production were changes in the rear axle carrier, whereby the width of the bolting flange was increased from .620″ to .800″ and the reinforcement ribs (on ring gear side of carrier) were extended to the outer circumference of this bolting flange. See Fig. 31 & 32.