Part IV


Rear Axle Disassembly

by John Ironside

(This article was originally published in the February, 2013 issue of the Spark Coil.)

After placing the axle on a couple of jack stands, the first task was to drive out the sleeves that were worn away in each of the spring perches (see photo below).

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The next step was to remove the bolts holding the housing together around the differential and pull both sides of the housings off the axles. The inner bearings were pulled out of the axle housings and found to be in good condition. There are three thrust rings located on each side of the differential, and the center ring in each group was found to be made of babbit which confirms that the drive train is probably original 90-year old construction—brass is the current preference for the center washer so the existing babbit material will be replaced. The outer steel washers were measured to be within spec and in good shape.

To hold the outer steel thrust washer in position, one pin is pressed into each side of the differential case and two pins are pressed into each of the axle housings. All of the pins were worn to an oval shape and needed to be replaced. The differential case is attached to the ring gear with ten bolts wired together in pairs. The severe wear of the pinion gear was matched on the outer edge of the ring gear which will be replaced. I observed excessive end play in the axles supported in the differential case, and this needs to be addressed during the rebuild by replacing the fiber disc between the axles with the proper thickness.

Removing the three case bolts allows the case to be opened for inspection of the internal parts. Measurement of the spider gears, spider gear arms, axle gears, and openings in the differential case demonstrated compliance with original specs. All of the gears appeared to be in good condition. The axles appeared to be straight and true with no signs of excessive wear in the bearing areas. The housings were measured for alignment by standing them on end. A carpenter square was held at multiple locations around the axle to take high and low offset measurements. Since the measurement variation was very small, I determined the housings to be true and in good shape.

As a result of the inspection, the following parts were ordered for the rebuild of the rear axle:
– Ring Gear – 40 tooth standard
– Center Thrust Washers (brass)
– Thrust Washer Pin Replacement Kit
– Modern Inner Oil Seals
– Outer Bearing Sleeves (left & right)
– Grease Cap, Grease Seal, & Washer Sets
– Spring Perch Sleeves
– Drive Train Gasket Set

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The cost of the parts order was about $450.

In the next issue of the Spark Coil, the discussion will focus on reassembly of the rear axle and the fitting of replacement parts into the assembly.