The Power Wagon Third Member

The fact that little attention is given our Dodge's differential-carrier ass'y. (Third Member) is testament to its design and construction. Generally, the incentive for removal is to enable the installation of 4.89 ring and pinion highway gearing. The third member consists of a cast steel housing supporting an integral pinion gear/shaft and differential case with attached ring gear.

The most common problems are caused by lack of lubrication, mechanical interference, or chemical corrosion. A properly built carrier with uninterrupted lubrication generally shows negligible wear even after extended use due in part to oversized bearings and components. Broken gear teeth or mauled bearings are most often caused by mechanical interference of broken axel pieces or fasteners. Most bearing deterioration is chemical which occurs when the carrier sets idle for extended periods in a hostile environment. (water laced lubricant or exposure) Luckily, all bearings are available.

After disassembly, housing and components must be solvent washed with particular attention paid to the oil galley behind the double race pinion bearing. A special retaining nut wrench is required if removal is necessary. The carrier should now be secured in a rigid stand for positioning and stability. If the inner pinion bearing is to be used on the new pinion shaft a specially designed pressing die must be used for its removal; there is no room for a splitter. The new pinion shaft assembly is then fitted and refitted in the housing using successively thinner spacers in order to achieve appropriate bearing preload. This assures no chance of any axial or lateral shaft movement under load. Whether a leather or rubber pinion shaft seal is elected it may be necessary to lathe turn and polish a new seal surface on the drive flange or install a redi-sleeve to assure leak free operation.

When inspecting the differential gears, if excessive end play is found it usually indicates a broken or missing thrust washer which must be replaced. To do so the differential case must be opened which will require a specially designed holding fixture and wrench. Since an interference fit exists between the differential cap and case, heat and significant torque will be required for separation. Upon reassembly, the differential case flange surface is inspected and the ring gear mounted. When installing the differential case with attached ring gear in the carrier, it is important to position the bearing caps exactly as removed. Bearing preload and drive gear backlash are adjusted simultaneously.

Observation of the resultant tooth pattern will give a good indication that the installation is sound and the check distance has been maintained. The new gear set should be broken in under light intermittent load using a mineral base gear oil with additive if desired.
 

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