Rolls-Royce 20/25 - dismantling the rear axle



jam bar


It should be noted that there was a modification to the pinion nose bearing preventing the pinion assembly sliding out without first moving the crown wheel away from the pinion.

A homemade jamming bar is used to hold the flange whist the pinion nut is released.

pinion #1


The pinion housing nuts were removed to see whether the unit could be removed.  The housing would only move about half an inch.  This axle had evidently been subject to the modification previously mentioned.


pinion #2


Note that there is a spacing shim placed between the housing and differential body, which is used to set the backlash of the pinion engagement.

The components should be marked to ensure re-assembly at the same alignment.

c/w view #1


The differential rear housing has been removed to inspect the state of the crown wheel.  Other than evidence of recent tooth misalignment the gear was in excellent shape.

c/w view #2


Very little sediment in evidence.

c/w view #3


The gear case and bearing housing also seemed to be relatively clean given that they had not been overhauled since the 1950s.

in bits


The axle is dismantled by removing the nearside (left hand) axle casing and then splitting the differential housing.


The pinion nose roller bearing was indeed the culprit preventing the easy removal of the pinion assembly. The roller race is held in place by the inner bearing ring on the pinion nose; only the outer ring stays in the housing. We subsequently learned that Rolls-Royce changed this bearing later to a type where the race stays with the outer ring in the housing and therefore the pinion nose will clear the crown wheel. This bearing looked reasonable at first glance; a closer inspection however showed many tiny nicks on the rollers and the ring surfaces, most probably from dirt. However, the condition of this bearing could not be the reason for the noisy axle.

o/s diff case #1


The left hand half of the differential case prior to cleaning.

o/s diff case #2  
bearing housing


Evidence of earlier work undertaken by someone not quite up on the standards expected in Rolls-Royce maintenance.  The service records for the car show that the axle was rebuilt in the 1950s.