18-08-2018, 01:59 PM
(14-06-2018, 09:16 AM)David Cochrane Wrote: Why Austin decided to increase the diameter of the journal by 1/64" has never been explained (like that master spline on the clutch). The tapers and the teeth are identical and interchangeable. You can ream out an earlier differential bush to take the thicker halfshaft, or fit a new bush (0.875") to use a thinner halfshaft.
There was a note in the Austin Service Journal Jan - Feb 1931 stating "The alteration to the differential shaft is to facilitate manufacture".
I'm not daft enough to assert this as definitive fact, but looking at a sample of 2 shafts, one has diameter 0.875 at the bushing and is rough turned for the rest of its entire length down to 0.865. Naturally the outer portion of the shaft has to be smaller than the inner or it wouldn't pass through the bush. We'll never know I guess whether the shaft started as a single diameter along its whole length but this is suggested. The rough turning op would have consumed a lot of machine time not to mention weakening the shaft.
By comparison the other (LWB) shaft with diameter 0.890 at the bush is unmachined beyond the bush area and has a minor diameter of 0.875.
My guess would be Austin changed the tool to provide a raised (or more raised) section on which to grind while leaving the rest of the shaft clear of the bush and without need for finish machining. If so this would have saved buckets of money.
And yes, both these shafts came out of the same axle!
By the way David, do your 0.875" bushes have enough meat on them to ream out to 0.890" and repair a worn later type axle?