Early half shafts

[Dave Wortley]

Does anyone know if early halfshafts were even smaller than 0.875” I have an early diff carrier but that will not accept a 0.875” shaft? Not sure how much smaller yet but say 0.010” smaller. The diff is the one shown in Austin Seven Companion p 167 “ Notes by J French on building a 750 formula car.” It’s the left hand diagram 1923-28.

[Parazine]

My earliest parts book is 1927, covering car numbers A1 thru A4 (and CH A1). There is only one half shaft catalogued, reference number BO18, which translates to 1A7017. There is an axle nut catalogued for a LH threaded half shaft but the LH thread shaft itself was out of production by '27 and was presumably the same size on the diff. bush as later. 

There's only one part number for the bushes as well.....

Pre-production cars may have had different parts fitted that Austin later failed to acknowledge as the cars probably weren't supposed to be sold to the general public.

[Ruairidh Dunford]

The prototype sketch book I have from Stanley Edge does not show the size of the half shafts, unfortunately.

You should be able to machine the bushes out to suit.

[Tony Griffiths]

What are you building up Dave? Something extra interesting?

[steve davidson]

I encounted a similar problem with my sports, the new half shaft would not pass through the bush in the carrier.  I used a flexihone to remove sufficient material and have had no isssues with it.

[Dave Wortley]

Thanks for the advice everyone. Measured the bush bore more accurately and it’s size minus about 0.004”. Could ream it out but have found another problem ie. the early diff carrier register is a smaller dia. than the crownwheel register bore on the 4.9 CWP I have. Next question! Has anyone fitted this later crownwheel to an early carrier or alternatively and preferably (as I have a later diff carrier which will fit my 4.9 crownwheel) will this assembly fit an early 23 to 28 axle case? Tony G, looking up rear axle bits for Chris W who is assembling parts for an early A7 factory racer, the one with the fabric body.

[Ruairidh Dunford]

I have done this - I will call you.

[Tony Griffiths]

"....looking up rear axle bits for Chris W who is assembling parts for an early A7 factory racer, the one with the fabric body."
I suspected as much! ....another welcome returnee to hobbies of the past and, knowing Chris, it's going to be a finely-executed job. BTW - tell him to get in touch with John ward who, I belive, has some interesting data on these early racers.

[Dave Wortley]

R, Thanks for your advice. Will see what we have axle case-wise. Tony, I will see Chris shortly and tell him to see John. Cheers, Dave.

[Bob Culver]

Fot those new to the topic it may be helpful to know that axles were originally .875 and later .890", hence the common problem when adapting diff carriers.
I have a barely used Australian Dufor brand which is the larger but finished small at the outer end. This provides no  taper engagement inside of the keyway and a crack has naturally started at the edge of the key. Something for Australasians to watch for, assuming some axles survive..