Thread Rating:
  • 1 Votes - 2 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Rear Axle Half Shaft Changes.
I am trying to sort out the rear axle half shaft changes for Spares.

From my notes the axle diameter at the differential casing end was increased from the original Axle No BO 18 at 7/8" to Axle No BO 128 at 57/64" from Chassis 126384 (excluding 126386 and 126467 to 126470)  I believe Chassis 126384 was produced at Longbridge January 1931. 

The diff case bush were also changed from BO23 to a larger bore BO129 to suit. As far as I understand there were no other case changes.

When the Axle half shaft diameter at the differential casing end increased from 7/8" to 57/64" in 1931, the 'List of Production Changes' shows the Axle length as 22 1/2". (our Spares List shows 22 1/8")
Our 'Spares List' also lists the longer Axle half shaft at 23 1/2" long coming in at 1932, but the
'List of Production Changes' doesn't specify a half shaft length, only noting the new 'D' type rear axle introduced in September 1932. The 'Austin Spare Parts' book shows this new Axle half shaft as BO136.

I would like help confirming the Half Shaft length details.       

Cheers Tony.
I can verify that the length of the SWB half shafts are 22 1/2" overall and the LWB 23 1/2" overall
Black Art Enthusiast 
(22-08-2017, 01:10 AM)Ian Williams Wrote: I can verify that the length of the SWB half shafts are 22 1/2" overall and the LWB 23 1/2" overall

Thanks Ian- that confirms the lengths.

Cheers, Tony.
Just trying to work out two secondhand halfshafts. 
Both are less than 22.5" - more like 22 1/4".
Of this measurement, approx 3/4" is the thread, so they are 21.5" to the end of the contact area.

They have different finishing to the toothed end... the clean one is 0.86" diameter (just behind the teeth), and there is more chamfer on the inner circle pictured. The tarnished one with less chamfer is 0.87". Tony's early and late measurements equate to 0.87 and 0.89 of an inch for the two shafts.

The 2 diameters of SWB shaft are apparently not interchangeable. Is this just because of the diff case bush alone? 

I presume both mine are "earlies"? Is the changeover to the fatter shaft came in with the last incarnation of the swb axle type (type III in the green Companion picture, accepting type 4 is the D type)?
For what it is worth....
My 1932 SWB steel "chummy" body AG tourer chassis 149497 (maybe March 1932?) has a narrow axle with half shaft dia. by the teeth of .890". As one is broken & I had a spare that came with a similar car & an RK I thought I was in luck. No! the spare was too long so a cherished supplier has provided a new "short fat one" The long fat one is in fair useable condition (well I was going to use it!) , but not tested. Open to offers to help defray the cost of the replacement...
The good news is that the CWP looks really good with little wear apparent
Should I touch the Adjustment collars/peg while all is apart? (not the diff/pinion assembly) or leave well alone? I have no idea if the unit is noisy as I have yet to hear it run....Where is the .004" backlash measured??
I will post some photos later
In haste Dave - you'll be lucky to get 0.004 with used parts. The important thing is that everything turns smoothly with no hint of tightness.
Photos of an AG axle. Any ideas about the numbers stamped on the casing? I think it is a Type 3 (page 164 green book)
And the broken shaft with it's strange repair. Pity because the keyway is perfect!
The axle has currently got one long & one short shaft!

Attached File(s) Thumbnail(s)
If you clean the paint away from above the number you have exposed you should find a date and the original ratio that was fitted into it.

The back axle was one of the last things fitted so the date can often give you a good indication of when it left the factory...

the axle ratio is at the end of the bit you have already cleaned... 9/44.

as R says, date will be above, the three sections quite widely spaced.

David - how long exactly are all your half shafts i.e. are they exactly 23 .5 and 22.5, or are they a bit less, as per my findings in post above?
When I split the axle to fit the new shaft I will measure it all. Probably next week now
There is a witness of a number or so where you suggest. I'll get the wire brush out!

Forum Jump:

Users browsing this thread: 1 Guest(s)