I am just about to place an order for a large number of crown wheel & pinions, and I would like to check that I have got the following information right! The four types I am producing are:
* 4.9:1 (7/8" dia long pinion shaft) to fit pre-1928 cars
* 4.9:1 (1" dia long pinion shaft) to fit 1929 - 1932 cars
* 5.25:1 (short pinion shaft) for post-1932 cars
* 5.67:1 (short pinion shaft) for sports / trials / racing cars

In particular, did the later type (1" dia) of 4.9:1 CWPs all have long pinion shafts? Which back axle casings have short pinion shafts (the later banjo with extended nosepiece and the D-type?).

David

From many articles read incl. the Austin7 journals I produced a list of the changes to c/w's,pinions casings etc. from 1928 to 1938 and maybe the following might help:
Crown wheel 44 teeth up to Oct.1931.
Pinion 9 teeth 7/8th dia. to May 1929.
1" dia. plain shaft for screw-in torque tube axle from May 1929 to Sept.1930, both the above were long shafts.
The following were short pinion shafts:
From Sept 1930 to April 1931 - A right hand thread was used for the locking nut for the double A/C bearing held from unscrewing by a 'grub' screw.
From April 1931 to Oct 1931 a left hand thread was used for the locking nut plus a 'tab' washer.
From Oct.1931 to Dec.1937 the pinion had 8 teeth and the crown wheel 42.
From Dec.1937 the C/W had 41 teeth.
THe short pinions therefore were used in the later banjo and D-type axles.

Best of luck in your new venture.
Brian.

Brian, thanks for that - does this mean that between Sept 1930 and Oct 1931 there was a short-shaft pinion w4th a 4.9:1 ratio? Or to put it another way, 4.9:1 ratios were made with both long and short 1" dia pinion shafts?

Hi David

Not sure if the following will be of any help. An old Remax catalogue I have lists the various Austin part numbers / teeth numbers / years. Unfortunately this only covers the CW&P's that Remax chose to copy.

1923 / 28 - part no. 1A7013 / 4
44 x 9

1929 / 30 - part no. 1A7069 / 7091
44 x 9

1930 / 32 - part no. 1A7127 / 7164
44 x 9

1932 / 35 - part no. 1A7168 / 7169
42 x 8

1932 / 34 - part no. 1A7206 / 7207
45 x 8

1935 / 39 - part no. 1A7168 / 7234
42 x 8

1935 / 39 - part no. 1A7206 / 7240
45 x 8

Jeff

Hi David

Confusingly an old (1938) motor catalogue listing Remax parts suggests the following additional CW&P for 1928 / 29:

1923 / 28 - part no. 1A7013 / 4
44 x 9
1928 / 29 - part no. 1A7069 / 7014
44 x 9
1929 / 30 - part no. 1A7069 / 7091
44 x 9

Jeff

Hi Jeff,

Thanks for your posting, but it doesn't really answer my query about pinion shaft lengths as per my second posting (Oct 8th). What I'm trying to do is to get as few types of CWPs made as will fit as many cars as possible (as cheaply as possible: £295 per set). So no 4.4:1 Brooklands ones (apologies to all you GE Brooklands owners out there)! Some alterations have been made, e.g. only the later size of crown-wheel is being produced: this is partly because it's cheaper to make just one sort, but mainly because the early 'cup & cover' diff assembly is very weak and good ones are now very difficult to find; the later symmetrical type is stronger, will fit in early axles and is readily available.

David
www.ingineur.co.uk/A7C/cwp.htm

Hi David,
I've read your last E-mail but I'll add my last penny worth!
4.9 ratios were made with both long and short 1" dia. pinion shafts vis:
Long plain shaft (May 29 to Sept 30 screw in axle)
Short threaded shaft (RH and LH for locking nut) for later banjo axles.
The part no. change refered to in Jeffs E-mail results from the modified crown wheel to fit (as you suggested!) the equal half diff.casing

Brian,

> 4.9 ratios were made with both long and short 1" dia. pinion shafts ...

Just as I feared! So now I have to decide which type to make - I shall probably go for the longer one (on the grounds that it can always be shortened if really necessary).

Thanks again for your help - much appreciated!

David
www.ingineur.co.uk/A7C

Hello again,

Thanks to kindly advice, I think that I'm getting a grip on the various ramifications of what was done and when in the back axle department! However, I have some more details & dates for which I would be grateful for any comments:
June 1928: Introduction of symmetrical differential housing, and crown-wheel with larger (3/8") fixing holes.
Sept 1930: Introduction of stronger banjo (with the extended nose-piece) - this continued until the D-type axle (Sept 1932).
Jan 1931: Thicker (0.890" dia) halfshaft (previously 0.875" dia).
Somebody was telling me earlier today that the very last axles had an even longer pinion shaft (c.24") but I can find no evidence of this in the Source book.

David
www.ingineur.co.uk/A7C

Hi David,

For what it's worth, this old (1938) motor catalogue of mine has illustrations of seven A7 CW&P's although small and of very poor quality / definition

1A7013 / 4 is described as CW - 5/16" bolt holes, pinion shaft 7/8" - 1923 / 28

1A7069 / 7014 is described as CW - 3/8" bolt holes, pinion shaft 7/8" - 1928 / 29

1A7127 / 7164 is described as CW - 3/8" bolt holes, pinion 1" screwed L.H. - 1930 / 32

The other four illustrations carry no descriptions unfortunately

Another old catalogue lists three Remax halfshafts by Austin part numbers:
1A7017 - 1922 / 31 @ 21·75"
1A7151 - 1931 / 32 @ 21·75"
1A7181 - 1932 / 39 @ 22·75"

Austin 'Big' Sevens are listed as 1A7603 - 1938 / 39 @ 24·5"

Jeff

David, the very last axles were, in effect, a Big Seven axle modified in width and length to fit, with rod brakes, large dia. half shafts, hubs with longer tapers, a Big Seven style torque tube and a longer pinion. Not very many about but the strongest axle fitted to a Seven. I had one once but sold it to a mate of Ron Bailey's in Nottingham.

STEVE

Jeff,

Thank you for those details - as far as I can tell, there is a fairly bewildering series of changes from mid-1928 to late 1932. Seven in total I think:
June 1928 - different CW to fit symmetrical diff case;
May 1929 - 1" dia pinion shaft & screw-in torque tube;
Sept 1930 - Shorter pinion shaft and stronger banjo;
Jan 1931 - Thicker halfshafts;
April 1931 - RH thread on pinion shaft changed to LH;
Oct 1931 - 5.25:1 ratio;
Sept 1932 - D-type back axle.

It now looks like I'll be making the 4.9:1 ratio (1" dia pinion shaft) with the shorter shaft rather than the earlier type (for the screw-in torque tube) because no-one has asked me for any of the longer type.

David