Juggling Differentials

[vtwinsideways]

Dad's '29 is running a '30-'31 rear with high speed gears. We disassembled the driver’s side brakes to clean and inspect them and found that the seals were blown- no big surprise. When he opened up the right side there were no brakes at all. To boot, the axle housing end had been chewed up pretty bad at one time. He now has another rear-end of similar model but with unknown gearing. Were there any changes in the housings (late '29 thru '31 bevel gear) that might interfere with swapping out the bad axle housing for the good axle housing of the second rear-end? Would we be better off having the bad axle housing repaired? Thanks. Luke

[Chris Haynes]

Be sure to check the wheel bearing races on your housings. The ones on mine were so worn on the bottom that they were "D" shaped instead of round.

[Neil Wilson]

FYI - There is no '29 bevel gear rear axle like the '30/'31 axle. The conversion from the worm gear axle to the bevel gear axle occurred in January 1930.

The high and low speed axle gears ('30/'31) are interchangeable in the axles.

[vtwinsideways]

Sorry about the mixup Neil, I thought I had read that they were available in late '29 in the AA Truck Supliment. I'll have to reread it as I was pretty tired when I was looking it over. Luke

[Hayslip]

Neil Wilson is correct. Any other sources are incorrect except the(Ford Factory) Service Bulletins. The 4 speed transmission appeared in October 1929 and the 1930/31 bevel gear rear end in Jan. 1930. These are announced in the Service Bulletins on those dates, qv. Sincerely, Ed

[vtwinsideways]

I ment no insult and I believe Neil, as I said I was pretty sleepy when I was reading through it two nights ago and the fault maybe mine. As the book is 30 miles away, I cannot re-read it right now to determine if it is wrong. Luke

[Neil Wilson]

It very well could be in the supplement that you reference (I don't know). Many AA'er think that the late '29 was the conversion to the '30/'31 style chassis. This is usually because many don't understand that the '29 cab was used until about Aug. 1930. Also, I have heard about several '29 AA's which had the '30/'31 rear axle installed (after production change).

BTW - I have an AA 4-speed with a August (maybe September) 1929 in the casting. So, it could be that August was the change over month. This needs to be research someday.

Note that I only know what I know based on research. And, there is always something new to learn which changes my mine frequently. So, I am a flip flopper (as it should be). Anyone on this forum that has information which shows that I am likely wrong on a subject should post the information. We all learn via information!

Even the Service Bulletins have mistakes in it (not many that I have found).

[gunmetal]

I have a mid 29 AA truck that has a worm gear rear end.

[jtw]

I saw a 28/29 AA truck with a rearend that looked just like a car r/e housing, except it was much bigger, and was told that they were used in delivery, ambulances etc. Does anyone know anything about these?

[Neil Wilson]

A few '29 AA's were released with a banjo style rear axle (see picture). Ford never did get this axle into full production and continued to use the worm drive axle through 1929.

[Drew Mashburn]

Neil:

Nice photo of the banjo-style differential. A few years ago, my wife and I were in Melbourne, Australia visiting Rob and Sue Turner. They graciously put us up and took us to their Model 'A' club's monthly outing where I got to ride in a right-hand drive tudor. The driver was Australian, the front seat passenger was a New Zealander fellow, my back seat passenger was a Scottish lady and I'm an American. Cool, to say the least! Anyway, I digress...................Rob has an AA. It had a rear differential of a type that I had never seen. It could have been a banjo-style, but I simply can't seem to recall what it was. I just sent Rob an email and asked him to tune-in to this forum and take a look at the photo you just posted. I seem to recall that Rob said many of the Australian AA's were either built in Canada or equipped with Canadian parts. Is it possible that the banjo-style differentials were of Canadian production and, therefore, that's why we don't see many of them?

-- Drew

[Bob C]

Drew, This is the rear end for a Canadian AA

[Downunder Rob]

Drew - All
the Australian Truck use a Timken Diff as Bob showed.
there are 2 different versions of the housings in Australia. the first is a open tail shaft and the diff has a talk arm running down the side and attached to the chassis. the second is an enclosed shaft with radius rods.
my truck is the later which was released in mid to late 1930 in Australia.
we also ran the 2 different ratios. the interesting thig is the ratios are stamped in to the diffs in fractions. i will try to get a photo for interest sake.
as you can see from the photos our braking mechanism is also different. the drums are also much bigger diameter than the US version.