AA 4 speed transmission counter shafts

AA Ford Discussion Group relating to the repair and restoration of your AA Ford.
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RustydoubleA
Posts: 97
Joined: June 18th, 2014, 10:22 pm
Body Type: express
Model Year: 1930
Location: N. Calif.

AA 4 speed transmission counter shafts

Post by RustydoubleA » December 29th, 2015, 6:13 pm

I noticed that the transmissions are very similar on the AA trucks and the WWII Dodge army trucks and Power Wagons. I bought a NOS counter shaft for a WWII Dodge 39- 46 tranmission on ebay and just received it. Attached is a picture showing the AA shaft on the bottom and the new Dodge truck shaft (New Process Transmission) on the top. They are both exactly 1" diameter and with a little grinding the Dodge shaft should work. $40 w/free shipping at dctruckparts on ebay. Steve.
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aacountershaft.jpg
aacountershaft.jpg (298.19 KiB) Viewed 1776 times

RustydoubleA
Posts: 97
Joined: June 18th, 2014, 10:22 pm
Body Type: express
Model Year: 1930
Location: N. Calif.

Re: AA 4 speed transmission counter shafts

Post by RustydoubleA » December 29th, 2015, 10:41 pm

Hi again, I noticed a slight "step" on BOTH shafts on the after end (keeper end) of the shaft. They are both 1" diameter for rear 1 1/2", then the diameter gets smaller by .004" for the forward 7 3/4" of the shaft. All of these measurements are approximate, I used cheap dial calipers and a ruler. The main concern (in case some one tries to use a continuous 1" shaft) is that the Model A shaft has the same step as the New Process shaft, probably done for ease of assembly. Steve.

vonheine
Posts: 43
Joined: September 30th, 2009, 8:02 pm
Body Type: none
Model Year: 1930
Location: Massachusetts

Re: AA 4 speed transmission counter shafts

Post by vonheine » February 2nd, 2018, 8:49 pm

You are right. I measured several BB-7111 counter shafts because I think I might make a few brand new ones. The keeper end is 1.0030 to 1.0035 for 1-1/2 moving forward, just as you described. then the shaft steps down to 1.0005 to 1.0000 all the way forward. I thought there might be a second step for the forward end to fit into the case, but after several careful measurements of three different shafts, I don't' think so. There is just one step. The largest OD keeps it where it belongs in the case, in addition to the flat stock keeper that locks both the counter shaft and the reverse gear shaft. You can get a good measurement at the "shadow area" of where the spacer prevents any shaft wear from the twin roller bearings. I was thinking about 4340 material, but I am not sure if I can get it hard enough after heat treating. My guess is that shaft is 56 to 62 Rockwell C . I considered O-1 tool steel, It definitely will get hard enough, but it might be too brittle, and if it fractures, the transmission will turn to junk in 3 seconds. I am now thinking 8620 case hardened or 9310 case hardened. Does anyone have any thoughts on this? Has anyone made this shaft from scratch?

Bob C
Posts: 1196
Joined: April 24th, 2003, 11:50 am
Body Type: Mail truck, Stake tr
Model Year: 1931
Location: SO CAL

Re: AA 4 speed transmission counter shafts

Post by Bob C » February 3rd, 2018, 3:10 pm

You can get the drawings from Ford and it usually has what the metal is.
Might be cheaper to just buy a new one. https://www.ebay.com/itm/NOS-1929-1952- ... SF&vxp=mtr

Bob

vonheine
Posts: 43
Joined: September 30th, 2009, 8:02 pm
Body Type: none
Model Year: 1930
Location: Massachusetts

Re: AA 4 speed transmission counter shafts

Post by vonheine » February 3rd, 2018, 3:58 pm

Bob, Thank you. I actually have been watching this particular shaft on e-bay, but it is the replacement shaft for a BB-7111. It has that weird step at the back that will be clearly be seen as not the regular shaft. I know it will work just fine, but it wont look stock, original. It would be great if we could get Ford drawings for all the parts for these trucks.

Bob C
Posts: 1196
Joined: April 24th, 2003, 11:50 am
Body Type: Mail truck, Stake tr
Model Year: 1931
Location: SO CAL

Re: AA 4 speed transmission counter shafts

Post by Bob C » February 3rd, 2018, 6:31 pm

You can get the drawings for all the parts. Go to MAFFI and look up the drawing dates and engineering information number
then fill out the form from THE HENRY FORD send in your money and they will email you the drawings.

MAFFI http://www.maffi.org/partsresearch/
THE HENRY FORD https://www.thehenryford.org/docs/defau ... /?sfvrsn=6

Bob

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