AA Ford Discussion Group relating to the repair and restoration of your AA Ford.
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I have a complete 7-1928 rail way express AA truck in very good condition, trying to find out what rear end it has no A or b casting marks it has a small symbol than an F bellow that TT2. ANY CLUES??
- Neil Wilson
- Posts: 2663
- Joined: February 5th, 2003, 9:42 pm
- Body Type: 82-A/89-A
- Model Year: 1930
- Location: Boulder, CO
The first AA's came with the 5.17:1 high speed worm drive rear axle (not markings since there was only one gear ratio). The speedometer driven gear is a good indication that the axle gears are 5.17:1. After this many years, the internal gears could have been changed.
If the rear axle is still assembled then the following procedure can be used to determine the ratio. Turn one rear wheel (with the other held stationary) for one turn and count the number of times the drive shaft or engine turns over. If you are counting engine turns, then make sure the transmission is in high (which is the 1:1 ratio or straight through position for the transmission). The count of turns times two is the axle ratio.
A 28/29 worm and bevel, high speed axle will result in slightly over 2-1/2 turns of the drive shaft to make the 5.17:1 or 5.11:1 ratios. When the drive shaft turns over 3-2/3 times the axle ratio is a low speed.