Gear ratios ???

marty in Ohio

marty in Ohio

Well-known member
A model 'A' friend of mine rode in my '30 town sedan and remarked that I must have a different gear ratio than his. In his car we were hardly moving before he was in second gear. He rarely downshifted from third when cornering. I've driven my car for more than 20 years and didn't know any difference. Other than in trucks, were there different gear ratios in stock Model A's?
 
Yes there were. Standard ratio is 3.78, the high speed ratio is 3.54 and there is a 4.11 for the mountains. There is also a 3.27 that was an aftermarket offered sometime in the '30s.
Vic
 
Lots of things can change in 80 plus years. Jacking one rear wheel up and turning the engine over by hand will let you determine the ratio. Easiest to pull your plugs and get your hand crank out,
Put it in 3rd Gear.
Make a mark on the jacked up tire at 6 o'clock and crank the engine over exactly 2 revolutions. When you hit exactly two revolutions, have a friend grab hold of the tire so it cannot move, or set the hand brake or whatever.

See where the mark on tire ends up:

Between 11 and 12 o'clock, ratio is 4.11
Between 12 and 1 o'clock, ratio is 3.78
Between 1 and 2 o'clock, ratio is 3.54

These are from notes of the procedure that I took from another Barner's post. A search here will find lots of info.
 
Last edited:
QGolden said:
Lots of things can change in 80 plus years. Jacking one rear wheel up and turning the engine over by hand will let you determine the ratio. Easiest to pull your plugs and get your hand crank out, Make a mark on the jacked up tire at 6 o'clock and crank the engine over exactly 2 revolutions. When you hit exactly two revolutions, have a friend grab hold of the tire so it cannot move, or set the hand brake or whatever.

See where the mark on tire ends up:

Between 11 and 12 o'clock, ratio is 4.11
Between 12 and 1 o'clock, ratio is 3.78
Between 1 and 2 o'clock, ratio is 4.54

These are from notes of the procedure that I took from another Barner's post. A search here will find lots of info.
Click to expand...

I think you failed to mention the transmission needs to be in 3rd gear to get the correct reading. :eek: Also between 1 and 2 o'clock should be 3.54 ratio.
 
Timberbeast said:
I think you failed to mention the transmission needs to be in 3rd gear to get the correct reading. :eek: Also between 1 and 2 o'clock should be 3.54 ratio.
Click to expand...

Thank You!

You are right on all counts, please pardon the typo. I will go back and edit so the incorrect info is not picked up from the search feature.
 
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