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Old 10-20-2020, 03:23 PM   #1
Tootall
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Question identifying rear gear ratio in 1931 model A

I am looking to purchase a Model A chassis and it has a transmission still attached. Ii wish to know the rear gear ratio and upon looking on the Speedo, I found the numbers 9-34. I am assuming this is an after market or special rear gear ratio.
Could someone help me out?
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Old 10-20-2020, 03:26 PM   #2
Kurt in NJ
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Default Re: identifying rear gear ratio in 1931 model A

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Old 10-20-2020, 07:21 PM   #3
Joe K
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Default Re: identifying rear gear ratio in 1931 model A

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Originally Posted by Kurt in NJ View Post
3:78
Yes, the 9-34 you found refers to the number of gear teeth in the rear differential. Different years, or more accurately have different ratios, this done by varying the gears.

My truck originally was 4.11. Now with high speed gears 3.54.

The speedo gears on mine are marked 9-34, but I mentally add a couple of mph. Now the proper speedo gears for the high speed rear are available.

You can confirm your ratio with your rear wheel (one) up on a jack, a starting crank, your transmission in 3rd gear, and understanding that a differential with one wheel held to the ground "doubles" the motion for the free wheel.

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Old 10-22-2020, 01:13 PM   #4
Chuck Sea/Tac
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Default Re: identifying rear gear ratio in 1931 model A

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Here’s info from an old post
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