1936 ford diff gear ratio ID

[29delivery]

Hi Guy's,I ve tried several searches and have not found the method of ID ing the gear ratio on the rear end of my 1936 ford.I was told that there is a "code" stamped on the housing. Can someone elaborate on the location of the marking and how to decipher what t is. Thanks Ken

[AlexLohmann1]

11-39 is 3.54
9-34 is 3.78
9-37 is 4.11

Sent from my SM-G975U using Tapatalk

[uncle buck]

On the bottom of the center section is a machined area and there should be 2 numbers stamped in it such as 9 (tooth pinion) and 37 (tooth ring gear). Divide the larger number by the smaller one. Like Alex shows in his picture.

[Mart]

Does your car have a starting handle (crank)?

If so, try this:
Jack up ONE rear wheel. chock the others.
Put trans in top gear. (3rd).
Turn handle until it is at the 12 o'clock position.
Mark the raised rear tyre with tape and a piece of tape on the ground next to the mark on the tyre.

Turn the handle 1 and 3/4 turns. (1.75 turns). Handle at the 9 o'clock position.
If the tape marks align it's a 3.54.
If not, turn it a little further until the handle is about the 11 o'clock position.
If the tape marks align it's a 3.78.
If not, turn it to a position just over halfway between 12 o'clock and 1 o'clock.
If the tape marks align it's a 4.11.
If not, continue to exactly the 3 o'clock position.
If the tape has just gone past the mark it's a 4.44. If it hasn't quite got to the mark it's a 4.55.

The above method is one I just invented.

The other method is the same principle, but you turn the handle until the tyre has done 2 full turns. the no. of turns of the handle equals the rear end gear ratio.

Here is a video I did on the subject:
https://youtu.be/bkvp3Fq21ZM

Mart.

[DavidG]

More often than not, the numbers I've found have been on the top flange, not the bottom one.

[29delivery]

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Thanks Guys,I'll take it from here for now. ken