Model A Rear End Ratio
 

Jacked up the drivers side rear wheel, put a piece of tape at the 6 o'clock position. Put a mark at the 12 o'clock position on the drive shaft splined end.
I then turned the rear wheel forward one full revolution and the driveshaft moved not quite 1 7/8 turns clockwise. What ration rear end do I have? Your help is much appreciated!

Re: Model A Rear End Ratio
 

I would think it should be a 3.78.

Re: Model A Rear End Ratio
 

Math wise: 2X1.875=3.75 Most likely a 3.78

Re: Model A Rear End Ratio
 

I believe you’re supposed to rotate the rear wheel twice and then note the drive shaft revolutions. Multiplying your current result by 2 gives 3.7, which I guess is a possible result if you have an early ‘28, but otherwise you should keep going to get a more precise answer.

Re: Model A Rear End Ratio
 

If you want to be really precise, count the driveshaft revolutions with 20 rotations of the wheel and then divide by 10.

Re: Model A Rear End Ratio
 

I think the ratio available at the time were 3.70 [early], 3.78 [later] and 4.11 [truck]. I think by far most had 3.78.

But the difference between 3.7 and 3.78 won't be noticeable.

Re: Model A Rear End Ratio
 

Thank all of you for your replies. Appreciated!