Gear ratio

fordy46

fordy46

Member
In my 46 I have a badly bent rear axle, I have another good complete rear end thar Iwant to use. How do I determine what ratio this rear is. The only stamp I could find was a faint 3and4 on the flat where the tube bolts to the pumkin. I have heard that by counting the number of turns on the u joint end to the actual axle turns you can do this. However I am brain dead and forgot how to do this. Any ideas. Dan
 
If you can read 34, there should be a 9 after it (34-9), or 34 teeth on the ring gear and 9 teeth on the pinion gear for a ratio of 3.78:1.

Other stampings / ratios would be:

39-9 / 4.33:1
39-11 / 3.54:1
34-9 / 3.78:1
37-9 / 4.11:1
 
If you lock one wheel ,and turn the shaft and count the turns to make tire turn 2 times/or turn tire 2 times and count the turns on shaft.3 and 1/2 turns 3.54 more then 4 but less then 4 1/4 =4.11 that should get ya close.
 
Thanks guys, This is amazing, Have a question and get a good answer in an hour. Great. Thanks guys and Fordbarn. Dan
 
It was bent when I got the car, it is right at the end where the hub fits. It runs out at good 1/8" I would get a vibration at about 50 MPH. Hope this helps.
 
I would check both axle assemblies closely as most 46 cars have a 3.54 ring gear and 47-48 have 3.78. If you want economy then the 3.54 is the one, if you want more "snappy" acceleration then go for the 3.78.
 
If you want to keep your ratio, I have an axle from 46/48. It's cheap plus shipping and I'm in IN. E-mail if interested
 
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