How to determine gear ratio on rear end out of vehicle?

[ckulchar]

Have a 1931 ccpu with a low gear ratio probably stock. My friend has three spare rear end assemblies. How would we determine the gear ratio of these units? What ratio would I want to use to get a little more top speed out of the stock motor?
Thanks in advance.
Charley

[grantsauder]

How about some pictures of what you got and maybe someone could help to put them together for you. Grant

[Jim/GA]

Figure out a way to turn the driveshaft with one drum on one axle free to turn and the other one fixed (not turning).

Then follow procedure here, post #2:
https://www.fordbarn.com/forum/showthread.php?t=223904

[Patrick L.]

Sponsored Links (Register now to hide all advertisements)

To figure out the ratio with the unit apart, just count the teeth and divide the two. If its a 9/34 set then it'll be a std 3.78.