Calculating Rear Diff ... check my math!

Well guys - Regardless of all my calculations, it appears I actually have a 3.23 rear diff. While up under the car working on replacing the fuel sending unit, I spun the rear wheel and counted the driveshaft revolutions. When I spun the LR wheel forward, the RR wheel would not turn. And the driveshaft spun quickly.

When I turned the LR wheel in reverse, the RR wheel would turn the opposite direction and the drive shaft would turn half speed. So, to simplify this for me, I just turned the LR wheel forward.

I started with the driveshaft in a specific position that was easy to remember and easy to know where that part of the driveshaft was at all times. Then I marked the start position on the tire. I spun the LR wheel 1 revolution exactly, and the driveshaft turn just barely less than 3.25 times. I think it would be clearly distinguishable if it turned just over 3.5 times versus just under 3.25 times. So, with that, I have a 3.23 rear end.

Since I'm going to purchase a Detroit / Eaton TrueTrac diff, I'm certainly not going to buy a 3.55, since it turns such high rpm as is.

Comments, questions, suggestions and concerns are welcomed and appreciated. Thanks!


7milesout