I just bought a Ford 9 inch rear end today that I am going to be building for my 84 Trans Am. my work is going to start with the 3rd member. I would like to know what the gear ratio is to start off. I counted the teeth on the ring gear at 39. before I took things apart I counted about 2 revolutions for the pinion and 1 for the wheel. anyone know for sure what I have???

 

you need to know the number of teeth on the ring and pinion gear. then do the math and you'll know what you have

 

what is the formula to figure this out?? divide one by the other or something like that?? also does the same formula go with gm,also?? in case other guys want to try and figure out what they have.

 

well I counted the pinion teeth and there are 13. if I divide 39 by 13 it comes to 3:00....is this right??? this rear end was out of an F150 pickup with 31 spline axles (I counted them to) so I would think maybe a steeper gear than this b/c it was supposed to be a heavier duty application.

 

you're right! ....... those are 9" 3:00's