How to determine rear gear ratio

[monsterstang70]

I'm about to get a 8.8 rear and the seller isnt sure if it have 3.27's or 3.55's in it. Is there a way to determine what gears are in the rear when the rear is out of the car?
Thanks
Jhery

 

[65ShelbyClone]

Its easiest to do when its out of the car. There are two ways:

1. Spin a wheel/axle exactly one revolution and count how many turns you get out of the pinion yoke. 2 3/4 = 2.73, 3 = 3.08, etc

2. Do the revers of above. Count how many turns of the yoke it takes to make an axle go around once.

Or if the diff cover is off, count the teeth on the ring gear and divide by how many are on the pinion. This will give you the exact ratio.

 

[giddyup306]

Is there a way to determine what gears are in the rear when the rear is out of the car?
Thanks
Jhery

pinion/ring=gear reduction

 

[HISSIN50]

Giddyup is right - to add in case of confusion, he is saying to count teeth and divide per his formula.