Donny72

Most likely been asked a million times but if one can't make the code because of years of rust, what is the easiest way to figure out the ratio? The rear end is out of the car. Count the pinion and the axles correct? Thanks gang, got a brain fade going.

djrammer

Count the pinion and the ring gear.

63mako

Easiest is mark the side yoke and housing with chalk with the front yoke vertical. Slowly rotate the front yoke and count how many full rotations and partial to rotate the side yoke 1 revolution back to your mark. If it is a stock automatic car it is more than likely a 3.08. That would be 3 full turns plus less than 1/10th of a turn of the front yoke for 1 revolution of the side yoke. It is one of these ratios. 3.08, 3.36, 3.55, 3.70, 3.90 4.11, 4.56, 5.13. Pretty easy to distiguish between these using the above method.

Donny72

Looks to be a 3.08. It was a 4 speed car. The pinion spins 3 to almost 1 on the side yoke. Thanks for the help!

63mako

Standard 1972 ratio is 3.36. Most auto cars I have encountered were 3.08 which was an optional ratio but seems the most common. Below is the list of available factory ratios and amount of cars made with that ratio.


3.08 Axle
15,845

3.36 Axle (Standard Ratio)
9,142

3.55 Axle
670

3.70 Axle
985

4.11 Axle
363

The other ratios I listed would be aftermarket.