1972 Rear End Ratio
Thread Starter
Pro
Joined: Mar 2012
Posts: 702
Likes: 10
1972 Rear End Ratio
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.
Instructor
Joined: Jul 2007
Posts: 167
Likes: 0
From: Sheboygan Wisconsin
Count the pinion and the ring gear.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
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.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
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.
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.
