Rear Axle
What is the best Rear Axle Ratio?
Remember that I am NOT building a “Drag” car, but one aimed more at “Road Rallying”.
Also, understand that people aiming for a 4.11:1 RAR are “drag” people with a manual transmission.
O.K., Lets assume that my engine is making ≈325 horsepower, my current 3.31:1 and Turbo 400 is in the realm of “Special”, more radical than “Performance”. Since I am “Road Rallying”, “Performance” should be my aim. If a 350 hp, “Standard” is OK to aim for.
Configuration
Usage Based Chart
RAR Based Chart
My Rear Axle:
My rear axle is a GM 12-Bolt out of (likely) a ’66 A-body.
It has a width of 60.5″ (wheel seat to wheel seat).
Casting & code pics are below.
← Flat Spring Perches were used on ’65-’66 Chevelle models, and possibly a few early ’67s.
Mine have 2 holes indicating a ’66.
= April 14, 1966
(The “377” is unusual)
= 3:31 Posi, May31, Eaton (Posi)
(Plant?)