Differential code

[91blaze]

I'm trying to figure out my axle ratio and can't seem to locate the code anywhere. Anyone got a picture if where it's at, mine is covered in crud.

[66Monza140]

Here's where to look: http://www.corvair.com/user-cgi/catalog.cgi?show_page=2

(middle of the page). My '66 was a greasy lump, took some cleaning of ancient grease/oil to find it.

[64powerglide]

It's stamped on the lower left side of the case at the rear just under the axle. Had a photo of my 64 but deleted it, sorry!! You should be able to reach it easy.

[Jerry Whitt]

You can count the teeth on the ring gear. Then count the teeth on the pinion gear. Divide the ring gear number by the pinion gear number. Out come is gear ratio.

[bbodie52]

http://corvaircenter.com/phorum/read.php?1,27400,180286

Left-click on image to enlarge for better viewing...

[91blaze]

64powerglide- completely different location on earlies and lates

I did manage to find it thanks to Brad's picture, but it's practically unreadable. "Looks" to be an AA which is a 3.27 although I will check for sure later down the road. The diff is still in the car so it's too much of a pain to count the teeth right now. Thanks for the help guys.

[Wagon Master]

If I've had my grubby little hands on it you won't want to trust the case stamping for gear ratio anyway. On a standard trans. you can put it in high gear and see how many engine revolution it takes to turn an axle 1 revolution.
Engine
3 1/4 turns =3.27
3 1/2 turns =3.55
not quite 4 turns = 3.89
easy peasy

[bbodie52]

When I was researching this, I discovered yet another error on the part of the Chevrolet technical writers when the were piecing together the 1965 Corvair Chassis Shop Manual...

The illustration below in Section 0, page 0-2 is supposed to point to the location of the differential number. The picture is clearly a photograph of a Late Model differential, showing the left (driver's side) with the throttle linkage visible. Yet the illustration indicates that the differential code is stamped on the LEFT SIDE, when in fact it was stamped on the right side. Also the example shown is labeled "HB612", yet we know that the code "HB" was only used on 1962-1964 EM differentials with a 3.55:1 ratio, and that all 1965 and later differential codes were stamped on the RIGHT SIDE and used code letters starting with the letter "A". SO THE PHOTOGRAPH, WHILE CLEARLY SHOWING A 1965 SUSPENSION CONFIGURATION, POINTED TO THE INCORRECT SIDE AND UTILIZED AN INCORRECT CODE DESIGNATION THAT SHOULD HAVE BEEN "AB", INSTEAD OF "HB".

I guess the technical writers failed to do their homework and used 1964 Corvair information associated with a 1965 photograph in the 1965 Corvair Chassis Shop Manual!

Left-click on image to enlarge for better viewing...