Hot Rod Forum banner

1 - 5 of 5 Posts

·
Chopper Builder o<>\o
Joined
·
171 Posts
Discussion Starter #1
Is it possible to figure out what type of axles I have without removing them?

I have a 78 Blazer with a 12 bolt rear axle with 3.73:1 gears. I'm using an Auburn limited slip with motive gear internals. Here is a picture.



 

·
Premium Member
Joined
·
2,233 Posts
I still have yet to figure out exactly what you are interested in by what you asked. :confused: :confused:

Your GM corporate 12 bolt has a ring gear measuring 8.875 (8-7/8) inches, axleshafts measuring 31-5/16 and 31-11/16 inches and having a spline count of 30. I'm not sure I remember right but I "think" the longer shaft goes in the drivers side.
The ring gear is held to the carrier by 12 bolts, same as the cover on the rear of the housing. The pinion shaft diameter measures 1.438 inches, the pinion shaft spline count is also 30, and 12 bolt 8.875 (8-7/8) axle ring and pinion gears will not owrk in the truck axle the car 12-bolt has a pinion shaft diameter measuring 1.625 inches.
Without checking into it further I don't think the car and truck pinion shaft bearings are the same outer diameter so I am not sure if they will be able to swap from housing to housing. You would also have to check the carrier bearing measurements to see if those would be able to swap also.
 

·
Chopper Builder o<>\o
Joined
·
171 Posts
Discussion Starter #3
Thanks for the information. What I was curious about is whether or not the axles were the stock originals by looking at the markings on the axle shaft.
 

·
Premium Member
Joined
·
2,233 Posts
Your axleshafts look very much stock to me. I have quite a few of them around here.

The aftermarket shafts will not have the hollowed out center section in the middle of the flange like the ones your picture shows.

Looking on the websites of the major aftermarket axle manufacturers, theirs are ALL identified by fully machined flanges, the ones in your pic are cast with only the necessary parts machined.
 
1 - 5 of 5 Posts
Top