OK..now I'm confused about my rear (again)

[Canada20]

All this talk about 14 bolt vs Dana60 vs coporate has me turned around on what's what....

I thought a 14 bolt was the same thing as an Eaton rearend and that the Eaton was pretty much the same thing as a Coporate rear. In fact I had it in my head that Eaton was the company that made the 14 bolt rear starting in the '70's, kind of like Tremec started making the Ford toploader in the late '70's for Ford. And Dana is short for Dana-Spicer, the company that makes diffs that the "big 4" (at the time, AMC was still alive) were using in trucks and jeeps and suchlike.

So what is a corporate rear, an Eaton and how do I tell the diff?

Thanks

Greg

[COBALT]

This is a picture of an HO72 under a 3/4 ton, or a 10-bolt GM corporate axle. Now there's some debate about HO52's and 72's and whether or not they're leaf or coil sprung, but all of the numbers on this diff point to an HO72--but that's not the point of this thread. The point here is that this carrier was made by Eaton, as were some of the components including the optional posi unit when the truck was brand new. The axle isn't really an "Eaton" axle. Typically they had various gear ratios including 4.10 and 4.56. You can buy 3.90s new off the shelf for them.

[ckhd]

14-bolt is not the same as an "Eaton". They both have "corporate" in their names - corporate 14-bolt, and corporate H-072 (Eaton). I'm sure you know what a 14-bolt looks like:



The H-072 looks quite a bit different:



That is the best pic I could find in a pinch. If you look at the rear, the cover is completely round, and basically shaped like a salad bowl.

It's possible that Eaton made/makes 14-bolts. I don't know. I'm sure that some 14-bolts have Eaton posi units in them...

Anyway, GM 14-bolt, Dana 60, and a "corporate" axle are all different. Here on this board, when we say "corporate" axle, we are referring to the 'Eaton' H-072 axle, since corporate 14-bolts weren't in production until after '72.

What's strongest? There will be endless debates about that. I think that the 'Corporate' (H-072) axle is stronger than the Dana 60 OR the GM 14-bolt. I probably wouldn't spend the money to overhaul one, because I could get a good Dana 70 for less than what overhauling a "corporate" axle. The 'corporate' axle in my '68 has worked flawlessly without a hitch for over 34 years now...

I think that hands down, a Dana 70 is is stronger than the other three.

[Mike C]

A corporate rear in a 67-72 usually referring to the Eaton. Technically a 12 bolt is a corporate rear as well, but usually not referred to that way. (Same as an 8.5" 10 bolt is a corporate 10 bolt but there is also a Chevy 8.2 10 bolt and a BOP 8.2 10 bolt) I believe the Eaton has 10 bolts, but it obviously is no 10 bolt! The last year of the Eaton was 72 at which time it was replaced by the 14 bolt GM for the 73 and up models. This is referred to usually as a 14 bolt but sometimes as the corporate 14 bolt. When talking about rear axles and using the term corporate, people should reference the year, but on the 67-72 board assume a corporate rear is the Eaton. Someone who has done a 14 bolt will usually specify. There is a full floater 14 bolt with 8 lug wheels where the axle just drives the hub and the hub has two sets of greased bearings like in the front and there is a semi-floater 14 bolt with flange type axles and uses 6 lug wheels that has pressed in/on single axle bearings. They also have different diameter ring gears 9.5 vs. 10.5 in the floater. The semi floater is a great upgrade for a 1/2 ton 4 wheel drive if you don't want to pony up for new wheels. Did I miss anything?

[COBALT]

That's a good assembly break-down of the HO72. I think I'll steal that!

Yeah, these axles are damn strong but when they go they go hard, and yes they are damned expensive to overhaul:

$500.00 - Carrier Bearing set
$500.00 - New detroit locker (replace spiders)
$250.00 - New Gear Set (3.90s)
$300.00 - Labor
-----------
$1550.00 - Holy Crap! You could buy one of those cool aftermarket Dana 60 w/ 3.73 with the carrier bearing deflectors built in for less than that.

[ckhd]

Steal away! I got it from a post here a while back myself.

Here's a larger version of it: It's not as clean of a scan, but it's larger!

http://www.udallart.com/pics/bowen/6772/h072.tif

Here's a pic of the locker that goes in it too, if you want it.

http://www.udallart.com/pics/bowen/6772/locker.tif

[adamls]

To make it easy, Eaton makes the guts (ring and pinion gears, usually a posi traction) inside the axle housing. The "XX Bolt" refers to the type of axle housing that the guts are in. Check out this site for a good picture of the different types of rear ends out there.

www.prestage.com/cars/RearEnds.asp

[Blazer1970]

All "current" (since 1973) GM "corporate" axles are made by American Axle and Manufacturing. This includes everything referred to as a 10 bolt (many variations with 7.5 and 8.5 inch ring gears), 12 bolt (car and truck axles), and 14 bolt (3 different ring gear diameters). AAM used to be owned by GM, but it was spun off a few years ago as a separate company. AAM installs Eaton Gov-locks and clutch type limited slips in some of the axles per GM spec, but Eaton and AAM are two completely different companies.

Those old drop out style "10 bolt" axles that were used in 3/4 and 1 ton pickups (and a lot of other applications) before the 14 bolt came out were made by Eaton.

Dana (Spicer Gear) is another totally separate company that makes tons of different live axle designs (model 30, 44, 60, 70, 80, etc.).

[Canada20]

Thanks for the pics, folks, that's going to help a helluva lot when I start crawling around under the ol' beast tomorrow to try and ID some things. Good links too, thanks for that.

I think I'm going to borrow a digital camera and post some pictures. I want to ID my tranny for sure as well so I might ask for help with that too.

Thanks

Greg