Hi Grant,
Well, here goes... Bear in mind that I am NOT the axle guru here!! Trust
me!!
There are several different rear axles you'll run across. The "corporate"
is kind of like the generic GM axle. There are DANA/Spicer's and other
brand name axles with notable differences from the corporate. The DANA's
have model numbers like "44" for example. That's supposed to directly
convert to the axle weight rating. 44 would equal a 4400 pound capacity
axle. Corporates are labeled differently, and parts do NOT interchange with
the "brand name" axles. I don't have a 1/2 ton, but there are major
differences between the 1/2 ton and 3/4 & 1-Ton corporate housings. The 3/4
& 1-Ton housings are the same with the exception of the gear ratio. The
half ton corporate units are Model #HL-53??, and the 3/4 & 1-Ton units are
Model #HO-72.
The 1/2 tons have a 6 wheel lug set-up similar to the more modern axles,
and somewhere between a 9 inch ring gear and a 10 1/2 inch ring gear. I'm
not sure on the specifics, as I don't own one, but those should be somewhere
within a mile of the ballpark at least. The brake drum covers the axle end,
and is flush. No big hunk of axle housing sticks out through your wheel
rim. To remove an axle, you're supposed to take off the inspection cover on
the differential, and remove some "C" clip type of a thingee that holds the
axle sections in place in the "Chunk". (Can't you tell I have "Major"
experience with these?!?! In addition, on the 1/2 tons, the differential
"chunk" itself is removed through the inspection cover at the rear of the
axle housing.
The 3/4 & 1-Ton has what's called a full-floating axle. It's an 8 wheel
lug set-up and has that huge hunk of axle housing that sticks out a few
inches beyond the center of the rear wheel rim. The full floater axle
actually comes out of that external end by unbolting all the little bolts
showing at the wheel ends of the axle housing. There are no internal
devices to keep the axle locked into the differential unit, or "chunk". The
3/4 and 1-Ton also has a 12 1/4 inch ring gear. They will NOT interchange
with a 1/2 ton. The 3/4 & 1-Ton "Chunk" is called a "drop-out" unit, and the
whole mess unbolts and is removed from the front side of the rear axle
housing. The drop-out includes the support section and flange for the
driveshaft. The 1/2 ton does not. In addition, the 3/4 & 1-Ton corporate
housing has a very smooth "round" inspection cover on the rear of the
housing that has 10 bolts.
On the NAPCO's, the front axle is a modified "corporate" housing, and the
differentials (1/2 ton) and drop out's (3/4 & 1-Ton) interchange between
front and rear axle. The center sections of the axles and housings are the
same front to rear. A NAPCO 4x4 conversion retains the stock rear axle,
which is the same as any two wheel drive truck.
Now, how about some "real" axle guru fix what I messed up!!! (Smile!)
Yours, Kevin P.
'59 Apache 38/NAPCO
-----Original Message-----
From: Grant Galbraith [mailto:trks@javanet.com]
Sent: Friday, January 21, 2000 5:13 PM
To: Kevin D. Pennell
Subject: Re: [oletrucks] Rear end question
Kevin,
I was going to buy a chuck tomorrow to put in my '52 GMC 3/4 ton. I'm not
familiar with corporate axle. Is that what I have? Will I have a problem
with
splines matching. I would check the ones on my 52 but it is 0 degrees and
the
wind is howling, I don't feel like working outside.
Also as long as we are talking rears, I found half ton axles for sale
from a
61 suburban. The seller say's they are corporate axles. Are they very much
different from Napco?
Thanks, Grant
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