Rear axles transmit engine power from the drive line to the rear wheels, multiply torque & serve as
a major load carrying member. The efficient performance if these functions are of major importance in
the design of truck rear axles. The GM H-072 rear axle is a Hypoid single reduction 4.57:1 ratio drive
axle. It had an option of a 5.14:1 ratio and Locking Limited Slip Differential. This is a "Full-floating"
design. Full-floating axles are used in medium and heavy duty trucks. Axle housing in this type carries
all the weight while axle shafts serve to turn the wheels. Wheel hubs rotate on bearing on the outside
of the axle tube, allowing shafts to literally float within the housing. See the Axle Data Page For More.
This is the axle in my 1965 One ton, as you can see in these photos, the pion seal and mount gasket are leaking.
Also the Wheel Cylinders were leaking bad, it had very poor brakes. One cylinder was rusted tight on one end.
It took me a year to find new one, no one listed them in there parts book. I found a GMC parts book on eBay
won the bid and looked up the GMC Number, I took that number to the local NAPA store and they found the
cylinders sitting on the self in SLC!!! Here are the NAPA numbers for these: 9344 & 9345, $106.86 each!!!
So I needed to tear down the rear axle to replace the Wheel Cylinders, and it need the brakes relined too...
NAPA had the new brake shoes, and spring kits, and turned my drums, but the bad news is the drums are
over and need replaced, but they can't find them and have been told the are out of podution. So I'm
looking for a early 90s GMC one ton Dually rear axle for this truck. Below are pics of the brake reline.
The truck now has new brakes on the rear but the axle will still need to be replaced, someting with
a gear ratio higher than 4.57:1 would be nicer to drive down the hiway as well.
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