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Rebuilding Rockwell Axles for Off-Road Abuse

Posted in How To: Transmission Drivetrain on July 31, 2019
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Rockwell deuce-and-a-half axles, named after the 2 1/2-ton military trucks from which they're pirated, are abundant, large, upgradable, and strong. Also, they have been the basis for some fairly awesome vehicle builds, from mud trucks and rock crawlers to rock bouncers and even a monster truck or two. We've been tripping over a pair of these storied axles for a few years now after they came out of another project that went a different direction, and we plan to build something big and bad with these axles as the base.

What are we going to build? A dedicated mud truck? A tubed-out, thousand-horsepower rock bouncer? A low and wide rock crawler? We answer with a question: How about a monster truck that can rock-crawl, hit the trails, and run down the road? Things may change, but that's the plan for now. A big, big-tire'd truck with Rockwells that gets used, come what may.

Lucky for us, Boyce Equipment of Ogden, Utah, is a longtime advertiser within the pages of Petersen's 4-Wheel & Off Road. The folks at Boyce know these axles and have a bunch of parts to both maintain and upgrade deuce axles. After a few phone calls to the company we had some trick parts headed our way to make these axles the perfect starting point for this project.

To start our teardown of the Rockwell axles, we removed the eight bolts retaining the front axle's drive flanges, and the rear axleshafts. The drive flanges easily slide off the axle stub, and the rear axleshafts slide all the way out of the axle like any full-floating rear axle. The lock nut underneath the axleshafts and front drivers require a 3-inch socket, but before you can loosen the huge spindle nuts you have to fold back the tab or two from the lockwasher securing the outer nut. We used a medium-sized chisel to do this. You can also use a chisel to loosen the big nuts, but it damages them and we would not recommend using a chisel to tighten any spindle nut unless it's an emergency. Use the proper socket or driver, 3-inch in this case.
With the spindle nuts off we used some longer 1/2-inch bolts as handles to remove the huge hub and drum. The drum may grab on the shoes inside it, requiring a puller, but with a little wiggling we were able to slide the drum over the shoes on both the front and rear axle. Once you have one drum off you can also see how to loosen the cam adjusters that hold the brake shoes against the drum. Turning the cam adjusters until they click should loosen them enough to pull the drum. If not, you'll have to rig up a puller.
The spindle nuts (12 of them per front wheel, to be exact) can now be removed so you can pull the massive spindle and then you can remove the axle. We are going to pull ours all the way out so we can remove the knuckles and replace this steering Rockwell's knuckle boots and upgrade to Boyce chromoly axleshafts. Our boots are in pretty good shape but do have some dry rot and a small hole or two (more on the boots later). You can see the huge stub shaft and axle U-joint covered in grease. There are at least three types of steering joints in Rockwell steering axles. One with U-joints, and two with CV joints with either five or seven balls. Supposedly the U-joint style is the strongest, but we are betting that the CV style joints are pretty strong, too, unless they're worn, dry, or damaged by water intrusion and rust.
It's hard to see, but this is a small cut or crack in our boot where grease could get out and water or dirt could get in. Since these axles have been sitting for a while we'd bet these cracks and splits would open up wide quickly with use. Our plan is to add some Eaton lockers to the axles so replacing the boots in the meantime is a no-brainer. Lucky for us, Boyce Equipment sells brand-new boots and boot clamps as a kit (PN BBCK250) with boots in five colors (if you're into that kind of thing). We got a set as part of the company's more comprehensive 2.5 Ton Front Axle Tune-Up Kit (BTK250A, $135) which includes boots, boot-clamps, seals, and gaskets. Boyce also tossed in some new spindle nuts and lock rings.
Here in the inside of the boot you can access the inner boot clamp (already loose) and get at the pull tab on the zipper to remove the boot. We'll clean up the old boots and use them for our post-apocalyptic warrior Halloween costume. We can now remove the last seals from inside the axlehousing and clean up the gobs of grease inside the knuckles and on the axlehousing. What does one do with two quarts of used grease?
For the rear axle we will have to remove these 12 rivets per side to remove the drum backing plates. We tried cutting a few rivets with the oxy/acetylene torch, tried drilling out a few, and finally learned that the easiest way to attack them was by grinding off one head and knocking them out with a drift and a hammer. This was probably the least fun part of tearing these axles apart so we can load the diffs with lockers—or maybe scraping up all that grease was the least fun part. Either way, while things are heavy (use an engine hoist) and there are many spindle bolts and rivets (be patient), everything came apart as expected on our axles without much fight at all.
With the axleshafts removed from the housing you can drain the differentials, remove the nuts retaining the axle's centersection (four of them require some slow work with a box end wrench), and then use an engine hoist to lift the centersection out of the axle. You may have to tap the housing with a hammer or pry with a screwdriver to get the centersection to separate from the housing.
The Eaton NoSPIN differential is what we would call a locker. Like its more familiar brother the Detroit Locker, this is an automatic differential locker. Installation requires removing the differential carrier from the centersection, splitting it in half, removing the spider gears and thrust washers, and of course installing the NoSPIN. The procedure is similar to that of a GM Corporate full-float 14-bolt axle. Leave that bolt through the middle of the locker in place until the two halves of the centersection are reassembled.
We've hinted at this fully hydraulic steering system from PSC for the Rockwell axles before. It includes just about everything we need to make the big axle steer. We will also fabricate a ram mount and get this steering system all sussed out on the front axle in the coming months.


Boyce Equipment
Ogden, UT
Cleveland, OH

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