Inside the 2 1/2-ton Rockwell Axle

Deuces Wild

Christian HazelPhotographer, WriterCurt SadlerPhotographer

You can be extremely dumb with Rockwell axles. Roll up to a ledge, place your 44-inch tire on the up slope, then lay into your 400-horse engine and get ultraviolent until you either make it to the top or your engine blows. Rockwells don't care. They'll take whatever you give them, then say, "Thank you sir, may I have another." Plus, if you look hard enough, you can pick them up for almost nothing.

We're starting to see a whole lot more 2 1/2-ton Rockwell axles on the trail, so we thought we'd better show you the ins and outs of these behemoths before they become yesterday's news. Lots of magazines have covered them in the past, but most have just skimmed the surface. We visited Mark Boyce of Boyce Equipment and Clifton Slay of Poison Spyder Customs to bring you the dirt you'll need to plan and successfully execute an installation.

Inside the 21/2-ton Rockwell

Centersection: Double reduction-style - The upper ring-and-pinion gearset drives an intermediate gear that, in turn, drives the big, gnarly bull gear. The differential or locker is housed inside the carrier sandwiching the bull gear.

Upper ring-and-pinion: 22-teeth on ring gear, 9-teeth on pinion = 2.44:1 Lower bull gear and intermediate gear: 33-teeth on bull gear, 12-teeth on intermediate gear = 2.75:1

Final gear ratio: 6.72:1 (combination of 2.44 ring-and-pinion and 2.75 lower gear)

Axleshaft: 1.62-inch, 16-spline

Differential: Open four-spider gear design or Detroit Locker (PN 225S-15)

Bolt pattern: 6-on-8 3/4

Problems and Solutions

Deuces can be configured in lots of different ways. In stock form, the fronts were bolted to the springs with the tie-rod facing behind the axle and the driveshaft flange on the passenger side. The rears also have the driveshaft flange offset to the passenger side. You can spin the axles 180 degrees on the springs or, because the centersections come with a driveshaft flange attached to both sides of the pinion shaft, you can rotate the centersection 180 degrees on the housing by redrilling a few holes. This will allow you to accommodate virtually any driveshaft offset or clearance issue you may encounter.

A few other things you may need to consider when locating these axles in your rig and deciding on the orientation of the driveshaft flanges is that the centersection is massive and sticks 9 1/2 inches above the top of the axle tube. Interference with oil pans, crossmembers or suspension links is a definite possibility unless you get creative with your swapping and flopping. Also, these suckers have 6.72 gears, so unless you're going to be running at least 42s or 44s and an overdrive, you can kiss highway-driving goodbye. From what we've seen, big tires, pliant leaf springs and even moderate power levels don't work well with these axles. There's so much gearing, weight and leverage involved that massive axlewrap is hard to avoid. Consider building a three- or four-link suspension off their square axletubes instead.

Finally, most military wheels with the Rockwell's big 6-on-8 3/4-inch pattern are for 20-inchers. You should be able to run custom 15-inch wheels with no clearance issues if you ditch the factory drums in favor of a pinion-mounted disc brake.

Options

Shaft Styles

DimensionsWheel mounting flange-to-flange
Front axle - 79 1⁄2 inches
Rear axle, single wheel configuration - 69 1⁄4 inches
Rear axle, dual wheel configuration - 79 1⁄2 inches

Rockwell Sources

Boyce Equipment Carries rebuilt and used (and sometimes new in crate) front and rear axles, locking hubs, pinion-mounted brakes, Detroit Lockers, replacement and custom axleshafts, U-joints, axle boots, wheels, steering components including full hydraulic conversions, any other part you could need to rebuild a deuce Contact: Boyce Equipment, 800/748-4269, www.boyceequipment.com

Chuck's Trucks Carries used or refurbished front and rear axles, Detroit Lockers, gears, custom housings and shafts, full hydraulic steering kits, pinion-mounted brakes, wheel-mounted disc brake kits for front or rear, wheels Contact: Chuck's Trucks, 407/650-3802, www.chuckstrucks.net

Matkins Frames Carries used front and rear axles, axles with new bearings and seals, custom- or stock-length axle shafts, pinion-mounted disc-brake kits, wheel (spindle)-mounted disc-brake kits for front (13-inch rotor) or rear (11-inch rotor), wheels Contact: Matkins Frames, 406/248-3797, www.matkinsextreme.com

Poison Spyder Customs Carries Deuce Skid skid plates, high-steering arms, full hydraulic steering parts, pinion-mounted brake kits, wheels, drive flange caps for raised tie-rod clearance Contact: Poison Spyder Customs, 303/777-4820, www.poisonspyder customs.com

Sam Winer Motors Carries used front and rear axles and used wheels Contact: Sam Winer Motors, 330/628-4881, www.samwinermotors.com

Wagoneer Machine Shop Carries steering arms, full hydraulic steering systems for front or rear steer, pinion-mounted brake kits, 3/8-inch-thick skidplates, machined front hubs, high-clearance steering arms, custom tie-rods Contact: Wagoner Machine Shop, 918/341-1722, www.wagonermachine.com

Related Articles