We win here or lose everywhere. If we win here, we improve our chances of winning everywhere." General Douglas MacArthur said that. Since he's practically as American as any one person can be, we thought it appropriate to start with in another segment of our Project All-American buildup.
Besides, if you get down to, it applies rather well to the building of the ultimate 4x4. How, you may ask? If you're going to do something, you have to do it right. You don't build a vehicle with an Achilles' heel after sparing no expense in every other aspect of it. Win in everything or lose everywhere. That's what Big Mac meant. And that's what we've set out to accomplish with Project All-American.
Since we'd selected a pretty hefty tire and wheel combination (37-inch Goodyear MT/Rs on 15x10-inch MRT steel bead locks), axle strength became of great importance. After all, you can't be snapping 'shafts or slipping tires while in combat, er, we mean, on the trail. For this matter, we opted to use one of the most common and reliable front-axle applications around, the venerable Dana 44. And when it came time to find a builder, we didn't have to look any further than the far south of California, where we discovered Mechanically Inclined Techs (M.I.T.) Drivetrain Specialists in El Cajon.
The crew at M.I.T. isn't just one of the most experienced around, they're also some of the wackiest and good-natured folks in the industry. They even didn't mind (so much) when we showed up an hour late only to discover we'd ordered the incorrect Yukon Gear & Axle gearset from Randy's Ring & Pinion and essentially blew a whole day of their calendar. Thankfully, Randy's Ring & Pinion remedied the situation by shipping the correct set faster than we thought possible, and we were back on track in no time.
Another end in the strength factor of our axles lay within our choice of axleshafts. Wanting the meatiest setup possible, we discovered Moser Engineering and its M/E Dana 44 Custom Alloy Front Axleshafts. The Moser units are redesigned and beefed up in critical weak areas around the U-joint and constructed of the same material that it uses for its racing applications.
We topped these with spindles, U-joints, and a pinion yoke from Spicer. Lastly, we desired a traction-aiding device that would allow us the same level of on-road control that it would offer in off-road capability. ARB reared its head with its innovative Air Locker and we were sold. Check out the sidebar about its functions for the low-down.
So here it begins, the mechanics of Project All-American. You can look forward to the buildup of the rear Tera 60R next month, and leaf spring and frame tech will be soon to follow. And, hopefully, with each stage, we'll continue to "improve our chances of winning everywhere." Stars and Stripes forever, people. Don't forget it.
The Workings of It:
The ARB Air Locker
Appropriate to its name, the ARB Air Locker is just that. It's a locking differential that is capable of being locked using pressurized air. What's the benefit of this? For one thing, it gives you the option of a conventional or fully locked differential at the push of a button. This means you can roll down the highway at speed and make turns without the typical locker bump, or traverse the most difficult of trails without losing grip. Since it's capable of being manually engaged and disengaged, the ARB is an excellent choice for front diff applications because it has no effect on the steering when disengaged.
When the unit is activated via an in-cab button, an air solenoid valve located on the compressor opens, allowing air to be fed down a nylon tube to a bulkhead fitting on the differential housing. Another tube runs from there into the diff case to an air-seal housing installed on the bearing journal of the ARB unit, where a small air inlet hole in the bearing journal enables air to be sent into the locker while it's rotating.
This compressed air, in turn, activates an annular piston inside the locker, which locks the axleshafts together with a large locking gear. Once the in-cab switch is shut off, the compressed air is spent out of the solenoid valve, and built-in coil springs within the Air Locker return the locking gear to the disengaged position. It's technology at its best, people.
The ARB Air Locker is provided with all the necessary components for installation. Note the new heavy-duty black air line in addition to the traditional ARB 6-meter length of blue, nylon tubing. You can read more about it in this month's "Product Review."
Moser Engineering produced these 35-spline Dana 44 custom alloy axleshafts to the specs we gave them. They also saved our rears by over-nighting the altered 'shafts back to us when we realized our measurements were off. It's good product from good people. Thanks, guys.
M.I.T. in El Cajon, California, did a great job of prepping the Dana 44 housing. Here, gear guru, Mitchell Wilson, drilled out the breather hole to 7/16-inch to accommodate the brass bulkhead fitting for the air line. Then the hole was tapped using a 1/4-inch NPT thread.
A second hole was drilled and tapped to function as the breather and fittings were installed, accordingly. Mitchell cleaned the housing thoroughly to remove any metal shavings.
After greasing the inner axle seals, Mitchell knocked them into place. Also note the brass air line that was halved from the seal housing with a cutoff wheel. It'll be re-coupled later on.
Randy's Ring & Pinion of Everett, Washington, supplied us with a fresh Yukon 5.13 gearset and the necessary seals for installation. Randy's also bailed us out by over-nighting a non-reverse gearset after we'd inadvertently requested a reverse set.
A 20-ton shop press was used to press the bearings onto the pinion gear.
Mitchell tapped a new crush seal into place, then installed the new pinion gear.
ARB suggests heating the ring gear to between 175 and 212 degrees Fahrenheit to facilitate assembly. M.I.T. did this in its monster oven. Once it was piping, Mitchell pulled it and bolted it to the ARB unit using the supplied bolts and Loctite. The bolts were torqued to 65 lb-ft. The bearings were also pressed on, of course.
Mitchell used a dial caliper to determine the proper widths of the shims. He started at 0.0040-inch and adjusted them accordingly for the correct backlash and pinion depth.
After greasing the seal housing, Mitchell positioned it on the air inlet side of the ARB. The procedure for assembly from that side out is: bearing cone, bearing cup, O-rings, seal housing, adjusting shims, then the 2.5mm spacer washer.
The ARB unit was set inside the housing with the seal housing's brass air line pointing directly up.
Once the unit was positioned in the housing, Mitchell marked the bearing cap on the seal housing side of the differential, then drilled a 1/4-inch hole in which the air tube will pass. The hole was also chamfered approximately 1/8-inch to remove any sharp edges that could damage the line.
The bearing caps were then torqued to 90 lb-ft.
Mitchell used a dial indicator to check the backlash, which should range between 0.006 and 0.0012 inch. He adjusted it by removing the unit and increasing or decreasing the number of shims per side.
With the unit bolted in place, Mitchell applied a bit of yellow marking paint to the ring gear and then used a wrench to rotate it forward and backward to determine how the gear teeth were meshing.
Here you can see the pattern created as the ring gear meshes with the pinion. Pinion depth and carrier shimming are two factors that can affect the pattern. Basically, it's a trial-and-error setup where you're looking for a balance between the drive side and coast side of the gears. The more balanced the pattern, the quieter and more smoothly the gears will operate.
When we found the correct shim setup, the ARB unit was positioned in the housing and the bearing caps torqued to spec. Then Mitchell coupled the brass air tube from the seal housing using the provided hardware.
As a final precaution, Mitchell hooked the air line to a 90-psi air source and used soapy water to look for leaks.
Mitchell lubricated the Spicer yoke with Permatex before bolting it to the pinion.
Gasket sealant was applied to the differential cover mounting surface, and the cover was bolted in place.
The 20-ton shop press was used again to press the upper and lower ball studs into the steering knuckle.
Mitchell mounted the knuckles to the axle flanges and secured them using jam nuts and cotter pins.
With the differential installation finalized, Mitchell went about prepping the Moser custom alloy axleshafts. Here, he installed the Spicer U-joints and tapped the caps in place.
New crush sleeves were installed on both outer axleshafts before installation, in addition to seal seats and bearings.
Mitchell slid the shafts into the axle tubes until they fully engaged the internal splines of the ARB unit.
The Spicer spindles were positioned on the axleshafts and lined up with the bolt studs on the knuckle.
M.I.T. supplied us with a used rotor shield, which Mitchell prepped and painted. Then it was bolted to the knuckle.
A new steering arm was secured to the right-side knuckle using new cone washers and bolts.
Mitchell packed four bearings with grease for the Raybestos hubs and brake rotors, then tapped them in place inside the unit.
The hub and rotor were then positioned on the spindle.
To secure the hub on the spindle, Mitchell used a spindle nut socket on an impact wrench. Then he used a pair of snap-ring pliers to apply the large snap-ring within the hub to lock it in place.
Warn Industries provided us with a set of its tried-and-true Warn Premium Hubs. Installation is a cinch, and the overall performance is unfailing.
An Allen wrench was used to secure the Warn hub caps to the axle assembly.