Ali Mansour
Brand Manager, 4WD & Sport Utility
The ’07-currenT Jeep Wrangler JK Unlimited is one of the best builder platforms to ever come out of the seven-slot stable. Four doors make the Unlimited JK more practical for the masses, the 116-inch wheelbase provides a nice balance of on- and off-road performance, and a multilink suspension allows for easy modifications. Given the immense aftermarket support for the JK, it’s no surprise that we see the late model Wranglers lining trails and highways across America. While the 3.8L V-6 in the ’07-’11 models doesn’t win much praise on the performance front, the early-model Unlimited JKs are proving to be an affordably-priced used rig. You can thank part of that lower resale price to the more powerful 3.6L engine launched in 2012.
Weighing in at roughly 4,300 pounds in stock form, one of the biggest drawbacks of the Unlimited JK is that it can quickly pack on pounds when modifed. In fact, it’s not uncommon for heavily-modifed Jeep Unlimited JKs to easily rocket into the high 5-, 6-, or above the 7,000-pound range! That’s as much as a ¾-ton truck! Aside from the fact that the V-6 isn’t the sprightliest engine, the real trouble lies in the stock axles.
Even the Next-Generation Dana 44 axles found under the Rubicon edition are no match for big-weight fgures and 37-inch-plus tires. If there was ever an excellent candidate for a vehicle that could use a factory full-foat axle option, the Unlimited JK would be it. Until recently, your axle upgrade options were limited to big name aftermarket axle builders. This was mostly due to the fact that companies such as Currie Enterprises and Dynatrac were the only option for those who wanted full-foat axle assemblies that would work with the JKs wheel speed sensors.
Luckily, there is now a more budget-friendly alternative for getting 1-ton differentials under your Jeep. It’s not too often that you can combine junkyard and JK, but there is a way that the two co-exist rather nicely. In this three-part build series, we’ll take you through the process of transplanting a set of wrecking yard sourced ’02 Ford F-250 Super Duty axles and placing them under an ’07 Jeep Wrangler JK Unlimited Rubicon. In this frst edition, we are getting right to the meat of the swap with the high-pinion Dana 60 front axle.
1. Prep work is a large part of any axle swap. The ’99-’04 Super Duty Dana 60 front axle only has a few suspension mounts to remove. After we ditched the stock brackets, we cleaned the axletubes with a grinder and tore it down completely. We then used our JK’s stock front axle to gather base measurements for where our new brackets will be placed.
2. One of the biggest hurdles of the Dana 60 swap is the limited space for brackets on the driver side of the axle. This is due to the large differential casting. While welding to cast can be done, in this case, we opted to remove a section of the driver-side casting to expose the more easily welded axletube. After taping off the area we wanted to expose, we used a Sawzall and chisel to peel back the small section of cast material. Since we are moving to a coilover mount, we don’t need as much surface area as a coil bucket would require. However, it is possible to ft a coil bucket on the driver side of the axle.
3. To minimize some of the fab work involved, we sourced a JK axle bracket kit from Currie Enterprises. The complete Currie kit comes with upper and lower control-arm brackets, track bar mount, sway bar tabs, coil buckets, and shock mounts. The passenger side of the axle provides plenty of room to set the brackets, so we quickly burned in the 3⁄16-inch steel set using our Miller Millermatic 212 MIG welder.
4. Since we intend to use the Jeep’s current TeraFlex long-arm suspension and didn’t want to weld directly to the differential casting, we built an axle truss to allow a spot for the upper control arm to attach. The custom truss is comprised of 3⁄8-inch steel plate. In addition to being welded to the axletubes, we bolted the truss to the top of the differential housing.
5. The high-pinion Dana 60 differential allowed us to upgrade to a 5.38:1 gearset, which we attached to the new ARB Air Locker. We say new since ARB not only ftted the Air Locker with a fresh logo, but a 40-percent strength increase. This was accomplished by moving from a three-piece case design to a patented two-piece case design with forged gears. The selectable Air Locker offers excellent strength and added maneuverability to the Unlimited and is a great ft for this daily driven JK.
6. The ’99-’04 Super Duty Dana 60 is ftted with 1.5-inch axleshafts and massive 5-806 U-joints. While the inner ‘shafts are ftted with 35-splines, the stock outers are 30-spline. There are plenty of aftermarket ’shafts for those looking to upgrade to chromoly and 35-spline outers, but we are going to stick with stock for now and see how well the combo works under the Jeep.
7. By far, this is the most important part of the axle swap. Take note. The reason that the Super Duty Dana 60 is the perfect junkyard axle for the JK is that it has unit bearings. OK, so we don’t always dig unit bearings, but in this case, they make life easy. The legendary axle builders at Currie Enterprises have done their homework and designed a unit bearing that can use the JK’s stock wheel speed sensors. The company’s custom F-450 unit bearing can be ordered in a few different bolt patterns, but we opted for 8-on-170 to match our rear axle.
8. Since the Super Duty Dana 60 is a ball-joint axle, we took a trip to our local parts house and got a new upper and lower ball joint set. Given the heavy diesel engine and abuse that the stock joints are designed to take, we doubt we’ll have much trouble out of them under the Jeep.
9. Steering is one area that you have a few options. First, it is possible to reuse the Super Duty’s tie-rod ends and stock lower bar, but the odd shape of the bar makes it less than desirable. We are staying with tie rods, but are moving up to larger Chevy 1-ton tie-rod ends, which required us to take a reamer to the top of both steering knuckles. Currently, we are keeping the stock differential cover as well, which means a straight tie-rod bar will not interfere with the cover.
10. From the factory, the JK has a separate drag link and tie rod. We wanted to mimic/improve this setup, so we sent out our Dana 60s passenger side steering knuckle to Weaver Fabrication in Redding, California. Weaver machines, drills, and taps six holes in the knuckle for the company’s high-steer arm to mount. Once we place the axle under the Jeep, we will drill out the arm in the appropriate spot and attach our custom drag link.
11. Our junkyard 60 still had the stock vacuum assist hubs, which were plastic and broken. To upgrade, we installed a set of affordable and durable Warn hubs. Unlike the JKs stock unit bearings, the selectable hubs allow the front end components to be completely disengaged, reducing wear and drag.
12. Brakes were another spot that just needed some freshening. A quick test showed that our JK’s aftermarket steel-braided soft lines bolted up to the Dana 60s twin-piston calipers using a 3⁄8-inch -24 banjo bolt.
13. The stock Jeep Wrangler JK axle measured just over 65 inches wide (measured between wheel mounting surfaces). The ’99-’04 Super Duty Dana 60 front axles are right under 69 inches. There are some pros and cons to gaining width, and once we get our 1-ton axles bolted under the Jeep, we will delve into this a bit more.
Sensor Smart
A few things we feel you should know about wheel speed sensors and the JK. The ’07-’11 Jeep Wrangler JK will operate (run, drive, do smoky burnouts) without a single wheel speed sensor, the ’12-current JKs will not. Unfortunately, running without wheel speed sensors means your dash will be ablaze with lights, your speedometer will no longer work, and your check engine light will be on. Since the JK uses the wheel speed sensors for your speedometer, you need to have at least one to make it work in the pre-2012 models. One speed sensor will also kill the check engine light, an important fact for some depending on your state’s inspection requirements. Essentially, you could grab a junkyard Dana 60 such as we have and purchase only one unit bearing from Currie. This would cut down the cost of the axle conversion even more. We don’t recommend ditching ABS and ESC for most daily-driven vehicles, but it certainly is something that we know many of you can live without.
