This is a JK Rubicon Dana...
This is a JK Rubicon Dana 44 front axle that has been converted and is ready to bolt in a TJ. It doesn't look like anything special, but it is.
If you're a Jeep TJ owner with a bit of JK jealousy, you're not alone. There are so many things to like about the new JK. Thing is, there's also a lot to like about the TJ. What if you could integrate some rugged JK components onto your TJ? Now that would be cool, wouldn't it?
Well, that's exactly what the team at Burnsville Off Road in Burnsville, Minnesota, has been doing lately. They've been transplanting JK Rubicon Dana 44 axles into the TJ using their JK-to-TJ Axle Conversion Kit. Why is this a big deal? Well, the JK Rubicon Dana 44 front and rear axles offer a number of upgrades over the TJ Rubicon Dana 44 axles. Hey, not all Dana 44s are the same. In fact, the Dana 44 has been trotted out with a vast number of variations over the years and the Jeep Wrangler Dana 44s are no exception.
Compared to the front TJ Rubicon Dana 44, the JK Rubicon Dana 44 has a larger diameter pinion, more outer axle splines, and larger axle joints. The JK axle is also a high pinion and it offers a knuckle with a 4-inch-higher steering mount so you can bid farewell to that "inverted Y" TJ steering. The rear JK Rubicon Dana 44 bests the TJ Rubicon Dana 44 in pinion diameter, axleshaft spline count, and axletube diameter. In addition, the JK Rubicon Dana 44 axles provide bigger brake rotors and calipers, and they offer electric lockers instead of air-actuated lockers. Taking it a step further, when the JK Rubicon Dana 44 axles are compared to the TJ Dana 30 and the Dana 35C, the improvements are even more dramatic.
We recently had the opportunity to travel to Burnsville Off Road and observe the process of how the Burnsville team converts a pair of JK Rubicon Dana 44 axles for fitment into a TJ. Here's how it works.
1. Here are a few JK Rubicon Dana 44 internals compared to TJ Rubicon Dana 44 internals. As you can see on the left, the JK axleshafts are longer than the TJ axleshafts. This is because the JK axlehousing is 5 inches wider than the TJ housing. We'll cover how that plays into the swap later on. Look closely at the axleshafts and you'll see that the JK axleshaft U-joint is larger than its TJ counterpart. The TJ uses a Spicer 760X and the JK uses a Chrysler-specific joint that is equal to a 1350. The ears on the JK yoke are wider and thicker, too. Further, the JK stub shaft has 30 splines, where the TJ only has 27 splines. On the right, you'll notice that the JK pinion is also larger in diameter.
2. Naturally, the JK's larger...
2. Naturally, the JK's larger diameter pinion requires a larger pinion bearing. Here you can see the smaller TJ pinion bearing atop the JK bearing. This larger bearing will handle torque better, which will increase its life.
3. This is the new bracketry...
3. This is the new bracketry for the front axle. Burnsville uses an off-the-shelf TeraFlex kit. The kit includes a track bar/steering stabilizer mount, lower control arm mounts, shock mounts, spring pads, and sway bar brackets. There are no new upper control arm brackets because the stock JK brackets are reused. Also included in the Burnsville kit, but not shown here, is a new Burnsville-supplied track bar, tie rod, and chrome-moly drag link.
4. The kit for the rear axle...
4. The kit for the rear axle is also from TeraFlex and contains coil spring mounts, lower control arm brackets, shock mounts, a track bar bracket, upper control arm mounts, and sway bar mounts. Slight grinding of some of the mounts is necessary to fit them to the 3-inch-diameter axletubes.
5. The first step in the conversion...
5. The first step in the conversion is to remove all of the factory bracketry from the front and rear axles. Here you can see some of the bracketry that was removed.
6. After all the bracketry...
6. After all the bracketry is removed from both axle housings, they're prepped for the new bracketry by being ground smooth. This step is lengthy and tedious and usually takes about four hours on the front axle and two hours on the rear axle.
7. Here's how the front axle...
7. Here's how the front axle looked when completely prepped and ready to receive the new bracketry. Note that the only factory brackets reused are the upper control arm mounts.
8. Positioning the new bracketry for welding is the tricky part, because these components must be placed in the correct position and angle. Improper placement or imperfect welding will result in improper fitment and the offending bracket(s) must then be cut off and repositioned. Technician Brian Ament has done scores of these conversions and he made the process look easy. First, he tack-welded the shock mounts and then the spring pads.
9. Next up, the lower control...
9. Next up, the lower control arm brackets were tack-welded in position.
10. The track bar mount was...
10. The track bar mount was the final piece to be tack-welded in place. Ament says that on average, it takes about an hour to place and tack-weld the bracketry to the front axle.
11. It takes another hour...
11. It takes another hour to perform the final welding on the new bracketry. After everything cools off, the axle is cleaned and then painted black. At that point, it's ready to be installed in the TJ.