The Dana Spicer 44 axle has been a pillar of the four-wheeling community since the first time some '49 flatfender Jeep was dropped into low range and taken off road. These light- and medium-duty axles have been under Dodge, Jeep, Chevy, International, and Ford trucks as well as many cars and SUVs, and came with many variations of splines, pinions, aluminum housing, and so on. But it's time for an upgrade.
With the introduction of the '07 Jeep JK Wrangler Rubicon, Dana and Jeep collaborated to bring the old Dana 44 up to date with larger parts, from ring gears to axleshafts. In fact, this New Generation Dana 44 should probably have been named the Dana 48 because of all its upgraded innards.
Many of you may not be in the market for a brand-new Wrangler, but some are looking for a stronger new axle. Lucky for us, Mopar recognized those buyers and began offering its new Rubicon JK Dana 44 axles to the public at any local Chrysler, Dodge, or Jeep dealership. Mopar then expanded from the improved Dana 44 by also offering the axles from its military JK variant known as the J8 as well as JK axles modified by Dynatrac to bolt into the earlier Jeep TJs.
But there are even more new models of Dana 44s available with Dynatrac's new JK Trail Series 44 and the new Pro-Rock high-ground-clearance 44. All these new Dana 44 variants fit the new style of gears and lockers, different from the Dana 44 axles of yore, but with many different gear ratios and lockers becoming available.
So if you're building a new Jeep, a mini-truck, or a small, lightweight buggy, it's time to look at the New Generation of the oldest 4x4 axle ever.
The Mopar Jeep JK 44 axles differ from the older Dana 44s in many ways. Both the front and rear use larger pinion shafts, and the rear low-pinion axle also has a larger-diameter ring gear and new 32-spline axleshafts. Though they use different gears, factory and aftermarket gear ratios are available, from 4.10 down to 5.38. The high-pinion front axle uses a 1350 U-joint. Previous Dana 44s all had a smaller 1310 steering joint. Both front and rear JK axles can be equipped with disc brakes, 12 inches in front and 12 1/2 inches in the rear.
The next axle Mopar offered is the military variant from the J8 military Jeep Wrangler. Designed to be slightly stouter than the standard JK axle, these 44 fronts and matching Dana 60 rears come with front open differentials and rear limited slips but slightly thicker wall tubes, much bigger brakes, and the old-style 5-on-51/2 wheel bolt pattern, making them a great swap candidate for earlier jeeps CJs or YJs looking for stronger and slightly wider axles, though the front axle is left-side differential. However, if you are planning on swapping these under anything, notice that they come with the standard front JK coil spring and link suspension mounts, though the rear is set up for leaf springs. The J8 front 44 is the only new New Generation-style Mopar 44 that can use an aftermarket ARB or Detroit locking differential, as all the 44s that come with the GKN locker are currently machined in a way that doesn't allow swapping in the aftermarket lockers.
The final Mopar axle we'll discuss is the Mopar JK Rubicon axle Modified for Jeep TJs, or what we like to call the TJK Dana 44s. These axles start out as JK Rubicon axles, but are then modified by Dynatrac for Mopar with narrower housings, thicker-walled axletubes, and beefier brackets attached and ready to bolt into a standard Jeep TJ Wrangler (built from 1997 to 2006). These axles are available through any Dodge, Chrysler, or Jeep dealership and come with 4.10 gears, locking differentials, and high-pinion front and low-pinion rear housings.
New to the Rubicon axle line manufactured by Dana in the USA is the Jeep Tru-Lok differential, also known as an electronic differential lock (EDL), built by GKN's Driveline Torque Technology division. The four-pinion design of the GKN EDL in the Dana Spicer Model 44 front and rear axles can withstand multiple shock loads over 12,000 ft-lb. The GKN EDL is electromagnetically actuated using a solenoid system with a simple two-wire connection. It locks in under 0.5 second, even at -30 degrees C, and is validated for operation between -40 and 140 degrees C, yet in tests continues to operate at even higher temperatures. Unlike some competing products, the GKN EDL can engage at any vehicle speed and at wheel speed differences over 200 rpm; stays locked through rocking cycles, reducing driveline impacts and improving control; and does not require special lubricants or oil additives.
Dynatrac, in addition to supplying Mopar with some axles and being a certified Mopar dealer, has also come out with its own Dana 44 offerings. The first is the JK Trail Series 44. These are simply a JK Rubicon axlehousing that has been retubed with thicker-walled axletubes and stronger Dynatrac brackets (0.188 thick versus 0.125) so that if you bend or damage your current JK Rubicon you can simply swap all your internal parts into this housing or buy it complete from Dynatrac ready to bolt in.
For the be-all end-all in new-generation 44s, you need to look into the Dynatrac ProRock 44. These high-clearance housings come with up to 3-inch tubes, stronger end forgings, and extra-thick brackets. They can be used to swap in all your current JK internals and knuckles or can be built to your specifications for any project that needs a high-pinion, high-clearance, light- to medium-duty axle. Plus these housings can be made to accept either the GKN or aftermarket locking differentials, but only the new-generation ring-and-pinions with the larger pinion shafts. However, unlike Mopar, Dynatrac will give you any gear ratio available whereas Mopar only supplies a 4.10 ring-and-pinion.