It’s a bold claimthe strongest Dana 44 ever built. And admittedly, you could argue a few exceptions in certain components. But overall, the Dana 44-based Dynatrac ProRock JK axle has to be the strongest ever built. Feel free to scratch your head for a second. We are in fact talking about a Wrangler-based axle, and it took us a few minutes to put together the fact that this axle is stronger than even the thick-tubed eight-lug Dana 44s found on ’70s F-250s. But after a review of the components list and options found on this axle, we think you’ll agree that this is an axle that could be considered overkill on any JK or even fullsize truck. And this is exactly why we built this one 74 inches wide (almost 10 inches wider than a standard JK housing) and are putting it under a half-ton truck with 37-inch tires. In an upcoming issue, we’ll have an update of how this axle is holding up to some prerunning, trail-running, and rock-crawling use. 1 The Dynatrac ProRock JK Housing has a nodular iron high-pinion axle centersection (left) that has more clearance than a standard high-pinion Dana 44 centersection (right) and more strength and metal in the casting where it was deemed useful. It already has a cast-in suspension control point, but you can obviously cut that off if you’re using this axle in something other than a JK. The ProRock JK housing uses a JK ring & pinion, and Dynatrac offers this centersection to fit both JK 44 differentials and standard (original) Dana 44 differentials (while still utilizing JK gears). The reasoning behind offering a JK housing with a standard 44’s differential: There aren’t nearly as many JK 44 differential offerings.1 The Dynatrac ProRock JK Housing has a nodular iron high-pinion axle centersection (left) 2 Dynatrac 3.0-inch, 0.5-inch-wall axle tubing dwarves the 2.5-inch, 0.25-inch-wall factory axle tubes of a stock JK axle. The strength difference comes from the added thickness of the axle wall, but more from the larger overall diameter of the axle tubing. These are hands down bigger axle tubes than any of the Dana 44s on any of the trucks in our stables.2 Dynatrac 3.0-inch, 0.5-inch-wall axle tubing dwarves the 2.5-inch, 0.25-inch-wall factor 3 Dynatrac uses a press-in bearing seat in the ends of the tubes so that a 30-spline axleshaft will fit into the differential. These are actually removable (though it’s definitely some work) so that a 35-spline axleshaft can be used. Since we’re using 35-spline axleshafts, we’ll be removing these pressed-in seats.3 Dynatrac uses a press-in bearing seat in the ends of the tubes so that a 30-spline axles 4 Pictured (middle) is the Dynatrac JK end forging, or inner C. On the right is a factory JK one, and on the left a Dana 60. The Pro Rock JK end forging is almost as big as the Dana 60’s.4 Pictured (middle) is the Dynatrac JK end forging, or inner C. On the right is a factory 5 Each JK housing is custom-built to order. Any length axle housing can be ordered, and the centersection can be offset to one side of the axle or another as much as necessary.5 Each JK housing is custom-built to order. Any length axle housing can be ordered, and th 6 After the end forgings are welded onto the tubes and the pinion angle and caster are taken into account, the tubes can be pressed into the centersection.6 After the end forgings are welded onto the tubes and the pinion angle and caster are tak 7 The JK ring & pinion set is used in the ProRock JK housing regardless if you’re using a standard 44 diff or the JK 44 diff. The JK gearset is different than a standard Dana 44 gearset. The pinion gear is shorter and has a larger diameter shaft. The JK pinion also rides on a bigger inner pinion bearing. The 8.8-inch JK ring gear is larger than a standard 44’s 8.5-inch-diameter ring gear. All JK high-pinion gearsets in front) meet on the driving side of the gear instead of the coast face of the gear (by far the stronger side of the gear).7 The JK ring & pinion set is used in the ProRock JK housing regardless if you’re using a 8 There are two options to bolt onto the JK pinion; a 1310 pinion yoke or this JK flange. The flange is obviously stronger than the 1310 yoke, and that’s what we chose to build ours with.8 There are two options to bolt onto the JK pinion; a 1310 pinion yoke or this JK flange. 9 How could you have the world’s strongest Dana 44 without a 35-spline locker? The Auburn Ected Max locker is one of only a couple 35-spline differentials made to fit a JK 44 housing. The Super 44 Ected Max acts like a limited slip differential when not engaged. When it is electrically activated, a strong magnet pulls the differential into a locked position and locks both axleshafts together.9 How could you have the world’s strongest Dana 44 without a 35-spline locker? The Auburn 10 The big difference in JK 44 and standard Dana 44 differentials is in the journal bearing seat where the JK’s is a slightly larger diameter.10 The big difference in JK 44 and standard Dana 44 differentials is in the journal bearin 11 RCV Performance offers factory replacement Ultimate JK 44 Rubicon front axle sets, but it can also custom build CV shafts to specification. To meet up to the 35-spline Auburn Ected locker inside this axle, RCV built very long hybrid JK CV shafts with 35-spline inners. The RCV shafts come with new wheel bearing bolts and a boot installation tool.11 RCV Performance offers factory replacement Ultimate JK 44 Rubicon front axle sets, but 12 The RCV shafts use constant velocity (CV) joints that are smoother at full turn and have no knuckle bind. A very durable urethane boot is pushed over the CV joint once the shafts are installed, and the boots keep grease in and moisture and contaminants out. The shafts and CV joints are made from a combination of 4340 and 300M steel.12 The RCV shafts use constant velocity (CV) joints that are smoother at full turn and hav 13 Dynatrac’s ProSteer ball joints are made for ball joint-equipped Jeep JK, Ford and Dodge solid axles. The ProSteer ball joints are completely rebuildable and are a stronger, more durable alternative to a standard ball joint. They are a little more costly than a standard ball joint, but considering they’ll last longer before servicing is needed, and servicing means rebuilding instead of replacing, they are well worth it. Without question, the strongest 44 needs the strongest ball joints possible.13 Dynatrac’s ProSteer ball joints are made for ball joint-equipped Jeep JK, Ford and Dodg 14 Instead of using a factory JK Dana 44 knuckle, we went with the strongest option possible; a Reid Racing high-strength ductile iron replacement JK knuckle. The Reid Racing knuckles are stronger, have raised steering linkage points, and dual steering stops. They are powdercoated orange to keep corrosion to a minimum. The increased strength comes from both extra material and extra ribbing.14 Instead of using a factory JK Dana 44 knuckle, we went with the strongest option possib 15 The tie rod is raised 1.5 inches higher on the Reid Racing knuckle than on a factory JK knuckle. The Reid Racing knuckles fit on the ProSteer ball joints (or stock ones) and can accept factory outer equipment or upgrades like our RCV axleshafts.15 The tie rod is raised 1.5 inches higher on the Reid Racing knuckle than on a factory JK 16 The RCV shafts come with their own wheel bearing bolts that have had their hats ground down so they can clear the large CV inside the knuckle’s hole. In this image you can see the boot installation tool still sitting in this housing.16 The RCV shafts come with their own wheel bearing bolts that have had their hats ground 17 We are using a factory J8 unit bearing on the Reid Racing knuckle. “J8” is the model number for the military JK Wranglers—the military wanted Wranglers, but with the old 5x5.5 wheel bolt pattern and larger brakes, so Chrysler made these Wranglers with a J8 designation. And though rebuildable hubs are always nice, the J8 unit bearings are excellent non-service units that do not pull apart if the stub shaft breaks.17 We are using a factory J8 unit bearing on the Reid Racing knuckle. “J8” is the model nu 18 Here is a standard Dana 44 brake caliper (left) next to a J8 brake caliper (right). The J8 one obviously dwarves the standard 44’s caliper and subsequently offers much better stopping power. It’s a factory caliper built by TRW for Chrysler. The only downside is that we’ll be swapping to 17-inch wheels in order to fit these large J8 brakes.18 Here is a standard Dana 44 brake caliper (left) next to a J8 brake caliper (right). The Why Build a High-End Dana 44? You may be asking yourself why you’d spend the money for a custom axle and not get a Dana 60. This is actually a good question, and there are a few reasons. Cost - Though a ProRock 44 is still a high-end unit, it is cheaper than a custom-built Dana 60 Clearance - The ProRock 44 has more clearance than a Dana 44 or Dana 60 made. Even more than the ProRock 60 Weight - The ProRock 44 is quite a bit lighter than a Dana 60 axle, yet still incorporates many components that are nearly as strong as a Dana 60’s. OR Sources Dynatrac 7392 Count Circle Huntington Beach CA 92647 714-596-4461 www.dynatrac.com RCV Performance 611 Beacon Street Loves Park IL 61111 815-877-7473 www.rcvperformance.com AUBURN GEAR, INC. 400 East Auburn Drive Auburn IN 46706 260-925-32__ www.auburngear.com Reid Racing 1917 Oak Park Blvd. Pleasant Hill CA 94523 925-935-3025 http://www.reidracing.biz/ Superior Axle & Gear 9580 Commerce Center Drive Rancho Cucamonga CA 91730 888-845-0470 www.superioraxlegear.com By Jerrod Jones Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!