Kevin McNulty
Former Editor, Mud Life
There are many ways to round up new axles for your 4x4. They range in price from junkyard-cheap to extremely expensive. We’ve scrounged through junkyards coming up with some great finds, only to spend days cutting and grinding and then welding on new hangers and mounts. Making a junkyard or hand-me-down axle fit is sometimes more trouble than it’s worth, and a guy really can’t tell how fatigued the metal is. There’s a simple philosophy behind axle swaps and upgrades: You get what you pay for. You can either have bolt-in quality or days of hard labor with a well-used axle that might end up leaving you stranded anyway.
Dynatrac has been producing quality axles for over 20 years. We’re sure you’ve noticed just as many Dynatrac axles under our rigs as you have junkyard axles. We really appreciate the engineering and quality craftsmanship that goes into the axles, and there’s always a fitment and price point we can deal with. Dynatrac’s new Standard and Unlimited Pro Rock 44 series axles are built with the same engineering and quality components the company has built its reputation on. The 44s are a great bolt-in replacement for Jeep JK and TJ axles, or custom applications for trucks and buggies.
There’s a major difference in the structural engineering and thicknesses between the factory Dana 44 end forgings (inner Cs) and tubing and the Dynatrac components. On the left is and end forging and the 21⁄4x1⁄4- wall tubing used on a factory Dana 44. Both have breakage and bending issues. The 3x5⁄16-wall tube in the center is standard on the Pro Rock 44, and the 3x1⁄2-wall tube on the right comes with the Unlimited axle. Both the Unlimited and the Standard axles are fitted with the massive end forging on the right.
The difference in quality is evident in comparison. Although the factory Dana 44 isn’t a bad axle, it is not built as well as a Pro Rock one. The much stronger high-pinion, high-clearance differentials are built for abuse. The bracketry fitted to the axles is also much larger and stronger. The stamped factory brackets are 0.120 inch, while Dynatrac’s are 0.188-0.250 inch depending on the bracket.
All aspects of building the high-pinion Pro Rock 44s are precise and designed to achieve proper pinion and caster angles on vehicles lifted 2 inches or more. Bare housings and custom setups are also available, great for shops and garage builders wanting to install their own gearsets and weld on their own suspension and mounting brackets.
The tubes, end forgings, bracketry, and diffs are precision welded on jigs so there are no mistakes. The Pro Rocks are designed to accept the stock or aftermarket JK gears, lockers, axleshafts, brakes, and knuckles. Complete assemblies are available with 4.10, 4.88, 5.13, and 5.38 gearsets. Front axles also include larger and stronger U-joints.
The new ProSteer Ball Joints (upgrade) are super strong and built to withstand hardcore use. The ProSteers can easily be pressed into any Pro Rock 44, 60, or 80. The ball joints can also be rebuilt without special tools.
There are two versions of the Pro Rock differentials. One is for conventional lockers such as an ARB Air or Detroit Locker, and the other is a differential configured for the factory Jeep JK electric locker. Both are high-pinion and offer better ground clearance than the factory axle. The Pro Rocks are definitely beefy and far stouter. With that stoutness comes additional weight; a Pro Rock 44 Unlimited with heavier axletubes weighs 153 pounds compared to the 93-pound factory axle assembly.
All axle assemblies are built with precise measurements and standards. Dial indicators and torque wrenches are used each and every times for exacting tolerances. No eyeballing or “it just feels right” is used on any axle. Each axle is completely documented and twice inspected, which gives us great peace of mind in the middle of no man’s land.
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