Dynatrac has been designing and manufacturing the very best drivetrain components for 4x4 vehicles for over 20 years. They created a revolution in ground clearance with the inception of the ProRock axle housing in 2002. Now, in collaboration with AxleTech International Motorsports (AIM) and Mopar, Dynatrac is pushing the envelope even further with these new American-made portal axles.
So what is the advantage of a portal axle? The gear reduction at the hub moves the axle center line up five inches for increased ground clearance. This is a dramatic change; the equivalent of switching from 35” to 44” tires on your vehicle. Additionally, the geared hub design provides a 1.5:1 gearing reduction through a massive 41 spline axle shaft designed specifically to account for increased torque loads. The nodular iron AIM portal gear boxes contain four 2.25 inch wide 8620 heat treated steel gears: a drive gear, two idler gears, and a gigantic driven gear that keeps the drive direction constant, making them a practical retrofit to traditional axle housings. By multiplying torque at the wheel, less torque is transferred through the driveshafts, transfer case, and other upstream drivetrain components. And a numerically higher gear ratio can also now be used, which results in a larger, stronger pinion gear.
The idea of using portal axles for more ground clearance is not new, however there have been a number of factors that have made them unfeasible… until now. In the past you had to overcome poorly functioning drum brakes, long pinions that result in short driveline lengths, excessive weight, and difficult to source foreign parts when trying to retrofit portal axles to your Jeep or 4x4. Dynatrac has worked closely with AIM and Mopar to address all of these issues (and more) with the introduction of their innovative new portal complete axle assemblies and sub-assembly components.
|Axle Comparison||Dynatrac ATI Portal||Unimog 404 Portal|
|Width||User Selected||69 Inches|
|Brakes||Wilwood 4 Piston Calipers and Vented Rotors||Drums|
|Gear Ratio||From 5.31 to 7.17||7.56 Only|
|Differential||User Selected (Eaton Detroit Locker, ARB Air Locker, etc)||Cable Actuated Locker Only|
|Spline Count||35 (inner), 41 (outer)||8|
|Bolt Pattern||Common 8 x 6.5||Rare 6 x 205 mm|
|Pinion Flange||User Selected (1410, 1350, or 1310)||Torque Tube|
|Pinion Length||Nex Gen 44- 10.77”, Dana 60-13.28”||19.5 Inches|
|Suspension Mounting||User Selected (JK, TJ, or custom)||Must be Custom Fabricated|
|Parts Sourcing||Dynatrac or Most Major Auto Parts Stores for Wear Items||Nearly Impossible in the USA|
|Origin (Design & Manufacturing)||USA||Germany|
Realistically these new portal axles aren’t for everyone. They are not recommended for highway use, and the leverage of the portal design places additional stress on suspension mounting points and control arms. Electronic controls such as ESP and ABS cannot be retained with the portal boxes, as they can with Dynatrac’s traditional ProRock, Pro, and Trail Series axles. There is no provision for a standard parking brake; however a driveline brake at the transfer case can easily be added to address this issue. Final suspension design will be determined by many factors and it is crucial that the suspension design address the added torque and leverage of the portal system. The end user will need to design proper steering and a strong 4-link suspension. Therefore, it’s important that a qualified specialist with fabrication skills and a thorough knowledge of suspensions install it. In short, this isn’t a ‘turn-key’ assembly that fits any application. With the caveats out of the way, it becomes clear that if you require the absolute greatest ground clearance, with gear reduction to overcome the most severe, boulder-strewn trails and obstacles, there is no substitute for Dynatrac and Mopar axles equipped with AIM portal housings.
The portal wheel ends are currently available for king pin steering knuckles and full floating rear Dana 60, Dana 70, and AAM 14-Bolt applications. Dynatrac can provide the AIM portal housings on their proprietary ProRock and Pro-series axle assemblies with suspension brackets for a wide variety of vehicle applications.
We are still very early in the evolution of portal axle systems. As more of these units are tested we’ll have more information regarding suspension and steering design to pass on to the installers. We are continuing work with Mopar and AIM on Jeep Wrangler JKs to refine the system to create a more ‘turn-key’ package. Mopar Performance part numbers P5155670 and P5155671 are available from Dynatrac and your local Dodge/Chrysler/Jeep Dealer. They are specifically designed to fit 2007 and newer Wrangler JK vehicle if used for off-road only purposes. Dynatrac is not only a dealer for Mopar parts and accessories, they are also a supplier of new and unique products to Chrysler and Mopar, with their axle assemblies being prominently featured on popular Mopar Underground vehicles such as the Lower 40, NUKIZER M715, The ImMortal, and the 1320 Dodge Challenger.
In addition to making the made-to-order custom axle assemblies that Dynatrac is famous for, AIM portal boxes and related components will also be available individually from Dynatrac for those who wish to retrofit the portal boxes to their existing axles. “People best know Dynatrac for providing high quality, US-made axle solutions,” explained Dynatrac founder Jim McGean. “The evolution of off road vehicles continues and once again, Dynatrac is in the forefront with the help of industry leaders like AIM and Mopar Performance”
August 2009 issue of Peterson’s 4 Wheel Drive and Sport Utility Magazine
Axle Tech Bolt On Portal Axle For 14 Bolt & Dana 60 Axles - Lift-N-Gears