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March 2013 Firing Order - Editorial

129 1303 01 March 2013 Firing Order Editorial Axle Tech Portal Axle
John Cappa | Writer
Posted March 1, 2013
Photographers: The Manufacturer

Bench Racing My Next Pair Of Axles

The axle assemblies are some of the most abused, overlooked, and often poorly maintained components on your 4x4. If you have added a lift and bigger tires, it’s very likely that your axles will be the next place on your wheeler that needs attention. Interestingly enough, we all think we can get by on our factory axles, and the truth is in some cases we can. Not every 4x4 needs 1-ton Dana 60 or Rockwell axles front and rear. Aside from vehicle weight, power, and the kind of terrain planned, your driving style and willingness to make trailside axle repairs dictate how much axle you actually need. The good news is that today, more than ever, there is an unbelievable amount of aftermarket support available to increase the versatility, strength, and durability of your 4x4s axles. A little over a decade ago your options were much more limited.

Most of the axle swaps I’ve made over the years involve the use of common junkyard axles. I mean, what’s the point of me writing about an axle swap if you can’t easily duplicate it? But lately I’ve been thinking about combining some aftermarket parts and trying some new ideas. I’ve always been fascinated by planetary hubs and portal axles, yet I have despised the idea of the added complexity. By using one of these designs you introduce more seals, oil, bearings, and gears that you have to maintain and concern yourself with at each wheel-end. I personally can’t really justify having planetary hubs on a traditional 4x4. I kind of feel like you need to run a minimum of 44-inch-tall tires to reap the benefits of the ultra-low gearing that is typical with planetary hubs, that is, unless you are building a trail-specific rig that won’t see much high-speed use. Since I frequent the wide open deserts and dunes and I often drive my 4x4s on the street at highway speeds, axles with planetary hubs just don’t make sense for me, but that doesn’t mean you should rule them out.

Not every 4x4 needs 1-ton Dana 60 or Rockwell axles front and rear.

Portal axles, on the other hand, have become significantly more lucrative to me. In the past the only viable option worth considering was the Unimog 404 portal ends, but their limited strength and availability (among other reasons) make them somewhat undesirable. The Unimog 406 ends are quite a bit more durable, but they are just too big for most applications, and like the 404s, they are not all that common here in the states.

In recent years AxleTech International (, Dynatrac (, and Mopar ( have opened up the portal axle possibilities with new heavy-duty portal parts and complete portal axles based on common centersections. While not exactly inexpensive, you really do get a lot of bang for your buck with these complete portal axle assemblies. They provide more than just increased axle strength. There are actually several significant bonuses. The most noticeable advantage is the increased axlehousing clearance over rough terrain. The AxleTech portal ends provide 4.9 inches more ground clearance than an equivalent traditional axle. That’s almost the same clearance you would gain from swapping out your 30-inch tires for a set of 40s! The AxleTech portal ends also translate into a lift kit of nearly 5 inches, and there is more! Since the AxleTech portal ends are geared 1.5:1 they help compensate for larger tires and increase your vehicles crawl ratio. Because the axle ends are geared they help decrease the amount of stress placed on the rest of the axle gear and shaft assemblies. You often can get by with a smaller (lighter) ring-and-pinion and axleshafts. This provides even more ground clearance over what you might typically need for an axle in your application. In a nutshell, with a well thought out portal axle swap you get stronger axles, correct gearing for larger tires, a locker upgrade, and a lift kit, all wrapped into one product. Of course, there are some disadvantages too. The only big one is the need to come up with a sturdy suspension system that can control the additional leverage portal axles put on leaf springs, suspension links, ends, and brackets. But I have a few ideas to keep that under control on my project, if I ever actually move it from the bench and barstool to the truck chassis.