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The Editors’ Jeep Axle Choices

New And Old Axle
JP Staff | Writer
Posted September 1, 2012

Axle Wrangling

What’s the best axle? The Dana 44? The Corporate 14 bolt? How about traction-aiding devices? The low-buck lunchbox locker? The anvil-simple spool? Or perhaps you like having the choice of a selectable locker. Whatever the case, the only right way to build an axle is the way that works best for you. Unfortunately, you can blow a lot of money and put a lot of miles under the tires before you figure out what exactly the best way for you might be. We’ve already blown our wad and we’ve worn down more tires than many truck drivers.

Some magazine editors have about as much difference of opinion as a flock of teenage girls in the same clique. It can be pretty funny to talk to them because it can be like talking to clones—they all say the same thing the same way. We are just a little bit different than that here at Jp. Our opinions differ and we like it that way. It can sometime show in the way we write and the way we build our Jeeps but you guys don’t often get to see behind the magical magazine curtain. It is our difference of opinion that often leads to the innovation and some of the wacky ideas we come up with. Sure, from time to time discussions can get heated, but at the end it is our differences that make Jp a better read than some of the other rags.

Can you run 40s on a Dana 44? Do you need a Dana 60? What about those Toyota axles? Do you need that high-buck selectable locker? Well, we’ve run ’em all and know how they work. So, follow along as we wax philosophical on what axle, why, where, and how hard.

Front Axle
Dana 25 and Dana 27
Simons— Old school. A great axle to do what it was designed for if maintained and not worn out. That is, run little narrow tires on an old Jeep. Keep it if your Jeep is gonna stay fairly mild but keep looking for a open-knuckle Dana 30. The 11-inch drums are okay, and it’s pretty easy to upgrade to 11-inch rotors and Chevy/FSJ calipers. In my experience the 9-inch drums are hard to work on and don’t work well even when they are functioning correctly.

Trasborg— In a time when 4WD vehicles were custom-built at the point of use, the Dana 25 was a milestone that was under-heralded. It showed up under the front of military Jeeps in the early ’40s and ran in Jeeps until it was replaced by the Dana 27 (shown) for the ’66 model year. The Dana 27 ran until AMC came in for ’72. Both are of a closed-knuckle design and feature drum brakes. They are 51 inches wide and they have a 7¾-inch ring gear. While they are available with low ring-and-pinion ratios from the factory, the housings are weak, the shafts aren’t that great, and they are really narrow. I tend to swap these out for narrow-track, open-knuckle, disc-brake Dana 30s.

Hazel— I don’t mind the closed-knuckles on Dana 25 or Dana 27 axles and if you own a fish scale, it’s easy to keep the kingpin bearings preload to the proper 12-16-pound force to turn the knuckle. Most will come with factory 4.27, 4.88, or 5.38 ratios so you save money on regearing for four- or six-cylinders with tires up to a 33-inches. I may even toss on some 35s, but never with a locker. Heck, I don’t think I’d even want a limited-slip with big tires, but the factory 10-inch brakes from some Dana 27s or swapped on 11-inch drums for a Dana 25 or Dana 27 will stop 31s or 33s just fine and the shafts will stay together if you’re smart with the loud pedal. Just get out of the gas if the tires go airborne and don’t give it hell with the wheels turned.

Dana 30
Hazel— I kinda like the little Dana 30. You feel like you’re earning your money if you’re running it in stock form. But the little 27-spline shafts would give me pause to think about running tires bigger than 33s with a locker. At the very least, I’d want a selectable locker so I could turn it off unless absolutely necessary. If you get a high-pinion model out of an XJ and add 30-spline shafts, axletube sleeves, and alloy stub shafts with good U-joints, it’ll rival a Dana 44 in strength. I’d feel comfortable running a Dana 30 built like this for up to 35 inch tires with a manual or maybe even 36s or 37s with an auto, but anything more than that and I’d start to worry about the ring and pinion.

Simons— I am a huge fan of the high pinion non-vacuum disconnect Dana 30s with 297X-size U-joints found in post-’95 XJs. They are great axles for 33s with lockers (Maybe 35s with a locker and chromoly shafts and a non-lead foot driver). The stock shafts are plentiful in the junkyard and they are pretty easy to change if you break one on the trail if you preload your spares with spare unit bearings. The only downside on the later unitbearing axle models are the relatively small axletubes and inner Cs that can bend if you try to sky your Jeep or prerun it.

Trasborg— I really like the Dana 30, and from 1966 to the present day it might enjoy the longest run of any axle anywhere. It first showed up in the Ford Bronco with the out-of-the-ordinary kingpin knuckle setup. It was used in Fords, Internationals, and Jeeps. The Dana 30 first showed up under a Jeep in 1972, but some of the early ones were the less desirable drum brake setup and the overall width was really narrow (50-52 inches), so swapping them into later Jeeps isn’t going to happen. Generally speaking, I’ll run any non-drum-brake, non-vacuum-disconnect (shown) Dana 30 with up to a 35-inch tires and not worry about it. I’ve seen ’em run successfully with 37s, but then the gas pedal makes me cringe.

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