The Editors’ Jeep Axle ChoicesPosted in How To: Transmission Drivetrain on September 1, 2012 0) (
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.
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.
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.
Hazel— The open knuckle, ’70s-to-’80s-era five-, six-, and eight-lug Dana 44 fronts are probably my favorite axle of all time. They’re durable in stock form, easy to work on, and enjoy huge parts availability. For me, I’m more than comfortable running 35s or even 37s with them in stock form. However, once you start adding chromoly shafts, fancy U-joints, and things like machined knuckles for high-steer arms, it almost starts to make sense to consider stepping up into a stock Dana 60 front with a narrowed long-side tube.
Simons— Open knuckle Dana 44s are awesome. I run and have abused them for years. You can squeak by with 36s or maybe 37s if you are running chromoly axles and U-joints and are easy on the throttle. Now having said that I am not much of a fan of the stock TJ and JK Dana 44s, because the tubes have a reputation for bending. Older Chevy, Dodge, and FSJ ½- or ¾- ton Dana 44s won’t bend nearly as easily and have nice, big brakes and strong, external-spline hubs. I was also always annoyed that the TJ Rubicon front Dana 44s have the same U-joint size as post-’95 Jeep Dana 30. That means the weak link is basically the same as a Dana 30. The smallish bendable axletubes are the same as a Dana 30—and you get less ground clearance than a Dana 30. Lose/lose.
Trasborg— I think that Jeep should have never put anything but a Dana 44 under a Universal-series Jeep, if that tells you what I think of them. With every Jeep I have, I am always looking for a Dana 44 to swap into it. The Dana 44 showed up under the front of a Ford Bronco in 1971 and was used in every worthwhile make and model of vehicle at some point. They are still available in the current Jeep Rubicon, but I sort of lost interest in them at some point. For me, if the Dana 44 has unitbearings, I’m not going to spend a lot of money to get it. The unitbearing 44s have housings of the same strength of the Dana 30 and they really aren’t half-ton equipment. I prefer my front Dana 44 with a 5 on 5.5 bolt pattern, somewhere around 60 inches wide, and run it either open, with an LSD, or a selectable locker.
Simons— In my opinion, Dana 60s are dead sexy. An upgrade to 35-spline hubs and chromoly shafts means that you can run 40s, a V-8, and romp on the gas with impunity.
Trasborg— The Dana 60 first showed up as a front axle in 1967 under the M-715, but it really had more in common with later Dana 44s than the Dana 60 we know today. That said, much like my Dana 44 prejudice, I think the Dana 60 should have been under the front of every ¾-ton and 1-ton Jeep truck. There is a lot of huff about kingpins versus ball joints, but I feel for most builds, either is fine. It is really easy to stuff them with 35-spline inner and outer shafts, so unless you are really abusive they will handle 40s just fine. For me, my Dana 60 will be eight-lug, at least 65-inches wide (no narrowing for me), dual-piston calipered, and either automatic or selectable locker’d. None of that sissy limited slip stuff here. If the Jeep I’m building is big enough to need a Dana 60, I need more than what a limited slip can give me.
Hazel— To me, price is the only downside to a Dana 60. The big pumpkin hangs lower than a Dana 44, but if you’re running a Dana 60 you’re most likely running 37s or larger tires anyway. Once you step up to one-ton axles, it’s a pretty noticeable relief from the driver’s seat. There’s no worry about breakage because you have to have some serious power and/or heavy tires to hurt ’em. If you value peace of mind more than your pennies, Dana 60 is where you need to be.
Simons— I think spending money to upgrade a CJ Model 20 is probably a waste of cash unless you are keeping tire size to 32s or maybe 33s. Sure the ring gear is relatively large, as are the pinion and pinion bearings, but the diff covers are paper thin and the housings are large and tend to get hung up easily. The center section has a relatively thin wall thickness when compared to other cast housings. I’d much rather have a Dana 44 rear. The covers do bear a striking resemblance to old military helmets. That’s funny to me.
Trasborg— American Motors Corporation has a good reputation for making some cool, albeit idiosyncratic cars in the ’60s, but they were never well known for reliability. Then they purchased Jeep and in an effort to keep production costs down they put this thing under everything, cutting corners at every, er, corner. This worked out to varying degrees of success. Basically if the axle has a big nut in the middle of where the wheel mounts, stay away from it. The tubes are prone to spinning in the centersection, the nut will always come loose and other axles have better gearing options. That said, I’ve beat the snot out of a lot of Model 20s. I wouldn’t waste money on a selectable locker. Instead, automatic, spool, or welded-spiders are my choice. The fullsize Model 20s make decent swap candidates, though, but look for six lugs.
Hazel— The only Model 20 I’d ever want to keep and would ever consider throwing money at would be a fullsize Jeep version. The steel recycler can have the CJ version. Other than the ring and pinion and brakes, you have to rebuild virtually the entire CJ Model 20 to make it reliable: new axleshafts, new carrier, new or severely upgraded housing. Why would I bother?
Trasborg— Sitting here in my elevated chair at magazine-land, I love to look down at the Dana 35. There are so many reasons not to waste a red cent on this axle that I could fill this whole story with just that. That said, I’ve beaten the hell out of many 35s in my various YJs and never had problems. But then, I never threw anything but gear oil, bearings, and brakes at them. You can find them under Wranglers, Comanches, and even many Cherokees. Basically, swap them into nothing, don’t pay money to regear or lock them, but whip ’em till they puke otherwise.
Simons— I have seen countless Dana 35 shafts break out on trails all over the U.S. I agree with Pete—run it till it breaks, but don’t spend much cash on it. If I see one on a trail, I know that Jeep is probably a liability.
Hazel— In my opinion, the Dana 35 is fine for most Jeep users until they want to add a locker or if they’ll actually do hard wheeling with tires larger than 32s. As long as you have 3.54-up gears, you can pay about $500 to regear your Dana 35 for bigger tires on the street, or piecemeal-build a stronger Dana 35 with bigger shafts, housing braces, lockers, and so forth. But if you’re pulling the trigger on all these upgrades at once, you’ll spend about $2,000 for a locker, 30-spline chromoly shafts, a bolt-on truss, and new gears. You’ll have shafts and a bolstered housing that will live with 37s or maybe even 38s, but a ring and pinion that won’t. At that point, it makes sense to spend about $1,000 more for a Dana 44 or Ford 9-inch rear.
Simons— I have abused rear Dana 44s for years including an early flatty or CJ-5 offset 44 that was running a 30-spline Warn full floating kit with a six-spline pinion. It survived life under my 3,000 lb-ish flattie for years with 33s and small 35s and a Detroit Locker. I also think the Isuzu rear Dana 44 is maybe the most under-swapped axle. You can’t swing a dead cat in junkyards out here in Arizona without hitting one with a limited slip, low gears, and disc brakes. One of the pinion bearings is weird relative to older Dana 44s and the factory carriers use thick ring gears and numerically low carriers (3.73:1 and down) Oh, and they are six-lug…which is a great pattern that matches many Dana 44 fronts.
Trasborg— Like I said for front axles, I love the Dana 44. Why this axle wasn’t under every 1⁄4- or ½-ton Jeep, I can’t fathom. It should be. With 30-spline shafts, seemingly unlimited gearing and locker options, and many bolt patterns and widths available in junkyards they are easy to find and easy to swap. I don’t hesitate to put 35s on them, and even 37s from time to time. There are lots of brake options; heck, really lots of every option. From the OE level to the aftermarket, a Dana 44 must be the easiest axle to get into your Jeep.
Hazel— It’s hard not to love a Dana 44 rear. Sure, the ’49-’58 versions had 10-spline shafts and the ’59-’70 models had 19-spline shafts, but the ’59-’70 models can be upgraded to a 30-spline full-floater with a kit from ATV Manufacturing. And the ’70-½-’71 offset CJ and ’72-’75 and ’86 CJ Dana 44 rears only have their narrow width as a downside. Most FSJ Dana 44 rears from 1973 on have 30-spline shafts and their 58.5-inch (narrow track) or 65-inch (wide-track) width makes them good swap candidates for a wide range of Jeeps. I’d keep the stock shafts; they have proper hardening for a nice balance of strength and torsional flexibility for longevity. The shaft twist helps absorb shock load that could otherwise bust ring or pinion teeth.
Simons— Another super strong and plentiful fullsize truck axle that should be plenty strong for most Jeep builds in full-float flavor. Avoid the Dana 61 found in some vans. Also older Dana 60s can be difficult to upgrade to 35-spline axles.
Trasborg— As married as I am to the Dana 44, the Dana 60 is the brick sh!#house barista girl who could make me leave my beloved 44. There are a lot of Dana 60 rears to be had in junkyards, they are wicked stout, and they enjoy as much, if not more, aftermarket support as the Dana 44. That said, they are heavy, they are more expensive to build, and it isn’t that easy to get back to a 5 on 5.5 bolt pattern. For me, if I’m starting thinking about axles for a particular Jeep, and 37-inch-tires even pass through my mind, I will keep an eye out for a rear Dana 60 as I go along.
Hazel— The Dana 60 offers a lot of possibilities in custom-built versions, but if you’re looking to score something straight out of the junkyard, there are better options. First, most will be full-float, eight-lug versions with 1.31-inch, 30-spline shafts. You’ll probably never hurt the ring and pinion, but speaking from experience, it’s a pain in the rear to hog the spindles for 1.5-inch, 35-spline shafts. If junkyard-cheap is what you’re after, I think it makes more sense to grab a GM 14-bolt or Dana 70 with 1.5-inch-diameter 33- or 35-spline shafts, respectively, and shave the housing for ground clearance. Add some disc brakes to cut the weight down, and you’ve got an affordable, 1-ton axle.
Simons— I’ve never owned one or had much experience with the Dana 70. I think I’d skip right to the shaved 14-bolt unless through some fairly odd set of circumstances a Jeep I bought already had a Dana 70.
Trasborg— I’m not going to say I dislike the Dana 70. It is the bigger, more burly version of the Dana 60, so what’s not to like? Well, there are many different iterations (U, HD, and B, to name a few), which make ring and pinion and bearing selection tricky. The axle got its start way back in a ’58 Dodge. The early axles are to be avoided because of coarse-cut axleshaft splines that are weaker than the rolled 35-spline shafts that came later. Also, the Dana 70 is heavier than the Dana 60, has less ground clearance and enjoys less aftermarket support. That said, the larger ring and pinion, heavier-duty centersection, and typically thicker axletubes all make it a good candidate for bigger and heavier Jeeps with bigger tires.
Hazel— Other than the big centersection (which can be shaved) and heavy brakes (which can be converted to lightweight discs), the issue is the huge differences in models offered through the years. There are three different pinion offsets (1⁄2-, 5/8-, and 31⁄32-inch), so you have to know which you have to order aftermarket gears three different spline counts (23, 32, and 35) which can complicate locker selection and availability, different bearings sizes, pinion spline counts, and so on. But they’re still a great candidate if you’re just going to weld up the spider gears and keep the factory gearing. If you feel the need to modify, popular convention holds the ’74-up Dana 70U and ’73-up Dana 70HD models with 5⁄8-inch pinion offset are the most mod-friendly versions.
Simons— Okay I’ll say it: It’s an option—one of many. It is an upgrade to a Dana 35, but it’s not as cheap or as great as some proponents have made it out to be. I think there are less expensive options, and I am not sure if money spent on an 8.8 should rather be spent on a 9-inch, Dana 60, or maybe shaved 14-bolt.
Trasborg— This should surprise no one. The Dana 44 with a 5 on 5.5 inch bolt pattern is the quintessential Jeep axle to me. So, do you think I like the Ford 8.8? I can’t argue that they are easy to find in junkyards and they are arguably as strong as a Dana 44, but they are too narrow for the later Jeeps, and require wheel spacers to match the front axle. The gearing and locker options pale in comparison to a 44, and I’ve not seen a cheap way to convert one over to 5 on 5.5.
Hazel— People read that we don’t heartily recommend the Ford 8.8 and misinterpret that to mean we don’t like it. That’s not the case. We don’t necessarily have anything against the Ford 8.8. But when you factor in all the things you actually have to do to get it in your vehicle and go down the road (yoke conversion, bracket replacement, wheel spacers, brake line changes, regearing, and so forth), it seems like you’re baby steps away from an axle that’s the right width and that didn’t begin life in the junkyard.
Simons— I love the modularity of the Ford 9-inch. There are gobs of parts and the axle is super-strong relative to its weight thanks to the sheetmetal housings and aftermarket race support. I think this would be my go-to axle if I were building a weight-conscious Jeep with 35-40ish-inch tires.
Trasborg— One of the reasons I like the Dana 44 is the interchangeability of junkyard parts, and it is that same thing I really like about the Ford 9-inch. Once there are no more junkyard options, the 9-inch can be built to rival Dana 60s and Dana 70s with aftermarket axleshafts and lockers all the way up to 45-spline. If that wasn’t enough, there are more gearing options for a 9-inch than any other axle anywhere. And, the modular nature of the axle means that as your Jeep grows, you can toss in larger shafts, different center sections, and so forth. For me, give me a trussed housing with the large-bearing ends and I’ll build off that until the day I sell the Jeep.
Hazel— Low pinion angle. There, I said it. That’s the downside to the 9-inch. I’ve built more Ford 9-inches than any other axle. And I’ve built quite a few axles. If you’re running a hardcore trail machine or building a fullsize Jeep, a junkyard-fresh version from a Ford pickup, van, or SUV will be a nice fit at 65 inches WMS for the SUV and pickup and 68 inches for the van. The 4x4s and Camper Special 2WD models will have 31-spline shafts rather than the weenie 28-spline. Upgrade to chromoly 31-spline shafts and they will survive with 350hp and 38-inch tires under punishing wheeling. Or, aftermarket housing and shaft packages are stupid-cheap. Order your housing, grab a cheap 28-or 31-spline centersection in the junkyard, regear it yourself ’cause the 9-inch has the easiest ring and pinion setup, throw in a 31- or 35-spline spool, and wheel it until the centersection splits. Then upgrade to a Nodular aftermarket centersection.
Simons— A heavy, strong, boat anchor that drags like a Cat D-9 ripper in stock form. Shave it and beat on it if you have a Dana 60 front, big tires, and a big motor or a super-porky Jeep.
Trasborg— The GM Corporate 14-bolt is like that about-to-expire ground meat at the supermarket. Lots of beef for really cheap. The big problems with this axle are its weight and its horrible ground clearance. If you aren’t worried about cutting and welding cast, you can get up to about 2 inches more ground clearance out of it. There are many aftermarket covers and kits to shave your 14-bolt. Beware though, there are semi-float versions and they are kind of turds. Stick to the full-float versions. I’m only coming down this road if the Jeep is a porker, or if I’m putting huge tires on it and flogging it like a red-headed step child. It will get a spool, whatever gears I need to match the front axle, and I’ll run the factory shafts ’cause they are near unbreakable.
Hazel— I kinda disagree with Trasborg in that the lighter-duty ¾-ton semi-float 14-bolt isn’t exactly a turd. With its six-lug bolt pattern, 9.5-inch ring gear, and 33-spline tapered (1.38-1.34 inches) axleshafts, and decent aftermarket locker and gear availability, it’d make a good junkyard upgrade for a six-lug FSJ requiring a centered-diff rear axle. That said, the big ol’ 11.5-inch ring gear 14-bolt we all know and love/hate is a big ol’ brute. Again, once you kill the drums, shave the rear, and drop in a locker, it’s way cheaper than many alternatives of equal strength. I’d leave the factory 4.56s alone, drop in a Detroit Locker, add GM ½-ton disc brakes, and probably wouldn’t even bother shaving the housing before slapping on some 40s and feeding it 500hp.
On the Fence
Here are some axles that we are on the fence about whether or not they are worth the time, money, or effort to swap into your Jeep. But still there are guys out there running them, so here are some of the pros and cons and ins and outs of the axles that we just aren’t sure about.
GM 10 Bolt
There are guys who swap these into Jeeps. Both front and rear are easy to find in junkyards and cheap to buy. They are cheap to buy because not many people want them. Strength comes in somewhere between a Dana 30 and Dana 44.
GM 12 Bolt
In the hot rod world, this is a great rear differential. So the dyed-in-the wool GM guys coming over from hot rods to Jeeps often look to this axle as well. But, the reality of it is that the housing isn’t up to the twisting and flexing that we subject stuff to, and the locker and gearing options are limited.
The Toyota truck 8-inch is pretty strong. Look for the ’86-’95 turbo/V-6 differentials. Or, go for a later 8.4/8.25/T100/Tundra/Tacoma diff. it has an 8-inch ring gear, 30-spline pinion and 30-spline shafts. This differential has a different third member bolt pattern and larger bearing caps that won’t work with the earlier axlehousings.
Limited Slip Differentials
— Limited slips are great in the rear of muscle cars. I guess I could see limited slips being used front and rear in a commuter Jeep that saw lots of snow and ice. Maybe in the front of a go-fast off-road Jeep. The clutch packs wear out, and in my experience limited slips allow differential action right at the worst times.
Trasborg— A limited slip to me is the Charlie Brown of the traction-aiding world. It has many of the downsides of an automatic locker, most of the costs of an automatic locker, and several deficiencies when compared to the automatic locker. That said, I’ll run them in the rear if I absolutely don’t want to have lane-swapping loading and unloading such as an automatic locker provides. I’m much more inclined to run them in the front if the rear is locked and I’ve got a marginal power steering system that would keel over if the front was full-on-locked.
Hazel— I’ve run every type of limited-slip differential that you can buy today. Of the lot, the Eaton Truetrac is my favorite and I’ve installed them in a number of project rigs over the years both in the front and rear. They’re unobtrusive on the street and surprisingly competent in the dirt. That said, I’m finding myself more and more willing to step into a selectable locker(s), even if that means forgoing a front traction-aiding differential for a while…or altogether.
Simons— Lunch box lockers are cheap traction. That means you are getting what you are paying for. That can be okay, I ran a used Lock-Right in a TJ Dana 30 for a while and loved the added traction, but I never would have expected it to last forever or be as strong as a full carrier locker. They just are not. They are also pretty easy to swap in and out if you wanted to run an open diff most of the year and enhance traction once or twice a year for that wheeling trip.
Trasborg— I’m a big fan, for a specific reason. Yeah, the weakness is the stock carrier you are stuffing it into, but often I just don’t like an automatic locker in the rear of a Jeep for one reason or another. Whether it is going boom at stop lights or switching lanes in the rain, there are a lot of Jeeps I’d rather have a spool in. So, for me, a lunchbox locker is the perfect test victim. Say I’m not ready to regear yet, but I’m getting close, and I’ve started to debate locker options. I can toss a lunchbox in the Jeep and drive it for a month or two the way I’d drive the Jeep and still only be out a couple hundred bucks if I decide I totally hate it.
Hazel— I’ve been there and done that with the lunchbox locker thing. Maybe it’s just me, but I tend to break them. To their credit, each company warrantied its product, but I still had to take the time and effort to swap out the broken pieces. I’d rather pocket the money and just weld up my spider gears if it’s for a rear application. And for the front, I’ll save my pennies and go with a good full-case locker or limited slip.
Simons— I love the idea of being able to turn on and off a spool. Automatic lockers are great, but they work so well they can make drivers lazy and can cause you to forget about tire placement. I sometimes like trying obstacles with open diffs and then resorting to locking the diffs if I can’t finesse my way up. That’s only possible with a selectable locker. Okay, sometimes parts fail and more parts are inherent in a selectable locker system. This means more chance of a failure and that’s not ideal, but pneumatic, electric, and cable systems can be quite reliable if built correctly. Also, adding on-board air for the lockers is great insurance if you lose air from a tire while off-road. For a dedicated trail rig, it’s probably best to opt for a spool or auto locker.
Trasborg— I usually like the idea of a selectable locker more than I like the reality of it. Once you factor in all the ancillary stuff needed to make them work, it’s often about double the cost of an automatic. That means you could have both ends locked for the same price. Since my money tree isn’t growing, the cost needs to be factored in. I’m most likely to leave the front axle open as long as I’m not regearing on the other side of a carrier break, and that way I can save my money for a selectable later. In a short Jeep, I really like them in the rear for their on-road manners.
Hazel— As an admitted hardcore spool and auto-locker guy, I’m becoming an ever-growing fan of selectable lockers. I’ve come to really appreciate the tight on-road turning afforded by an open diff and the ability to turn off the lockers on the trail to make things more interesting. So far, my all-time favorite is the Eaton ELocker. I like the simplicity of the electric switch operation and the fact it doesn’t require a special cover or other external stuff. However, I don’t discount the bombproof strength of an Ox Locker especially now that the company offers air- or electric-operated engagement solenoids in addition to its cable. I’ve dipped into the tried-and-true ARB arsenal in the past and the ARB Air Locker’s proven strength and versatility will surely have me coming back to the land of Oz to get my traction fix again. I think where applicable, I’d be more inclined today to run an auto locker than leave a diff open if funds permit.
Simons— I love auto lockers, but they do occasionally scare me. In my experience they seem to have personalities like people. Some are incredibly loud and lock or un-lock with surprising force with no warning. Others are relatively quiet and only cause a fairly predictable, slight shimmy in corners. I had one in a Cherokee Chrysler 8.25 that was loud and violent. Occasionally I thought I had snapped an axle shaft when it unlocked. Conversely, the one in the Dana 44 in my ’49 Willys is quiet and fairly seamless. Auto lockers can be fun on road in the rain, but they can be very, very, scary on an icy curve if you are carrying some speed.
Trasborg— I like the simplicity of the autos. No switches, usually no special oil, just put it in there and drive further without the winch than you could before. That said, in poor road conditions, you need to keep your wits and reflexes about you to avoid movie-like, 360-degree spins. So if the Jeep isn’t going to be a commuter or long-distance driver, I’m more likely to put an automatic in than anything else when I regear. They are relatively inexpensive and will work until you explode an axleshaft.
Hazel— If I have locking hubs it’s a no-brainer that I’ll go with a Detroit Locker in the front of my Jeep. It’s a personal preference thing. I find that with a manual transmission I can modulate the gas to lock/unlock the Detroit for tight turning in a variety of terrain. Only seldom am I limited in my turning ability. That said, on those seldom occasions I do find myself wishing for a way to turn off the locker without disengaging a hub. The only downside is that a Detroit can be vulnerable to internal breakage if you ever bust a hub or shaft under power. That’s never happened to me personally, though. Out back, I’ll almost always go with a spool in lieu of an auto locker for handling and cost reasons.
Simons— If you hate the inconsistency of an auto locker and don’t mind the chance of chirping tires on road at possibly inconvenient times then a spool is a great choice for you. They are strong, cheap, and stupid simple. Welded diffs can be even cheaper and every bit as consistent, but are only as strong as the weakest weld in them.
Trasborg— When I moved to magazine-land, I had Lincoln-locked enough differentials to have had more experience with them than I had with automatic lockers. As long as we were talking rear axles, I thought the grass was greener on the automatic side of the fence. Now that I’ve had more experience with automatics in everything from short-wheelbase lightweight Jeeps to long-wheelbase heavy Jeeps, I’m back in the spool/welded spider camp. Now, that’s for rear axles. For the front, been there, done that too, and getting out to unlock the hub for every turn sucks. So, spool rear? Yes. Spool front? No.
Hazel— Spools are not evil. That’s old-school magazine myth perpetuated 20 years ago by editors who didn’t know any better and probably had never driven a spooled axle. When done properly, a welded diff, mini spool, or full-case spool is safe and livable. As with any traction device that joining together two tires that want to travel at different rates of speed, you have to make sure your shafts will handle the strain and drive accordingly in foul weather. I think most 30-spline and larger shafts are fine when spooled with tires 35 inches and up. I’d never run a spool or welded diff in a front application, but I have absolutely no reservations on doing it in a rear application.