The XJ, boxy Cherokee, little Cherokee, the not-Grand Cherokee—no matter what you call it, the ’84-01 XJ is quite a Jeep. The first Unitbody Jeep designed by AMC has a strong following amongst Jeepers, and for good reason. Lightweight, 101-inch wheelbase, and your choice of two- or four-doors—these things are amazing. All of us here at Jp have owned, built, and spent plenty of time behind the wheel of an XJ, and some of us are willing to admit that we are XJ enthusiasts. The fact is that the little boxy Cherokee broke the mold for many future Jeeps to come. The engineering cues cut in the XJ can be found in ZJs, WJs, TJs, YJs, JKs, and practically every coil-sprung solid-axle Jeep built since. The front suspension with four control arms, a track bar, and coil springs are so similar to ZJs, TJs, and WJs that parts interchange between them and the XJ. The added wheelbase makes XJs pretty capable off-road, and the extra set of doors on four-door models gave Jeepers space for their youngsters long before the four-door JK was even an idea.
But those building any XJ for any off-road use should follow a few rules. There is little question that the first few years with the GM 2.8L V-6 should be avoided unless you plan on an engine swap—in fact, the 2.5L four-banger from a similar year might be a better engine. Also avoid the Peugeot BA10/5 five-speed, which should have been phased out in 1989, identifiable by its clamshell-style housing. Also, as the XJ aged, Jeep made improvements to the Unitbody, drivetrain, and other components, so the platform got better over the years. The last few years don’t have the high-pinion Dana 30 that is better than the low-pinion Dana 30 that replaced it. Otherwise, if you have a XJ of almost any year, someone has built it. Long-term wheeling will cause the Unitbody to develop cracks, but there are many ways to add strength to the XJ platform with several different aftermarket vendors offering chassis stiffening parts. We also have a recurring dream where we build an early XJ with a lightweight fuel-injected small block V-8. Can anyone say sleeper? Truly the limit of how you can build an XJ is boundless. Also don’t forget the ’86-’92 Comanche or MJ pickup truck. With very similar anatomy to an XJ, we’ll lump the MJ in here, ’cause most of these building ideas and plans apply to them, too!
If your passion is for sticking your XJ in the muck, you’d better aim for the post-’91 HO 4.0L I-6, of which either the manual transmissions (AX15 or NV3550) or the AW4 would be good for slinging the muck. Lifting an XJ is almost as old as mud itself, but anything over 3.5 inches of lift is gonna need a slip-yoke eliminator and probably should have front control arm drop brackets or a long-arm conversion. You can build an XJ for 35s with 3.5-4 inches of lift with proper bumpstops and fender trimming. As for T-cases, the early years with the NP207 offer few aftermarket upgrades, but either the NP231 or the NP242 would work in the mud, with the NP231 being the cheapest to modify and the strongest when modified. As for axles, the non-disconnect high-pinion Dana 30 can be built to support 37s in the rocks, but these housings do bend when air time is involved. As for the rear axle, the rare Dana 44 would be the best, with the much more common post ’97 29-spline Chrysler 8.25 in coming in a close second. Getting back to front axles, the low-pinion non-disconnect Dana 30 phased in the last year or two of XJ production as the supply of high-pinion front axles ran out is fine for mud, rocks, or sand, but not quite as desirable as the high-pinion version. That’s because a high-pinion gear in a front-drive axle is inherently stronger. Some earlier XJs with the vacuum-disconnect Dana 30 can be a liability if the vacuum lines or axle disconnect mechanism are not maintained. If it fails and you don’t have a locker in the front, you don’t have four-wheel drive. The solution is simply maintain the vacuum disco system, swap to a Posi-Lok, or drop the vacuum disco system in favor of a new seal and solid axleshaft. Lastly, some XJ Dana 30s came with front axles with CV axleshafts. These tend to wear out quickly and are not as strong as the later ’95-’01 axles that feature Dana 44-sized 760X U-joints. If you hear CV shafts clicking or popping on corners, it’s too late for them!
Cherokees have been used for rockcrawling since before rockcrawling was rockcrawling. As long as you beef up the Unitbody, add a cage, plenty of body armor, and don’t mind the possibility of broken glass, an XJ can work well in the rocks. We’ve seen several budget-minded XJ rockcrawlers that work well with 33s or 35s. For anything bigger, especially with lockers and heavy bumpers and armor, you are gonna need some aftermarket axle assemblies and deeper gearing. We like the factory 4.10s in four-cylinder XJs, and have often contemplated a budget two-door XJ crawler-based one. Just imagine it with lunchbox lockers, high-pinion Dana 30 front axle, a 29-spline Chrysler 8.25 in the back, 4:1 gears in an NP231 in the T-case, and some 32s or 33s.
Ever heard of Jeepspeed? Yeah, it’s a desert race class that was built around the XJ. That means the parts and know-how are all out there in the aftermarket for you to use as a guide when building a go-fast XJ. Again, beefing the Unitbody will make for a longer-lasting vehicle. In our experience the front axle likes to bend when really flogged. Limiting straps may a good idea to keep that front axle from drooping too much in the air, and a long-arm front suspension is gonna make the ride smoother and afford the most travel. Fiberglass body parts are also out there for more tire clearance. We also have had pretty darn good luck with the XJ’s AW4 transmission. This tranny with a decent First gear and a nice Overdrive is pretty stout. The AW4 can be set up with electronic shifting controls and manual torque converter lock-up, resulting in a tranny with torque converter slip when you want it and manual-shifting options—both in one package. Check RADesigns Products for its shifting options.
Keeping the XJ cool in the dunes may take some work, but with big aftermarket radiators available and other tricks like louvered hoods, you can keep a 4.0L in an XJ below 230 degrees. Just be sure your ’84-’96 XJ’s cooling system is not trapping an air bubbles—they are notorious for that—and you should be good to go. We also always thought that it would be pretty easy to add some spacers under the rear of the hood at the hinges to get a little cowl induction action on a boxy Cherokee hood for the price of a bag of peanuts.