Even though Willys wasn’t granted the trademark for Jeep with a capital “J” until 1950, the company still slapped a “CJ” (Civilian Jeep) designation on their new civilian offering for 1945. The CJ stayed around all the way through the ’86 model year and went through quite a few changes along the way. From the beginning, with flathead four-cylinders, closed-knuckle front axles, and two-piece rear axleshafts, all the way to open-knuckle front axles, V-8s, and even a stop at flanged rear axles along the way, there are a lot of things to cover. The springs started narrow, short, and thick for a truly horrible ride. By the end, they were longer, wider, and had less leafs for a better ride and better flex. Over all the years and all the CJs we’ve owned, we find ourselves often doing some of the same modifications. You might say our Jeeps taught us what they need, and we want to pass that on to you.
These Jeeps are all fairly light, but unless your Jeep came with a V-8 from the factory, it is likely it can use a kick in the power department. While a V-8-powered flattie can be a lot of fun, sticking an eight in one often leads to overheating problems, drivetrain clearance issues, and driveshaft problems. A healthy V-6 is often a better choice. A fuel-injected GM 4.3L, Buick 3.8L, or even an odd-fire V-6 are all good choices and fit under the hood well and are easy to keep cool. Plus, they are lighter than most V-8s.
The factory axles in the early CJs have really deep gears and help to spin the tires so toss a couple of lockers in there and go to town. They will often live under a V-6. If all you are doing is mudding, and not mud/rock crawling, power steering really isn’t needed so as long as whatever steering you’ve got in there is good, leave it. Lots of guys go right to the wide axles, but if all you are doing is mud, those silly little narrow axles are beneficial. Because the tires are tucked further under the body, you are less likely to get a face full of muck. But the downside is that it’s easy to pack the inner fenders up with the sticky stuff.
Even the flathead four-cylinders do okay in the rocks. Here it is less about power-to-weight than it is gearing and picking lines. If your engine is running well, keep it. There are lots of throttle body and even multiport fuel injection solutions to be had. If you are on more of a fixed budget, a Motorcraft two-barrel or Quadrajet four-barrel can both be adapted to many engines and made to work at goofy angles. Once you’ve got the angles taken care of, look into a lower low range for your T-case. If you have a Spicer 18, Dana 20, or Dana 300, there are many companies making lower low-range kits for them. If you’ve got the Quadra-Trac you are out of luck, but there was a 2.57:1 low range for those ’cases at one point.
If you are playing in big rocks, you are going to want a ’cage of some sort. Be especially careful if you have one of those factory bars that bolts only to the rear inner wheelwell—it’s a common place for rust to form, and that obviously affects the structural integrity of the ’cage. Whatever the size of the rocks you are in, do yourself a favor and get or build rocker guards. There are lots of them on the market, or you can have your local metal place bend some plate to work for you. Front and rear lockers are almost mandatory, but we’d advise against a front locker in the closed-knuckle axles with any size of tire bigger than stock. A narrow-trac Dana 30 might be a good swap for you. If you are doing lots of off-camber, wider axles would be good and factory YJ springs flex like no one’s business but do take some fabbing to get under there. And power steering makes the trip that much more enjoyable.
Sort of like the mud, running in the sand needs more power than what many of the factory engines put out, but many of these factory axles are so narrow that we’d probably look at swapping in wider axles first just for stability. Now we aren’t saying like full-width axles necessarily, since 70 inches WMS to WMS is a full 20 inches wider than what many of these Jeeps came with originally. But Wagoneer and FSJ axles at 62 inches or 65 inches can give a good wide stance without looking cartoonish. Stick a rear locker in there or a spool; if you’ve got power steering, a front locker can help as well.
Most of these Jeeps can clear 33s with some trimming on factory springs that are in good shape. If yours can’t, look into a 1-inch polyurethane body lift. Leave the spare, the hardtop, and the margarita machine back at camp to lighten the load, and you’ll have a lot more fun in the sand with your Jeep.