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September 2008 4x4 Tech Questions - Techline

Wrench
Posted September 1, 2008

I am planning a project rig based on a Jeep Cherokee. Short term, I am thinking gears and 35-inch tires. Long term, I am thinking motor buildup, winch, lighting, Atlas transfer case, and so on. This rig will be mainly for camping, trails, and medium-difficulty wheeling with my family. Can you offer any advice on a year and trim package best suited for what I am trying to do? What additional modifications will I need to make in the short term to get the bigger tires on and perform? Does one year have a better motor/transmission/transfer case/axle setup than the others? I don't want to replace the axles, but would upgrade the shafts and so on if need be.

Brian Cracraft
Mesa, AZ

The XJ Cherokee makes for an excellent trail vehicle. You just might want to go to your back issues and read our Grand Cherokee "Project Ain't it Grand(er)" series, which dealt with the suspension, and front and rear axle upgrades. You can find these stories on our Web site at www.fourwheeler.com.

Yes the rear suspension is coils on the ZJ, versus leaves on the XJ, but the front is nearly identical. I would start out with a '97-'00 model, mainly because you didn't want to change out axles and you can get the high-pinion front and the Chrysler 8.25 rearend with the 29-spline rear axle. There were some '96s that also used the 29-spline axle over the earlier '91-'96 27-spline axles.

Starting in '97, there were some body improvements that were also worth having. We used the ARB locker up front, and over the last year it has worked just great, other than you really have to remember to unlock it when making a turn. Finding room to mount the air compressor under the hood is kind of a magic trick.

In all reality, I would suggest that you stick to 33-inch tires unless you plan to upgrade the front axle with the three-spline locker and 44-style axles such as Superior Axle & Gear sells. Even with 33s, it would be a good idea to do the upgrade. To make the 35s fit, you need some aftermarket fenderwell cut-out flares such as those from Rusty's Off Road or Bushwhacker.

The Chrysler 8.25 isn't as strong as the Ford 8.8 that we installed in project "Ain't it Grand(er)," but it should handle 33s without a problem, especially with an axleshaft upgrade. Again, 35s bring up the subject of strength, especially in the smallish Dana 30 front end. I think that if I were going to run 35s, I would want to use a 4.89:1 gear ratio, but this makes for a mighty small pinion gear and I would not recommend anything lower than a 4.56:1 ratio, strength-wise. I know (and am sure someone is going to write and tell me it's not a problem) there are people who are running these lower gears with 35s, but I don't like to break things and they will break in time with any serious four-wheeling.

Suspension-wise, I definitely recommend a long-arm suspension up front for any lift over 3.5 inches. The factory-length control arms are just way too short, and with the lift, the operating angle is such that with any bump, the wheels have to travel in a steep forward arc as they move upward, making for a terrible ride as well as putting more of a load on the subframe mounting locations. There are a lot of good long-arm kits available, with each having its own good points. I would also recommend using a full set of springs in the rear instead of just an Add-A-Leaf or lift blocks to gain the needed tire clearance. Again, it has a lot to do with ride quality.

An Atlas transfer case is an excellent choice, but the 231 with a slip-yoke eliminator kit and possibly an update to 241 planetary gears and drivechain also make for a good combination.

For engine performance modifications, two of my favorites for the 4.0 are a K&N air intake system and a set of Borla headers. I have used these on two different 4.0 XJs, and cannot get over the performance gains. I am sure that there are other intake and exhaust systems that work equally well.

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