1999 Jeep Cherokee XJ - Project XJ TrailRunnerPosted in How To on September 20, 2006 0) (
Project XJ TrailRunner is a winner! Carefully selected equipment turned this stone-stock '99 XJ Cherokee into a versatile, dual-purpose, daily driver and trail 4x4. As for off-pavement prowess, the XJ more than proved its mettle at Moab, Utah, during the 2006 Easter Jeep Safari.
A film crew outing for Four Wheeler TV provided just the right setting to test the XJ Cherokee in a variety of terrain and traction situations. The Lockhart Basin Trail, a designated route that took a hard pounding of rain and snow melt in the early spring, offered the landscape and texture for great four-wheeling and breathtaking scenic backdrops. Lined up amid a string of high-end trail runners, the XJ Cherokee faced newly created rock obstacles and challenges of near-Rubicon proportions. Locals described the trail this year as worse than usual, which kept the cameras rolling steadily for a full day of trail pounding.
Project XJ Cherokee TrailRunner passed every test. Full-Traction Suspension's 6-inch long-arm lift and the Toyo 33-inch tires delivered the ground clearance desired and even more breakover clearance than the lifted Wranglers among the group - despite the TJ's shorter 94-inch wheelbase. The XJ's transfer case tucks well up in the body tunnel, placing the NP/NV231 unit and its crossmember higher than on TJ and LJ models.
The beefy ARB front bumper and Warn's rugged Rock Crawler bumper with tire carrier at the rear made for exceptional approach and departure angles. Great breakover clearance and picking decent lines in the boulder-strewn trail sections contributed to the XJ never touching its chassis or bumpers to the ground. Wheel travel and control were exceptional.
Traction never faltered, with ARB Air Locker differentials and 4.10 gearsets providing a versatile setup for crawling through the rocks. Up or down, even with the AW-4 automatic, control was excellent. ARB lockers assure that each wheel receives equal torque, and gearing felt plenty low, even with the stock 2.72:1 Low range ratio. The PowerTrain Industries CV-type rear driveline and Advance Adapters slip-yoke eliminator provide an extra margin of safety and reliability, while Borla's header and exhaust system add a nice performance edge. The exhaust system rides high in the chassis, readily clearing debris and obstacles.
As we wrap up the project with our Moab tests, is there any room for improvement? Well, as intended, the 4.10-ratio axle gearset choice for 33-inch tires has precisely restored the engine speed to stock rpm for each given mph. 4.56:1 might provide more snap on the highway though. By adding bumper mass and armor, a Warn winch, and hefty suspension, the increased curb weight increases the load on the XJ's 4.0L inline-six. 4.56:1 gears would bring the engine speed further up the horsepower and torque curves at highway cruising speeds, delivering better performance - and maybe even improved fuel efficiency.
Also arguable would be the wheel backspacing on the 16x8 wheels. The selected 4.5 inches offers a useful, tighter track width for trailrunning on narrower trails. A shallower 3.75-inch wheel backspacing would widen the track width and allow for more front-end steering angle and a tighter turning radius.
Overall, the XJ Cherokee has made clear its dual-purpose capability. Driven on-highway with good handling and stability, the XJ has all of the ingredients for serious trailrunning as well. So, are we happy with the results? You bet! Building up a stone-stock XJ to face the challenges of Moab, without losing on-highway capability, is ideal. Air conditioning, room for four people and two Labrador retrievers, a stable 101-inch wheelbase for the highway and light towing - who could ask for more? The installed equipment, featured in OFF-ROAD from Nov. '05 to now, is readily available in the aftermarket and proven on the trail. It works great for us!