First Drives: 2007 Jeep JK And Unlimited Rubicons
You might think us crazy for getting on an airplane (actually, three planes) and flying halfway around the world, 22 hours and 10 time zones in all, to test some new 4x4s for two days before turning around and heading home. Then again, it isn't every day that the vehicles we're invited to drive are the all-new incarnations of Jeep's flagship Wrangler. And it certainly isn't every day that the folks at DaimlerChrysler ask us if we'd like to 'wheel their newest 4x4s in the bush country of Zambia. (Hint: Turn right at Angola.) So when DC's invitation arrived in our mailbox, we got our vaccinations, packed our duffel, and brushed up on our pidgin Swahili before hitting the friendly skies for a 21,000-mile round trip. Here's what we trail-tested:
All new for 2007, the Wrangler JK has been completely redesigned. The engine is new to the vehicle, and the drivetrain, suspension, steering, and brakes have all been completely reengineered using bigger, stouter components.
Our test unit was powered by the longitudinally mounted, driven-by-wire Chrysler 3.8L V-6 rated at 205 hp at 5,200 rpm and 240 lb-ft of torque at 4,000. At present, it's the only engine available for the Wrangler, though 'wheelers abroad can get a 2.8L VM Motori I-4 turbodiesel. Our test JK sported the NSG370 six-speed manual transmission mated to the NVG241 Rock-Trac transfer case, now engaged by a cable shifter and equipped with fixed yokes and CV joints. Axles for Rubicon JKs remain Dana 44s at both ends, though the front is now a reverse-pinion unit, and both axles' ring gears, tubes, and 'shafts (now 1.4-inch diameter) have increased in size and strength. Selectable lockers are still stuffed in the pumpkins, but now they're engaged magnetically (no more vacuum). For base-model Wranglers, the Dana 30 front and 35 rear are still standard, but they've also been upgraded, and the 35 finally loses the C-clips. Rolling stock remains 32-inch BFG Mud-Terrains on 17x7.5-inch rims (now on a 5-on-5 bolt pattern) with the Rubicon package.
The JK's suspension utilizes the same basic coil-spring/five-link arrangement as the TJ, though all the links and bars are stouter this year, the shocks are higher-pressure monotubes, and the electronic sway-bar-disconnect system used by the Dodge Power Wagon now resides on the frontend. Steering is a power crossover setup using a high-steer knuckle, and brakes are four-wheel discs on all models. The JK's new hydroformed chassis is said to be 100 percent more resistant to bending and offers 50 percent greater torsional resistance. And, of course, the whole package is 5 inches wider and 5 inches longer than its predecessor. But is bigger necessarily better?
On the trail in low-range, the six-speed/Rock-Trac combo, in tandem with 4.10:1 axle gears, provides a whopping 73:1 crawl ratio-great for inching down deeply rutted washouts and over rock-strewn riverbeds. The suspension flexes reasonably well, and with the sway bar disconnected (and the ESP turned off), keeping the fronts on the ground was rarely a problem, though cycling at both ends could be hindered somewhat by limited shock droop. (We'd opt for a set of premium aftermarket boingers as a worthwhile first upgrade.) Especially welcome in loose dirt and on rocks, locker engagement is seamless and smooth-a big improvement.
As soon as the terrain grew less challenging, though, and we needed to vary our speeds, the V-6's shortcomings became more transparent. A conventional 60-degree short-stroke block sourced from the Chrysler minivan line, the 3.8L's torque peak requires generous throttle to maintain, and with the six-speed's wide ratios and long, clunky shift throws, we found ourselves losing power whenever we needed another gear. The fact that a JK in motion equals 4,100 pounds of rolling resistance doesn't help, either.
Another concern was the extra girth. While the JK's increased track width improves lateral stability-as well as offering more interior legroom, elbowroom, and overall levels of creature comfort-all that extra space and sheetmetal can impede the driver's ability to peer over the hood, and over the too-high-for-hip-point doorsills. At least the driver's seat can be adjusted up slightly, but we never did get a really good look at the trail until the doors had been removed (see "Where We Wheeled" on page 34 for details). The greater overall width could also affect maneuverability in tight spots. Squeezing through a very narrow two-track at night, with acacia branches and 10-foot-tall elephant grass buffeting our sheetmetal (and us) with bonks and scratches, we kept asking ourselves, "They made it 5 inches wider for ... why, exactly?"
On the other hand, we like the vehicle's muscular lines and its overall exterior dimensions. It doesn't really look much bigger from the outside, and its approach and departure angles (44 and 40, respectively) and minimum ground clearance (over 10 inches) are still outstanding. Overall fit and finish-inside and out-were very tight on our tester, too, given its preproduction status. And needless to say, in Rubicon trim, we'd wager the new Wrangler would easily outwheel anything else in its class. It'll certainly outcrawl anything that isn't a Unimog.
Due to our trail-heavy test schedule, we didn't get to drive the JK on paved roads, so we'll withhold assessing its street manners until we can get one for further evaluation-in this case, for our 2007 Four Wheeler of the Year test, coming up in just a couple of months.
Vehicle model: 2007 Jeep Wrangler Rubicon
Base Price: $18,765
Engine Type: 3.8L 60-degree V-6
Bore x stroke (in.): 3.78 x 3.43
Valvetrain: OHV, 2 valves/cyl
Mfg.'s hp @ rpm: 205 @ 5,200
Mfg.'s torque (lb-ft) @ rpm: 240 @ 4,000
Transmission: NSG 370 six-speed manual OD
Transfer case: NV241 Rock-Trac part-time two-speed
Low range ratio: 4.00:1
Crawl ratio: 73.14:1
Axle ratio: 4.10:1
Suspension (f/r): Solid axle, coil springs, track bar, electronic sway-bar disconnect/Solid axle, coil springs, five-link with track bar, stabilizer bar
Steering: Power recirculating ball
Brakes (f/r): 11.9-inch vented disc/12.44-inch solid rotor
Wheels/Tires: 17x7.5 cast aluminum
Tires: LT255/75R17 BFG Mud-Terrains
Wheelbase (in.): 95.4
Length (in.): 152.8
Width (in.): 73.7
Height (in.): 70.9
Track, f/r (in.): 61.9/61.9
Curb weight (lb.): 4,104
Ground clearance f/r (in.): 10.5/10.2
Approach/departure angle (deg.): 44.3/40.4
Max towing capacity (lb.): 2,000
Max cargo capacity (cu. ft.): 61.2
Fuel capacity (gal.): 21
EPA mileage estimates (mpg): N/A
Seating capacity: 5