Taking the JK off road onto trails that I have previous run in a 98 TJ, 03 TJ Rubicon, and an 05 Unlimited Rubicon would allow me a good basis for comparison between the Jeeps. The first thing I noticed running out to the trails was that the estimated MPG was 22.7mpg. Not to bad compared to the older TJ's. There of course is a descrepancy between what the computer estimates and what the actual filling the tank numbers are, but even at 2mpg difference it still gets much better gas mileage. After waiting for the owners of the CJ's, YJ's, and TJ's that were in the group to get out, lock in hubs, and disconnect sway bars, we were on our way. The trails around here are mostly a sand clay mixture that features slippery steep hill climbs or decents, extreme breakover's and gulley's that task the articulation of a vehicle. My first question of the day was "Aren't you going to get out and disconnect?" My answer was "I will when I need to, I'll just push the button." Which of course launched into a discussion of how the electronic swaybar works. The one nice thing about todays test ride was having a stock 06 Rubicon along for the ride. Everyone was really interested in how the JK would actually perform on the trail. I drove the trails with every intention to see how far I could push the JK without using the capabilities of the Rubicon package.
I tried to drive as much of the trail in 2wd and 1st or 2nd gear as possible. I wanted to see how well the new ESP system actually worked, especially the dynamic braking to control wheel spin. The trails cross over a few dirt roads that are in the area, and the entrances and exits have a small dirt berm that you drive over. With the TJ I would be able to turn onto the dirt roads and with a little goose of the throttle get the rear end to slide over, not so much luck with the JK, the ESP kicks in immediately and you just make the turn. After it did it the first time, I really tried for the rest of the day to get the rear end to slide, with no luck. You don't even feel the system kick in, I had expected to at least feel something but I didn't. I looked for some type of feeling with the system activation, but every time there was nothing, just seamless. I did try a gravelly hill climb in 2nd gear 2wd, and of course only made it about two thirds of the way up the hill before I killed it. A quick restart, first gear, a little throttle to keep it running, and ESP kicked in again walking the jeep right up the hill. I of course couldn't feel anything from the system, but having the windows open I could hear the passenger rear spin, then hear it slow and then I heard the drivers side tire dig in and drive up the hill. The driver behind me described what he saw from the tires. The passenger side was spinning, the drivers side was stopped, you could see the passenger side slow down and then the drivers side started spinning, both were turning at about the same speed as they dug in and went up the hill. He asked me if I had lockered it, and was really surprised when I told him I was in 2wd still.
I did manage to find a log to play on that had a decent diameter. Enough that I was pretty certain I would be on my gas tank skid when I went over it. I was more than willing to take a strap if needed. I drove over the log with the front end and set it down on the gas tank skid. I didn't have the ground clearance to clear the log, but I did have the articulation to keep the tires on the ground and keep going. I just slid over the log with the skid. I may not have had the full weigh of the Jeep on the log, but I would have gotten hung up with the 03 and up TJ's skid plate.
We hit an obstacle that pushed the articulation at the same time was about the wheelbase of the jeeps, so at 1 point both the drivers front and passenger rear tires were completely off the ground. I ran this obstacle a bunch of times, just to play with the system. The unlockered TJ's had to bump their way through this just to get up and over the tetter-totter portion of the obstacle. The Rubicon made it through by riding the brake and getting the limited slip to engage, he didn't use the lockers. The main problem with the obstacle was taking the 2 normal drive wheels off the ground. Of course I had to try it in 2wd, but not having the front to dig in and climb the obstacle in front only resulted in me killing it. I could have probably made the obstacle if I had gunned it, but as a TJ with a shattered front u-joint proved later in the day, skinny pedal hurts. I then tried the obstacle in 4wd, and when I picked up both tires, you could feel the jeep slow to a stop, the wheels spin, and then just drive forward. My observer let me know that both tires came off the ground, spun, then slowed as the other two tires drove the Jeep forward. So around I went for a third shot, this time in 4lo. Not much difference here between the TJ 4lo and the JK 4lo on the Rubicon package. I did notice that the TJ has more torque in 4lo, 1st gear, but even with the JK you are still standing on the brake with futility, it just drives forward. I hit the rear locker just to see how much of a joke the obstacle was to the Rubicon package. I probably should have brought War and Peace, I could have read the first couple chapters just getting to the obstacle. I actually even hit the anti-sway bar disconnect this time. Almost too boring. I did get the comment "That was to easy, run it in reverse." Hmmm... Okay. So around for the fourth time, this time I ran it in reverse, 4lo, unlocked, anti-sway bar locked. I don't know if the ESP kicked in or not, but the JK walked through the obstacle again in reverse.
The last item for the day was an offcamber gully with a wall about the height of the Jeep. I decided to follow a couple of CJ's on 36" boggers through this. I just ran it in 4lo, 4th gear. The BFG's did a good job of gripping the clay and keeping me off of the wall. I did slide in right at the end and had to run a large tree root down the side of the JK with only about 2" of clearance. I did use the door handle at one point to keep the root out of the sheet metal. The door handle held up nicely, and even the taillight that I clipped with the root, only left a rub mark.
In my opinion the JK is an improvement of the the older TJ's. The extra width wasn't even noticeable on the trails. The CJ-7 on 36" boggers was wider than the JK. The ESP system worked flawlessly, keeping traction when you really needed it. The Rubicon package performed just like it's predecessors. The only complaint I have is that the 3.8L V6 just does not compare to the down low torque that the I-6 had. This is really evident in it's ability to recover from near stalls. I could lug the I-6 down to about 200rpm's and a quick push of the clutch it would recover, not with the V-6, it's gone. I would say that a stock JK Rubicon package is a better vehicle than a stock TJ or TJ Unlimited Rubicon. I would believe that it will give a few mildly modded TJ's a run for their money.
