2008 Jeep Wrangler Jk Rubicon - TrailRunnerPosted in Project Vehicles on September 16, 2013
TrailRunner, our ’08 JK Wrangler Rubicon, was built to work well, whether it was crawling or hauling. The project was a success. It’s now a couple of years later and time to refresh the yellow two-door JK with the help of John Williams at Impulse Off-Road.
The 3.8 V-6 was reliable, but gutless. It works great in minivans, but struggles in heavier JKs. Enter MoTech. MoTech developed a way to install GM aluminum-block LS architecture V-8s and GM transmissions into the JK and integrate the drivetrain into the JK’s CANbus. There are no warning lights or other issues. MoTech installed a 5.3 aluminum-block V-8 and 6L80 six-speed automatic into TrailRunner. Wow. What a difference an infusion of power and torque makes! The MoTech V-8 works perfectly and runs cool, no matter how hot the desert is. The only issue we addressed was that the Rubicon 241OR’s 4.0:1 low range was too low with the 6L80’s 4.0 First gear. So, we swapped our Rubicon transfer case for a 241J T-case with a 2.72:1 low range. Perfect. In low range, TrailRunner has just about the same gearing in First with the 241J as it did in First gear with the 42RLE and the Rubicon 241OR 4.0:1 low range.
As you saw on our website and Facebook page, we thought that detuning TrailRunner by going to 35-inch tires and stock flares would make the TrailRunner more of a sleeper. This didn’t work. The 35s hit the OE flares, so we installed Bushwacker flat-panel flares and returned to 37-inch tires to fill the voids. We use two sets of wheels and tires: 37-inch Goodyear Wrangler MT/R with Kevlar tires are mounted on Interco Birddog wheels for long highway trips with trails at the end, and 37-inch BFGoodrich Krawler KX tires mounted on Black Rock Yuma wheels with OMF Rocklight beadlocks for the local hard-core areas. Every time we change tires, we measure the static-loaded radius and enter it into the computer with our AEV ProCal programmer.
Our 2.5-inch coils had become 2.0-inch coils. Because of this, there wasn’t enough uptravel. We installed 3-inch TeraFlex coils, which gave us another inch of uptravel. It was surprising what a difference this made. There was a reason we started lifting vehicles to begin with. New Fox 2.5-inch internal bypass reservoir shocks are valved perfectly for the JK and allow the TrailRunner to really move over the rough stuff.
With the TrailRunner tackling more difficult trails, we wanted beefier axles. Currie Enterprises’ RockJock 60 front and rearends were installed, equipped with Yukon 4.88 gears and Yukon Grizzly Lockers front and rear. We ordered the RockJocks with a 6x5.5 bolt pattern, as there are more wheels and backspacings available with this bolt pattern than the old 5x5.5 pattern.
The front bumper was the Expedition One Basic DX with foglight wings and Rubi Skid. The Warn Zeon 10-S winch fits perfectly in the lightweight bumper system. Expedition One introduced its Trail Series rear bumper in aluminum, so one of those immediately found its way onto TrailRunner. Lighter is better, in our opinion.
Finally, our interior was in great shape, but there’s nothing wrong with making things more comfortable. We like Hotheads headliners, so when the company introduced its seat covers, we installed a set of 100 percent leather Hotheads Seat Covers. The quality of the leather is unsurpassed and the seat covers easily slip over the existing seat covers. As you see in the photo, they don’t look like seat covers.
TrailRunner’s updates made it a better JK. It works on the highway or in the dirt. It’s powerful, comfortable, and capable. Refreshing.
|Vehicle:||2008 JK Wrangler Rubicon|
|Owner/Hometown:||Phil Howell/Hurricane, Utah|
|Engine:||MoTech 5.3 GM aluminum-block V-8|
|Transmission:||GM 6L80 six-speed automatic|
|Transfer case/low-range ratio:||Jeep 241J/2.72:1|
|Frontend:||Currie RockJock 60|
|Rearend:||Currie RockJock 60|
|Front Differential:||Yukon Grizzly Locker|
|Rear Differential:||Yukon Grizzly Locker|
|Suspension:||3-inch TeraFlex LCG long arm with Fox 2.5 internal bypass reservoir shocks|
|Tires:||LT37x12.50R17 BFGoodrich Krawler KX|
|Wheels/Backspacing:||Black Rock Yuma alloys with OMF Rocklight beadlocks/4.5-inch|