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2008 Jeep Wrangler JK Rubicon - Trailrunner

Posted in Features on October 1, 2010
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I like two-door JK Wranglers. I like the way they look and the way they work on the trail. I also like dual sport 4x4s that work as daily drivers and trail vehicles. Therefore, when I found a good deal on this 2008 Jeep Wrangler JK Rubicon, I snapped it up. The Trailrunner, a JK that can go fast like a prerunner and still tackle tough trails, is about to be born.

The Wrangler came with pretty much everything on it, including navigation. This will be good for entertainment on long backcountry forays. It has the 3.8L V-6 with 42RLE automatic tranny, NVG241OR Rock Trac transfer case, and the Rubicon 44 front and rear ends with E-lockers and electronic swaybar disconnect. I plan to build this in stages, with Stage I including bolt-on parts and minor fabrication.

I took the JK to Mount Logan Off-Road so they could install their Bombproof Axle Kit that addresses the weak inner knuckles and tubes of the JK 44. An RCV Performance Ultimate Dana 44 JK Rubicon Front CV Axle kit replaced the OE axles. While this was being done, JKS control arms and track bars were installed, as were KORE coils and KORE/Fox reservoir shocks. An R-SE swingaway tire carrier bumper and a Shrockworks stubby front bumper with a Warn PowerPlant HP winch guard the front and rear of the Jeep. A set of 37x12.50R17LT Goodyear Wrangler MTR with Kevlar tires were mounted on 17x8 Black Rock Viper wheels.

The JK then went to Kevin Hawkins for the installation of a PSC JK Extreme Duty Cylinder-Assist kit. Kevin is a ram-assist expert and enjoys installing the systems on everything from Jeeps to buggies. As a result, the PSC system works great and the Trailrunner's steering is flawless. Currie Enterprises' beefy new CurrectLync tie rod and drag link were also installed. Being a believer that lighter is better, a pair of Teraflex aluminum rocker guards were procured that are light, yet strong.

The Trailrunner was now in my garage. It looked good, but was generating Diagnostic Trouble Codes (DTCs). P0055 and P00F9 kept popping up. I couldn't find what P00F9 was, but P0055 was supposed to be HO²S Heater Resistance (Bank 1 Sensor 3) according to an Internet search. This was a downstream O² sensor problem, so I changed both downstream O² sensors, cleared the DTCs, and started the Jeep. The Check Engine light immediately illuminated. P0055 and P00F9 were there again. I could also smell gas fumes every time the JK was started. I always use a Kilby vapor-recovery canister relocating kit when building a JK and this Wrangler was no exception. The Kilby kit was installed the same as all the other kits had been, but when I pulled on the rubber hoses that went over the plastic hard lines, they moved easily. Hose clamps cured the gas fumes. Guess what? No more DTCs, either. I bet P00F9 means a fuel system leak. P0055 may have something to do with that, too, as neither code has returned. Maybe the internet key to DTCs has a GM code description and Chrysler uses the codes to mean something else? Who knows?

PhotosView Slideshow

I used a trusty AEV ProCal to clear DTCs and program the Trailrunner. With the ProCal, I can program tire size, gear ratio, and TPMS threshold. I dislike TPMS, so I turn it off with the ProCal. The ProCal can do a number of other things, including SmartBar (electronic swaybar) activation/deactivation, daytime running lamp activation/deactivation, one-touch lane change management, set extended idle mode, new PCM setup, and set throttle tolerance. It can even provide a dead center steering wheel indication for perfect alignment.

I tried adjusting the headlights and found that the driver's side light mounting ring was broken. Jeep wanted $139 for the part (!), so I called around and found a used ring at Burnsville Off-Road. The grille is easily removed and I replaced the locating ring. This is a JK weakness and Jeep shouldn't charge so much for a cheap part that fails easily.

See the photo captions for details on the suspension, but even though the coils and shocks weren't designed for a two-door JK and the Jeep was sitting too tall, I took the Trailrunner out for a drive and was impressed. It not only crawled up obstacles easily (slow), I was able to hit 80 mph on a graded dirt road (fast). Graded, yes, but it had big ruts from when it had been muddy and some bad washboard in places. Driving 80 mph is admittedly fast, so I slowed down a bit and found that I was comfortable driving the Trailrunner at 60 mph in the dirt. That's quite a change from years ago when I traveled the same type of road no faster than 15 mph in my CJ. With the rear seat removed, there's plenty of room for the ARB Fridge Freeze and other gear.

Stage I is finished. As my motto is, "If it isn't broken, fix it until it is," I will now start Stage II. In the meantime, Trailrunner is slow, fast, and fun!

PhotosView Slideshow
PhotosView Slideshow


Currie Enterprises
Corona, CA 92880
ARB 4x4 Products
Renton, WA 98057
JKS Manufacturing
Alliance, NE 69301
American Expedition Vehicles
Wixom, MI 48393
Poly Performance
San Luis Obispo, CA 93401
RCV Performance
Loves Park, IL
Murray, UT 84107
Tom Wood's Custom Driveshafts
Ogden, UT 84404
Goodyear Tire & Rubber Co
Akron, OH 44316
West Coast Differentials
Rancho Cordova, CA 95742
PSC Motorsports
Azle, TX 76020
Warn Industries
Clackamas, OR 97015
JB Conversions
Sulphur, LA 70664
Expedition One
Ogden, UT 84401
Kilby Enterprises
Burbank, CA 91504
Misch 4x4 Products
Coffeyville, KS 67337
Valley Center, CA 92082
Mount Logan Off-Road
North Logan, UT 94341
Houston, TX 77066
Black Rock Wheels
Ontario, CA

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