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Weekender Jeep Wrangler JK Part 2

Posted in Project Vehicles on May 1, 2012 Comment (0)
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Last month we brought you the foundation of a buildup on our 2012 Jeep Wrangler Unlimited Sahara. You’ll remember that we wanted to make a durable daily driver, a capable family hauler, and competent trail rig. The plan was to overbuild the JK for our needs using quality components, ensuring reliability in the backcountry. This month we’ll focus on the items we installed at the shop before turning to our driveway upgrades in next month’s installment.

With the ’12 Wrangler comes some substantial upgrades, such as an all-new engine that necessitated a complete redesign of the exhaust system. The entire driveline is also tilted back an additional three degrees for a total of nine and a new vacuum pump is located right where you want to install a front bumper and winch. Fortunately, the aftermarket has come to the rescue for solutions to each of these issues. For example, aFe’s Mach Force XP Y-pipe is a bolt-on piece that reroutes the exhaust crossover behind the T-case, substantially increasing space for an aftermarket front driveshaft.

For our suspension needs, we turned to EVO MFG and its EVO Enforcer 3.5-inch short-arm system. This suspension was developed for the Bureau of Land Management’s fleet of law enforcement Wranglers. The officers complained that the stock JK ride suffered and was the cause of fatigue on long shifts where the vehicles were heavily loaded while traversing rough terrain at varying speeds. The answer was a simple suspension upgrade that consisted of EVO Plush Ride linear lift coils, front adjustable lower control arms, sway bar endlink extensions, brake line extension brackets, and a rear roll center correction kit. Specially valved shocks are optional, or you can supply your own, as we did with our Bilstein 5160 remote-reservoir shocks. We also included the optional EVO drag link flip kit. The EVO Enforcer uses all of the stock arm bracketry and everything is bolt-on, although welding is encouraged.

Stock, our Sahara traveled a measly 34 inches up a 30-degree ramp for an RTI score of 293. After our modifications it nearly doubled the distance traveled to 67 inches, for a score of 578.

The EVO Enforcer allows fitment of either 35- or 37-inch tires. We settled on the 37x12.5R17 size and went with the popular BFGoodrich Mud-Terrain KM2s mounted on 17x8.5-inch AEV Savegre wheels. The AEV Savegre cast aluminum wheels are hub centric for an OE-like fit, offer a lifetime structural warranty, and have a backspacing of 4.7 inches. They were designed specifically for the JK and are not universal-fit. We especially like the recessed valve stems, which keep them safe from trail troubles. This wheel and tire package is a perfect pairing and allows factory flare coverage for those who want to keep a more OE-look or are bound by local tire coverage laws.

Moving to a 37-inch-tall tire required us to beef up our axles and gear components. As discussed in last month’s installment, JT’s Parts and Accessories built us a Rubicon-sourced Dana 44 housing that was sleeved and gusseted. The diff was filled with an ARB Air Locker and JT’s in-house brand Nitro gears in a 4.88:1 ratio. JT’s topped off the build with a set of 35-spline RCV CV-style axleshafts. In the rear, we kept our stock Sahara Dana 44 and filled it with an ARB Air Locker and 35-spline rear axleshafts, a setup that JT’s co-developed. JT’s also supplied thick cast aluminum Nitro gear diff covers, which help to shed heat, as well as protect the gears. After the gear and tire changes, we used AEV’s ProCal to calibrate our speedometer and lower the Tire Pressure Monitoring System threshold to 10 psi. This allows us to air down on the trail without triggering the system, while keeping it operational for highway use.

Adding 35- or 37-inch tires to any JK will put a lot of stress on the stock steering box. From the factory, the box lacks lower support for the sector shaft, which means it is susceptible to bending or breaking from the increased leverage caused by the addition of bigger tires. To combat this, we added what we consider to be an absolute must-have to any JK running stock steering with a 35-inch or larger tire: JKS’ sector shaft brace kit. This system is one of the best-engineered pieces on the market and should be considered a priority for those wanting to get longevity out of their stock steering system.

Wrapping up our time in the shop, we installed a set of Expedition One Trail Series bumpers. Expedition One’s Trail Series front bumper compliments the JK’s styling, while the rear has the Smooth Motion Spare Tire Carrier (STC) system, where the swing arm is attached to the tailgate, allowing the tire and tailgate to swing together. We paired the front bumper with Warn’s 9.5cti thermometric, 9,500-pound self-recovery winch (January ’12, page 80).

The majority of our parts were ordered from Jeep mail order specialist Quadratec, which has an astounding catalog of Jeep parts with superior customer service to go with it. Off Road Evolution in Fullerton, California, did the heavy lifting, assisting us with the install for this segment of the build. Read on to follow our progress as we tore apart our brand new Sahara, building it back in to a daily driver that can take on just about any terrain.

How It Works
Thanks to the above upgrades, we have a great-looking JK that remains a comfortable daily driver, yet is as capable as we’ll ever need on the trail. The Bilstein 5160s are responsive without being harsh on the street, and they do a phenomenal job of soaking up big trail undulations. We are incredibly pleased with how much flex we are getting out of this short-arm kit, nearly double the articulation of stock while the Jeep remains totally streetable. We are looking forward to hitting the trail and getting some backcountry exploring under our belts.

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Sources

Warn
Clackamas, OR 97015
800-543-9276
www.warn.com
Dynatrac
Huntington Beach, CA 92647
714-596-4461
www.dynatrac.com
Bilstein
Poway, CA 92064
858-386-5900
http://www.bilsteinus.com
Off-Road Evolution
Fullerton, CA 92833
714-870-5515
www.offroadevolution.com
JKS Manufacturing
Alliance, NE 69301
308-762-6949
www.jksmfg.com
American Expedition Vehicles
Wixom, MI 48393
248-926-0256
www.aev-conversions.com
BFGoodrich
877-788-8899
www.bfgoodrichtires.com
Quadratec
West Chester, PA 19380
800-745-2348
www.quadratec.com
Tom Wood's Custom Driveshafts
Ogden, UT 84404
801-737-0757
www.4xshaft.com
JT's Parts And Accessories
Cashmere, WA 98815
509-888-2953
www.justdifferentials.com
EVO MFG.
N/A, AK
714-870-5515
www.evomfg.com
AFE
Corona, CA 92879
9514937155
http://www.afepower.com
Expedition One
Ogden, UT 84401
801-726-4338
www.expeditionone.biz
ARB
866-293-9078
www.arbusa.com

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