By Harry Wagner JP Magazine on January 1, 2013
We see stretched TJ Wranglers all the time, to the point that they have become somewhat tiresome. Don’t get us wrong, the formula works well for technical terrain and steep climbs. But this same phenomenon has not occurred with the JK, since you can just buy an Unlimited off the showroom floor with a schoolbus-like 116-inch wheelbase. Not everyone wants that much wheelbase though, or the extra sheetmetal and weight that come with the four-door JK. Jack Stanko has one of the first stretched two-door JKs that we have seen, and while we still aren’t too fond of comp-cut corners, there is enough innovation on this vehicle that it is certainly worth sharing.
Chassis
Nate’s Precision of Reno, Nevada, chose a Synergy rear stretch kit for Jack’s Jeep that adds 8 inches of wheelbase. The Synergy links are constructed of 1¾-inch, 0.188-wall 1026 DOM tubing with Currie Johnny Joints at the frame end. The JK uses an entirely different frame and component packaging when compared to the TJ, so you need to take a different path to get to the same end result. With the introduction of the JK, the fuel tank was moved from the traditional location in the rear to in front of the rear axle on the passenger side. The muffler now resides where the TJ fuel tank did at the back of the vehicle. In some ways, this makes it easier to stretch the wheelbase since you do not run into gas tank interference as you push the axle rearward. The biggest downside is you can’t run a triangulated four link on the rear of a JK like you can on a TJ due to the position of the fuel tank.
After choosing to stretch his JK, Stanko still had a few tough decisions to make regarding the rear suspension. He could retain and relocate the coil springs or swap to coilovers. Coilovers bring more choices, like punching them through the tub, having them hang down below the axletube, or using a cantilever setup. A cantilever suspension uses a pivot to allow more suspension travel out of a shorter shock. It also allows you to position that shock in more locations than usual. While Evo Manufacturing offers a popular cantilever rear suspension for JKs, Nate Jensen of Nate’s Precision designed a system of his own.
Nate and his crew fabricated their cantilever system around King 2-inch-diameter, 8-inch-travel remote-reservoir coilovers in conjunction with King 300lb/in springs. While the Evo cantilever system mounts under the vehicle where the muffler was originally located, Nate’s Precision used the area freed up inside the wheelwell after the tire was moved rearward. The coilovers sit in front of the tire, laid back at a 30-degree angle for a ratio of 1.7:1. In other words, the suspension moves 1.7 inches for every inch of shock movement. The front suspension is more traditional, with an Evo Manufacturing long-arm kit and King 2-inch-diameter, 14-inch-travel diameter remote-reservoir coilovers.
Drivetrain
Being a ’10 Jeep, Jack’s JK has the underpowered 3.8L beneath the hood backed by the factory four-speed automatic. He previously had a Hemi-powered JK Unlimited, and we wouldn’t be surprised to eventually see a Hemi between the framerails of this Jeep. Currently Advance Adapter’s Rubi-Crawler is swapped in place of the factory tranny-to-T-case adapter and adds not only more overall gear reduction, but also more options than the factory 4:1 Rock-Trac T-case in terrain like sand and snow, where super-duper low range is not required.
Downstream from the 1350 U-joints on the Reno Driveline Service driveshafts, the axles were upgraded with every conceivable component. “The front tubes are ¾-inch thick!” Nate Jensen explains. This is accomplished with Evo inner sleeves and a Synergy outer shell that required all of the factory brackets to be removed and then replaced. The front axle also received Evo knuckle gussets, Dynatrac ball joints, RCV chromoly axleshafts, and 5.38 Superior gears wrapped around the factory locker. Steering comes from a PSC box, pump, reservoir, and ram. All the rear needed was Superior axleshafts and gears to match the front.
All of these upgrades were deemed necessary to withstand the combined 136:1 gear reduction and the 40-inch Goodyear MT/R tires on black powdercoated Walker Evans beadlocks. Will the Dana 44 axles live? They have been given every possible upgrade, so we certainly hope so. Looking at the pile of receipts, Dynatrac ProRock 60s wouldn’t have cost much more in retrospect and Dynatrac’s replacement Dana 44 housing might have even cost less overall.
Body and Interior
The first thing that you notice on the JK is the front stinger, which has an aggressive look that people either love or hate. The stinger sits atop an Evo Manufacturing 1⁄4 Pounder front bumper, which is also adorned with a Warn 9500ti winch and a Vision X Evo Prime LED light bar. More Evo steel covers the front fenders, protecting the thin factory tin, while Poison Spyder Ricochet Rockers flank the sides of the JK.
In the rear, GenRight’s new aluminum tire carrier holds a spare 40-inch MT/R. Little details like the boxed in fuel filler and recessed LED rock lights help make up for our aversion to comp cut rear fenders. There was only one source for comp-cut JK fenders when Nate’s Precision built the Jeep, but they had to do so much work to make the fenders fit that Nate felt they would have been better off just starting from scratch. All of the armor was powdercoated by Advanced Powdercoating of Reno in a two-stage silver vein finish that has a distinct textured look and is very durable.
Inside the JK, Mastercraft Safety Baja RS reclining suspension seats are fitted with heating elements for those chilly mornings, while the rear seat received a Mastercraft cover to match. The only other additions were the Synergy rollcage and the shift lever for the Rubi-Crawler, which Nate’s Precision cleanly integrated to the transmission tunnel.
Hard Facts
Vehicle: 2010 Jeep Wrangler JK
Engine: 3.8L V-6
Transmission: 42RE four-speed automatic
Transfer Case: Advance Adapters Rubi-Crawler, NVG241OR Rock-Trac
Suspension: Evo long-arm (front); Synergy long-arm with Nate’s Precision Cantilever (rear)
Axles: Dana 44 (front & rear)
Wheels: 17x9 Walker Evans beadlock
Tires: 40x13.50R17 Goodyear MT/R
Good, Bad, and What It’s For
Jack likes articulation, a lot of it. The cantilever suspension delivers in spades, yet still handles wonderfully on the street. The only downside is that Jack put all of this effort into a ’10 JK, and Jeep came out with a new interior in ’11 and a more powerful engine in ’12. Oh well. The Rubi-Crawler and Rock-Trac transfer cases give this Wrangler a crawl ratio that makes Toyotas blush, and as a result it will idle over the most technical obstacles Jack can find.
Why I Featured It
There are a lot of nice Jeeps out there, but usually it is one detail that makes me pursue a feature. It might be an oddball engine choice, vintage design cue, or even just a great story from the owner. In this case, it was the cantilever rear suspension. It works great on the road, flexes like mad, and solves a host of packaging issues usually associated with stretched wheelbases. The fact that it is part of a very well-built, well-balanced JK sealed the deal.
—Harry Wagner http://www.fourwheeler.com/staff/harry-wagner/
From: http://www.fourwheeler.com/features/154-1301-2010-jeep-wrangler-jk-elastic-man/#ixzz3PCtREYyI
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