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Discovering Your JK Wrangler’s Off-Road Potential with a JKS Jspec 2.5-inch Suspension System and the Right Tires

Posted in How To: Suspension Brakes on September 5, 2017
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When Jeep introduced the JK Wrangler with a four-door option in 2007, they created a new type of Wrangler owner. While the two-door JK customer stayed closer to the conventional Wrangler customer’s roots, the new JK Wrangler Unlimited was flying off dealer lots, often to serve a more domesticated role in some cases: commuting to work, carpooling to school, picking up groceries, and yes, crawling the mall. In 2012, Jeep introduced a refreshed JK with a modernized interior, an adequate 3.6L Pentastar V-6, and the stellar Mercedes-sourced W5A580 five-speed automatic transmission, further cementing the JK Unlimited’s place in the mainstream.

Like generations of Jeepers before them, the aftermarket bug has bitten JK Unlimited owners too. Today, there are a dizzying number of options, from spacer lifts to Ultra4-inspired coilover suspensions. What’s the JK Unlimited owner to do?

We were invited to Krusher Offroad in Burbank, California, a specialist in late-model Wranglers, to watch a ’13 JK Unlimited Sahara be transformed from mall machine on bald tires to off-road ready. This Jeep’s owner uses his rig for daily tasks typical of a four-door SUV, but also likes to travel off-road. Drivability and reliability were some of the key requirements when it came to suspension selection.

Here it is! Everything you need to create a reliable weekend warrior. Note the awesome packaging of the Jspec base kit

A basic 2.5-inch JKS Jspec suspension system was chosen along with several upgrades to beef up the Jeep’s drivetrain components. It’s worth noting that there’s also a 3.5-inch Jspec suspension available for the JK Unlimited and both 2.5- and 3.5-inch Jspec suspension systems for the two-door JK Wrangler. The JKS Jspec line takes the entire Jeep into consideration with its complete suspension kits that are designed for the driver who wants performance and durability but wants to maintain good handling and ride quality. The takeaway is you don’t have to go big. With a little planning and proper application, a high-quality, moderately sized suspension lift and tire combo can create a very capable JK that is at home on city streets and the dirt. Follow along as we cover some of the highlights of the install.

Disassembly of a JK suspension and prep for the Jspec lift was very straightforward, and JKS provided detailed instructions. The factory front driveshaft was disconnected from the pinion, and the driveway installer will want to disconnect the drag link from the pitman arm to allow for easy manipulation of the front axle.
Before putting the rear suspension back together, Robert got to work on the OGS169 rear track bar brace. This optional piece is a weld-on job, but well within the skillset of the entry-level driveway fabricator. If you’re doing a home installation and don’t have a welder, don’t fret, you can save it for your local shop later. A rear track bar brace is cheap insurance against catastrophic failure of the rear track bar bracket, a notorious weak point on the JK Wrangler’s rear axle, even with the additional hassle of installation.
Rear assembly includes bolting on the new track bar bracket (shown), the bumpstop extensions, rear brake line brackets, coil springs, and new shocks. It’s important to note the orientation of the coil springs, installed per JKS’s instructions, which ensure a level Jeep with proper ride height and performance. The optional rear control arms and new rear track bar were also bolted in. The rear sway bar links needed to be cut to length, but are a worthwhile upgrade over the factory links.
Front installation started with drilling a 5/16-inch hole in each front bumpstop pad to install the supplied 2-inch bumpstop spacers. These spacers keep the suspension from bottoming out and will keep the tires out of the factory fenders. The new coil springs reused the factory coil spring isolator and the new Fox 2.0 shocks were bolted at the stock locations.
A set of optional 2-inch by 1/4-inch-wall J-Link fixed lower control arms were chosen as a strength upgrade for front caster correction instead of cam locks. As a bonus, the slightly lengthened rear arms re-center the rear axle in the wheelwell.
Installation of the rest of the front suspension consisted of bolting in and setting an approximate length of the new track bar (final adjustments are to be done after setting the Jeep on the ground), installing the brake line brackets, and the Quicker Disconnects sway bar links.
Before we bolted the driveshaft back in place, it was time to install the exhaust extensions. For ’12-and-up JKs it is vitally important that you install the optional JKS 8150 exhaust extensions to the exhaust pipe that loops under the driveshaft. Without it, the driveshaft boot will contact the exhaust pipe, and the driveshaft will rub on the loop during even mild suspension movements.
Our Jeep got a set of Nitto’s LT285/75R17 Ridge Grappler tires on factory Rubicon wheels that were scored on the cheap. This is a great tire size for a JK, giving an appreciable bump in ride height without killing performance with the factory gears. Wheel spacers are highly recommended for using factory wheels. For our application, 1 1/4-inch spacers from Nitro Gear & Axle were chosen. If you do run a wider tire, a 1 1/2-inch spacer may be a better choice. Wheel spacers work well and can be a much more affordable option than new wheels, but always use a quality wheel spacer and always follow the installation procedure.
Once final track bar adjustments were done, it was time to set the Jeep on the ground and torque down all hardware to spec. Marking the bolts is always a good idea so you can visually check them to ensure they haven’t moved.
The optional Superchips Flashcal is available alongside the Jspec kit. This is necessary to correct the speedometer for the larger diameter tires. The Flashcal includes the ability to manipulate the TPMS and even an optional horsepower upgrade.
On the road, the new Jspec suspension is taut while yielding a very pleasant ride. JKS’s proprietary dual-rate springs combine with the Fox Adventure 2.0 shocks to provide a big improvement in handling, despite the increase in ride height. The additional increased uptravel means the suspension doesn’t bottom out during normal street maneuvers. For our road test, we decided on a jaunt over the famed Mulholland Drive in Los Angeles and were very impressed, and a little freaked out, about the speed with which you can take the sharp corners on this windy mountain road.
For our off-road test, we wheeled around an OHV park. The difference between the stock and lifted Sahara is even more noticeable on the dirt. In stock form, the lack of uptravel and soft spring rates mean that rutted dirt roads can be a slow, agonizing experience. The Jspec suspension turned dirt roads into a downright fun place to be; the spring and shock combo really comes to life and does a great job soaking up the bumps while providing great stability.
In the rocks, there was absolutely no comparison between the modified and factory versions. While a Rubicon is competent in the rocks for such a low-slung vehicle, a Sahara, with its street tires, low ride height, and fixed factory sway bar is simply not equipped for this type of terrain out of the box. It is amazing what a couple inches of ride height, a little flex, and some aggressive tires can do. With the JKS Quicker Disconnects, we can have the sway bar disconnected in less than two minutes, and since we opted for the lanyard kit, we can easily tuck the factory sway bar out of the way. Suspension flex is impressive. Even though the base Jspec kit does not focus on wheel travel per se, it is a great demonstration of how a moderate suspension lift and the proper tires can really make a JK Wrangler live up to its potential.

Kit Specs
Our JKS Jspec 2.5-inch kit is specific to the four-door Unlimited JK. It contains coils, Fox 2.0 Adventure series shocks, a front track bar, rear track bar relocation bracket, brake line brackets, and JKS Quicker Disconnects sway bar end links. JKS recommends up to a 35-inch tire for the 2.5-inch kit. MSRP at time of print is $1,245.

Additional components:
PWT3571, Superchips Flashcal Programmer, MSRP $180
JKS8150, exhaust spacer for ’12-’17 JKs, MSRP $45
JSPEC111K, front and rear J-Link control arms, MSRP $450
JOGS169, rear track bar brace, MSRP $50
JKS2943, adjustable rear sway bar links, MSRP $85
OGS159, adjustable rear track bar, MSRP $180
2039, sway bar lanyard kit, MSRP $15


JKS Manufacturing
Alliance, NE 69301
Krusher Offroad

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