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JL Rising: A Rock Krawler Lift Helps Fit 37s on Our 2018 Wrangler

Posted in How To: Suspension Brakes on August 6, 2018
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The all-new ’18 Jeep JL Wrangler was eagerly welcomed after a long run of JK Wrangler production. Among other things, on- and off-road performance has been improved and the flagship Rubicon models come from the factory with 33-inch tires.

However, the owner of this JL Wrangler Unlimited Rubicon wanted a bit more height to improve approach and departure angles, and the ability to run 37-inch tires. Enter Rock Krawler Suspension. The company offers both 2.5- and 3.5-inch suspension systems for the new JL. Additionally, Rock Krawler offers several kit options based on the performance you desire for your Wrangler. The owner of this Wrangler opted to use the company’s 2.5-inch X Factor Mid Arm System. The kit includes beefier adjustable control arms, a new adjustable front track bar, triple-rate coil springs, sway bar disconnects, and rear track bar relocation bracket. We also installed Rock Krawler’s brand-new RRD 2.25 shocks. (See sidebar for more info.)

The control arms and track bar come preassembled and Rock Krawler provides suggested starting lengths based on the lift kit height. We set lengths on a workbench and proceeded with the installation. The kit was installed at Done Right Diesel in the Phoenix, Arizona, area and Larry Zager was the technician that completed most of the project. It took about eight hours for Zager to perform the job using a lift, and the work only required common tools. We see little reason the Rock Krawler kit could not be installed in a home driveway over a weekend by following the detailed instructions provided.

Read on for the highlights of the install.

Here is the complete kit, less shocks. It includes all replacement control arms, a front track bar, coil springs, sway bar links, and all the hardware needed to install the lift.
The front tires, shocks, sway bar links, control arms, front track bar, and front springs were all removed, leaving the axle sitting on a pair of jackstands.
At the frame, all four lower control arms are fitted with Rock Krawler Pro Flex Joints. Krawler Joints are used elsewhere. All are greaseable and rebuildable. Rock Krawler recommends clearancing the lower arm mounts on the axle with a hole saw to allow access to the zerk fittings.
Rock Krawler also recommends adding included bumpstop pads to the top of the factory bump on the front axle. Zager drilled a 1/2-inch hole in each bump to accommodate a mounting bolt.
All the new control arms mount to the existing frame and axle mounts with the factory hardware. The new upper arms are bent slightly to clear the framerails during full articulation. Here you can also see the installed bumpstop pads.
The Rock Krawler control arms are much beefier than the stock pieces. The lower control arms are constructed from thick-wall 1.75-inch-diameter tubing. Each is also bent upward to improve ground clearance.
Even with the lower axle mounts opened up, it seemed the zerk fittings on the joints may not be easily accessible. We made a quick swap to 6x1mm 45-degree zerk fittings in this location. Another option would’ve been to use a 90-degree fitting on the grease gun.
New coil spring seats were placed on the axle and new springs installed, followed by the RRD 2.25 shocks. The kit includes a heavy-duty track bar that was bolted in place using the factory hardware.
With the front axle fully drooped on the lift, the brake lines, ABS wiring, and breather hose were all checked to ensure there would be ample slack in them when the suspension was flexed out. New sway bar links are included for the front axle, along with lower relocation brackets that simply bolt in to position. The lower link ends can be disconnected from the axle by pulling the quick-release pins to completely disable the sway bar.
Straps are also included to secure the disconnected sway bar links away from the axle. The Rubicon model was equipped with the electric sway bar disconnect feature. Rock Krawler recommends manually disconnecting the links for extreme off-roading or high articulation of the front axle.
Moving to the rear installation, Zager started by pulling the brake rotors to disconnect the parking brake cables. Both cables were rerouted under a rear crossmember to gain a bit of length to the axle before being reconnected. As with the front suspension, the factory shocks, sway bar links, and coil springs were all removed.
The four control arms and the axle-side bolt for the track bar were removed. Again, the axle sat on a pair of jackstands, with a third one to support the pinion.
The rear axle received a new track bar relocation bracket. It bolts in place on the original axle mount, and a saddle is also clamped onto the axletube with a U-bolt.
One rear control arm joint is right-hand threaded, while the other is left-hand threaded to make pinion angle adjustment easy. The joints all come pre-greased.
The lower control arms on the rear are similar to the ones in front and are also curved upward to improve clearance.
After the new spring seats were installed on the axle, the new coil springs were put in place and the RRD 2.25 shocks were bolted in to position.
The Rock Krawler bumpstop mounts and pads are included and were bolted on to the existing metal pads on the axletubes.
New sway bar links were added to the rear axle and bolted in place. All the jam nuts were tightened on the link components, and all hardware was rechecked before the new tires were installed and the Jeep was set back on the ground.


The Jeep got new wheels and rubber to take advantage of the taller height, and to further increase performance. It now turns 37x13.50R20LT Nitto Ridge Grapplers mounted on one-piece 20x10 Fuel Coupler wheels.

Driving tests showed the street ride was smooth; the multi-rate coils soaked up the small pavement bumps well, and then allowed the Jeep to corner without excessive body roll as the spring rate advanced under compression. Off-road, the ride was also well behaved with the coils soaking up bumpy dirt trails effectively while providing supple flex when needed.

With the added lift and new tires, the approach angle of the Jeep increased impressively by about 12 degrees, while the departure angle increased by 7 degrees. It was a noticeable improvement off-road. Ground clearance went up by approximately 2 inches due to the larger-diameter tires. The stance of the Jeep remains reasonably low and very stable. The kit comes with multiple bumpstop pads that can be stacked as needed. We installed the recommended two pads up front and a single pad in the rear. At full flex, we found very minor tire rubbing on some of the plastic inner fender panels and on the trailing edge of the stock front bumper, but we opted not to add additional bumpstop pads.

About the New RRD 2.25 Shock

We paired the 2.5-inch X Factor Mid Arm System with Rock Krawler’s hot new RRD 2.25-inch shock. Some of its features include a fluted-aluminum body that not only makes the shock lightweight, but also improves vital cooling with its increased outer surface area. The body is hard-anodized to prevent corrosion. A heavy-duty 3/4-inch Nitrotec steel shaft is supported internally with a pair of high-quality DU bearings, and then sealed up with Viton O-rings and double-lip Buna-N shaft seals to keep shock fluid in and external contaminants out. A billet aluminum–valve circuit with digressive valving controls the damping of each shock, which comes tuned specifically for the lift kit application. The RRD emulsion shocks are also fully serviceable and can be re-valved as needed.

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Rock Krawler
Done Right Diesel

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