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Lift and Caster Correction in One Wrangler JL Suspension System

Seeing Red and Saving Green

Jered KorfhagePhotographer, Writer

Energy Suspension is known for its red polyurethane cure to the deteriorating rubber bushings found on stock vehicles. The company’s patented Hyper-Flex material is said to be more durable than rubber and foam when faced with chemicals and salt, and it can also resist permanent deformation typical of the stock components that receive regular compressive force.

With the dawn of the JL Wrangler, Energy Suspension dug into what made the new Jeep move and flex, and realized the springs, sway bars, and control arms were a stout platform as they were—but with room for a bit of polyurethane improvement. Enter the Rock-Flex suspension system. The kit was designed to maintain many of the stock suspension components, using polyurethane bushings, spacers, and more to improve the vehicle’s suspension flex while also lifting the vehicle. Beginning with the bumpstops, the company’s polyurethane replacements are not just there to keep metal from striking metal when you hit a bump at speed. Instead, they are performance units, slowing the axle’s movement as it reaches the end of its uptravel.

Energy Suspension tells us “we are not a metal company,” so the polyurethane spacers for the sway bars and coil springs are designed to augment the already capable factory components, allowing for the adjustable 1.5-2 inches of lift. The secret sauce of the Rock-Flex kit is in the control arms. Using polyurethane bushings, the suspension system not only unlocks 25 percent more flex per arm, but the lower control arm bushings allow for 1 degree of caster correction per bushing, making alignment after lifting a simple task.

Depending on your choice of shocks, the kit makes lifting your JL less stressful on the wallet, while also being completely removable. Follow along for the highlights as we install the Rock-Flex kit on an ’18 Wrangler JL.

With the wheels and tires removed and the stock RTI score gathered for reference, we went to work taking the stock components off the rear of our ’18 JL Wrangler, starting with the rear factory bumpstops. The yellow microcellular urethane bumps can handle most tasks, but hit a trail irregularity with enough force, and you will certainly feel the bump exceeding its limit. Energy Suspension’s polyurethane bumpstops slip easily in place of the factory bumps and offer more progressive damping, designed to perform similarly to pneumatic or hydraulic bumpstops.

Energy Suspension supplies 2-inch bumpstop spacers for where the bump contacts the rear axletube. The poly blocks stack and bolt easily into place.

While in the back of the Jeep, we took off the factory sway bar so we could add Energy’s bushings and spacers. The bushings are greaseable with the company’s proprietary Formula Five grease, which was applied liberally. A closer look at the bushings reveals small grooves designed to contain the grease.

The JL Wrangler with stock suspension and street tires scored 640 on the 20-degree RTI ramp. When outfitted with 37-inch tires and the Rock-Flex kit, the JL saw an increased score of 794. While lofty RTI scores do not always directly translate into trail performance, the polyurethane components accomplished their job at unlocking flex on the JL, with more longevity and an improvement over the stock system.