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2007 Jeep Wrangler JK Rubicon - JK Jounce - Tech

Posted in How To on July 1, 2009
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It's been 18 months since we installed our Rubicon Express 3.5-inch Super-Flex suspension system on our 2007 two-door JK Rubicon. With nearly 20,000 miles on the odometer, we've been very satisfied with the ride quality, handling and durability of the kit so far. But after accessorizing our ride with hundreds of pounds of bumpers, winch, and larger spare wheel and tire, we were overwhelming our factory bump stops. Case in point; when you bottom-out your suspension while driving across a rain gutter on a city street, it's time for some much needed help

In come Rubicon Express and Light Racing to the rescue. Rubicon Express developed a patented Hydraulic Bump Stop Mount System for 2007 and newer JK's, designed for use with Light Racing's JounceShocks. The mount system replaces the front factory bump stop tower and positions the JounceShock with a brilliant red-anodized machined multi-piece billet aluminum mounting system. The key to the RE mount system is the retaining collar with O-ring that allows the JounceShock to flex with the front coil spring, which is crucial when articulating the suspension. If this weren't the case, the JounceShock would rub the coil and not align itself with the domed target point on the axle. After completing extensive desert and high sierra (i.e. Rubicon Trail) R&D testing on the JounceShocks, the Rubicon Express crew chose the 1.5-inch travel version for the JK, because of its compact 6-inch-long base size.

In a nutshell, the JounceShocks act as a secondary suspension system. At ride height, the JounceShocks do not engage and do not alter the on-road ride quality of your Jeep. In normal daily driving, you will not even notice that they are there. But, in off-road conditions, as the suspension cycles through, let's say a whooped-out sand wash, the more your springs compress over dips and jumps, the more the JounceShocks do their job.

Rubicon Express hadn't fitted the JounceShocks on a short-arm JK yet, so our JK became a test mule for them. After installing the JounceShocks to all four corners and installing our 3.5-inch RE coils, we soon found that the springs were too short for this application. The distance between the shaft end mount (cupped for the front and domed for the rear) and the target point was less than an inch. This meant that the JounceShock would act as part of the primary suspension, which it isn't designed for, severely hampering the coil from doing its job. So, we dropped in a set of 4.5-inch RE coils to alleviate this problem. Our short-arm JK became the prototype 4.5-inch Super-Flex suspension system as well. Follow along as we install Rubicon Express and Light Racings hydraulic bump stop mount system to our JK.

Driving Impressions
On city streets, the JounceShocks are hardly noticeable. When the suspension does engage the JounceShocks over pot holes or rain gutter dips, you can hear the tapping of the bumps stop on the axle contact point, but best of all, no more bottoming of the suspension.

Off-road, the ride is much improved. The JounceShocks eliminate bottoming as well as improve handling and increase stability at all speeds. The suspension simply floats over whoops and smoothes out the ride. While slow-speed rock crawling, the typical side to side rocking motion is controlled. There are four parameter settings that can be manually adjusted; nitrogen pressure, compression damping, rebound damping, and oil level. You can fine tune your JK's bump stop settings like a pro. Initially, we filled the JounceShocks to 200 psi, but found this to be very harsh over bumps. This setting would probably work well in a trophy truck, but not a light weight Jeep. Even with the compression adjustment backed all the way out to soft, the ride was still uncomfortable. So, we consulted with the guru's at Light Racing and they recommended charging the front to 60-psi and 40-psi for the rear. This was the hot ticket and we are very satisfied with the ride. We can easily add more nitrogen, if needed. The cool thing is, if you are planning your next outback adventure trip, you can easily add more nitrogen pressure to accommodate a heavier payload. Since the rear bump stop is mounted outside of the coil spring, you can simply unscrew the Allen set screw, spin off the JounceShocks, turn upside down on a workbench and let stand for 30 minutes to allow the nitrogen and the oil to separate. Fill the nitrogen to the desired pressure, re-mount the JounceShocks, and you are ready to hit your favorite trail. Enjoy the ride!

PhotosView Slideshow

Sources

Rubicon Express
Rancho Cordova, CA 95742
877-367-7824
www.rubiconexpress.com
Light Racing
Longmont, CO 80504
800-525-6505
www.lightracing.com

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