For years the Jeep Wrangler JK has been referred to by many as one of the (if not the) most capable off-roaders available, right out of the box. However, there’s always room for improvement, and that’s what we’re all about here. Aftermarket tires and wheels can move the Jeep’s overall performance farther up the scale, but it’s when you start to tinker with the suspension system that you often begin to see the first real dramatic progress toward increased trail-worthiness.
Our subject, a 2017 Jeep JKU, had some serious miles on its current aftermarket 4-inch suspension system, and we wanted to step things up a bunch without tearing apart the entire undercarriage again. A shock-absorber upgrade would be a perfect way to achieve that goal. At the same time we hatched this plot, we were talking to the Fox shocks people about the company’s new Performance Series 2.0 iQS (PN 885-26-145) Intelligent Quick Switch shock-absorber system designed fit 2007-up Jeep Wrangler JK models.
The Fox Intelligent Quick System shock-absorber package for the Jeep JK (2017-up) is centered upon the company’s Performance Series 2.0 Reservoir iQS shock absorber. These new shocks feature electronically controlled on-the-fly compression damping adjustments from inside the vehicle’s cab. All four corners adjust simultaneously from a single three-position rocker switch, offering Soft, Medium, and Firm settings. Fox engineers told us that the Medium setting in this system is just a shade firmer than the factory shocks on the Jeep JK.
The Fox Performance Series 2.0 iQS system includes four electronically controlled reservoir shocks (each one tuned to its specific side and end of the Jeep); the ECU and a three-position switch to control the shocks; and complete plug-and-play wiring harnesses for battery power to the ECU, signals to the shocks, and direction from the dash-mounted damping position switch. The system’s settings are Soft, Medium, and Firm. The Medium setting will increase off-road performance over the factory Jeep shock and is useful for moderate to extreme off-roading and everyday on-road use. Soft has the least amount of low-speed compression damping—60 percent softer than Medium—and is good for slow-speed off-roading and rockcrawling. Firm delivers the highest amount of slow-speed compression damping—60 percent more firm than Medium—and is best suited for higher-speed off-road driving with minimized body roll and increased suspension control.
The complete installation took about four hours, and it went together easily because it’s a direct-replacement kit. There’s no cutting, drilling, or welding. It can all be done in your home garage with the right tools and a little patience. Fox currently offers the iQS system for Jeep JKs running 2.5-inch to 4-inch suspension lifts; a new Jeep Wrangler JL kit may already be available by the time of this report, and more vehicles applications (one of the Fox engineers is testing it on his Jeep Wrangler TJ) for the Fox Performance Series 2.0 iQS system are in the works. Check out how easy the installation was on this 2017 Jeep JKU.
Each shock is specifically engineered and tuned for the side and end of the vehicle it was designed to fit. To make sure you get it right the first time, the bumper caps of each of the four Fox Performance Series 2.0 Reservoir iQS shock absorbers are marked with their intended positions.
High-end nitrile rubber bushings on the bottom eyelets of the Fox Performance Series 2.0 Reservoir iQS shock absorbers provide exceptional durability and capture while remaining flexible and quiet.
Removal of all four shocks (right front pictured) that were on this 2017 Jeep Wrangler Unlimited was the first step in this direct-replacement swap. Retain the mounting hardware; some of it will be reused when mounting the Fox Performance Series 2.0 Reservoir iQS shock absorbers.
The new stem bushings, washers, and 3/4-inch hex nuts supplied in the iQS kit were used to connect the top of the front Fox Performance Series 2.0 Reservoir iQS shock absorbers (right front shock pictured) to the upper shock mounts. The 3/4-inch nuts were tightened until three quarters of an inch of the stem was visible above the nut.
Using the OEM 16mm locking nut, bolt, and washers saved from the lower front shock mounts, we zipped the bottoms of the front Fox Performance Series 2.0 Reservoir iQS shock absorbers into place on the lower shock mounts.
Note the bright green stripe painted on the stem and locking nut, making it easy to do a visual check on the connection. Orientation of the Fox Performance Series 2.0 Reservoir iQS shock absorbers (right front shock pictured) are critical. Each has its own side and end it’s been tuned for. The front shocks must be mounted so the reservoir is toward the back of the Jeep; the Fox logo on the reservoir clamp must be facing outward.
Tiny Schrader valves are on the bottoms of reservoirs. The valve stem covers help keep dirt and other contaminants out. This is where nitrogen would be introduced if the shocks were serviced or rebuilt. That’s one of the nicest things about the Fox Performance Series 2.0 Reservoir iQS shock absorbers—just like all Fox Performance Series and Factory Series shocks, they are serviceable and rebuildable.
The Fox Performance Series 2.0 Reservoir iQS rear shocks feature a bar pin–style top. To complicate matters, accessing the upper mounts on the Jeep JK is not a walk in the park, as they are up high and jammed between the frame, fuel tank, and exhaust system. The 16mm OEM bolts you saved from the stock shock removal go right back into their places with the new rear shocks. This is where a good socket wrench, extension, flex-joint, and long socket really came in handy.
The rear Fox Performance Series 2.0 Reservoir iQS shocks (left side pictured) are oriented correctly when their reservoirs are toward the inside of the vehicle with the reservoir clamp toward the rear of the vehicle. After torquing (to factory spec) the lower shock mounts using the OEM 18mm locknuts, washers, and bolts, the locknuts were striped with black permanent marker to make visual checks easy.
Plug-and-play appropriately describes the kit’s electrics. The wiring harness to string the ECU to all four shocks, and the three-position accessory switch and its wiring harness, are pre-assembled to the right lengths and ready to install. A fistful of zip ties is included.
The entire front cowl must be removed to access spare space near the engine compartment for the Fox iQS system ECU. To do this, the windshield wiper arms must be removed (it’s a 13mm nut), and then the T30 Torx bolts on the ends of the cowl and the plastic push-in rivets fastening the cowl’s center must also be removed. A trim removal tool came in handy for the cowl center.
The empty space under the cowl and next to the passenger-side wiper is close enough so power isn’t too far away from the Fox iQS ECU, but far enough away to not have it get cooked by engine heat. The factory 10mm side panel bolts and 13mm hood hinge bolts were removed and then reused to secure the kit-supplied ECU brackets (already mounted to the Fox iQS ECU) securely for maximum rigidity.
The head of the wiring loom dragon, so to speak, plugs right in with a snap to the Fox iQS system’s brain. Its four shock cables stretch to the four corners of the Jeep and bring instructions to the Fox Performance Series 2.0 Reservoir iQS shocks.
The electrical connections on the ends of each of the four shock cables are marked with their intended shock. The front Fox Performance Series 2.0 Reservoir iQS shocks (right front shown) were connected to its cable quite literally with a snap. The front shock cables were snaked down into the fenders and secured into place with enough room to stretch but not snag.
Shock cables for the rear Fox Performance Series 2.0 Reservoir iQS shocks (right rear pictured) were strung along the inside or the top of the framerails to their destinations and plugged in to the shocks. We settled on this looping for installation expediency but plan on inspecting all four corners later after our first trip on the new shock system to make sure it’s not rubbing on anything or vibrating against something.
For this application, which did not already have some sort of aftermarket electrical switching main box, we decided to incorporate the Fox iQS three-position switch into the same little switch panel to the left and down from the steering column that holds the OEM locker and sway bar switch. First, it had to be carefully removed from its perch.
With gentle attention from a small rotary tool, and then a bit of cleanup and final adjustment with a small fine-cut file, we fashioned a rectangular cutout in the OEM locker and sway bar switch panel that was a perfect fit for the Fox iQS three-position switch.
All plugged into its power harness running from the Fox iQS ECU, through the firewall, and into the dash behind the OEM locker and sway bar switch panel, the Fox iQS system three-position switch offers instantaneous and on-the-fly changes from Soft to Medium to Firm damping settings in the Fox Performance Series 2.0 Reservoir iQS shocks.
With all electrical and mechanical shock connections double-checked and battery power wired up, it was time to do a test run. If you listen closely, you can hear the tiny motors in the Fox Performance Series 2.0 Reservoir iQS shocks whirring up when you turn on the system and make an adjustment through the dash-mounted three-way switch.
Fox also makes a number of steering stabilizers. We have heard good things about the Fox ATS steering stabilizer, and Fox has recently launched its upgraded Performance Series 2.0 TS steering stabilizer line. With a through-shaft (TS) design the damping force is linear, and there’s no ramp-up force. Equal control in both directions (left and right) is achieved by having the shaft come out the other end of the body when compressed, as opposed to a traditional steering stabilizer that compresses inside the body.
Since we had just finished installing a new high-tech electronically controlled shock system on the Jeep JKU, we figured it was probably a good idea to replace the old steering stabilizer with a new Fox Performance 2.0 TS steering stabilizer.
Once the rod end of the new steering damper was bolted to its mount on the front axle and the valve body mount was loosely attached so it can slide on the tie rod for adjustment, the steering was cycled all the way toward the passenger side until about one quarter of an inch of rod was showing. This keeps the damper from bottoming out at full steering lock.
With the 1/4-inch damper compression allowance dialed in and the tie-rod mount tightened down, the steering system was then turned full lock toward the driver to make sure there was no interference between the damper body or rod, any other steering component, or the front axle. Some aftermarket axle covers are larger in volume than stock, protruding out more and requiring that the damper-end mount be clocked forward on the tie rod. Clocking the two ends out of registration is not ideal for the damper, and it should not be a long-term solution.