Rough Country’s Flexy New Long-Arm Jeep Grand Cherokee SuspensionPosted in How To: Suspension Brakes on October 1, 2011 0) (
When Jeep trotted out the Grand Cherokee ZJ for the ’93 model year, it was aimed squarely at the Ford Explorer and Chevy S-10 Blazer. Compared to its XJ sibling it was larger and more luxurious, but underneath it retained proven simplicity with a pair of solid axles and a coil spring at each corner. The ZJ was a hit and Jeep sold a passel of ’em during the models six year run. Today, these vehicles are plentiful and inexpensive and a popular rig for buildups.?>
Rough Country Suspension offers six suspension kits for the ’93-’98 Jeep Grand Cherokee ZJ. One of the newest is a member of Rough Country’s X-Series line and it’s a long-arm system that improves off-highway handling and articulation while raising the SUV four inches. The kit includes adjustable, high-clearance X-Flex upper and lower control arms with Clevite bushings, featuring rebuildable X-Flex joints with Adjustable Retainer Rings that allow you to preload bushings by compressing them prior to install. The kit also includes new coil springs, a front adjustable track bar with drop bracket, ¼-inch-thick steel crossmember and skidplate, sway bar disconnects, and Performance 2.2 Series shocks.
We recently traveled to Rough Country headquarters in Dyersburg, Tennessee, to watch a stock ZJ get the long-arm transformation and then we had a chance to hit the paved road and the trail in the newly modified rig. Following are the highlights of how Rough Country long-arm’s the ZJ and also an in-depth look at how the rigs performance improved from stock to modified.
Rough Country says this kit was developed using a 31x10.50-15 tire with factory wheel, and that’s the recommended tire size. However, they say that this kit is capable of fitting a 32-inch tire or larger with some body/fender modifications. Aftermarket wheels will fit with 35⁄8-inch backspacing. Installation time is said to be 8-9 hours. At time of print, the MSRP on this kit is $1,499.95.
In stock form, the ZJ was equipped with 245/75R16 (30.5-inch-diameter) Goodyear Wrangler RT/S tires. After the suspension install we mounted a set of 32x11.50-15 (31.3 inches actual diameter) Wild Country Radial MTX tires.
When stock, the rig traveled 56 inches up our 20-degree RTI ramp to earn a score of 531. After the install, it traveled 61 inches with the sway bar connected to earn a score of 578. With the sway bar disconnected it traveled a whopping 83 inches up the ramp to earn an impressive score of 787. This translates to a 9 percent improvement with the sway bar connected and a 48 percent improvement with the sway bar disconnected.
Stock, the ZJ’s approach angle was measured at 45 degrees and the departure angle was 35 degrees. This improved to a 50-degree approach angle and a 40.5-degree departure angle after the install. This is an 11-percent and 16-percent improvement, respectively.
On the twisty Tennessee asphalt roads the lifted ZJ exhibited an outstanding ride and good handling. This is no doubt due in part to the fact that the Performance 2.2 Series shocks are valved specifically for this application. The minor overall tire diameter change meant there was no perceptible loss of power in the ZJ. It is worth noting that the kit requires removal of the rear sway bar because it would contact the longer control arms. We didn’t notice any handling weirdness on our test rig in its absence.?>
We took the ZJ to the Bikini Bottoms Off Road Park and hit the trail. It was clear that the ZJ was in its element, and the suspension was at home cycling through its travel on the undulating trails. At one point, we purposely directed the Rough Country test driver into a rut-filled, off-camber area so we could see how the suspension reacted. In short, the design of the lift kept the belly and underbody components from snagging on obstacles and the ample flex of the long-arm X-Series suspension easily allowed the tires to stay in contact with terra firma.
We like that this suspension significantly improved suspension flex and it made the ZJ into an above average street/trail machine—and with only four inches of lift, the vehicle’s center of gravity remains low. We also like the design of the control arms, which contribute to good ground clearance. And we dig the large, flexy X-Flex joints and the fact they’re greasable and rebuildable. Oh, and the price of the kit is right, too.