Rubicon Express Long-Arm Jeep Grand Cherokee ZJ Suspension - 4-Wheel & Off-Road Magazine

Kevin McNulty Former Editor, Mud Life

As we build our '97 Jeep Grand Cherokee ZJ project, we have been trying to find the right mix of on- and off-road performance. From the start our goal has been to build the Jeep into an overland and capable 4x4 that's comfortable on the highway without the typical clunky, rattling, and excessive body-roll feel of a purpose-built trail rig.

grand Cherokee Long Arm Suspension Upgrade reticulation Test Photo 28052030

In factory form the ZJ is a good 4x4 and can be found on the cheap. The Grand is also a good build platform due to the availability of aftermarket parts. Fitting the Grand with a long-arm suspension makes it even more capable because it improves the suspension's geometry and allows it to cycle and articulate with less binding.

Rubicon Express (RE) offers a 41/2-inch-lift Extreme Duty Long Arm System for the '93 to '98 Jeep ZJ, which uses a four-link system in the rear and radius arms up front. The spring rates and shock valving included in this kit are designed for the ZJ. This long-arm kit is a full suspension replacement and not a bolt-on kit; it does require welding, cutting, and grinding. The guys at Overkill Engineering were a great help installing the long-arm suspension.

grand Cherokee Long Arm Suspension Upgrade kit Photo 28052084 The 41/2-inch-lift Extreme Duty Long Arm System allows the use of 33-inch tires on the Grand Cherokee. The kit includes high-quality components like 2x1/4-inch-wall chromoly control arms and Super-Flex joints. The kit comes with almost everything needed to install the suspension except a steering stabilizer, which is sold separately. Also, the factory axle hardware (control arm bolts) needs to be reused to connect the Rubicon Express control arms

After the installation of RE's Extreme Duty suspension, the Grand had a good increase in suspension articulation and travel while four-wheeling and a far more comfortable highway ride.

PhotosView Slideshow To make the installation easier, we first sprayed the chassis of the Jeep off with a high-pressure sprayer and then removed the old suspension and axles from the rig.
The lower factory control arm mounts must be removed from the Jeep's unibody. This can be completed a number of ways, but the fastest is with a plasma cutter. Great care must be taken when using a plasma cutter so that the unibody's sheetmetal isn't damaged and weakened.
After cutting off most of the mounts with the plasma cutter, we drilled out the factory spot welds and then chiseling off the remaining metal to protect the unibody under the mounts. Any place where metal was removed from the vehicle was ground smooth with a grinder and then coated with good-quality paint.
PhotosView Slideshow The upper and lower control arm mounting points in the rear of the system use a three-piece crossmember. The lower control arm pockets mount around the lower frame of the unibody. Four mounting holes must be drilled into the frame for fasteners to hold this mount in place.
The rear control arm mounts use a new crossmember that mounts over the driveshaft. The crossmember requires the relocation of the exhaust and muffler. We used a smaller Jardine muffler and fabricated the new exhaust tube for rerouting out the back.
With the new front and rear crossmembers in place we installed the new control arms. RE has recommended control arm lengths; however, we played around with ours to lengthen the Jeep's wheelbase. The factory wheelbase of the Grand is approximately 106 inches. Lengthening the control arms extended the wheelbase to 108 inches, which helped improve ride quality.
PhotosView Slideshow The front lower control arm mounts are part of a four-piece crossmember, the center piece holds the transmission mount. After the factory mounts are removed, the new mounts are bolted in place and nine holes are drilled along the unibody's inner framerail for additional bolts and support.
The long-arm suspension system comes with outer crossmember supports, which we couldn't use due to an existing chassis stiffener. We welded the new outer crossmember pieces to the existing chassis stiffener where we could.
This kit comes with heavy-duty front and rear track bars and mounts. The track bars are fully adjustable and use Super-Flex joints that allow the suspension to articulate freely. Also included in the system are quick release front sway bar links, rear sway bar links, and extended-length braided steel brake lines.
PhotosView Slideshow The front heavy-duty transmission crossmember and control arm mounts offer more ground clearance and are much stronger. After a day of wheeling on the trail we found the RE Extreme-Duty Long Arm System offered superior articulation and ride quality over the old short-arm suspension.

It is recommended that a slip yoke eliminator and CV-style driveshafts be used. After a little exhaust engineering we were able to get the exhaust exit neatly to the rear of the rig without rubbing against any other parts or suspension components.

We fitted the ZJ with 17x81/2 high-quality American Expedition Vehicles alloy beadlock wheels. The wheels were fitted with 265/70RX17 Toyo Open Country M/T tires, which offer excellent off-road traction with a quiet and comfortable highway ride.