Nth Degree Mobility's New Jeep TJ Long-Arm Suspension
It's an engineered thing-and Jim Frens understands. Back in the November 2004 issue, we introduced you to a new company from Carson City, Nevada, that was making some cool skidplates and suspension bits for Jeep YJs and TJs. At that time, Nth Degree Mobility's products had to be used in conjunction with other brands of lift kits, since the company didn't offer a full suspension kit of its own. Today, that's all changed. Nth Degree's owner, and former Jeep chassis engineer, Frens has been hard at work designing a suspension for the TJ that picks up where the factory bean-counters left off. Since Frens worked for Chrysler during the TJ's development, he saw a lot of potential in the vehicle's chassis that was left out for cost or regulatory reasons. Now that he has his own company, Frens is able to offer a suspension system that is engineered to the level of the original factory stuff, but offers performance the factory engineers could only dream about.
One of Nth Degree's primary goals with all their products is to not create trailer queens. A Jeep equipped with an Nth Degree suspension must perform better on the road as well as off-pavement. It must drive to the trailhead safely and comfortably, and then be able to 'wheel with the best of 'em. After 'wheeling all weekend, it should be able to take its owner to work all week without weird handling compromises. Having ridden with Frens around his road test course, and driving several TJs equipped with his long-arm kits-both on long road trips and over the Rubicon Trail-we can say enthusiastically that he has surpassed his goal. The silver '05 Unlimited we photographed for this article rides on 35s with a 6-inch lift. It can hike a front tire 42 inches over an obstacle before any other tire leaves the ground, yet it drives down the road with better manners than a stocker. We crawled boulders with it like a rock buggy, and then drove it over a mountain pass like a sports car. No stock or lifted TJ we've experienced has ever performed like this.
There are numerous reasons the Nth Degree suspension performs like it does. Many of them are just little details-small changes in tuning and geometry that amount to big performance gains. These are details that only an engineer with a lot of knowledge about chassis dynamics could figure out. Check out our photos taken during the installation of the 6-inch long-arm kit on this brand-new Unlimited, and also the shots taken during its maiden 'wheeling trip over the Rubicon. Our goal here is not a "How To Install It" article or a "Before and After" test, but rather we'll try to highlight many of the unique features of the Nth Degree kit that sets it apart from the others.
The Nth Degree long-arm kit is a substantial collection of parts. It took two full days for the guys at Nth to install it while we took photos. All the parts are CAD/CAM designed, laser-cut and precession-welded in jigs, before being powdercoated in a dark gray. The 2-inch-OD, bent, rear lower control arms are made from 3/16-inch, 4130 chromoly tubing and are post heat-treated after the bends and all the welding are completed. This kit we installed is a 6-inch version, but a 4.5-inch version is also available. A lot of engineering has gone into the springs, resulting in rates and heights that vary depending upon application. The front springs feature a fixed rate, while the rears are progressive to allow for load carrying while minimizing changes in ride height-and most importantly, handling. While this article focuses on the company's long-arm kit, there is also a standard-arm-length kit that still features many of the same trick components such as the GyroJoints, Stinger, Tummy Tucker, custom springs, and more.
The subassembly of the four GyroJoints is one of the first steps. These joints are used to mount the control arms to the frame. They consist of a steel ball, similar to a trailer-hitch ball, encased within two special durometer urethane sockets. GyroJoints offer 360 degrees of flexible movement and also provide "give" to isolate road harshness from the chassis. The different-colored sockets represent different durometers-the measure of the material's "spring rate." The white half is a softer material than the black half. It is installed to the rear of the front axle socket to cushion rearward blows encountered by the axle when hitting a bump, rock, or pothole. Unlike a metal-on-metal Heim joint and other "flexy" joints, a cushioned joint delivers much less jolt and/or vibration into the vehicle's chassis so it stays tight and crack-free. Your butt will appreciate this isolation a lot too.
With the control-arm rails installed (seen attached to right-hand framerail in this shot), the Tummy Tucker skidplate/tranny mount is next installed. The Tummy Tucker (TT) is probably Nth Degree's most famous product to date and replaces the deep-scoop, low-hanging factory "shovel" with a smooth, almost flat, 1/4-inch steel plate. The TT gives up only 1 1/4 inches of ground clearance below the framerails and can support the entire weight of the vehicle. Like most of the parts in Nth Degree's kits, the TT is modular. If you already own a TT, a Stinger, Shock Shifters, the company's front track-bar relocation kit, or various other bits, all these parts can still be utilized with the new long-arm kit, greatly cutting down on the cost of upgrading to long arms. Also, this modular feature could allow you to build up your Jeep in stages; however, if you opt for that approach, it would be a good idea to consult with Nth Degree's staff to make sure you have the best possible combination of parts along the way.