2007 Jeep Wrangler JK Buildup - Project Jeeponomics

Nth & AEV
The man behind AEV suspensions is Jim Frens, a former Jeep engineer with Daimler/Chrysler and the father of Nth Degree Mobility suspensions. Nth Degree made quite a name for itself in a short period of time offering (among several products) a unique long arm suspension for the Jeep TJ. The Nth suspensions are known for providing serious off-road wheel travel, yet manners on the highway that out perform a stock setup. The entire Nth Degree TJ suspension line is now owned and offered by AEV. With the ownership of Nth came Frens, and now his talents have been channeled toward designing a suspension upgrade for the JK that enhances both it's on-and-off-highway performance, perfect for a true, all around "American Expedition Vehicle."

JKs ain't TJs
At first glance, the Premium 3.5-inch suspension featured in this article doesn't appear to contain a lot of parts - and that's the beauty of it. Where are the new control arms? Well, the blunt answer to that is, stop thinking TJ! With the TJ, it became a "lift-kit standard" to replace control arms, either with beefier stock length or longer arms because TJ arms are short and weak. For a TJ to run 35 inch tires it require a 4-inch lift. For it to retain any suspension manners at that height, a long arm kit is necessary. Despite the JK's suspension looking similar to a TJ's, the JK chassis is entirely different with subtle geometry changes that a guy like Frens can recognize and work with. Bottom line is a JK can handle 3 to 4 1/2 inches of lift without the need of longer arms, different pickup points and all the associated hardware and complexity that goes with a suspension of this type. Stock JK arms are as beefy as any aftermarket replacement arm and feature quality, factory-durability-tested bushings that will last a long time. Why throw them in the dumpster just because "that's what has always been done?" AEV decided that for your money, they would offer features like exclusive frequency-tuned springs, Bilstein shocks, and engineered brackets that address real geometry issues (see below) instead of selling you old school thinking and forcing you to throw away perfectly good parts.

A Swiss-Army Knife Jeep
With the JK, American Expedition Vehicles had a pretty good platform to start with when designing an ultimate exploration-type vehicle. AEV's focus is on a Jeep of this nature, not an all-out, one-dimensional rock crawler. AEV's vision is a rig that can carry its owner thousands of high-speed highway miles with stability and comfort while hauling perhaps a month's load of supplies, tools, fuel, etc. This same Jeep would then be capable of turning off highway and traversing the roughest of terrain, offering articulation, ground clearance, traction, and stability, while still carrying the same load and offering the same comfort it did back on the highway.

A good exploration/expedition rig needs relatively big tires and a healthy dose of ground clearance. Unfortunately, these two features a stock JK sorely lacks. AEV's Nth Degree suspension certainly addresses lift and provides for larger tires, but there is much more engineering going on that can't be seen, but can certainly be felt when driving. The company offers two heights: 3.5 inches for 35 inch tires, and 4.5 for 37 inchers. The suspensions are available as "Standard" or "Premium," with the Premium kits mainly including enhanced steering components and a magic black box for adjusting your computer (more on this later). Standard kits are only available with the 3.5 inch lifts, all 4.5 kits are Premium. Both kits provide progressive-rate, frequency-tuned lift springs and vehicle/load-specific-valved Bilstein shocks built to Jim Fren's specifications and AEV's exacting standards. Designing progressive springs and matched shocks that provide lift and a good ride are only part of the equation though. Frens felt from the beginning that the JK's on-road handling behavior could be improved by addressing its rear roll center.