Liberty Balance - Jeep Liberty 2002

Automotive Manufacturing & Production, June, 2001 by Gary S. Vasllash

As Dieter Zetsche, president and CEO of the DaimlerChrysler Group, puts it: "We're coming back to what the business is about: product." He's talking about the 2002 Jeep Liberty. It is a Jeep--as in go anywhere, do anything--with good on-road manners. Talking about the overall scheme, he says, "It's the right segment, the right brand, the right product, the right price, and the right timing." And he may be right.

Strengthening. The DaimlerChrysler (DCX) people--engineers and marketers alike--refer to the car-based sport utility vehicles proffered by competitors as "cute-utes." Although they also roll out with phrases like "noble liberator" when describing the Jeep--which may be lost on an entire generation with the exception of those who have seen "Saving Private Ryan"--the point is that a Jeep is characterized by its ability to drive in places where the others would not only fear to tread, but which would be incapable of treading, even if they wanted to. And so this was kept in mind, front and forward, as the newest Jeep, the 2002 Liberty, was designed and engineered.

This Jeep go-anywhere capability doesn't come without a price, however. First of all, there is the fundamental "uniframe" construction, which is one part body-on-frame, one part unibody. Basically, there is a longitudinal rail structure to which body load points are aligned. According to Phil Jansen, director of Jeep Body Engineering, there was extensive finite element analysis (FEA) performed to help develop the necessary design, which was followed by an assortment of physical tests, including four-post shaker and what is called "AK3." That military-sounding test (which actually has its roots in the military's Aberdeen Proving Grounds) was performed for Liberty at the company's proving grounds in Arizona. The test, which also validates the suspension, is performed on roads that are so spine jarring that Jansen admits that he was able to handle only 15 minutes in the vehicle. Although mild steel is not uncommon in underbody applications, more than 70% of the Liberty underbody is produced with high-strength steel. Additionally, there is even the use of ultra-high strength steel, a cross-car beam. Jansen explains that this is used for impact protection at the rear of the vehicle: "We want the back end to be pretty much like a rock." As the spare tire is mounted back there and the gas tank is below the rear cargo space, and as the wheels are pushed out to the edges so that there is little overhang, the ability to have something like ultra-high-strength steel providing protection, which resists deformation, is important.

(Speaking of steel: One of the previous assignments of Craig Love, vice president, Jeep Platform Engineering, was the Prowler, an aluminum-intensive vehicle. There are no aluminum body structures on Liberty. The body is steel. There are some aluminum applications, however. For example, there is an aluminum housing that is part of the front suspension. And the heads of both the 2.4- and 3.7-liter engines are aluminum.)

Also, in order to help achieve strength (for both being a Jeep and for purposes of safety) without excess weight, there is the extensive use of laser-welded tailored blanks throughout the vehicle--13 panels in all, which represent in excess of 20 ft of welds. The Liberty includes what Jansen believes is the first production application of a remote, 3D laser welding system. Instead of having the [CO.sub.2] laser beam manipulated around the part by, say, a robot, this is done with mirrors.

The part in question is a reinforced swinggate inner. Sixty-five welds are produced in 32 seconds. This work is being performed in the DCX Sterling Heights, Michigan, stamping facility. Jansen says that they had developed approaches for both spot welding and laser welding the component; thanks to a reduction in equipment (e.g., transfer devices) that the laser setup permitted, the total investment proved the case for the laser rather than traditional spot welding. To put some of this into context: compared to the Liberty's big, older brother, the Grand Cherokee, its bending stiffness is 58% better and its torsonal rigidity is 43% better.

Smoothing. Okay. So it is rough and tough. One problem. The market doesn't necessarily want just the ability (or the perceived ability in the case of some of the competitors) to climb up the sides of mountains. Most of the time--whether this is a Jeep owner or a non-Jeep owner--people keep their vehicles on the road, not the Rubicon Trail. They don't want to do their daily commute in a go-anywhere vehicle that may be well-appointed on the inside (the Limited version can be tricked out with leather seats; there are technical-looking brushed chrome accents; buyers of either model can get a sun roof; etc.) but which feels like they're riding on a rock. So the Liberty features a newly engineered coil spring independent front suspension--which undoubtedly caused there to be gasps of disbelief among those engineers who know that "Jeep" is synonymous with solid axles--and even rack-and-pinion steering.