1/13/2004 | 8 MINUTE READ

Durango: Designing, Engineering & Producing A Better SUV

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Chrysler Group is taking the opportunity with its second-generation Durango to create a product that has all of the fundamentals right so that it can be competitive in a marketplace that has more than its share of contenders.


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When the Dodge Durango first came out of the box in 1997, it was essentially a modified Dakota pickup truck. Chrysler Corporation had the Jeep models (this preceded the merger, which occurred on November 17, 1998), but otherwise it didn’t have anything in the full-size SUV category. Ford was doing exceedingly well in that segment of the market with its Explorer and GM was gaining traction. Frank Klegon, vice president, Truck Product Team, Chrysler Group, says that the first Durango achieved popularity in its own right, thanks to the fact that it was offered with three rows of seats. While they weren’t the most comfortable seats—even if you were significantly less than a full-size adult—they were still a differentiator. Yet fundamentally, the original Durango wasn’t always quite up to what the competitors were offering.

This time out of the box—undoubtedly because this is now a wholly active category (with more than 67 models in the market), with the sales for the combined “full-size” and “large” SUV categories accounting for 2.5 million units—the ‘04 Durango is based on nothing but the Durango. It is the basis of a new platform that is likely to spawn other products, such as the next Grand Cherokee and a Chrysler SUV. Sure, there have been some borrowings from the Ram for the Durango, like disc brakes all around (13.2-in. rotors in the front and 13.9-in. in the rear). And there have been some learnings from the Ram experience, as well, like the hydroformed frame rail technology. But otherwise, the Durango is pretty much all-new. Given the plethora of vehicles to select from in the SUV category, Chrysler designers, engineers and production personnel were faced with both an opportunity and a challenge. Fundamentally, they had to find the ways and means to provide consumers with more (with regard to both size—the vehicle is some seven inches longer, three inches taller, and three inches wider—and amenities) for less (as in a price point for the new entry-level model that’s $1,100 less expensive than the one it replaces). Klegon says that the new Durango has fewer parts and requires fewer hours to assemble than its predecessor, which translates into economic efficiency. Of course, economic efficiency means absolutely nothing in the market if the vehicle isn’t well designed, well engineered, and well produced.

As he walks around the vehicle, Chrysler Group designer Robert McMahan frequently uses the word “chiseled” to describe what’s going on with the design, as in “There are chiseled sections, from the hood to the grille” and even, zeroing in on a detail, the headlamps: “There are chiseled lines between the lamp and bulb surface.” In effect, the notion is one of something that has been precisely machined from a chunk of material. The rear window wiper on most vehicles tends to be an assembly consisting of several discrete pieces, but the visual provided by that on the Durango is that of a single angular piece. Once again, something machined from a single billet. There’s no trim molding around the backlight and the CHMSL is integrated into the sheet metal above it: this is a look of functionality. But not everything about it has the edgy lines, as there are a series of arching bulges, such as not only the fender lines, but also on the side of the vehicle where the tail lamps are fitted: McMahan describes the lights as being like “afterburners,” which is part of the American design vocabulary that Chrysler Group is using to define the vehicles that it is producing. Although it is a subtle transition, when you look at the side view of the Durango you can see that there is actually a slight tapering of the roofline from front to back.

Inside the vehicle is a place where utility (e.g., neoprene rubber-lined integrated cup holders; a capacious bin at the bottom of the center console, ostensibly to carry fast food) meets refinement (e.g., the gauges have clean white faces; the edges of the plastic parts are crisp and defined without being sharp). Inside the vehicle is a place where there is, comparatively speaking, plenty of space: fold down the third row and achieve 68.4 ft3 of cargo room (get rid of all but the front row passenger and achieve 102.4 ft3 for cargo). Getting into the rear is not a contortionist’s challenge: not only does the rear door open 84°, but the seats are designed so that they fold and tumble with a simplicity that even a child can do it from the point of view of strength and even an adult can do it from the point of view of complexity.

Mike Cairns, senior manager, Vehicle Development, talks about the new frame that the Durango rides on. A frame that’s hydroformed and fully boxed. He points to the front frame rail tips. Yes, they are boxed, but they are also octagonal in shape. This, he explains, helps with crash energy management. But there’s another aspect to the tips: they can be removed so that in the case of an accident, they can be replaced; a frame replacement isn’t necessary. And, yes, the frame is a whole lot stiffer than the predecessor: 2.5 times better in bending, and 2.8 times better in torsion.

The independent front suspension includes elements like aluminum upper control arms and knuckles to help reduce weight. The steering rack (for the rack and pinion steering) is located behind the front suspension—not ahead of it, where it had been—to help minimize the crash energy that might get to the driver in the case of an accident. The rear suspension is not an independent type. Klegon: “We examined independent rear suspension designs, but found that we could save weight with our design and still achieve our ride targets with a link coil setup.” The link coil design is mated with a solid rear axle. One of the reasons for that is to provide additional towing capacity (the Durango offers the ability to tow 8,950 lb.). A Watts-linkage design on the rear axle helps minimize rear-end movement, particularly when driving over rough terrain, and allowed the engineers to lower and widen the cargo floor so that the seemingly obligatory 48-in. sheet of plywood can fit back there. Whereas Durangos were once built with different suspensions for the 2 x 2 and 4 x 4 models, they’ve standardized on a single version for purposes of simplicity and quality.

Under the hood there is the potential of the 5.7-liter Magnum V8 hemi that provides 335 hp @5,400 rpm and 370 lb.-ft. of torque @ 4,200 rpm. That is not, of course, the base engine. That’s a V6. A 3.7-liter that provides 210 hp @ 5,200 rpm and 235 lb.-ft. of torque @ 4,000 rpm. It’s the same engine that can be obtained in the Jeep Liberty (which is about 800 lb. lighter, which makes a whole lot of difference.) A third engine is available: a 230-hp, 290-lb.-ft. of torque, 4.7-liter V8. All are mated with automatic transmissions (a four-speed for the 3.7 and a five-speed for the other two).

Like the previous generation vehicle, the Durango is built at the Newark, Delaware, Assembly Plant. Given the fact that it is a whole lot different than the preceding vehicle, Chrysler Group spent $180-million in the plant for the new vehicle—and while that is a non trivial number, it is said to be some 30% less than might ordinarily be spent on changing over a facility. This is part of Chrysler’s effort to reuse manufacturing equipment and tool-ing whenever possible and thereby save money and its concomitant effort to increase manufacturing flexibility in its operations. Tom LaSorda, Chrysler Group executive vp-Manufacturing, says of a plant that started out in 1951 as a tank manufacturing facility: “We are demonstrating through the launch of this vehicle that flexibility can be applied to an existing, and quite mature, manufacturing operation.”

One of the issues that is of concern to Chrysler Group executives is the actual and perceived quality of its products. So within the plant, there is a new quality verification program in place, one that spans the entire operation, from the body shop to pre-shipment to dealers. In all, there are some 125 separate quality checks. But quality isn’t simply built-in. It must be designed in. So there was extensive work done by engineers in both the product and process realms to make sure that Durango was designed to be built.

Carolin Bart, manager, Design for Manufacturing, DCTC & Components, Advance Manufacturing Engineering and her staff work as the “voice of the operator” in “all aspects of the program, from concept to launch and beyond.” In other words, Bart and her colleagues worked to assure that there would be the most efficient and operator-friendly build possible. And that meant that she and her people worked with people like Bruce P. Mattarella, manager, Vehicle Packaging, Truck Platform Engineering, Advance Vehicle Engineering. Matarella points out that this vehicle program included the digital design of both the product and the process so that they were able to quickly identify and resolve issues, and that the Durango represents the first time that they’ve worked so extensively in this mode. Some interesting things were discovered through this process. For example, it was determined that the hood-opening angle—47°º—was too little to facilitate as many as 20 under-hood operations. So, Michael Johnson, Dynamic Digital Scroll supervisor, says, they digitally developed a fixture and determined how big a prop rod would need to be in order to assure that the operators could get the necessary access (it turned out that they needed an 80º° opening). They determined that the door switch bezel, as originally designed, would require more than 100-lb. of force to seat it, which was certainly not something that an operator could be expected to provide. So it was redesigned. There were concerns about a variety of things, from radiator installation to the design of the fuel filler tube. Sometimes there were redesigns (as in the cases of the radiator and the fuel filler); sometimes they were determined to be unnecessary. But safety, quality and cost are all improved by these methods, which should assure that the Durango is a better vehicle as designed and built.


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