In 2004, Chrysler tasked its full-size truck team to come up with the next Dodge Ram full-size pickup, the one that would be launched in '08 as an '09 model. It was a good time to be assigned to trucks: sales of light trucks reached their historic peak during the year and gasoline prices were hovering at around $1.88/gal. How times have changed: The full-size truck segment has gone through the biggest and fastest volume decline in history-sales of the Ram have fallen from 426,289 units in 2004 to 358,295 in 2007 and were running another 30% lower through the first seven months of 2008 at 150,272, as gas hovered above $3.52/gal. and the overall U.S. economy weakened. So maybe now isn't such a good time to be assigned to trucks.
But Scott Kunselman, who has spent the past four years as the leader of Chrysler's truck product team, doesn't think so: "There's no doubt the segment is down, but the last thing I would want to do is have the worst and oldest truck in the segment right now." Even though the market dictates a shift toward improved fuel efficiency, Kunselman admits his team was focused on making the Ram more competitive in three other key areas:
It's not that fuel efficiency was ignored: '09 Rams equipped with the 5.7-liter HEMI engine achieve 1 mpg better than their predecessors on the highway.
The most noticeable changes to the Ram may seem only skin deep (see"Designing the Ram" at the bottom of article), but the most important engineering feat is found under the rear bed. The reengineered rear suspension utilizes a multi-link coil-spring design-the architecture of which is taken from the Dodge Durango and Chrysler Aspen SUVs-with forward-facing shock absorbers positioned outside the frame for improved ride comfort. "The Aspen and Durango have a bit more float and we intentionally made this more taut. All of the parts for the Ram are unique because of the duty cycle-the fore and aft links, control arms and frame brackets are beefier," Kunselman says.
The biggest challenge was integrating the configuration and tuning the ride for proper balance. The pivot points, length of travel and bushing rates all had to be reconfigured; advanced simulation and engineering tools were used to assure performance under different load scenarios. "It all came down to determining the right dynamic behavior, lateral compliance and steer angle needed so we could create the geometry that could perform all the functions we needed and have good NVH characteristics," Kunselman says.
Modifications were also made to the frame, most notably a redesigned front section utilizing advanced, high-strength steel, the same used in the Ram 5,500 chassis cab truck. Dodge claims the steel has the same structural density as railroad rails, yet weighs 30 lb. lighter than traditional steel in this application. "What we found is that we had to be very careful using these grades of steel in particular applications because while they traditionally allow you to reduce gage requirements, they don't act the same as traditional steels elastically and plastically," Kunselman says.
Unlocking new material solutions were critical for the Ram team, particularly when it came offsetting the added weight of new features like infotainment systems, thicker window glass, electronic stability control, in-floor storage, and larger seats, all while meeting more stringent regulatory requirements. The team had one goal: "I said right from the start that I could not afford for this Ram to creep up in weight class because that would cause a big problem for everyone in the company because it would degrade our fuel economy labels and the company's overall CAFE score," Kunselman says.
The team developed a competitive spirit when it came to meeting strict weight targets. Tasks were assigned for each portion of the truck and engineers were instructed to scrutinize the weight of each part number and identify areas where weight could be shed without sacrificing performance, while at the same time limiting cost overruns. One innovative solution was an early decision to use a magnesium structure on the instrument panel, which was rescinded when another engineering team discovered utilizing a high-strength steel beam tube structure would provide equal weight savings, yet cost significantly less.
Kunselman says his team is finalizing plans for the introduction of the light-duty diesel and two-mode hybrid models of the truck in 2010. Beyond that, the focus will be on further refining the truck to gain marked improvements on fuel economy. "We're going to start asking the fundamental questions as to what is expected of a truck in its base format. We're going to have to continue to optimize the vehicle to reduce losses and look at the driveline, brake drag and loads from the electrical system," Kunselman says, adding all these factors will have to be taken into account while still assuring future generations of the Ram will be capable of towing boats, trailers, campers and other gear.
These rapidly changing times would send chills down the spine of any veteran engineer or designer involved in the truck side of the business, but Kunselman remains optimistic the market will improve and the challenges that lie ahead will provide an opportunity to reinvent the definition of what a truck is.