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Chevy Silverado and GMC Sierra: Function Trumps Form

Jully Burau, chief engineer for the General Motors full-size truck program, vividly remembers when GM’s senior executives pushed the team: it was the exact same week her team was told they had to move prototype build operations from a facility at GM’s truck group operations center in Pontiac, MI, to another facility 25.4 miles southeast at GM’s tech center in Warren. “I immediately gathered my team the day we got the message and told them, ‘We have got to roll up our sleeves and see what we can do,’” she says.

Jully Burau, chief engineer for the General Motors full-size truck program, vividly remembers when GM’s senior executives pushed the team: it was the exact same week her team was told they had to move prototype build operations from a facility at GM’s truck group operations center in Pontiac, MI, to another facility 25.4 miles southeast at GM’s tech center in Warren. “I immediately gathered my team the day we got the message and told them, ‘We have got to roll up our sleeves and see what we can do,’” she says. The team focused on reducing part validation timing, which was accomplished through several processes, including reuse of more parts from the sibling GMT-900-based SUVs—Chevrolet Tahoe, GMC Yukon and Cadillac Escalade—while relying on suppliers to take on more part validation responsibilities. “We literally took a week and went through every subsystem and part with our validation engineers.” They started testing earlier, thought about ways to compress testing, and considered having suppliers do testing at their own facilities rather than at outside test facilities. The team also relied more heavily on math-based solutions, another key piece of the process that was initially used on the SUVs. While math modeling was sparsely used on the previous generation truck, the GMT-800, the team used it to validate assembly, parts sequencing and design at an unprecedented level on the 900 platform. One model—10553, which stands for light duty (10) small length box (5) extended cab (53)—was developed without building a single physical prototype. “We called that one our BHAG—Big Hairy Audacious Giant,” Burau explains, slightly modifying author and management consultant Jim Collins’ “Big Hairy Audacious Goal.” Because bookend models—crew cabs and regular cabs—had already gone through the process meant conducting full validation on 10553 would be redundant, adding unnecessary costs. Relying on virtual modeling reduced prototype build expenses by $12 million, with the first model of the 10553 running off the Fort Wayne, IN, assembly line at 2:30 p.m. on July 19, 2006.

 

Framing the Issue

While the GMT-800 shared its frame with both the truck and SUV variants, engineers on the 900 set out to devise a unique frame for the pickups, one that is more robust and refined. The move wasn’t without some controversy and challenge, as the decision to devise a separate frame wasn’t approved until June 2004. There was an enormous amount of study of the investment needed, not to mention the fact that engineers were ordered to make the changes without adding any mass to the vehicle. The rear section of the truck frame—measuring 42 mm higher than the on the GMT-800—features a fully boxed construction, which improves torsional stiffness by 234% and vertical bending stiffness by 64%. “We also changed the taper of the rear frame to align it better and the nodal point was changed to tie it better into the rear axle,” Burau says. Again, the team relied on math modeling to assure the frame would meet performance targets before a single piece was fabricated. “We did 187 computer simulations before we had a frame that we physically built,” Burau says. Once the final geometry was selected, GM challenged both its internal metal fabrication unit and supplier Magna to conduct a competition to see who could deliver a mule of the frame the quickest. After 10 days, both GM and Magna delivered the mule frame within 24 hours of each other. The mule was sent to the Warren prototype shop, where a body was fixed within 24 hours. Managing all of these complexities, along with more than 300 engineering professionals, was a daunting task for Burau, who has worked at GM for 31 years, the majority of that time spent developing safety systems, including the first production driver and passenger side airbag systems. And, yes, she’s the first female to claim the title of chief engineer for GM’s full-size truck program: “I think I bring some diversity to the team.” And, no, she did not experience any sort of animosity from her testosterone-laden colleagues: “Maybe I would have if I was a little more young and tender,” she quips. “I know that I am working on pickup trucks and they have a dedicated purpose and exist for a reason.”—KMK

 

“We’re heading back to where design has the only voice in how vehicle’s look,” GM Vice Chairman Bob Lutz.
With these most vital new products—the Chevrolet Silverado and GMC Sierra pickups—GM may have decided to punt its exterior design leadership in lieu of improved functionality and engineering. There’s little doubt the exterior design of both trucks can be best characterized as conservative, but Lutz doesn’t seem to mind. “Pickup buyers tend to be fairly conservative. Every time you try to do something radical it tends not to work,” he says, noting the key to pickup truck exterior design is to improve overall aerodynamics without making the truck look aerodynamic. “Bold, massive and tough never fail,” he maintains.