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Chevy Avalanche: SUT Alors!

The Chevrolet Avalanche is General Motors’ attempt to simultaneously enter and dominate the nascent sport utility truck (SUT) market.

The Chevrolet Avalanche is General Motors’ attempt to simultaneously enter and dominate the nascent sport utility truck (SUT) market. Built on the underpinnings of the Suburban, the massive Avalanche is poised to become the next icon in our big-truck-obsessed nation. It is styled for those who wear their testosterone on their sleeves, with aggressively angled head- and taillights, acres of unpainted body cladding, and beefy sail panels. Ride and handling are remarkably smooth for such a behemoth, and cabin noise is quite low, even with the rear window removed and stowed. But the real story behind the Avalanche is about getting several small things and one very big thing right.

The big thing is what Chevy calls its “Convert-a-Cab” system, which allows the vehicle to be quickly configured for either 6 passengers or for an 8-ft. protected cargo box. The system is built around a lightweight midgate that forms the rear wall of the cab, and folds into the cab to form the 8-ft. bed. According to the Avalanche’s total vehicle integration engineer, Rick Gjestvang, “The challenge was to make a door that was as thin and strong as possible and would give you a flat floor.” GM’s engineers knew that a midgate made entirely of steel would be too heavy for a customer to easily raise and lower, so they utilized the institutional knowledge gained through the company’s composite pick-up box program to come up with something lighter. The result was a fiberglass reinforced SRIM (structurally reinforced injection molded) outer with high strength SMC (sheet molded compound) reinforcements. This composite panel is light enough to be operated by one person, which was a key design criterion. Above the midgate is a crossbar made of high-strength steel and above that is the removable rear window. The cross bar stays with either the midgate or the rear glass, depending on the configuration. A mechanical control mechanism in the midgate senses if the window is in place or not. If it is, the mechanism trips a set of latches that attach the crossbar to the window to protect the glass. If it isn’t, another set of latches are activated that allow the crossbar to fold down with the midgate. With the midgate alone down, long objects like the obligatory sheet of plywood can be hauled without completely exposing the cab to the elements. With the window removed and the midgate down, cargo space is further increased; with the window alone out, the cab is ready for open-air driving. (This last configuration may be why GM research shows a significant number of sports car owners are interested in the Avalanche.) Realizing that a removable piece of glass is an accident waiting to happen, the Avalanche engineering team designed a form fitting pocket in the midgate where the glass can be securely stowed. There is even a metal finger which catches the window after it has been unlatched and keeps it from tumbling into the cab.

Focus groups told GM that they wanted more passenger room than an extended cab pick-up without sacrificing bed length. The Convert-a-Cab system meets that market demand, but it also creates an engineering problem : how to restore the body’s structural integrity lost when the SUT’s rear wall became a door. The answer is the addition of boxed steel reinforcements throughout the rear section of the vehicle tied to the solid member of the C-pillar structure by the sail panel. Gjestvang says that the engineers came up with the sail panel’s 45° angle to “tie everything together as a structural system.” From there they worked with the designers to achieve a part that was both structurally sound and aesthetically pleasing, and ended up creating the signature design cue for the vehicle.

Another focus group demand was a secure cargo box. A hard tonneau cover seemed the only way to ensure protection for items in the bed, but the length and weight of the cover would violate the one-person convertibility theme. To solve this conundrum, GM again looked to light-weight materials. Using a design that is common in aircraft construction, the vehicle’s engineers built a three-piece tonneau cover that can be removed easily and stored by one person. The cover sections are made of two thin sheets of aluminum that sandwich a strong but light hexagonal structure. Each section is encased in TPO (thermal plastic olefin) and injected with a polyurethane foam similar to the material used in instrument panels. The sections weigh approximately 18 lb. each, but when locked together covering the bed, they can support 250 lbs.

The Avalanche incorporates myriad clever features: lighted, lockable storage units built into the cargo box walls, integrated rear bumper steps and grab handles to aid in scaling the vertiginous tailgate, and pocket shelves molded into the side walls that allow for two tier loading.

The SUT will be built at GM’s Silao Assembly Plant in Mexico on the same line as the Suburban. New equipment investment was kept to a minimum since the two vehicles share 85% of their parts. In part because of this high common parts ratio, the development time for the Avalanche was just 24 months from clay freeze to job one. Gjestvang says that this makes the project the fastest of its kind in GM, but admits that there are vehicles in development now that will be quicker.

Chevrolet officially lists its competitor targets for the Avalanche as the Ford F-150 SuperCrew, the Dodge Dakota Quad Cab and the Ford Explorer Sport Trac. But Chevy officials also hope to draw in customers from Durango and Explorer without cannibalizing their own Tahoe owners. They are less worried about taking sales from the Suburban, since they reckon that those customers really need nine passenger capacity. (Inexplicably, Chevy’s sales and marketing executives were cool to my suggestion that they offer optional third and fourth row seating in the bed of the Avalanche, thus bumping it up to a whopping twelve passenger hauler.) When faced with the possibility that the Avalanche is so versatile that it might allow owners to get rid of either a pick-up or a sport-ute, and thus reduce GM’s sales, Gjestvang’s optimistic reply was, “Then they can buy that Corvette that they’ve always wanted.”