User:SteveCof00/Chevrolet Impala (sixth generation)

The sixth-generation Chevrolet Impala is a line of full-size cars produced by the Chevrolet division of General Motors from 1977 to 1985. As a central part of the redesign, the Impala was downsized, returning approximately to the footprint of the 1958 and 1959-1960 generations. As the Biscayne and Bel Air were both retired during the previous generation, the Impala now served as the base model of Chevrolet full-size line, slotted below the Caprice Classic.

As with previous generations, the Impala used the General Motors B platform. During its production, the sixth generation served as a divisional equivalent of the Buick LeSabre, Oldsmobile Delta 88, and Pontiac Catalina. Two-door and four-door sedans were offered, alongside a five-door station wagon.

Following the 1985 model year, Chevrolet discontinued the Impala nameplate, rebranding the vehicle as the base (non-Classic) trim of the Chevrolet Caprice, lasting through the 1990 model year.

Project 77
Development on what later became known as "Project 77" began life at the end of 1972. Even prior to the 1973 oil crisis, GM designers had considered the continued growth of full-size American cars was no longer sustainable and the introduction of higher-efficiency vehicles was of critical importance.

Project 77 was launched with five key objectives for a completely new design for full-size cars. First, the new cars were to maintain their market placement in the eyes of the consumer. Second, though lighter and smaller, the new car designs were to improve their structural rigidity. Third, interior space usage and efficiency was to be improved (as the bodyshells were to be physically smaller). Fourth, alongside fuel economy, the road manners of the vehicles was to improve. As a final objective, GM sought to use the most advanced technology available to bring Project 77 to market. Rather than reengineer the previous generation to a smaller size, Project 77 sought to develop an all-new design to its full potential and reducing design limitations.

Project 77 marked several firsts for a GM redesign. Along with accommodating federal emissions and 5mph bumpers from the start of the design process, Project 77 was the first GM design undertaken to accommodate multiple divisions at once (including both the B platform and the "senior" C platform used by Buick, Oldsmobile, and Cadillac), and the first design engineered entirely on computer.

In two styling objectives, the exterior design team sought to reduce front and rear overhang, tumblehome, and the poor integration of 5mph bumpers. Dubbed the "sheer look" by GM stylist Bill Mitchell, the exterior of the vehicle shifted away from the "fuselage" theme popularized for full-size cars in the late 1960s and early 1970s. While not as boxy as Volvo or Mercedes-Benz, the style was European in origin, similar to the Fiat 130. With less curved body sides, a slightly narrower bodyshell is allowed to be used. The style of the lower body was finalized first; the initial design proposal for the two-door used a roofline similar to Buick and Pontiac. Before 1975, the four-door sedan was styled with a "six-window" greenhouse (similar to the 1991 Caprice), ultimately receiving its four-window notchback roofline.

Model downsizing
Along with making the body physically smaller (saving over 230 pounds without reducing the gauge of body panels ), many of the weight reductions related to Project 77 resulted from incremental design and engineering changes. The frame was designed to save 65 pounds, with 120 pounds reduced from the bumpers (in a design change, the rear bumper was added as a frame crossmember ). Another 100 pounds was removed following a redesign of the suspension and changes to the brakes. The doors were made 35 pounds lighter; though wider, another 35 pounds were removed from the structure of the B-pillars. The rear fenders and trunklid reduced 55 pounds together. Alongside other engineering changes, other weight reductions involved the deletion of the Turbo-Fire 400 and Turbo-Jet 454 V8 engines, as Chevrolet sought to match the performance of the 400 from the 350 V8. The B-body Chevrolet was to share its standard engine (a 250 cubic-inch inline-6) with the Chevelle and the Nova, offering optional 305 and 350 V8s.

For 1977, Project 77 downsized the Chevrolet Impala/Caprice to a 116-inch wheelbase (from 121.5 inches). At 212.1 inches and 75.5 inches wide, the Impala had lost 11 inches of length and 4 inches of width of body width. To increase interior room, the passenger compartment led to the model line gaining 2.5 inches in height. Overall, Impala/Caprice sedans lost over 660 pounds (630 for coupes), with station wagons losing 820 pounds of curb weight. Slightly larger than the Tri-Five Chevrolets, the 1977 Impala/Caprice was sized between the 1958 and the 1959-1960 full-size Chevrolet lines.

Model overview
As a result of Project 77, the sixth-generation Chevrolet Impala was no longer the largest Chevrolet car, now sharing its 116-inch wheelbase with the intermediate-segment Chevelle/Malibu and 0.6 inches shorter in length than the Monte Carlo coupe.

Chassis
In line with previous generations of the model line, the sixth-generation Chevrolet Impala uses the General Motors B platform. While using an all-new design for 1977, the B platform returned to a full-length perimeter frame chassis with rear-wheel drive. As with the previous generation, the control-arm front suspension was coil-sprung; the live rear axle was also fitted with coil springs (replacing the leaf-sprung rear-axle on station wagons). The power-assisted brakes were 11-inch vented discs in the front and 9.5-inch drums in the rear.

Body
The sixth-generation Impala shifted entirely to pillared rooflines, with no more hardtops offered. The two-door sedan returned as a fastback coupe; in contrast to other B-body two doors, the Impala/Caprice was fitted with a wraparound "hot-wire bent" rear window (a design feature later used as an option for the Monte Carlo SS during the 1980s ). For its 1980 model revision, the two-door sedan was restyled with a formal notchback rear roofline. The model line also was offered as a four-door sedan and as a five-door station wagon.

All Impala two-doors and four-doors were six-passenger vehicles, with Impala six or eight-passenger station wagons. The "clamshell" tailgate configuration of 1971-1976 was retired, with GM full-size wagons returning to a 3-way tailgate design (in line with Ford, Chrysler, and AMC). Sharing a common wheelbase with its divisional counterparts, the Impala wagon used a rear-facing third-row seat (introduced to Buick, Oldsmobile, and Pontiac).

Trim
Following the retirement of the Biscayne and Bel Air, Chevrolet had increasingly marketed its full-size line with the Impala and Caprice Classic serving as two trims of a combined Chevrolet line. In moving the full-size Chevrolet upmarket, marketing emphasis was further placed on the Caprice Classic.

1977-1979
For 1977, the Chevrolet Impala was redesigned alongside the Caprice Classic; following the 1975 retirement of the Bel Air, the Impala now served as the base-trim full-size Chevrolet. Coinciding with the overall downsizing of the body, several functional upgrades were made to the model line. The turn signal stalk gained additional features, adopting the high-beam dimmer switch (replacing the floor-mounted foot switch) and cruise control switch (if ordered).

For 1978,

For 1979,