GM A platform (RWD).html



See also: GM A platform (FWD)

The General Motors A platform (commonly called A-body) was a mid-size car automobile platform. The A-bodies were mid-sized cars that evolved from rear wheel drive to front wheel drive mid-size cars over the course of more than 30 years. The switch in drive layout in 1982 spawned the G-body. In the end, every A-body car line was cancelled, but new nameplates on the GM Epsilon platform have taken their place.

"Platform" does not mean sharing the same frame, but does mean sharing common parts.

1953-60

In 1953, GM came up with platform names for all it's vehicles, and from 1953-1960, standard Chevrolet's (150, 210, Bel Air, Del Ray, Biscayne, and Impala) and Pontiac's (Chieftain, Star Chief, Super Chief, Bonneville, Catalina, and Ventura) were called A-Body's. These cars were moved to the new B Body in 1961.

1964-72

The A platform was intermediate-sized platform introduced for the 1964 model year for the mid-sized cars of four GM divisions including the FR layout Chevrolet Chevelle, Buick Special, Oldsmobile Cutlass and Pontiac Tempest. It grew through the 1960s and 1970s as a rear-wheel drive platform, finally to be discontinued for 1982. High sales, however, kept the platform alive as the renamed G-body. This A-body was used in a wide variety of GM's most famous cars of the muscle car era, including the GTO, Chevelle, Oldsmobile 442 and Buick GS.

Initially, when the A-body cars were first introduced for 1964, GM had set a corporate policy prohibiting V8 engines larger than 330 cubic inches in these models. However, Pontiac would drop a larger 389 cubic-inch V8 in its Tempest to create the GTO — which is often considered the original muscle car. Though this was technically in violation of that 330 cubic-inch limit, Pontiac got around the rules by designating the GTO as a low-volume option package rather than a specific model. However, the sales success of the '64 GTO led the corporation to increase the cubic inch limit for the A-body cars to 400 cubic-inches starting with the 1965 model year to open the door for the other three divisions to offer similar muscle cars. The 400 cubic-inch limit for A-body cars, as well as all other GM cars that were smaller than full-sized with the exception of the Chevrolet Corvette, would continue through the 1969 model year. In 1970, the 400-inch limit was tossed, which led each of the four GM divisions to offer engines of 454 (Chevy) and 455 (Buick, Olds, Pontiac) in the A-body muscle car variants such as the Chevelle SS-454, Pontiac GTO, Oldsmobile 442 and Buick GS.

The Chevrolet Chevelle and its line mates were the first intermediate-sized cars to be designed with a full perimeter frame and 4-link coil-spring suspension, similar to what was introduced on full-sized Pontiacs and Oldsmobiles in 1961 and then all other GM full-sized cars in 1965.

The Chevelle line also included the El Camino a half-car/half truck body which amounted to a Chevelle station wagon with the rear seat and cargo area removed in favor of a pickup bed.

Two station wagons built off the A-body used stretched wheelbases and raised rear roof sections with skylights. Those included the 1964-1972 Oldsmobile Vista Cruiser and the 1964-1969 Buick Sportwagon.

All A-body cars except the long-wheelbase wagons rode on 115-inch wheelbases from 1964 to 1967, with the wagons using a 120-inch wheelbase. For the 1968-1972 models, wheelbases were 112 inches for two-doors, 116 for four-doors, El Caminos and station wagons; and 121 for the stretched-wheelbase wagons.

Also using a variation of the A-body chassis and suspension were the 1969-1972 Pontiac Grand Prix and 1970-1972 Chevrolet Monte Carlo - both of which were marketed as intermediate-sized personal luxury cars and coded as G-body cars with the GP riding on a 118-wheelbase and the Monte on 116 inches. When the A- and G-body cars were restyled for 1973, that G-body design was renamed the A-special body.

1973-77

All GM A- and A-special body cars were completely restyled for 1973 with hardtop and convertible bodystyles completely eliminated due to pending Federal safety regulations. The 1973-77 cars were available in Colonnade hardtop sedans, coupes and station wagons, which amounted to pillared bodystyles with frameless doors and windows. Wheelbases for this generation were 112 for two-door coupes and 116 for four-door sedans and wagons.

By this time, the American performance car was considered extinct, but these "forgotten years" had some performance left.

• 1973 Pontiac LeMans with the GTO option and the Pontiac Grand Am — Available with a 400 cid 230 hp (170 kW) V8 which was available with a 3 speed (LeMans, GTO) or 4-speed manual (LeMans, GTO, Grand Am) transmission or an automatic (LeMans, GTO, Grand Am), or a 250 hp 455 with an automatic transmission only. Also announced for the '73 GTO and Grand Am was the Super Duty 455 V8, which was rated at 310 horses. Cars magazine tested an SD-455-equipped 1973 Pontiac GTO and chose it as Car Of The Year, yet that engine never made it to production in a GTO or other Pontiac A-body, but would be limited to the Firebird Formula and Trans Am.
• 1973 Chevrolet Chevelle SS and 1974-1976 Chevelle Laguna S-3 — Offered with 350 small block or 454 big block V8 with up to 245 horsepower with manual or automatic transmissions. The SS was replaced for 1974 by the Laguna Type S-3 which offered the same engine/transmission offerings as the '73 SS plus the addition of a 400 small block V8, along with a urethane front end surrounding the grillework. The 1975-76 Laguna S-3 featured a more aerodynamic slanted front end but engines were further detuned due to emission requirements and the advent of the catalytic converter, leaving the big 454 V8 unavailable for California cars in 1975 and discontinued altogether for 1976, when the 180-horsepower small block 400 V8 was the top engine.
• 1973-1974 Buick Century GS — Still available with the Stage 1 455 cubic-inch V8 rated at 270 net horsepower, mated to either a Turbo 400 or four-speed manual transmission, the latter transmission reportedly only installed in seven cars that year. The '74 Stage 1 455 was only available with the Turbo 400 automatic and detuned to 245 horsepower. This engine was also offered on other Buicks in 1974 including the Riviera, LeSabre and Electra.
• 1973-1975 Oldsmobile Cutlass Hurst/Olds W-30 — These were built using 455 cid V8 engines in the W-30 trim. This engine was also available as an option on the Olds 442 of those years along with other Cutlass models.
• 1976 Buick Century Turbo — These were originally built as Indianapolis Pace Car replicas with a turbocharged and carbureted 3.8 L V6, and were faster than the 455 V8 version of that year. There were only a little over 1,200 built.
• 1977 Pontiac Can-Am — This car was basically a LeMans Sport Coupe with a Grand Prix interior and a Trans Am "Shaker" hood, a one-off wing and a 400 cid V8 rated at 200 hp (150 kW) with federal emissions, or an Oldsmobile 403 with California emissions. Only 1,100 or so of these were made and are getting quite collectible.

1978-81

• All GM intermediate-sized cars were downsized for the 1978 model year in response to the 1973 Arab Oil Embargo and CAFE requirements. (Help fill this in)