1948 Pontiac Streamliner coupe |
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| Manufacturer | General Motors |
|---|---|
| Production | 1940–1996 |
| Successor | GM H platform (FWD) |
| Class | Full-size car |
| Layout | FR layout |
The B platform, or B-body, was General Motors' full-size rear-wheel drive automobile platform. It was closely related to the C-body and D-body and was used for convertibles, hardtops, coupés, sedans, and station wagons.
From at least 1940 until 1958, GM used at least three different designations for various bodyshells/platforms including the A-body for Chevrolets, most Pontiacs, and the Oldsmobile Series 60, B-body for Pontiac Streamliners, Oldsmobile Series 70 and Series 88, Buick Specials and Centurys, and the Cadillac Series 61 and Series 63, and the C-body for Oldsmobile 90s, Buick Supers, Roadmasters and the 1958 Limited and all remaining Cadillacs except for the Series 75 (which was designated as being built on the D-body from as early as 1952). For the 1959 model year, the previous A and B bodies were bult on the new B-body that lasted until 1996. The A-body designation would be resurrected by GM in 1964 for a new series of intermediate-sized cars including the Chevrolet Chevelle, Pontiac Tempest, Oldsmobile Cutlass and Buick Skylark.
The GM B-body had at least 10 major re-engineering and restyling efforts, in 1941, 1949, 1954, 1957, 1959, 1961, 1965, 1971, 1977, and 1991; along with interim styling changes in 1942, 1969 and 1980 that included new sheetmetal and revised rooflines. The platform was downsized in length by approximately 10 inches in 1977 and reduced in weight by an average of 800 pounds. In 1991, the platform received its last major redesign, regaining several inches in length, numerous frame improvements and reinforcements, while the shorter wheelbase remained unchanged. The last B-cars rolled off the line in 1996, leaving only Ford producing domestic large rear wheel drive sedans, with Chrysler reentering the market with their LX platform in 2005.
Known for being durable and reliable, most B-body cars used suspensions utilizing coil springs both front and rear, exceptions include the 1959-60 Oldsmobile 88 and 98, and the 1971-76 station wagons from all four GM divisions, both of which used coil springs in front and multi-leaf springs in the rear. All B-body cars since 1965 have used perimeter frames with side rails, along with the 1961-64 B-body Pontiacs and Oldsmobiles. The 1958-60 Buicks used a ladder-type frame while an X-frame without side rails was used on 1958-60 Pontiacs and 1959-60 Oldsmobiles, 1958-64 Chevrolets and 1961-64 Buicks.
The Rear Drive B-body was the last platform design to have the gasoline tank filler port behind the license plate. Exceptions included all station wagons, as well as all 1961-64 cars - which had the tank filler in the rear fender on the driver's side and 1965 Buicks which had their fuel filler door above the license plate.
By 1986, the Buick LeSabre and Oldsmobile Delta 88 moved to the GM H platform. No rear drive successor for this platform was made after 1996, when the Buick Roadmaster and Chevrolet Caprice ceased production.
Sedans built on the rear wheel drive B platform include:
Coupe-only offerings include:
Station wagons include:
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