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GM H platform (RWD)
Encyclopedia
The General Motors H platform or H-body is an automobile platform
designation used for the 1971–1980 model year rear wheel drive line of subcompact cars. The fourth character in the Vehicle Identification Number (VIN)
for an H-body car is "H".
H-bodies were available as two-door Notchback, Hatchback, Wagon, and Sedan delivery body-styles, and have 4, 6, and 8-cylinder GM engines, solid rear axle, and unibody construction. The platform was introduced with the 1971 Chevrolet Vega
. The Pontiac Astre, Chevrolet Monza, Buick Skyhawk, and Oldsmobile Starfire were introduced for the 1975 model year, while the Pontiac Sunbird was introduced a year later as a 1976 model.
The Vega engine
is a 140 CID aluminum-block L4. A 1972 GM
prototype had an all-aluminum 302 small-block V8, but this was not approved. Chevrolet hand-built 5000 122 CID L4 Cosworth Twin-Cam engines for the 1975 Cosworth Twin-Cam Vega.
Only 3508 1975-76 cars were built. The remaining engines were scrapped. The GM-rotary (GMRCA)
Wankel engine was destined for the 1975 Monza 2+2 but the engine was canceled.
The Vega and the Astre were discontinued at the end of the 1977 model year, but the Monza, Sunbird, Skyhawk, and Starfire continued through 1980. The GM J platform
replaced the GM H platform in 1981. The H platform
designation was later used for the unrelated front-wheel drive
GM full-size
cars in the 1980s.
Automobile platform
An automobile platform is a shared set of common design, engineering, and production efforts, as well as major components over a number of outwardly distinct models and even types of automobiles, often from different, but related marques...
designation used for the 1971–1980 model year rear wheel drive line of subcompact cars. The fourth character in the Vehicle Identification Number (VIN)
Vehicle identification number
A Vehicle Identification Number, commonly abbreviated to VIN, is a unique serial number used by the automotive industry to identify individual motor vehicles. VINs were first used in 1954...
for an H-body car is "H".
H-bodies were available as two-door Notchback, Hatchback, Wagon, and Sedan delivery body-styles, and have 4, 6, and 8-cylinder GM engines, solid rear axle, and unibody construction. The platform was introduced with the 1971 Chevrolet Vega
Chevrolet Vega
The Chevrolet Vega is a subcompact, two-door automobile that was produced by the Chevrolet division of General Motors for the 1971-1977 model years. Named after the star Vega, the car was powered by a lightweight aluminum-block inline four-cylinder engine...
. The Pontiac Astre, Chevrolet Monza, Buick Skyhawk, and Oldsmobile Starfire were introduced for the 1975 model year, while the Pontiac Sunbird was introduced a year later as a 1976 model.
The Vega engine
GM 2300 engine
The 2300 is a 2.3 L/140 cu in inline-4 automobile engine produced by the Chevrolet division of General Motors for the 1971–1977 model years. The Chevrolet Vega engine was ahead of its time with its die-cast aluminum-alloy cylinder block. The high-tech block features an alloy with...
is a 140 CID aluminum-block L4. A 1972 GM
General Motors
General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...
prototype had an all-aluminum 302 small-block V8, but this was not approved. Chevrolet hand-built 5000 122 CID L4 Cosworth Twin-Cam engines for the 1975 Cosworth Twin-Cam Vega.
Only 3508 1975-76 cars were built. The remaining engines were scrapped. The GM-rotary (GMRCA)
General Motors Rotary Combustion Engine
The General Motors Rotary Combustion Engine is an internal combustion Wankel engine which uses a rotary design to convert pressure into a rotating motion instead of using reciprocating pistons. In November 1970, GM paid $50 million for initial licenses to produce their version of the Wankel rotary...
Wankel engine was destined for the 1975 Monza 2+2 but the engine was canceled.
The Vega and the Astre were discontinued at the end of the 1977 model year, but the Monza, Sunbird, Skyhawk, and Starfire continued through 1980. The GM J platform
GM J platform
The J platform, or J-body, was General Motors' inexpensive front-wheel drive automobile platform from the 1980s and 1990s. The platform replaced the GM H platform. The J-platform is the only platform of GM to have a model in each of its "Original 5" passenger car divisions...
replaced the GM H platform in 1981. The H platform
GM H platform (FWD)
The H platform, or H-body designates a General Motors front wheel drive full-sized automobile platform beginning in 1986. It is related to the C, G and K platforms.Previously the H platform designation was used for unrelated rear-wheel drive compact cars....
designation was later used for the unrelated front-wheel drive
Front-wheel drive
Front-wheel drive is a form of engine/transmission layout used in motor vehicles, where the engine drives the front wheels only. Most modern front-wheel drive vehicles feature a transverse engine, rather than the conventional longitudinal engine arrangement generally found in rear-wheel drive and...
GM full-size
Full-size car
A full-size car is a marketing term used in North America for an automobile larger than a mid-size car. In the United States, the EPA uses "large car" to denote full-size cars....
cars in the 1980s.
| Years | Wheelbase | Model | Previous platform | Next platform |
|---|---|---|---|---|
| 1971–1977 | 97.0 in (2464 mm) | Chevrolet Vega Chevrolet Vega The Chevrolet Vega is a subcompact, two-door automobile that was produced by the Chevrolet division of General Motors for the 1971-1977 model years. Named after the star Vega, the car was powered by a lightweight aluminum-block inline four-cylinder engine... |
||
| 1973–1977 | Pontiac Astre Pontiac Astre The Pontiac Astre is a subcompact automobile that was produced by the Pontiac division of General Motors. Essentially a rebadged Chevrolet Vega, it was introduced in Canada for the 1973 model year and sold there exclusively through 1974. It debuted in the U.S... |
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| 1975–1980 | Chevrolet Monza Chevrolet Monza The Chevrolet Monza is a subcompact, four-passenger automobile produced by the Chevrolet division of General Motors for the 1975–1980 model years. The Monza is based on the Chevrolet Vega, sharing its wheelbase, width and 140 CID inline-4 engine... |
GM J platform GM J platform The J platform, or J-body, was General Motors' inexpensive front-wheel drive automobile platform from the 1980s and 1990s. The platform replaced the GM H platform. The J-platform is the only platform of GM to have a model in each of its "Original 5" passenger car divisions... |
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| 1976–1980 | Pontiac Sunbird Pontiac Sunbird The Pontiac Sunbird, produced by the Pontiac division of General Motors, was Pontiac's second small-car offering of the 70's. The Sunbird model ran for 18 years and was then replaced in 1995 by the Pontiac Sunfire... |
GM J platform GM J platform The J platform, or J-body, was General Motors' inexpensive front-wheel drive automobile platform from the 1980s and 1990s. The platform replaced the GM H platform. The J-platform is the only platform of GM to have a model in each of its "Original 5" passenger car divisions... |
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| 1975–1980 | Buick Skyhawk Buick Skyhawk The Buick Skyhawk are automobiles produced by the Buick division of General Motors in two generations for the 1975 through 1989 model years. 1975 through 1980 models, all 2-door hatchbacks, were built on the subcompact, rear-wheel drive H-body platform... |
GM J platform GM J platform The J platform, or J-body, was General Motors' inexpensive front-wheel drive automobile platform from the 1980s and 1990s. The platform replaced the GM H platform. The J-platform is the only platform of GM to have a model in each of its "Original 5" passenger car divisions... |
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| 1975–1980 | Oldsmobile Starfire Oldsmobile Starfire Oldsmobile Starfire are automobiles produced by the Oldsmobile division of General Motors in two generations from 1961–1966 and 1975–1980. The Starfire nameplate was also used for the 1954–1956 Ninety- Eight series convertibles, and all 1957 Ninety-Eight series models. 1961 was the first year for... |
GM J platform GM J platform The J platform, or J-body, was General Motors' inexpensive front-wheel drive automobile platform from the 1980s and 1990s. The platform replaced the GM H platform. The J-platform is the only platform of GM to have a model in each of its "Original 5" passenger car divisions... |
See also
- Chevrolet VegaChevrolet VegaThe Chevrolet Vega is a subcompact, two-door automobile that was produced by the Chevrolet division of General Motors for the 1971-1977 model years. Named after the star Vega, the car was powered by a lightweight aluminum-block inline four-cylinder engine...
- Chevrolet Cosworth VegaChevrolet Cosworth VegaThe Chevrolet Cosworth Vega is a subcompact four-passenger automobile produced by the Chevrolet division of General Motors for the 1975 and 1976 model years. The Cosworth Twin-Cam is a limited production, performance version of the Vega...
- Pontiac AstrePontiac AstreThe Pontiac Astre is a subcompact automobile that was produced by the Pontiac division of General Motors. Essentially a rebadged Chevrolet Vega, it was introduced in Canada for the 1973 model year and sold there exclusively through 1974. It debuted in the U.S...
- Chevrolet MonzaChevrolet MonzaThe Chevrolet Monza is a subcompact, four-passenger automobile produced by the Chevrolet division of General Motors for the 1975–1980 model years. The Monza is based on the Chevrolet Vega, sharing its wheelbase, width and 140 CID inline-4 engine...
- Pontiac SunbirdPontiac SunbirdThe Pontiac Sunbird, produced by the Pontiac division of General Motors, was Pontiac's second small-car offering of the 70's. The Sunbird model ran for 18 years and was then replaced in 1995 by the Pontiac Sunfire...
- Buick SkyhawkBuick SkyhawkThe Buick Skyhawk are automobiles produced by the Buick division of General Motors in two generations for the 1975 through 1989 model years. 1975 through 1980 models, all 2-door hatchbacks, were built on the subcompact, rear-wheel drive H-body platform...
- Oldsmobile StarfireOldsmobile StarfireOldsmobile Starfire are automobiles produced by the Oldsmobile division of General Motors in two generations from 1961–1966 and 1975–1980. The Starfire nameplate was also used for the 1954–1956 Ninety- Eight series convertibles, and all 1957 Ninety-Eight series models. 1961 was the first year for...