Chevrolet Corvair
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The Chevrolet Corvair was a rear-engined automobile produced by General Motors from 1960 to 1969. The Corvair was offered in a wide range of body styles (such as a four-door sedan, coupé, convertible, station wagon, pickup, and America's first mini-van, the Greenbrier) and featured an air-cooled engine, which was unusual for American cars at the time.
The Corvair remains one of GMs most unusual creations. Design began in 1956 under the auspices of Ed Cole, and the first vehicles rolled off the assembly line in late 1959 as part of the 1960 model year (in which it was named Motor Trend magazine's Car of the Year).
The Corvair—like the Ford Falcon, Studebaker Lark, Nash Rambler, and Chrysler Valiant—was created in response to the small, sporty and fuel-efficient automobiles being imported from Europe by Volkswagen, Renault and others.
The Corvair was part of GM's innovative A-body line of cars, but this was by far the most unusual, due to the location and design of its engine. It was a rear-engined vehicle in the style of the Volkswagen Beetle and the Porsche 356 Speedster. The "trunk", on the other hand, was in the front of the vehicle.
The entire line (which eventually grew to incorporate sedans, coupes, convertibles, vans, pickups and station wagons) initially shared an aluminum, air-cooled 140 in³ (2.3 L) flat-6 engine. The first engines produced as little as 80 hp (60 kW), but later developed as much as 180 hp (134 kW).
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History
The Corvair name originated as a Corvette-based fastback in the early to mid fifties. Many future Chevrolet models were based on the Corvette, including the Nomad and Impala.
The early 1960 models were rather boxy and had few amenities, but the line quickly grew from plain 4-door sedans with bench seats (the base 500 and slightly more upscale 700) to sportier 2-door coupes with bucket seats, the Monza 900.
1961
For 1961 Chevrolet added an optional 4-speed manual transmission to augment the standard 3-speed manual and optional 2-speed automatic. The Corvair engine received its first size increase to 145 in³ courtesy of a slight increase in bore size. The base engine was still rated at 80 hp (60 kW) when paired with the manual transmissions, but 84 hp (63 kW) when mated to the optional automatic transmission. The high performance engine was rated at 98 hp (73 kW).
A rear-engine station wagon, the Lakewood, was also added to the lineup in 1961, and it contained a total of 68 ft³ (1.9 m³) of cargo room -- 58 in the main passenger compartment, and another 10 in the "trunk" under the hood. Engine heat and gasoline odors migrating up through the floor of the station wagon proved to be a persistent problem with this particular model, however.
That same year, Chevrolet also added a panel van (the Corvan), a window van (the Greenbrier), and a pickup, which was notable not only for the fact that the air-cooled engine was mounted under the pickup bed, but that the side of the pickup bed folded down to form a ramp, hence its name, the Rampside.
The most notable addition in 1961 was the new "Super De Luxe" Monza trim package available. The Monza package included bucket seats up front and carpet all around in addition to a few extra chrome dress up items. Most commonly it was seen with a 4 speed on the floor shifter and the high performance engine. At the time this package was heralded by some as "the poor man's Porsche" since it was the closest thing to an affordable sports car on the american streets. Though introduced half way through the 61 model year, the Monza Coupe was the best selling model in the line up.
1962-1963
In 1962, Chevrolet began to phase out the austere 500 series. They introduced the 150 hp (112 kW) turbocharged Monza Spyder, making the Corvair only the second production automobile to come with a turbocharger as a factory option, after the Oldsmobile F-85 Turbo Jetfire of the same year. The Super Deluxe Monza Spyder introduced improved brakes and suspension, and a multi-gauge instrument cluster which included a tachometer. A convertible option was added as well. The 1963 model year saw the end of the Lakewood stationwagon and the availability of a long 3.08 gear for improved fuel economy, but the Corvair remained largely the same as in 1962.
1964
The lineup remained relatively unchanged for the 1964 model year, with the exception of the engine growing from 145 to 164 in³ (2.3 to 2.7 L)due to an increase in stroke; the base power growing from 80 to 95 hp (60 to 70 kW), and the high performance engine growing from 95 to 110 hp (70 to 80 kW). The Spyder engine remained rated at 150 hp (112 kW)despite the displacement increase of the engine.
However, 1964 also saw a critical improvement in the Corvair's suspension; the car's swing axle rear suspension's tendency to lose traction suddenly and without warning when pushed to the limit was tamed by use of an additional transverse leaf spring coupling both rear wheels.
However, a young lawyer named Ralph Nader had written a book called Unsafe at Any Speed in which the 1960-63 Corvair (and its purported greater tendency to roll over) was used as a dramatic case study. Even though a 1972 safety commission ultimately exonerated the Corvair and declared it no more unsafe than any similar vehicle of its era, Nader's book, which was published in 1965, was a severe blow to sales of the Corvair line. The sporty, inexpensive Ford Mustang, based on the conventionally designed Ford Falcon and introduced in late 1964 in response to the Corvair, ultimately finished off Chevrolet's bold experiment.
1965
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A dramatic redesign of the Corvair body and suspension and several powerful new engines came in 1965. The new body style lay somewhere between that of a baby Chevrolet Corvette Stingray and a mid-1960s Italian sports car and foreshadowed the 1967 Chevrolet Camaro that eventually replaced the Corvair. A new fully independent suspension similar to that used on the Corvette replaced the original swing axle rear suspension.
The previous 150 hp (112 kW) Monza Spyder was replaced by the normally-aspirated 140 hp (104 kW) Corsa and the 180 hp (134 kW) Corsa Turbo. The base Corsa was notable for the fact that the engine used 4 linked single-throat carburetors. Other models were available with the 140 hp engine as an option. The base 95 hp (71 kW) and 110 hp (82 kW) high performance engines were carried forward as well.
By this point, the more utilitarian station wagon, Panel Van, and pickup body styles had all been dropped in favor of the sportier coupe, sedan and convertible styles, and 1965 would be the last year for the Greenbrier window van.
1966-1969
The 1966 lineup remained essentially unchanged from 1965, and sales began to decline as a result of Nader's book, the popular new Mustang, and rumors of the upcoming Camaro. One change of note was a more robust 4 speed synchromesh transmission for 1966. The new transmission was capable of handling more stress, though generally wasn't as smooth shifting as the earlier transmisison.
In 1967 the Camaro was introduced and the Corvair line was trimmed to the base 500 sedan and coupe, and the Monza sedan, coupe and convertible.
In 1968 the line was trimmed even further to just the coupe and convertible, and only a few thousand were sold.
Corvair production finally ceased in 1969 with sales of only a few hundred cars, a victim of Nader's book, Ford's Mustang, and Chevrolet's own Camaro.
Engineering
The Chevrolet Corvair engine, unique for an American car, presented a different set of requirements for mechanics, many of whom treated the engine in the same way as they would an engine of normal design, leading to problems.
An engineering weakness not generally highlighted (and uniquely dangerous) related to fumes and gases entering the passenger area via the heater system, a problem endemic to an air-cooled engine. Carbon monoxide and other noxious or deadly gases could enter the sedan passenger areas if exhaust system gaskets aged or failed, since the gaskets were inside the heater box air intakes and air for engine cooling and passenger heating was mixed together as one common airflow. Chronic oil leakage from the pushrod tubes, which was endemic to the engine, also contaminated the heating air, as did the tendency for earlier engines to blow a head gasket. That air would also become noxious if a 6 inch wide rubber seal almost 16 feet long, located between the engine assembly and the body, was not maintained in like-new condition.
The interior air would also be contaminated if the owner did not keep the carefully engineered battery container, located in the engine compartment, intact and in like new condition. The Volkswagen Beetle, another automobile with an air cooled engine, located the battery in the passenger compartment under the rear seat. This may have been a source of noxious interior fumes in that vehicle as well, though perhaps on a lesser scale. VW better isolated fresh air, and used no-joint one-piece exhaust pipes inside their heater intakes to prevent exhaust leaks and ensure clean interior air.
Another criticism in Nader's book concerned the steering column design. Like most cars of its era, the Corvair's steering column was rigid and could be forced into the driver by a front-end collision. However, in the Corvair, the steering column actually terminated ahead of the front axle. This forward positioning, plus the lack of an engine in front to minimize crumpling, made dangerous rearward displacement of the steering column in a collision unusually likely. A collapsible steering column was eventually provided in 1967, towards the end of the model's life span.
In defense of Nader's criticism of the Corvair's swing-axle rear suspension, some writers have pointed to a critical factor in the combination of soft "American-style" springs together with an unusually large and heavy engine for a rear-engine, air-cooled car. Both of these factors would have greatly increased the potential for excessive body lean and over-cambering of the suspension in sharp turns, as compared with smaller and lighter contemporary Volkswagens, Renaults, Porsches, and other rear-engined cars. In addition, the car was designed to avoid terminal oversteer by using very low air pressure in the front tires, typically twelve to fifteen pounds per sqaure inch, so that they would begin to understeer (slip) before the swing axle oversteer would come into play. Although this pressure was quite adequate for the very lightweight Corvair front end, owners and mechanics, either through ignorance of the absolute necessity for this pressure differential between front and rear or thinking that the pressure was too low for the front, would frequently inflate the front tires to more "normal" pressures, thus ensuring that the rear of the car would lose traction before the front, causing it to spin.
Although Nader probably overstated the severity of the handling problems, Chevrolet themselves made changes to the suspension: in 1964 they added a transverse leaf spring extending between the rear wheels to minimize rear wheel camber change, and in 1965 the Corvair got a state of the art fully independent rear suspension closely resembling that of the contemporary Corvette, and even sharing some components. These changes were, however, viewed as Chevrolet's recognition of possible problems with the original design.
See also
External links
- CORSA home page - Corvair Society of America (http://www.corvair.org/)
- The Corvair Corsa - An exceptional Corvair resource (http://www.corvaircorsa.com/)
- Rear Engine Specialists - Corvair History and Customization (http://rearenginespecialists.com/)
- Corvair Project - Massive Corvair Internet Link Resource (http://www.corvairproject.com/)