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Revision as of 11:03, 3 January 2006 by Shawnc (talk | contribs) (references section)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)In Automobile design, an FR, or Front-engine, Rear wheel drive means a layout where the engine is in the front of the vehicle and drive wheels at the rear. This was the traditional automobile layout for most of the 20th century.
Overview
This layout is typically chosen for its simple design and weight distribution. Placing the engine at the front gives the vehicle a traditional long hood (in British English "bonnet") and engine cooling is simple to arrange. Placing the drive wheels at the rear allows ample room for the transmission in the center of the vehicle and avoids the mechanical problems of transmitting drive to steered wheels. The layout is still more suitable than front-wheel drive for engine outputs of more than about 150bhp, as the weight transference during acceleration loads the rear wheels and increases grip.
History
The first FR car was an 1895 Panhard model, so this layout was known as the "Systeme Panhard" in the early years. Most American cars used the FR layout until the 1980s, exemplified by the Ford Mustang, Chevrolet Corvette, and originally German vehicles from BMW and Mercedes-Benz. The Oil crisis of the 1970s and the success of small FF cars like the Mini, Volkswagen Rabbit, and Honda Civic led to the widespread adoption of that layout.
Some manufacturers, such as Volvo, retained this layout but moved the gearbox from behind the engine to between the rear wheels, putting more weight over the driven axle. This configuration is often referred to as a transaxle since the transmission and axle are one unit.
Right after the Arab Oil Embargo of 1973 and the 1979 fuel crises, a majority of American FR vehicles (station wagons, luxury sedans) were being phased out for the FF layout - this trend would spawn the SUV/van conversion market. Chrysler went 100% FF by 1990; only GM and Ford retained FR for their luxury and performance vehicles.
GM phased out its FR luxury cars after the 1996 model year, and its F-car (Chevrolet Camaro/Pontiac Firebird) in 2002. GM reintroduced North American FR luxury cars with the 2003 Cadillac CTS. Currently they produce the Pontiac GTO (imported from Australia), Chevrolet Corvette/Cadillac XLR and the Cadillac CTS/STS.
Today, most cars are FF, though the limitations of that layout, such as poor traction under acceleration and excessive nose weight, are beginning to become apparent. Many of the newest models have adopted all wheel drive, and some, like the Chrysler 300 are switching back to the FR layout. Most sports cars and luxury cars have always been FR.
FM Layout
Recently, a new layout called FM for Front-midships has appeared. An FM car places the engine in the front like an FR car, but pushed back enough that the engine's center of gravity is to the rear of the front axle. This aids in weight distribution and handling. Technically FM is a smaller sub-catgeory of FR, since the engine is still in the front third of the car, and FM cars still have rear wheel drivetrains. FM cars are often recognizeable by an extensively long hood and front wheels unusually close to the bumper of the car. Typical FM cars are high performance models such as the Aston Martin Vanquish and V8 Vantage 2005, Chevrolet Corvette, Dodge Viper, Honda S2000, Ferrari 612 Scaglietti, Maserati Quattroporte, Mazda RX-7 and RX-8, Mercedes-Benz SLR McLaren, BMW Z4, Nissan 350Z, Porsche 928, 944, and 968.
References
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