FR layout
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 200bhp, as the weight transference during acceleration loads the rear wheels and increases grip.
The FM layout is based on the FR layout.
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 Porsche (944,924,928), 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. GM Holden continued to produce RWD cars through this period.
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.
See also
- Front wheel drive
- All wheel drive
- Rear wheel drive
- FF layout
- MR layout
- MF layout
- RR layout
- FM layout