Front-engine, rear-wheel drive layout
In automotive design, an FR, or Front-engine, Rear-wheel-drive layout is one where the engine is located at the front of the vehicle and driven wheels are located at the rear. This was the traditional automobile layout for most of the 20th century. Modern designs typically use the front-engine, front-wheel-drive layout (FF).
The first FR car was a 1895 Panhard model, so this layout was known as the "Système Panhard" in the early years. The layout has the advantage of minimizing mechanical complexity, as it allowed the transmission to be placed in-line with the engine output shaft, spreading weight under the vehicle. In comparison, a vehicle with the engine over the driven wheels eliminates the need for the drive shaft (replacing this with the transaxle of lighter combined weight), but has the disadvantage of concentrating all the weight in one location.
In order to reduce the relative weight of the drive shaft, the transmission was normally split into two parts, the gearbox and the final drive. The gearbox was normally produced with its highest gear being 1:1, which offers some mechanical advantages. The final drive, in the rear axle, would then reduce this to the most appropriate speed for the wheels. As power is the product of torque and RPM, by spinning the shaft more quickly for any given power, the torque in the shaft is reduced, and it can be built lighter.
In an era when gasoline was cheap and cars were heavy, the mechanical advantages of the FR drivetrain layout made up for any disadvantage in weight terms. It remained almost universal among car designs until the 1970s.
After the Arab Oil Embargo of 1973 and the 1979 fuel crises, a majority of American FR vehicles (station wagons, luxury sedans) were phased out for the FF layout - this trend would spawn the SUV/van conversion market. Throughout the 1980s and 1990s, most American companies set as a priority the eventual removal of rear-wheel drive from their mainstream and luxury lineup. Chrysler went 100% FF by 1990 and GM's American production went entirely FF by 1997 except the Corvette and Camaro. Ford's Mustang has stayed rear-wheel drive, as it must maintain a sporty presence, as were Ford's full-size cars based on the Ford Panther platform (the Ford Crown Victoria, Mercury Grand Marquis, and Lincoln Town Car) until they were discontinued in 2011 in favour of the Ford Taurus, which has a transverse front-wheel-drive layout.
Some manufacturers, such as Alfa Romeo, Porsche (944, 924, 928) and Chevrolet (C5 and C6 Corvettes), 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.
In Australia, FR cars have remained popular throughout this period, with the Holden Commodore and Ford Falcon having consistently strong sales, though Ford has regularly threatened to replace the Falcon with some kind of front-wheel-drive car. In Europe, front-wheel drive was popularized by small cars like the Mini, Renault 5 and Volkswagen Golf and adopted for all mainstream cars. Upscale marques like Mercedes-Benz, BMW, and Jaguar remained mostly independent of this trend, and retained a lineup mostly or entirely made up of FR cars. Japanese mainstream marques such as Toyota were almost exclusively FR until the late 1970s and early 1980s. Toyota's first FF vehicle was the Toyota Tercel, with the Corolla & Celica later becoming FF while the Camry being designed as an FF from the beginning. The Supra, and Cressida remained FR. Luxury division Lexus has a mostly FR lineup. The fact that a driveshaft is needed to transfer power to the rear wheels means a large centre tunnel between the rear seats. therefore, cars such as the Mazda RX8 and the Porsche Panamera simply forgo putting a centre rear seat, and divide both seats by a centre tunnel.
Currently most cars are FF, including all front-engined economy cars, though FR cars are making a return as an alternative to large sport-utility vehicles. In North America, GM returned to production of the FR luxury car with the 2003 Cadillac CTS, and with the removal of the DTS, Cadillac may become entirely FR (with four-wheel drive available as an option on several models) by 2010, and the 2009 Camaro returns as a FR sports car. Chrysler returned its full-size cars to this layout with the Chrysler 300 and related models. After the 2011 model year, the only FR cars produced by Ford are the Mustang and the Australian-market Falcon.
- ↑ "Development of a New Hybrid Transmission for RWD Car". www.sae.org. http://www.sae.org/technical/papers/2006-01-1339. Retrieved 2008-01-11.
- ↑ "Comparison Test: Front-Wheel Drive Vs. Rear-Wheel Drive". Popular Mechanics. 2004-09-10. http://www.popularmechanics.com/automotive/new_cars/1266931.html. Retrieved 2011-11-11.
- ↑ "2005 Ford Mustang - Popular Hot Rodding Magazine". Popularhotrodding.com. http://www.popularhotrodding.com/features/0501phr_2005_ford_mustang/index.html. Retrieved 2011-11-11.
- ↑ http://blog.vehiclevoice.com/2005/12/why_good_enough_isnt_1.html
- ↑ "Automaker Ratings". Rearwheeldrive.org. http://www.rearwheeldrive.org/rwd/rwdrate.htm. Retrieved 2011-11-11.
- ↑ Template:Dead link
- ↑ Yoffe, Emily. "Chrysler brings back rear-wheel drive. - Slate Magazine". Slate.com. http://www.slate.com/id/2082761. Retrieved 2011-11-11.
- ↑ Johnson, Drew (2008-02-14). "2011 Chrysler 300, Dodge Charger to remain rear-wheel drive". Leftlanenews.com. http://www.leftlanenews.com/2011-chrysler-300-dodge-charger-to-remain-rear-wheel-drive.html. Retrieved 2011-11-11.