GARRETT COMAN
Staff Writer
The influx of cheaper import cars in the ’80s brought a dramatic shift to the way cars were built, and we’re just now recovering from the disastrous effects of the front-wheel-drive economy car.
In the early ’80s, Toyotas and Hondas appeared with front-wheel drive. Folks then thought front-drivers were the new “sophisticated” way to get power to the wheels. It made sense on paper: better traction, packaging and fuel economy. Why weren’t all cars front-wheel drive?
That’s exactly what automakers evidently thought because throughout the late ’80s, Ford, General Motors and Chrysler began a massive conversion to front-wheel drive. By the end of the era, dozens of model lines – including GM’s famed Cadillac Deville – had made the great “leap” to front-wheel drive. The age of enjoyable cars was dead.
Do the driving wheels actually make any difference? Ask anyone who has driven both, and they will say yes.
The difference is apparent at the first quick corner or stomp on the gas. While a front-wheel-drive car’s steering will skew a larger turning trajectory, a condition known as understeer, a rear-wheel-drive car will tend toward the opposite or oversteer. Both terms indicate which wheels — front (understeer) or rear (oversteer) — are slipping through a corner. Understeer usually results in a sensation of mushy, unresponsive steering, while oversteer often allows drivers to countersteer the car and execute movie-style corner slides.
There are many reasons front-wheel drive still is considered superior. Since the engine is over the drive wheels, there is more weight on the wheels powering the car. This equates to better traction. Also, it is cheaper for automakers to package everything up front (the engine, transmission and drive axles). It also clears up space in the rear of the car, and gas mileage increases because there are fewer components for the power to go through.
But why is it that true sports cars are almost all rear-wheel drive (or all-wheel drive, but that also uses the rear wheels)?
Ed Zellner, GM’s vehicle chief engineer, gave several reasons in an interview on MSN’s Slate.com.
One component Zellner mentioned is balance. While front-wheel-drive cars carry about 60 to 70 percent of their weight up front (which helps in slippery situations), rear-wheel-drive cars have a weight distribution closer to 50-50. This means that when the car is accelerating, the weight shifts to the rear wheel, giving better traction in heavy acceleration. And when a front-wheel-drive car is under severe braking, up to 90 percent of the weight can be on the front tires, severely limiting braking distances. In a rear-wheel-drive car, more weight stays in the back because more is originally there. Balance is everything in a car, and the closer to 50-50 it can get, the better the handling and the more fun it will be.
Another component is torque steer. In a rear-wheel-drive car, the rear wheels push the car and the front wheels steer the car, so steering is not directly related to the amount of power at the pushing wheels. But in a front-wheel-drive car, when power is heavily applied to the front wheels through unequal-length drive shafts, the car will actually not want to go straight. Drivers will have to counteract this force by resisting the steering wheel’s urge to turn left or right, which doesn’t enhance the driving feel.
Zellner’s final reason for rear-wheel drive was oversteer, as I discussed earlier.
With all of these factors, it’s easy to imagine why BMW, Porsche and Ferrari have never relied on front-wheel drive. But it’s baffling why American cars do. Today, it’s welcome to see some of them — particularly GM’s Cadillac division — return to rear-wheel drive. With a bit of luck, it’s possible things may eventually change back to the way they used to be.
11-10-2005
