Front-wheel drive vs rear-wheel drive

The Mini.
Photo / Richard Robinson
The Mini. Photo / Richard Robinson

Ever wondered why some cars have their front wheels driven, while others are driven by their rear wheels?

It used to be that almost all cars, with the exception of odd ones out like Citroen, DKW and Saab, used rear-wheel drive (RWD), but then half a century ago the Mini came along and turned the automotive world from back to front.

The Mini, its engine turned sideways, included front-wheel drive (FWD) as a key part of its brilliant packaging. This arrangement eliminated the driveshaft from the gearbox to a rear differential, saving cost and freeing up interior space because there was no transmission tunnel.

Weight dropped because the gearbox and differential were in one housing and there was no driveshaft. Less power was lost through mechanical inefficiency and, with engine weight directly over the driven wheels, traction was better on slippery roads.

That was all good stuff and it wasn't long before manufacturers worldwide embraced FWD. At first it became the favoured configuration for small cars but nowadays FWD can be found in most sizes, although it's common for large cars to still be driven by the rear wheels - the Aussie Falcon and Commodore are cases in point.

So why haven't all cars gone FWD if it's such a great configuration? Unfortunately, there are disadvantages - and there are also different points of view. The debate has gone on for decades about which is the better configuration.

Manufacturers of large, powerful cars have tended to stay with rear-drive, partly because of the potential for excessive FWD understeer, an undesirable handling characteristic. Understeer is the tendency to turn less sharply than the driver intended. There has also been the issue of stress and component wear on larger, more powerful FWD cars.

With more weight over the front of a FWD car, the back end tends to become light, especially during acceleration. Ideal weight distribution for a car is said to be 50-50 front and rear, but FWD cars rarely get close. (Neither, for that matter, do many of the nose-heavy RWD cars.)

There's a saying among experienced and enthusiastic FWD drivers: "Put the gas to the floor and steer; the rear will follow." The hard-worked front tyres must transfer all acceleration, steering, cornering and most braking to the road. The rear set has little load and more or less goes along for the ride. That's why you'll often notice front tyres wearing significantly faster.

On a RWD car, the two rear wheels take care of acceleration, leaving the front pair to do the steering and most of the braking. A skilled driver can "steer" a RWD car with the accelerator by applying power and sliding the rear end, which is why the configuration is often favoured for sports cars.

Meanwhile, today's electronic traction and stability controls have tamed one of RWD's worst habits - the rear-end breaking traction on wet or loose surfaces. Electronics have narrowed or even eliminated the traction advantage of FWD.

Extra rounds

Front-drive and rear-drive layouts are based on using only half a vehicle's wheels to deliver power

to the ground.

So if those other wheels are

just sitting there, why not use

them too?

The concept of all-wheel drive is not new. The Dutch manufacturer Spyker had such a vehicle on display at the Paris Motor Show back in 1903, but it took decades before all-wheel drive became popular on road cars.

Miller's racer first off the line

The 1924 American Miller 122 racing car is generally credited with being the first successful front-wheel drive car.

Ruxton, Cord (well before its iconic 810) and Alvis all made a few during the 1920s, but the configuration became commercially successful with the 1931 German DKW F1 and the 1934 Citroen Traction Avant.

- NZ Herald

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