- Front-wheel drive
- Rear wheel drive
- Four wheel drive
Front or rear wheel drive means to which wheels the driving forces of the engine are transferred. Most car manufacturers opt for front-wheel drive. The motor provides the driving forces. With a manual gearbox, the gearbox is operated with the clutch, with a automatic gearbox this happens in the tank itself. Via the drive shafts the power eventually gets to the wheels.
With front-wheel drive, the front wheels are coupled with the drive shafts to the gear box (with internal differential). Usually the engine block is placed transversely to save space. Car manufacturers often opt for front-wheel drive. This is cheaper than rear- or four-wheel drive because fewer materials are used, and it is more space-saving and less prone to vibration than front-wheel drive.
On cars with rear-wheel drive, the engine block is longitudinal. A runs from the gearbox cardan shaft (or intermediate shaft) under the car (which is placed above the exhaust out of sight) to the cardan.
Cars with a lot of power and rear-wheel drive are often more prone to oversteer (the car makes a bigger turn than necessary, the rear wants to pass the front). An option such as ASR is therefore not an unnecessary luxury. Rear-wheel drive is used less by manufacturers than front-wheel drive. Especially cars that have to deliver a lot of power (including BMW and Mercedes) are driven by the rear wheels. They also want to have an ideal weight distribution between the front and rear axles. By placing the engine longitudinally, the gearbox hangs under the center console in the interior. The gearbox is thus placed closer to the rear axle. The center of gravity is now moved more backwards.
Another advantage is that more power can be transferred to the road surface in this way. When accelerating hard with a car with more than 250 horsepower, the weight on the rear wheels of the car will increase much, just as the weight on the front wheels increases when braking. When accelerating, the weight increases on the rear wheels, so that the chance of skidding is many times less than if the car were driven on the front wheels.
Rear-wheel drive cars also have a specially shaped fuel tank, because the cardan shaft and the cardan are mounted underneath. A saddle tank with an additional suction jet (fuel) pump is then mounted.
Four wheel drive:
In four-wheel drive cars, as the name suggests, all four wheels are driven.
The advantage of this is that all the engine power can be used to accelerate without the wheels slipping and that there is much more grip on unpaved roads. Off-road vehicles often have four-wheel drive, because with the help of the ASR system, sufficient power can often be transferred to surfaces on which only a front-wheel or rear-wheel drive car can get stuck (such as snow, sand or mud). Even sporty cars with a lot of power are sometimes equipped with four-wheel drive.
There are different systems, where there is no permanent drive on all four wheels at the same time. Two different systems are described on this website, namely from the Haldex coupling and from one transfer case which is mounted on the gearbox.
Applied to VAG brands; VW, Audi, Seat and Skoda. The haldex clutch is located at the rear axle and controls the drive forces of the cardan shaft on the drive shafts of the wheels. The front wheels are constantly driven.
Click here for more information about the Haldex coupling.
Applied at BMW, among others. The transfer case is mounted on the gearbox and controls the drive forces to the front wheels.
The rear wheels are directly connected to the gearbox and are always driven.