Transmission Layout

This week we were looking at transmission layouts. The layouts covered in the lesson were;

1. Front engine, front wheel drive

2. Front engine, rear wheel drive

3. Front engine, four wheel drive

4. Mid-engine, rear wheel drive

5. Mid-engine, four wheel drive

6. Rear engine, rear wheel drive

7. Rear engine, four wheel drive

We debated over the course of the lesson about the pros and cons of each layout.

The advantages of 1 is that we can generally have a lot more room inside the car for people and possessions as we don’t need a transmission tunnel for the gearbox and prop shaft to go to the rear of the car. We also can have a larger boot space because we don’t need a driven axle at the back so we can have a simple suspension setup, saving costs and space.

The disadvantages include a tendency to understeer when driven hard, this makes this layout difficult to race well against rear wheel drive cars, it can also be harder to work on as everything is tightly packaged in the front under the bonnet and it can be hard to access components, especially in modern cars as manufacturers have a tendency to put plastic covers on components under the bonnet and with there being more electrical components on modern cars they can be quite complicated to work on but this applies to all layouts.

The rear wheel drive layouts are all prone to the same pros and cons, preferring oversteer to understeer and less space in the boot and in the seating of the cars (not including estate cars) they also tend to be faster cars as they have good weight distribution and a better centre of gravity, they are usually more streamlined than hatchbacks as they can have longer lower bonnets.

Four wheel drive vehicles also can suffer from both oversteer and understeer and they need a high bonnet to fit the components in to allow for the front axle to be driven, four wheel drive is also a lot more complicated because we need more differentials and more prop shafts and more drive shafts, we also in newer systems have to monitor how much power is being sent to each wheel so therefore these systems are a lot more complicated than any other. Four wheel drive is also more expensive on the whole because not only is it a selling point for manufacturers but it is more expensive to engineer and to build because of the amount of components and the complexity. However in cars such as the Subaru Impreza and the Mitsubishi Evolutions we have four wheel drive four seat road cars with big boots so it is possible to make these cars that are a blend of practicality and four wheel drive performance.