Differentials

A differential, also known as a 'diff', is a component of a vehicle's drivetrain. It ensures that the driven wheels (usually the rear wheels in rear-wheel drive vehicles, or the front wheels in front-wheel drive vehicles) can rotate at different speeds, which is particularly important when the car is turning a corner.

With non-driven axles and wheels, a difference in rotation is not a problem because the wheels on both sides of the vehicle rotate independently of each other. However, this is not the case with driven axles, where the wheels rotate in relation to each other (at the same speed). This would cause the two wheels to work against each other in a turn and move along the road by scraping instead of rolling. The use of a differential prevents this and allows the wheels to turn at different speeds.