What Is a Car Differential?
The differential is part of the car's axle assembly. It connects the driveshaft to the axles and also connects the transmission or transfer case through the driveshaft. Its function is to transmit the energy generated by the engine to the wheels, and it plays an integral role when your car turns.
The main task of the differential is to distribute, change, and then transmit rotation. In short, the differential transmits the engine's torque to the wheels so that they can turn. If necessary, the differential provides torsion of two elements with different angular speeds.
For example, when your vehicle goes around a corner, the wheel on the outside must travel faster than the wheel on the inside. The differential distributes equal amounts of torque to both wheels. This permits the wheels to react to resistance, or provide traction, giving the wheel with more resistance the ability to rotate less. The wheel with less resistance rotates faster.
Where Your Differential Lives
Every vehicle has a differential system based on its wheel drive, and the differential is located in different places:
- AWD (all-wheel-drive) cars utilize both front and rear differentials to direct power to all four wheels.
- 4×4 / four-wheel-drive vehicles carry the differential in the axle housing (front or back); it distributes power to the front and rear wheels. The newest cars have electronic all-wheel drive that adjusts the speed of the wheels using electric motors.
- Front-wheel-drive cars are equipped with a front differential next to the transmission, in the transaxle.
- Rear-wheel-drive vehicles house it in the rear axle housing between the rear wheels, connected to the transmission by a driveshaft.
Not all vehicles are equipped with a differential, though. Go-kart wheels rotate at the same speed, often with a common axle powered by a chain drive.
The Three Types of Differential
Even though any differential will help your car turn, there are different types — and some are better than others. There are three: open, limited-slip, and torque-vectoring.
Open Differential
This is the oldest and most common design — the most simple, reliable, and widely-used type of differential. The powered pinion gear, located at the end of the driveshaft, engages with the ring gear, which then transmits power to both axles through another set of gears.
The only flaw in its design is that when one wheel begins to slip, all power is in essence sent to the wheel with the least traction, making this setup unfit for rock climbing or high-speed racing.
Limited-Slip Differential
This is similar to an open differential but utilizes an integrated clutch system. The clutch mechanism locks the left and right sides of the axle together when a wheel loses traction. This is the preferred system for high-performance vehicles such as drag racers and those towing heavy loads.
Torque-Vectoring Differential
This is the latest and greatest in differential technology. Torque vectoring encompasses a complicated collection of sensors and electronics to obtain data from the steering system, throttle position, road surface, and more, giving it the ability to distribute power to each wheel according to the data. This option provides maximum traction while cornering, increasing performance significantly.
When a Differential Fails
The differential adjusts the spin of your wheels, making it possible for the car to make turns efficiently. If it doesn't work properly, other parts of the car will be stressed, and that causes more damage — sometimes irreversible damage. If you suspect a differential problem, have it diagnosed before it takes the driveline with it.
