What Is A Differential In A Car?

Differentials have been installed and operated in vehicles for around two hundred years. There are various types of differentials, such as limited-slip, locking, or open. While you might be aware of them, you may be unaware of how differentials work to power your car. In this article we will cover the different types of differentials and how they operate.

What Is A Differential (Diff)?

It’s fairly common knowledge that when you run around a circular orbit, the inner track is faster because it covers a shorter distance than the outside track. This is basically what a differential is, it adjusts the spinning of the inner wheel when you are cornering so it spins faster than the outside wheel, and you can maintain traction without dragging one of the wheels.

How Does The Differential Work?

A differential is a part of your car's drivetrain, it helps the engine deliver power to the wheels. The engine itself is a series of moving parts that, in most configurations, moves up and down, to spin the crankshaft. This spinning is then transferred to the driveshaft. In a rear-wheel drive vehicle, the driveshaft comes to a t-junction shape when joined to the rear axle.

The differential is the name for the series of gears in this t-junction. The driveshaft spins against the gears inside, and transfers that power to the axles that are connected to the wheels. The gears inside a differential allows the axles to spin at different speeds, depending on where the load is, which then spins the wheels.

What Does An “Open” Differential Mean?

You’ll find an open differential on most cars. It is a cheap but effective and non-complicated differential. It generally allows the wheels to rotate independently of each other. This means that the wheels are free to turn at their own speeds, during turns. Basically the wheels turn at different speeds until the turn is completed and the vehicle returns to a straight path.

One problem with open differentials is that they accomplish by sending more power to the wheel that needs to turn faster, and that’s okay when you are driving on dry bitumen roads. But things can get a bit pear-shaped when you are driving on slippery or dirt roads. If one wheel hits a wet spot on the road it can start to lose grip, then the open differential offers more power to that wheel. This makes traction harder for the car. A better solution is having a differential; send power to the wheel that has more traction, for that you’ll need a limited-slip differential.

What Does A “Limited-Slip” Differential Mean?

A limited-slip differential allows, under certain conditions, for the rear axle to be locked together and operate as a single element. This usually occurs when one wheel is spinning too fast and losing traction. When more power is sent to the wheel that has more traction, it allows you to have more control over the car in slippery conditions. A limited-slip differential is perfect for performance vehicles, as they are most likely to have problems from slippery roads and high power situations.

The way that the axles lock together varies depending on your cars manufacturer. Some use clutches, or helical gears and viscous couplings using hydrodynamic friction, or a series of clutches. There are also many aftermarket limited-slip differential available, such as the Torsen; it uses proprietary gear sets, even though it works similarly to the helical gear method.

A few manufacturers offer electric models, these are similar to a clutch style differential, but the power is delivered by an electric sensor.

What Does A “Locking” Differential Mean?

Locking differentials are usually found in off-road vehicles. It locks the axles together and they turn at the same time. It is perfect for when you need maximum traction while driving in a straight line, if only one wheel has any grip it can receive a hundred percent of the power available.

The negatives for a locked differential is that it feels like there isn’t a differential at all when turning corners. The wheels will seem to skip and skid as they struggle to turn a corner, as they are spinning at the same rate. This can wear your tires prematurely and will offer the occupants a ‘rough and ready’ ride. For a better solution in an off road vehicle that needs to drive on standard roads as well, is to look for what is called a ‘lockable’ differential. These differentials are able to be locked at the push of a button, with this you can choose to lock the diff when it best suits the conditions.