What is a Differential On A Car and How Does it Work?

What Is a Differential On a Car?

The differential is a set of gears that transmits engine power to the wheels, allowing them to rotate at different speeds on turns. If your vehicle has a four-wheel-drive system, then it more than likely has a front and rear differential. A differential works with the transmission to deliver power from the engine to the axle that turns the wheels.

The differential is designed to drive a pair of wheels, allowing them to rotate at different speeds. This function provides proportional speeds between the left and right wheels. If the inner tire rotates 15 rpm less in a corner than when driving straight, then the outer tire rotates 15 rpm more than when driving straight.

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, to give the wheel more resistance to rotate less. The wheel with less resistance rotates faster.

In front-wheel drive (FWD) the differential is located next to the transmission in the housing and the unit is called a transaxle. With rear-wheel drive (RWD), the differential is located between the rear wheels, which are connected to the transmission via a driveshaft. All-wheel drive (AWD) and four-wheel drive (4WD) vehicles add a center differential or transfer case to distribute power front and rear.

Some hybrid vehicles have “electronic” AWD. These use electric motors to drive the rear wheels, turning them faster or slower around corners as needed.

How does differential work in a car?

In simple terms, a differential is a system that transfers the torque from an engine to the wheels. The differential takes the power from the engine and divides it so that the wheels can spin at different speeds. Rotate it around a corner and you won’t have any problems as each wheel can turn independently from the other.

When you look at a complete modern differential, it looks incredibly complicated.

However, if you systematically break it down and understand the basics of what it is trying to achieve and how it is trying to achieve it, you will find that it is really a beautiful thing.

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Check out this video of Chevrolet engines for a retro look at the differential.

Now that we understand the basics of a differential, or in this case an “open differential,” let’s discuss a little more about a limited-slip differential (LSD).

Imagine you are on the track trying to get out of a tight corner at 50km/h. All of this power will take the path of least resistance.

All weight has been shifted to one side. All of that power will only spin the inner wheel, resulting in a tremendous amount of power lost or spinning and a major crash.

The LSD is in place to minimize this drive loss. A clutch system creates friction on each side of the axle so that the car can redistribute torque to each wheel so you can get as much power as needed. If you know your way around the wheel, you can steer the car with nothing but power, even in a curve.

As you can imagine, the entire differential mechanism has to withstand an enormous force. This is just one reason why these components are made from the strongest possible materials. No straws and milk bottle caps.

Differentials have to be extremely durable. When cars were slower and less demanding, you could get away with cheaper metals. This is simply no longer the case.

Even today’s simplest vehicles can travel comfortably at over 150 km/h and are capable of safely cornering at relatively high speeds. High-quality components are no longer reserved for the racetrack.

Parts of Differential

Following are Differential Parts:

  • Bearing kits
  • Individual seals and bearings
  • Ring and pinion sets
  • Axle shafts
  • carrier/pinion shims, pinion nuts, crush sleeves, and ring gear bolts
  • Posi traction and internal gear kits
  • housings carriers
  • These are just some of the component parts in stock. We even have used parts for most differential applications.
  • Pinion Drive Gear: this part transfers the power to the ring gear from the drive shaft.
  • Differential case assembly: this part holds the Ring gear along with other components which drive the rear-drive axle.
  • Ring Gear: this section transfers the power to the previous part which is the Differential case assembly.
  • Rear-drive axles: these are the steel shafts which transfer the torque from differential case assembly to drive wheels.
  • Axle housing: these are the metal body that encloses the rear axles and also supports the rear axle assembly.
  • Rear axle bearings: these are the ball bearings which fit between the axle housing and the axles.
  • Side gears: these gears help both the wheels to turn independently while turning.
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Types of Differentials in Cars and Trucks

There are four common differentials used between vehicles – open, locking, limited-slip, and torque-vectoring.

Here are the four types of differentials:

  • Open differential – This type of differential is often found in family sedans and economy cars. It splits the engine torque into two energy outputs to allow the wheels to rotate at different speeds. If one tire loses traction, the other will lose power to maintain traction.
  • Locking differential – Sometimes also known as a welded differential, this differential connects the wheels so they spin at the same speed. This typically makes turning a little more difficult. Vehicles that use this type are full-size trucks and Jeep Wranglers.
  • Limited-slip differential – Offering the best of both worlds, the limited-slip differential operates as an open differential until slippage occurs, then the differential will automatically lock. This type is found in vehicles like the Nissan 370Z and Mazda MX-5 Miata.
  • Torque-vectoring – Used by the BMW X5 M or Lexus RC F, the torque-vectoring differential uses additional gear trains to send a specific amount of torque to each wheel for added control on turns.

1. Open Differential

The simplest and most common unit is the open differential, so-called because the wheels can always rotate independently. Its main disadvantage is that if a wheel doesn’t have traction, such as if it hits the ice, it still gets lots of power. It spins helplessly, and you’re going nowhere.

To compensate for the loss of traction while driving, all new vehicles must be equipped with traction and electronic stability control. These use sensors from the anti-lock brakes to determine if a wheel is spinning faster. It then reduces engine power or breaks the spinning wheel or both to get things under control.

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Sometimes you want a wheel to spin, such as when trying to get out of deep snow, allowing traction control to be temporarily disabled with a button on the dash.

2. Limited-Slip Differential

Some vehicles, mostly performance models, use a limited-slip differential instead of an open one. When one wheel loses traction, power goes to the other wheel. This reduces wheel spin and, in a more powerful FWD vehicle, helps prevent torque steering – the tendency of a front-driver to pull from side to side when you step on the accelerator.

Limited receipts all serve the same purpose, but how exactly they do it depends on what type it is. A mechanical-clutch differential has clutch plates alongside the gears, and when needed, pressure rings press on the plates to provide resistance. An active differential system works the same way, but uses a computer to monitor driving conditions and engage the differential’s clutch.

A viscous differential contains friction discs immersed in oil, and when a wheel slips, the movement of the fluid causes the discs to spin at different speeds, delivering more power when needed. A Torsen differential – it’s a brand name derived from Torque-Sensing – adds worm gears to the differential gear set to activate the required drag.

3. Locking Differential

A locking differential lets the wheels turn at different speeds most of the time, but when its locking function is activated, the wheels both turn at the same speed. It’s primarily used for off-road driving.

In addition to a rear-wheel locking differential, the toughest 4x4s will also have a locking front differential. A vehicle with one or both differentials locked can crawl forward over rocks or tough surfaces, but it’ll be very hard to turn.

4. Torque-Vectoring Differential

The most complicated and advanced type of differential, a torque-vectoring differential uses a collection of sensors and electronics to obtain data from various things (road surface, throttle position, steering system, etc.) to activate electronically actuated clutches and a controller.

Also known as active differentials, they work in the most efficient way which results in a truly dynamic, high-performance driving experience. Torque-vectoring differentials can be found in some high-performance rear-wheel drive and all-wheel drive vehicles.

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