Differential Buyer’s Guide
- One component of the drivetrain that distributes power to the drive wheels is an arrangement of gears known as the differential.
- When making a turn, the outer wheel would have more distance to travel compared to the inner wheel. With the differential bisecting the drive axle, the outer wheel could spin faster than the inner wheel so they can navigate a turn at the same time.
- A pinion gear connected to the propeller shaft drives a ring gear, rotating the housing of the spider gears that are meshed perpendicularly to the side gears connected to the drive wheels.
- The main types of automotive differential are the open differential, locking differential, and limited slip differential.
- A differential could also be classified by the drivetrain that it is part of with a front-wheel drive having a front differential, a rear-wheel drive having a rear differential. Meanwhile, a four-wheel drive (4WD has both front and rear differentials and an all-wheel drive has a center differential connecting the front and rear differentials.
- Signs of a bad differential include steering problems, unusual noises, and damaged tires or drivetrain parts.
- A new differential can be bought as an assembly, a kit, or as an individual part. Depending on the type, this can cost from around $265 to $600.
The concept of how cars move may seem simple—the engine makes the wheels turn, moving the car forward or backward. What is overlooked in this notion is that, regardless of how powerful the engine is, the car cannot be driven without a series of components to transfer and translate the generated torque to the wheels. This complex network of gears, shafts, axles, and other mechanical automotive parts that deliver the power from the engine to the drive wheels is called a drivetrain.
In addition to serving as a connection between the engine and the drive wheels, the drivetrain is also meant to deliver torque properly so that no power is wasted and driving would be smooth. One component of the drivetrain that distributes power to the drive wheels is an arrangement of gears known as the differential.
What Is a Differential?
The differential distributes power to the driver-side and passenger-side drive wheels. While driving down a straight, even road, the wheels would be traveling at the same distance and speed. When making a turn, however, the outer wheel would have more distance to travel compared to the inner wheel. If the wheels were locked together to the same axle, the inner wheel would have to slide or slip for the outer wheel to catch up. With the differential bisecting the drive axle, the outer wheel could spin faster than the inner wheel so they can navigate the turn at the same time. This also helps when the drive wheels are on different or uneven terrains, such as when one drive wheel is on ice.
How Does a Differential Work?
At the end of the propeller shaft that connects the differential to the engine is a pinion gear. This pinion gear meshes and drives a ring gear that translates the rotation of the propeller shaft to be parallel to the spin direction of the wheels. Attached to the center of the ring gear is the differential case or carrier that houses the spider gears that mesh perpendicular to the side gears. As the ring gear and differential carrier are rotated by the propeller shaft and pinion gear, the spider gears drive the side gears that are attached to the half shafts of the drive wheels. When one of the drive wheels is restricted, the spider gear would simply travel along the non-moving side gear, allowing the other drive wheel to keep spinning.
Types of Automotive Differential
Depending on the purpose, every type of vehicle has different power and performance needs. To help a vehicle fulfill its purpose, it would have to be equipped with parts that are specifically designed to support its function. As such, there exist different types of differentials.
With the open differential, both wheels receive the same amount of torque, but this is limited by the applicable torque for the drive wheel with the least traction. This type features the most basic gear arrangement and is used in most road vehicles.
The locking differential is designed to be able to rotate the drive wheels it supports at the same speed as if the wheels share the same axle. This differential can either lock and unlock itself automatically when certain driving conditions are met or be engaged manually by the driver with a form of switch. Vehicles that need constant traction, such as off-roaders and trucks, usually have this type of differential.
Limited Slip Differential
Adding a mechanism that creates resisting torque to the basic differential configuration results in a limited slip differential. This type acts much like an open differential but is able to send different amounts of torque to each drive wheel. One type of limited slip differential is the Torsen differential, with Torsen being a combination of the words ‘torque’ and ‘sensing’. Limited slip differentials are mostly used in performance vehicles.
A differential could also be classified by the drivetrain that it is part of. For instance, a front-wheel drive vehicle would have a front differential and a rear-wheel drive vehicle would have a rear differential. Needless to say, a four-wheel drive (4WD) would have both front and rear differentials. As for all-wheel drives (AWD), a central differential links to both the front and rear differentials.
How to Tell if a Differential Is Bad
Like with all other parts of a vehicle, the differential is also bound to wear or break due to time or improper handling. Those symptoms include the following:
Since the differential is what distributes power to the drive wheels, issues with this component could make steering difficult or unpredictable, especially when turning.
Bad differential gears would make noises such as whining due to poor lubrication; grinding, humming, or clanking when stripped or worn; and clicking, clunking, and banging when broken. Meanwhile, bearings in the differential would make howling or whining noises when loose and whirring or rumbling sounds when worn.
Damaged Tires or Drivetrain Parts
When the steering is not smooth, the tires would get unnaturally worn or damaged, particularly on the outer tread or the sidewall. There could also be harsh vibrations that escalate as the vehicle goes faster when the drive shaft is out of balance or the universal joints or u-joints are worn. The wheel bearings could also make rumbling noises when damaged.
Replacing the Differential
A broken differential should be replaced immediately to prevent other parts of the vehicle, such as the engine, from getting damaged. Promptly changing a damaged differential could also prevent potentially fatal accidents.
In looking for a differential replacement, keep the make, model, and year of your vehicle in mind. For efficient delivery of power from the engine to the wheels, all parts of the drivetrain, including the differential, should fit together properly.
A new differential can be bought as an assembly, a kit, or as an individual part. Depending on the type, this can cost from around $265 to $600.
Buying the Best Differential for Your Vehicle
Are you having a tough time controlling your vehicle when going around bends or turning corners? If you answered yes, then there must be something wrong with your vehicle's differential. Before you rush to the nearest automotive shop to get a replacement differential, here are some things that you need to know first.
The differential's function
Now, the same way it's virtually impossible to turn a Matchbox car without skidding or lifting half of the toy, it's also impossible for your ride to function without a differential. See, the differential is what allows your wheels to move at different speeds. By controlling the amount of power that moves each wheel, the differential is able to regulate wheel speed to ensure safe cornering and turning.
Types of differentials
Before buying a replacement, you have to know the basic types of differentials used on vehicles. Here are the five kinds of differentials that are commonly used in vehicles:
- Open differential- The open differential is the most commonly used differential today. It offers excellent drivability, reliability, and value. The only downside to this component is that it lacks the strength and traction needed in towing and racing applications.
- Automatic locking differential- This type of differential is often used for off-roading because of its superb traction. The automatic locking differential locks and unlocks automatically without requiring input from the driver.
- Limited-slip differential- This particular type of differential is another favorite for off-roaders. The limited-slip differential offers excellent traction and is ideal for both on- and off-road use.
- Manual locking differential- As its name implies, the manual locking differential must be locked or unlocked manually. The driver can usually do this from behind the wheel. When not engaged, the differential remains open. Should the driver need better traction, he can choose to lock the differential.
- Spools- This type of differential is recommended for drivers who want to experience excellent traction, strength, and value when it comes to off-road applications. Because spools are slip-free, there's very little risk of problems when you're turning tight corners.
When purchasing your new differential, it's important to know your options. This enables you to pick out the best differential for your ride based on your requirements.