Differentials have a long history which many say go all the way back to the 1st millennium BC and recorded by China.
While they didn’t have cars back then, chariots, wagons, and carts still experienced the problem of wheels slipping and dragging when cornering which damaged wheels, axles, and roads. The avoid this, a simple differential was invented.
In this article, we’ll look at the common, and not-so-common, differential types found in vehicles on the road today.
Overview of Differentials
Today’s differentials serve two important functions:
- Transfer engine power to your drive wheels.
- Allow those wheels to rotate at different speeds.
This second function is critical. Without it, your car would hop and skip around corners as the outer wheel tries to travel further than the inner wheel.
The basic design uses a ring gear and pinion gear to take power from your driveshaft and turn it 90 degrees to reach your wheels.
Inside this assembly, additional gears called spider gears or differential gears let the left and right wheels turn at different speeds as needed.
While this basic concept hasn’t changed much in centuries, modern technology has given us many types of differentials to suit different driving needs.
From basic open differentials to advanced electronic systems, each design has its own advantages and specific uses.
#1. Open Differential.
Found in most everyday vehicles on the road, an open differential is the simplest and most common type you’ll encounter. If you drive a standard passenger car or crossover SUV, there’s a good chance this is what you have.
How It Works
An open diff splits engine power equally between two drive wheels using a set of gears. When your car travels straight, both wheels receive the same amount of power and spin at the same speed.
During turns, the internal gears allow each wheel to rotate independently without binding or causing damage.
Advantages
- Simple, reliable design that requires minimal maintenance
- Can last the lifetime of the vehicle with proper care
- Inexpensive to manufacture and lower repair costs than others
- Better fuel economy due to less internal friction
Disadvantages
- One spinning wheel means zero power to the other wheel
- Poor performance in snow, ice, and off-road conditions
- Not suitable for performance driving or heavy towing
- Can leave you stranded in low-traction situations
#2. Limited-Slip Differential (LSD).
Limited-slip differentials are a step up from open differentials, designed to address the traction limitations while still allowing for smooth cornering. They’re commonly found in sports cars, performance vehicles, and higher-end trucks and SUVs.
How It Works
These differentials use special mechanisms to detect when one wheel starts to spin faster than the other. When this happens, they automatically transfer more power to the wheel with better traction.
This helps prevent the single-wheel spin that plagues open differentials while still allowing wheels to turn at different speeds during normal cornering.
Types of Limited-Slip Differentials
Clutch-Type LSD
The most common design uses a set of clutch plates that engage when wheel speeds differ too much.
These clutches force both wheels to turn together, preventing excessive wheel spin. You’ll find these in many performance cars like the Mazda Miata and Ford Mustang.
Viscous LSD
These use thick fluid to transfer power between wheels. When one wheel spins faster than the other, the fluid thickens up and forces both wheels to turn more closely together. This design is smooth but less aggressive than clutch-type LSDs.
Torsen LSD
Short for “torque sensing,” these use special worm gears to redirect power. They react to torque differences rather than wheel speed, making them popular in high-performance vehicles like some Audi models and the Toyota 86/Subaru BRZ.
Advantages
- Better traction in slippery conditions
- Improved performance during acceleration
- More predictable handling in sporty driving
- Useful for light off-road use
Disadvantages
- More expensive than open differentials
- May require periodic maintenance
- Can wear out over time, especially clutch-type LSDs
- Some types can be noisy or cause tire wear
#3. Locking Differential.
For serious off-road capability or maximum traction, nothing beats a locking differential. Most commonly found in dedicated off-road vehicles and heavy-duty trucks, these differentials can force both wheels to spin at exactly the same speed.
How It Works
A locking differential (or “locker”) physically locks both axle shafts together when engaged. This means both wheels must turn at the same speed – perfect for powering through mud, rocks, or deep snow. When unlocked, it functions just like a standard open differential for normal street driving.
Types of Locking Differentials
Manual Lockers
These require driver input to engage, usually through a switch or lever. The Jeep Wrangler Rubicon’s push-button lockers are a perfect example. Here, you decide when to lock and unlock them.
Automatic Lockers
Also called “Detroit lockers,” these engage automatically when needed. They use internal ratcheting mechanisms that lock up when one wheel starts to spin faster than the other. The Ford F-150 Raptor uses this type for its rear differential.
Advantages
- Maximum possible traction in extreme conditions
- Perfect for serious off-road use
- Very durable and reliable design
- Nearly impossible to get stuck with both lockers engaged
Disadvantages
- More expensive than open or limited-slip differentials
- Can cause binding and tire scrubbing during tight turns
- May create noise or vibration when engaged
- Not ideal for regular street use
#4. Torque-Vectoring Differential.
Found in high-performance and luxury vehicles, torque-vectoring differentials represent the cutting edge of differential technology. They can actively control exactly how much power goes to each wheel, even during normal driving.
How It Works
Unlike simpler differentials that just react to wheel spin, these systems use computers and sensors to predict what each wheel needs.
They can send more power to the outside wheel during cornering, reduce power to a spinning wheel, or even help the car turn by creating a yaw effect.
Types of Torque-Vectoring Systems
Mechanical Systems
Using additional gear sets and clutch packs, these can overdrive one wheel faster than the other. The Audi Sport differential is a prime example, helping their performance models corner like they’re on rails.
Electronic Systems
These use sophisticated computer control to manage power distribution. Some, like BMW’s Active M Differential, can adjust power split in milliseconds based on driving conditions, steering angle, and throttle position.
Advantages
- Significantly improved handling and cornering ability
- Better traction in all weather conditions
- Helps reduce understeer in front-wheel drive cars
- Can make a vehicle feel more agile and sporty
Disadvantages
- Most expensive differential type to manufacture
- Complex systems with more potential failure points
- Expensive to repair if something goes wrong
- Added weight from extra components
#5. Welded Differential.
While not something you’ll find from the factory, welded differentials are a popular modification in certain motorsports (particularly drifting).
As the name suggests, this involves permanently welding the differential gears together to lock both wheels.
How It Works
The process is straightforward but permanent since the spider gears inside an open differential are welded together, forcing both wheels to turn at the same speed. It’s essentially a homemade locking differential that can’t be disengaged.
Unlike a proper locking differential or spool, welded differentials are usually done as a budget modification to an existing open differential. While effective, the results can be unpredictable depending on the quality of the welding job.
Advantages
- Very inexpensive compared to other locking solutions
- Perfect for dedicated drift cars
- No maintenance required
- Maximum traction when accelerating straight
Disadvantages
- Permanent modification that can’t be reversed
- Causes excessive tire wear and drivetrain stress
- Makes parking and tight turns difficult
- Not street-legal in many areas
Center Differentials
If you drive an all-wheel drive (AWD) or full-time four-wheel drive (4WD) vehicle, you have an additional differential in the middle of your car.
This center differential allows the front and rear axles to turn at different speeds, which is necessary since your front and rear wheels often travel different distances when turning.
How Center Differentials Work
Just like the differentials at your axles, a center differential splits power between two outputs. In this case, between the front and rear of your vehicle.
Most can vary the power split, sending more power to either the front or rear depending on conditions.
Common Types
Torsen Center Differential
Used in Audi Quattro systems, these mechanical differentials can instantly vary the front/rear power split based on available traction. They’re completely mechanical and very reliable.
Active Center Differential
Found in vehicles like the Subaru WRX STI, these use electronic controls to actively adjust power distribution. Drivers can often select different modes for various driving conditions.
Advantages
- Enables full-time AWD without binding or drivetrain wear
- Better traction in all weather conditions
- Improved handling and stability
- Can often be adjusted for different driving conditions
Disadvantages
- Adds weight and complexity to the vehicle
- More expensive to manufacture and repair
- Reduces fuel economy due to additional drivetrain losses
- Some systems can be confusing to operate
Additional Specialized Designs
Beyond the common differential types, there are some specialized designs worth mentioning. While you’re unlikely to encounter these in everyday vehicles, they represent interesting engineering solutions for specific applications.
Epicyclic Differentials
These use planetary gears (similar to those found in automatic transmissions) to split power between wheels. Their compact design made them popular in some Land Rover models, but they’re relatively rare due to their complexity and cost.
Their main advantage is packaging – they can fit in tight spaces where traditional differentials won’t.
Spur-Gear Differentials
Instead of using bevel gears like most differentials, these use straight-cut (spur) gears arranged parallel to the axles.
The classic Oldsmobile Toronado used this design in its front-wheel-drive system. While efficient, their size and noise levels have limited their use in modern vehicles.
Differential Location By Drivetrain Type
Front-Wheel Drive (FWD)
(differential integrated into transaxle)
Engine → Transaxle with Built-in Front Differential → Front Wheels
Rear-Wheel Drive (RWD)
(standalone rear differential)
Engine → Transmission → Driveshaft → Rear Differential → Rear Wheels
All-Wheel Drive (AWD)
(front, center, and rear differentials)
Engine → Transmission → Center Differential → Front and Rear Differentials → All Wheels
Full Time Four-Wheel Drive (4WD)
(front, center, and rear differentials)
Engine → Transmission → Transfer Case w/ Center Differential → Front and Rear Differentials → All Wheels
Part Time Four-Wheel Drive (4WD)
(front and rear differentials)
Engine → Transmission → Transfer Case (lockable) → Front and Rear Differentials → All Wheels
Manufacturer-Specific Systems
Many car manufacturers have developed their own unique differential systems. Here are some notable examples that you might encounter:
GM Positraction
General Motors’ answer to limited-slip technology, Positraction became so well-known that many people use the name for any limited-slip differential. Early versions used clutch packs, while later designs incorporated more advanced technologies.
Subaru DCCD (Driver Controlled Center Differential)
Found in performance models like the WRX STI, this system lets drivers adjust front/rear power distribution using electronic controls. It combines a mechanical limited-slip design with electronic management for maximum control.
Other Notable Systems
- BMW M Active Differential – Uses electronics to control a multi-plate clutch system
- Mercedes AMG Torque Vectoring – Combines electronic differential control with selective brake application
- Porsche PTV (Porsche Torque Vectoring) – Uses brake-based torque vectoring with a mechanical limited-slip differential
- Honda SH-AWD – Active torque vectoring system that can overdrive the outside rear wheel
Emerging Technologies
As vehicles become more electrified, differential technology continues to evolve. Here are some developments to watch:
- Electric motors replacing mechanical differentials in some EVs
- Predictive torque vectoring using AI and road conditions
- Disconnectable differentials for improved fuel economy
- Integration with hybrid powertrains for better performance and efficiency