In the world of automobiles, there are many critical components under the hood and beneath the chassis that most of us may overlook, whether that’s the muffler or the cabin air filter, and in this case the differential.
While it might sound complex, the differential plays a crucial role in making your car function as smoothly and effectively as it does. But what exactly is a differential? How does it work? And what happens if your car doesn’t have one?
Driving without a differential is ill-advised. The differential allows wheels to rotate at different speeds for controlled turning. Without it, you’d face resistance, tire scrubbing, and loss of control, particularly while turning. The Differential is generally crucial for everyday driving, affecting performance, safety, and tire lifespan.
As you can see it is unsafe to drive a car without a differential, resulting in difficulty and unpredictable steering handling, damage to tires, etc. All of these could result in an accident.
This article delves into the intricate world of differentials, so whether you’re a car enthusiast wanting to broaden your knowledge, or a novice looking to understand more about your vehicle, this comprehensive guide is designed for you.
So, buckle up and join us as we journey through the nuts and bolts of the differential in your vehicle!
What Is A Differential And How Does It Work?
As the name implies, Differential solves the difference between the distance traveled by the outside wheel and the inside one.
The differential is a set of gears that transmits engine power to a vehicle’s wheels while enabling them to turn at different speed levels on turns. In turning around corners, the car’s outside wheel travels faster and farther than the inside wheel.
This video does a great job demonstrating how exactly the differential works:
Vehicles with front-wheel-drive (FWD) have their differential with the transmission inside a housing unit known as a transaxle. While cars with rear-wheel-drive (RWD) have their differential between the rear wheels, they are connected to the transmission by a driveshaft.
Vehicles with four-wheel-drive and all-wheel-drive distribute power front and rear with an added center differential or transfer case.
What Are The Types Of Differential?
There are various types of car differential. Some are meant for the wheel speed difference, while others are designed to accentuate or counteract it. The following are some types of car differential.
- Open Differential: The open differential is designed to enable differences in wheel slip or wheel speed. The drive shaft pinion gear is responsible for driving the differential drive gear. A pair of differential bevel gears drives a pair of driven bevel gears that connect to the axle shaft, which drives the wheels.
The open differential enables the outside wheel to rotate faster than the inside one. Most vehicles have open differential, except off-road or performance cars.
- Limited-Slip Differential: When it was discovered in 1932 that the open differential could not drive through hard corners because the inner wheel loses traction during high-speed turns, another type of differential was developed.
Ferdinand Porsche designed the limited-slip differential. This differential works like the open differential by enabling wheel speed differences under normal driving conditions – straight roads and corners.
However, in the case of heavy acceleration and hard cornering, the limited-slip differential uses its plates and clutches to prevent it from sending all the torque to the wheel with the least resistance.
This system enables race cars to power through high speed and high power corners. Limited slip differentials are found in most off-road and performance vehicles.
- Locking Differential: Looking differential was designed to tackle the challenge of any wheel slip being too much at times.
Lockers, as it is sometimes called, can be an extension of limited-slip, which uses springs and clutches in activating a locking mechanism, thereby sending equal torque to every wheel, irrespective of the availability of traction.
Although lockers they can be considered an extension of limited-slip differentials in terms of functionality, they essentially lock the two wheels on an axle together, as if they were on a common axle. This contrasts with a limited-slip differential, which still allows for some difference in wheel speed.
Locking differentials or lockers of different kinds are found on some performance and off-road vehicles.
Selectable locking differential or lockers use electricity, cable, or air. Click lockers or Detroit lockers provide a great locking and torque transfer. However, they are not really differentials because they disengage an axle during turns.
- Torque-Vectoring Differential: The most advanced and complicated kind of car differential is the torque-vector differential. It accentuates the differences in wheel speed in the process of vehicle cornering.
The torque-vectoring differential uses a separate controller and electronically actuated clutches to slow down the inside wheel of the turn forcibly. It sends torque to the outside wheel to power the vehicle through the turn.
Active differential is also found on all-wheel-drive (AWD) and rear-wheel-drive (RWD) performance vehicles.
What Happens If Your Car Has No Differential?
If there were no differential on your vehicle’s axle, both wheels would revolve at the same speed. Hence, they would both cover the same distance, and the result is moving only in a straight line.
The differential is in charge of delivering the power generated by the engine and transferred to it by the driveshaft to the wheels of your car. It allows certain wheels on your vehicle to receive additional engine torque when it is needed the most.
Whether you drive a car with a front-wheel-drive (FWD), rear-wheel-drive (RWD), or all-wheel-drive (AWD), the differential is necessary for your vehicle because it enables your vehicle to turn to corners rather than to drive on a straight line.
Are There Cars That Work Without Differential?
The automotive differential is meant to drive a wheel pair while enabling them to rotate at different speed levels.
The driving wheels of vehicles without a differential, such as carts, are forced to rotate at the same level of speed, especially on a common axle driven by a simple chain-drive mechanism.
Certain vehicles in their conventional forms, such as three-wheelers, do not have a differential. Only one of the wheels is powered, while the other wheel is free to rotate. As a result, they do not need a differential to function properly. Both wheels on the axle work independently of each other.
The mechanism on three-wheelers makes the vehicle unstable during high speed. It produces an unbalanced torque, which must be balanced by applying an equal magnitude counter-torque via its steering system.
Do All Modern Vehicles Have Differential?
Yes. All modern vehicles, such as cars and trucks, have a differential. It is also found in many all-wheel-drive (AWD) vehicles. They need a differential between each set of drive wheels and one in between the front and back wheels because the distance traveled by the front wheels through a turn is farther than the distance traveled by the vehicle’s rear wheels.
There is no differential in between the front and rear wheels of part-time four-wheel-drive systems, unless they may have a transfer case, which functions similarly to a differential in that it can distribute power between the front and rear axles.
If there is no transfer case then, instead they are locked together, making the front and rear wheels turn at the same average speed level. It is why the vehicles are hard to turn on concrete when the four-wheel-drive system is engaged.
Can I Drive A Car With A Bad Differential?
You can manage to drive your car with a bad differential, but you shouldn’t do that. Suppose you consistently go with a bad differential without fixing it. In that case, the problem may degenerate to a worse state, to the extent of total failure, thereby leaving you unexpectedly stranded somewhere.
Driving with a bad differential can also result in further damage to other close components of your car.
Therefore, it would be best not to drive with a bad differential; instead, get an auto mechanic to fix the problem before driving your vehicle again.
It would save you the stress and cost that may result from a total breakdown of your car’s differential.
What Causes A Rear Differential To Go Bad?
Technically, your car’s differential would go bad as a result of aging. Remember, nothing lasts forever, especially machines and devices. Every component of your vehicle is designed to last an expected lifespan, including your vehicle’s rear differential.
Additionally, there could be other factors at play as well, such as manufacturing defects, extreme driving conditions, or damage from road hazards.
Your vehicle’s differential may go bad quickly if you don’t have a culture of proper and regular maintenance. Therefore, the simplest way to avoid your vehicle’s differential from going bad (except due to aging) is to ensure regular and proper maintenance.
How Do I Know That My Car’s Differential Is Bad?
The following are some common bad differential symptoms you should look out for in a vehicle.
- Whining noise: One of the most common symptoms of a bad differential is a whining noise. The sound is primarily traceable to inadequate lubrication of the differential. It could also be a result of a leakage in the differential fluid.
- Vibrations: Worn-out universal joints of a vehicle’s differential could cause the driveshaft to vibrate. The vibration could become very hash in the course of rapid acceleration.
- Tire damages: Failing differential components can also result in strange damage to your vehicle’s tires’ outer tread and sidewall. This damage is due to the force of spinning at speed and the stress of turning to corners while driving.
- Hard steering handle: A bad differential can lead to the hardness of your steering handle, thereby making it difficult to go around a corner. However, difficulty in steering can often be related to the steering system itself.
- Differential Fluid Leaks: A leaky seal or gasket can cause differential oil to leak out, often visible under the car where it’s parked. If the differential runs with too little fluid, it can cause damage to the gears.
How Do I Service My Car’s Differential?
As you maintain changing your car’s engine oil and topping off fluids, you must also ensure that you don’t forget the maintenance of servicing your car’s rear differential.
Knowing how and when to service your car’s rear axle is an essential maintenance culture.
The rear axle housing supports the axles and differential carrier, responsible for transferring the power from the car’s engine to the rear wheels.
The process of servicing your car’s differential would require the following.
- Jack-up the car: Using a floor jack to raise the vehicle and supporting it on jack stands is one of the foremost actions you must perform in servicing your vehicle, except in the case of trucks. It enables you to create enough space to carry out the servicing.
- Remove cover bolts to enable you to drain the fluid: After jacking up the car, locate the cover or drain port of the differential. It could either have a drain plug at the bottom of the housing, which allows you to remove it and let the gear oil drain out, or a rear cover that you must remove before the servicing proper.
Place an oil catch pan under the differential housing, and remove the cover bolts. Ensure to leave at least three bolts at the bottom to support the cover. Then separate the cover from the differential with a screwdriver, as the gear oil flows until the point of dripping. After that, remove the three bolts left at the bottom to enable the cover to fall off the housing, thereby exposing the inner workings of the differential.
- Clean the cover and scrape the gasket: Use carburetor cleaner and a shop towel to clean the cover properly. Then properly scrape and clean off old gasket material from the differential housing gasket. It will enable the cover to properly seal the housing when reinstalling.
- Install cover gasket: Remove the cover gasket from its packaging and properly inspect it. Then, match it to the cover or backing plate. Use a gasket sealer to hold the gasket in place as you reinstall the cover. Also, prevent leaks by applying the sealer inside the holes of the bolts.
- Reinstall the cover: Hold the rear cover and tighten the bolts by hand in a cross pattern. Do not over tighten the bolts beyond 5-foot pounds of torque so that the cover is not distorted and the gasket is made to split and leak.
- Refill the gear oil: Having reinstalled the cover, locate the differential fill port in the rear cover or near the pinion snout and remove the plug. Then fill the differential with the specified fluid recommended by your vehicle’s manufacturer.
After that, recheck the cover for any leaks and tighten the bolts the more as the case may be.
I also want to add that the method of servicing a differential can vary depending on the type of differential and the specific vehicle, and that some differentials may not be serviceable at all outside of a professional mechanic shop.
Considering the discussion above, it is worth noting that the differential is an essential component of a vehicle because of its role in ensuring that the car can turn around corners rather than moving along a straight line.
Driving with a bad differential can also be dangerous. Besides the further damage a bad differential can cause to other components of your car, the whining noise, tire damage, hardness of the steering, vibrations, etc., can also lead to an accident.
If you do not drive a three-wheeler, it is most likely that your car has a differential. Endeavor to service your vehicle’s differential regularly and use materials recommended by your vehicle’s manufacturer.
Also, if you are not a DIYer, ensure to take your car to a professional auto mechanic for necessary maintenance or repairs to prolong the lifespan of your vehicle and protect yourself from damaging it.
Hi! My name is Stefan; I’m the owner and lead writer at TheDriverAdviser.com.
I’m an active writer on this blog myself, as well as a novice car mechanic. For the really technical stuff, I find writers with experience as a mechanic or who have studied mechanical engineering.
Read more about our fantastic team on our about page!