Bad Differential Symptoms, Problems and Solutions: The Ultimate Guide

Bad differential symptoms: All modern cars have some sort of a differential, even the front-wheel-drive ones. If you ever played with toy cars, you know that they are amazing at going fast in a straight line, but once they turn, troubles arise. That is where the differential comes in, and it is the reason why your car surely has one. In this article, we are going to quickly cover what a differential is, how it works, how to maintain it and how to recognize bad differential symptoms, problems and the solution to those issues. Stay tuned!

What is a differential?

The differential is a vital component of a vehicle that transmits the engine’s power to the wheels via driveshafts. If you have a rear-wheel drive vehicle, the differential is located between the rear wheels. In a case of a front-wheel-drive car you have something that is often called a transaxle, it is integrated into the automatic or manual gearbox and transmits the power directly from the gearbox to the front wheels. 

All-wheel drive vehicles come with 3 differentials; front, center and rear. The center differential is present to allocate torque between the front and back wheels. The differential between the front or rear wheels decides how much power to assign to each wheel depending on the situation. The last type of vehicle is a four-wheel-drive vehicle that works slightly differently compared to an all-wheel-drive vehicle. Instead of a center differential, it uses a center transfer case. The center transfer case also allocated power and torque between the front and rear axle but it also has one or more low range gears for more serious off-roading.

How does a differential work?

When you approach a corner and turn, the outer wheel covers more distance at a faster speed than the wheel on the inside of a turn. The differential assigns more power to the outside wheel which allows them to decouple and turn at different speeds on corners. By applying more of the engine’s power to the wheel on the outside of a turn, your car corners smoothly. The differential is just there to provide the difference in wheel speeds with a set of gears. It is super simple but highly effective!

Do differentials require maintenance?

Car manufacturers like to claim that no, car differentials do not require maintenance as they are filled with oil that does not require changing. Car manufacturers call these units “lifelong oil-filled units”. However, what these manufacturers often forget to say is that they do not expect their cars to last for more than 8-10 years. But they do, and their differentials need certain maintenance.

Vehicles today are covering far greater distances than they did 20 years ago. When a vehicle reaches the 200,000km (120k mile) mark at approx 10 years old, you can believe that the oil inside of the differential has started degrading and it does not lubricate the differential gears as it once did. 

We recommend that you have your mechanic regularly check your differential for any signs of leaks. As your car ages, bad differential symptoms are bound to appear at some point. Make sure to have your differential oil replaced with a factory-approved oil type. It is a measly cost compared to the cost of a differential rebuild or a new differential. That is all you have to do, just change the oil.

differential construction image

Bad differential symptoms

Fortunately enough, your differential is not just going to fail in an instance. Symptoms of a faulty differential will present themselves in many ways. It is up to you not to ignore these symptoms and notify your mechanic about the new sounds or things you notice while driving.

  • Damaged tires
    The tires on the axle with the bad differential might be unevenly worn out. This might indicate problems with the differential as it does not allow for a different speed of each tire when cornering. However, there might be other causes for uneven tire wear, you can check those here.
  • Vibrations
    If you ever feel a weird vibration that is affecting the entire car as you accelerate, corner and brake, you could consider this a warning from your differential. Any vibrations are not to be ignored as they can pose a danger to your safety. Visit a mechanic immediately.
  • Grinding gear sounds
    The sound of grinding metal gears can only mean one thing, trouble. If you hear a grinding sound coming from your differential, it is likely that you are lacking the correct amount of differential oil. Get your car to the mechanic as soon as possible, even if it is not a differential problem, any gear grinding in a car is not good news.
  • Whining sounds

A whistling, whining noise is the most common symptom of a worn-out differential. It is the first sign that the differential is either not lubricated enough or that the differential oil is completely worn out. The key is to have enough differential oil that actually does its job, which is to lubricate the moving parts of a differential.

  • Handling difficulties

We already mentioned that a healthy differential is essential for smooth handling, especially in tight and fast corners. Driving through a corner without a healthy differential might feel as if your car is unstable, you might hear the tire rubbing and skip. Overall, it is a big threat to your safety, visit a mechanic as soon as possible.

Bad differential symptoms, problems and causes

There are three main problems and causes that take a toll on your differentials’ health. They can all be prevented if you are mindful of your driving and car maintenance.

  • Differential problems due to a lack of differential oil
    The differential can be opened, and as all things that can be taken apart, it has a gasket which is a potential source of a leak. Preventive checkups of the differential can quickly rule out any oil leaks and keep you safe and reassured on your next roadtrip. A lack of differential oil can lead to a complete differential failure which first starts with whining sounds, grinding sounds etc.
  • Differential problems due to overheating

Differential oil is meant to lubricate all the moving parts inside the differential but at the same time, it is responsible for the cooling of the same parts. If you lack differential oil, or if the oil is completely worn out, the differential can overheat to the point where the inner components start melting. Trust us, you do not want to experience this. Be on the lookout for any signs of burning oil that is not emanating from your engine.

  • Abusing the differential

Differentials are built to last forever, and they can last longer than many other components of your car. However, they are not meant to be constantly abused and messed with. Cars that are regularly driven on rough terrain, or cars that are frequently driven hard (burnouts, hard cornering…) are more prone to differential failures. If you want to keep your car running smoothly, make sure you drive it smoothly and calmly.

  • Normal wear and aging

Even if you do everything just right (change the oil, drive smoothly, prevent leaks…) your differential is still going to wear out with years and mileage. This usually happens with extremely high mileage vehicles, but it is worth mentioning. Nothing lasts forever.

Frequently asked questions about differential problems:

How can you keep your differential healthy and running?

  1. Don’t drive recklessly. Avoid constant burnouts, drifts, slides and extreme off-roading.
  2. Keep up with the regular differential oil changes. We recommend changing the differential oil every 40-60k miles (70-100k km)
  3. Make sure that the correct differential oil is used. Differential oil is generally thicker than engine oil. Using oil that is not viscous enough can lead to the same damage as having worn out differential oil.

Can I continue driving if im experiencing bad differential symptoms?

You can, but it is highly dangerous and we do not recommend it. In our opinion, you should only drive it to your mechanic. Do not plan any big road trips with a worn-out differential as it can leave you stranded or potentially in a car wreck.

What is the lifespan of a differential?

We often see a differential lasting anywhere from 150k to 300k miles. It all depends on the way a car is driven and the way it is maintained. Differentials suffer more in sports cars and off-road vehicles. In a commuter car that spends its life mainly on the highway, you can expect the differential to last you for a long, long time.

Can other problems cause the same noises and problems as a worn out front or rear differential?

Yes, that is why we highly recommend that you visit a mechanic to find out the real reason behind the grinding and whining noises. Some other parts that can be easily replaced for differential problems include:

  • Unbalanced driveshaft – causes vibration.
  • Worn carrier bearings – can cause whirring as you accelerate.
  • Worn U-Joints – can cause vibration, clunking noises and squeaking noises.
  • Worn out wheel bearings – cause unsettling sounds when cornering.

Here is a short video depicting the differences between a bad differential and bad wheel bearings.

Are differential problems different for the front and the rear differentials?

No, all differentials, front, rear and center are generally the same, they are just located in different places. What you can observe is the location of the weird sounds, leaks, and vibrations, so you know which differential is causing you trouble. If you only have one differential, then it is easier to diagnose the differential problem.

Can a differential be repaired?

Yes, it can be repaired but it depends on the level of damage. Some bad differential symptoms are indicators of definitive damage that cannot be repaired. In any case, the repair should always be only trusted to a specialist. The same goes for differential maintenance work. To work on the differential, you need special tools for removing the bearings and gauges. Other differential maintenance parts like gaskets and oil are available at most car part stores and online.

You can check the prices for different differential repairs here.

Bad Differential Symptoms: Conclusion

A worn-out differential can pose a danger to you and your passengers. That is why we take any problems with the differential as a serious matter that should be addressed as soon as possible. As always we urge drivers to take notice of any weird sounds and vibrations coming from various locations under their car. Let us know in the comments below if you have any more questions!