Symptoms of a Bad Differential: What are the Causes & Fixes

If you feel an unusual vibration or noise from your wheels, then it’s most likely a bad differential. Whether it’s an all-wheel (AWD) or four-wheel drive (4WD), knowing those bad differential symptoms will save you from more expensive repairs and drivability issues.

Both the all-wheel drive and four-wheel drive use differential for their front and rear wheels. Irrespective of the differential type, you should ensure it is in good shape all the time. Continue reading to learn about the symptoms, causes, and quick fixes for a bad differential.

What is differential in car?

allows a pair of wheels to rotate at various speeds


The component of your vehicle that plays a vital role in those turns you make is your differential. It is a component that forms part of your front and rear axle assembly and allows a pair of wheels to rotate at various speeds.

To better understand this, if your inside tire rotates at 15 (Revolutions Per Minute) RPM less while turning, the external tire will do 15 RPM more. However, both wheels have the same torque while this is ongoing.

The wheel with more resistance rotates less and the other with less resistance spins faster. Not all vehicles have a differential; an example is the go-karts, which allow both wheels to have equal rotational speed. This is possible due to their simple chain-drive apparatus.

In front-wheel drive vehicles, the differential assembly and the axle are located in the transaxle (transmission axle), a deviation from the AWD and 4WD designs.

Symptoms of a Bad Differential

Every mechanical part in any vehicle develops some symptoms before finally breaking down. Sometimes, those symptoms might not be noticeable except if you are observant or intentionally inspect your vehicle. For example, a bad differential could be the problem if you notice the following.

Damage To The Tire

Damage To The Tire

If you notice wear on the outer tire or sidewall, that could indicate a bad differential. While turning, the differential controls the spinning of your tires at different rates. A failing differential will lose control, causing both tires to spin at the same speed.

So next time you notice a strange mark or damage to your vehicle’s tire, give it some careful attention and ensure that the problem is not a bad differential.

Difficulty in handling the wheels

A bad differential could lead to an unpredictable accident because the driver might lose control while making a difficult turn. In addition, handling the wheels becomes more complicated when your differential fails. An experienced car owner will notice this symptom almost immediately and pull over to check both the universal bearing and its propeller before driving it down to the mechanic.

Vibrations

the differential


It would be best to visit your mechanic when you notice vibrations increasing with speed and vice versa. For example, if the joints of the differential are out of place, the shaft increases in harsh vibrations as you increase the speed of your vehicle.

Differential overheating

Due to lack of lubrication, the differential can experience overheating. Although excessive bearing load, overloading, worn gears, backlash between pinion and ring, and so on can lead to overheating yet, most times, differential overheating is a result of either the wrong type of oil or low lubrication around the differential.

Grinding Gears

Grinding gears is a significant sign that you have a terrible differential because it can lead to an unprecedented locking of your rear wheels. This is very dangerous and should be given immediate attention by your mechanic because it means your gears are wearing themselves out.

Whining Noises

Poor lubrication can also lead to a whining noise, another alarming differential symptom. Either leaking or insufficient lubricant often causes it. A reddish fluid beneath your differential is a sign of leakage.

Important note

Most of these symptoms are not sufficient in themselves to be indicative of a bad differential. A visit to your mechanic will give you appropriate information about the actual problem.

Causes of a Bad Differential

Let us take a look at what could lead to bad differential symptoms so that you can pay more attention to them during your routine maintenance checks.

Wrong oil type

Continuous usage of the wrong oil type can cause a differential to go bad. It is often noticeable with oil spots or puddles on the differential cover beneath your vehicle. Sometimes, the wrong oil type will lead to a burning smell whenever you turn.

A wrong oil type will not lubricate the spider gears, ring and pinion, and the differential while driving. As a result, friction increases and can even lead to differential failure. Wrong oil types include engine oil and automatic transmission fluids (ATFs).

about the correct type of oil


It is not a bad idea to consult your mechanic or manufacturer about the correct type of oil if you do not know the appropriate oil to use. However, avoid causing more harm to your car with the wrong oil type.

Insufficient oil

Lack of oil is the common cause of differential failure because it leads to grinding gears which could block the rear wheels and break the carrier at high speeds. In addition, insufficient oil could result from oil leakage due to a cracked housing or broken differential seal.

Reckless driving

Sports cars often suffer from differential failure because they have undergone several turns and drag races. Pushing your differential too hard can lead to burnout, especially if made with light steel.

Wear and tear

Every mechanical component in your vehicle undergoes wear and tear in varying degrees. This is as natural as breathing. Over time, your differential is expected to go bad because of this natural deterioration.

How long do differentials last?

Some differentials last as long as the useful life of the vehicle. However, the exact mileage depends on the manufacturer, type of vehicle, and individual usage. The focus should be to change the differential oil every 30 thousand miles or 15 thousand (if towing is involved). Under proper use and maintenance, your differential should last for 150,000 miles.

Important Tips and Tricks for a long-life rear differential

Now that we have shown you the symptoms and causes of a bad differential, how do you ensure a long-lasting rear differential?

Drive Safely

Many maintenance problems and spare parts replacements are minimal if you drive safely. However, on bad roads, ensure you avoid hitting the rocks since the differential is under your vehicle and could break if you drive recklessly.

Scheduled oil change (maintenance)

Maintenance attitude also affects the differential and other mechanical parts of any vehicle. Since the differential needs sufficient oil, it is vital to change it regularly. It is recommended to do so after every 30 to 60 thousand miles. In addition, you can prolong the life of your differential by a scheduled oil change.

Differential oil is thicker than the usual engine oil


Differential oil is thicker than the usual engine oil; ensure to use only recommended oil. A wrong oil type can result in more harm than good. So, it is best not to use any oil than using the bad oil.

FAQs

What happens when your rear differential goes out?

The first noticeable thing is the strange noise from the differential. You hear all kinds of noise (whirring, whining, growling, and howling noise), which changes as you change the speed or acceleration of the vehicle. Other bad differential symptoms are vibration, overheating, difficulty steering your vehicle, burning smell while driving, and many more.

What noise does a bad rear differential make?

You often hear a whining or howling noise from your vehicle, indicating a bad ring and pinion. Depending on the condition, a whirring or growling noise is heard.

Can you drive with a broken rear differential?

Driving your vehicle with a broken rear differential is possible but not without causing more damage. This will buy you additional time for your car’s movement to the mechanic workshop. On the other hand, continuous usage of a bad rear differential can lead to unprecedented problems.

How often should you flush your differential?

Flushing your differential is a messy task that only a skilled mechanic can carry out. Just like all other mechanical parts of your vehicle have their recommended service or replacement intervals, automobile manufacturers recommend every 30 to 60 thousand miles before the differential oil is flushed.

Can a bad differential cause a transmission problem?

Yes, a bad differential will disrupt the power transfer from the car’s engine and transmission system to the wheels. More reason you should sort out your bad differential immediately is to avoid more costly repairs.

Wrapping Up

With our help, you can now identify bad differential symptoms, the causes, and how to have a long-lasting differential. Anytime you notice a bad differential symptom in your vehicle, you should visit your mechanic’s workshop immediately before the problem gets worse.

Without the turning ability, your car is immobile. Naturally, you do not want to be caught in such an emergency in the middle of nowhere, especially when you have somewhere important to go. Sometimes, there are no symptoms to indicate a bad differential, hence the need for scheduled maintenance.

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