Symptoms of a Bad Rear Differential: Causes and Fixes

Knowing the symptoms of a bad rear differential will save you from a lot of drivability issues. A differential is an essential component that helps in the handling of your wheel system. It transfers power from Vehicle transmission and engine to individual wheels. Instead of the wheels turning at the same rate, a differential offers more precise control over your vehicle. 

If you start hearing weird noises from the wheels or start feeling unusual vibration, check it out. They are likely to be the signs of a bad differential. Continuous driving with a bad front differential can lead to an accident.

Rear-wheel-drive vehicles are equipped with a rear differential. Front-wheel drives are fitted with a front differential or transaxle, which has the same function as differentials. All-wheel-drive (AWD) and four-wheel-drive (4WD) vehicles are equipped with both front and rear differential.

Regardless of the kind of differential you have, you need to ensure it’s working properly. So, if you have ever wondered thinking what are the signs of a bad rear differential, sit tight and have a 5 minutes read.

Symptoms of a bad rear differential

Like every other mechanical component, a failing or bad rear differential will develop some symptoms to notify the driver of a problem. Here are some of the symptoms of a differential going bad. 

bad pinion bearing symptoms

Excessive Noise:

A failing differential [both front and rear] will make a whirring noise, whining noise, howling noise, and humming noise. These noises will gradually change during acceleration, deceleration, or when turning around the corner.

When a vehicle makes a humming or whirring noise, it is usually caused by a damaged or worn-out bearing in the axle or carrier. And when it makes a whining or howling noise, it is usually caused by a damaged or worn-out ring and pinion gears. 

A ring and pinion gear failure is usually caused when worn, scored, or out of adjustment.

Furthermore, when there is too much clearance or backlash between ring and pinion, you will hear a clunking noise when shifting from park to drive. You can use a telescope to detect whether it is the differential or rear axle problem that is causing the noise.

Moreover, when the differential requires service or maintenance, the axle itself also requires service and inspection for possible damage that can result from a bad rear axle bearing. Simply put, excessive noise is a common bad rear axle shaft symptom.

Differential failure due to lack of lubrication:

First, you need to make sure there are no leaks around the rear differential gasket. Next, check for leaks in the rear axle area. Leaks can occur at the pinion gear seals, and when the leak is bad enough, dirt and oil will accumulate right below the carrier, pinion gear, or at the brake system areas.

Differential overheating:

Differential overheating can be caused by using the wrong type of oil, lack of lubrication, worn gears, excessive bearing preload, backlash between the ring and pinion, overloading when hauling a heavy trailer, or loading equipment. Differential overheating is a significant sign of low differential fluid.

Difficulty in handling the wheels:

Suppose you’re finding it difficult to handle your wheels, especially in a corner. In that case, you may have to pull over and inspect your differential and other components attached to it, such as the propeller and the universal bearing. Handling your vehicle may become problematic if your differential is worn out, resulting in an accident.

Vibration:

Feeling unusual vibration from your vehicle should be of great concern. It could be a symptom of a rear-end differential or a sign of other automotive issues from the rear wheels. Whenever you feel a vibration from your rear wheels, quickly inspect your differential or contact your mechanic for a thorough inspection.

What causes a differential to go bad?

Since the differential is not a complex but a simple mechanical device, few symptoms can cause it to fail. Let’s explore these causes.

Lack of Oil:

The most common cause of a bad differential is lack of oil, which could result in grinding at high speed, cause the carrier to break, or in most cases, block the rear wheels. Low differential fluid or lack of oil can occur as a result of several reasons. It often happens when you have a worn-out differential seal or a cracked housing which could cause oil leaks.

Wrong oil type:

Another reason for a differential to fail is using the wrong type of oil. You might notice an oil puddle under your vehicle or oil spots on the differential housing because the wrong oil type can cause leaks. Or you might perceive a burning smell while driving. 

If the oil is not working as it should, it won’t be able to lubricate the differential, spider gears, and ring and pinion gears very well. Once this happens, it will lead to friction, causing the differential and ring and pinion to fail. 

Examples of wrong oil types include using automatic transmission fluid (ATF) and engine oil. There are oils made explicitly for differentials and manual gears. If you don’t know the proper oil type to use, consult your owner’s booklet.

Normal wears:

Normal wear can cause the differential to fail. What is normal wear? It is the natural deterioration that occurs on mechanical components due to frequent or regular use over time.

You should not confuse normal wear as a result of poor maintenance and services, lack of lubrication, or the wrong oil type. It happens naturally for using your vehicle.

Reckless driving:

Finally, differentials can fail by pushing them too hard, which means they have undergone several drag races, burnouts, and so on. Also, differentials can go bad if they are made with light steel that cannot withstand engine power and torque for a long period. 

Important Tips and Tricks for a long-life rear differential

Now that we have cleared the air and answered that mind-boggling question; how do you know when your rear differential is bad? Let’s look at the essential tips and tricks to prolong your rear differential lifespan.

Scheduled oil change:

The first and most important tip and trick of prolonging your differential lifespan is a regularly scheduled differential fluid change. The differential fluid is much thicker than engine oil. The oil change intervals should be between 30k to 60k miles.

Recommended Oil:

During servicing, make sure that you use the recommended oil. Using the wrong oil type is as bad as not changing it at all and can even cause more harm.

Drive safely:

Since the differential is located under the vehicle, always drive safely, especially on a bad road, to avoid hitting it on the rocks. Hitting rocks can break the differential housing and result in leaks.

FAQs

Q: What happens when your rear differential goes out?

Typically, the differential will start giving strange noises when it goes out, or when the bearing fails. You will hear a whirring noise, whining noise, a growling noise, or howling noise. The noise will increase or decrease as you accelerate or decelerate the vehicle. Sometimes, you may not hear the noise when you step on the throttle panel.

Aside from these noises, you may experience difficulty in handling, vibration, differential overheating, and in some cases, a burning smell.

Q: What noise does a bad rear differential make?

A bad rear differential will develop a series of strange noises. It could be a whirring noise, a humming noise, growling noise, or whining noise. However, the most common sound of a bad differential is whining or howling noise, indicating a damaged or worn-out ring and pinion gears.

Q: Can you drive with a broken rear differential?

You can still drive your vehicle with a bad rear differential, but it can cause severe damages. The problem may increase to the point of stopping you in the middle of nowhere. And, if you are asking about driving with a total broken differential, no, don’t do it unless you want to damage the entire drivetrain system.

Q: How often should you flush your differential?

Automakers have different replacement and service intervals for each component, and differential flush is no exception. However, most automakers recommend differential flush every 30,000 to 60,000 miles. It is a messy job and should be done by a skilled mechanic.

Q: How long do differentials last?

The lifespan of a differential depends on various factors, such as driving habits, level of maintenance, the type of oil used during servicing, and many more. Under regular use and proper maintenance, differentials should last 150,000 miles or the life of a vehicle.

Q: Can a bad differential cause a transmission problem?

A differential has one significant function; to transfer power from vehicle transmission and engine to individual wheels. The differential allows the driver to optimize the handling and control of the vehicle. It offers more precise control over your wheels, instead of the wheels to be turning at the same rate.

Final Thoughts

It doesn’t end at knowing the symptoms of a bad rear differential but knowing bad pinion-bearing symptoms and figuring out the problem on time. Once you figure out the fault, the next thing is to contact your mechanic for a proper diagnosis and fix.

At this juncture, I believe this content has uncovered the signs of a failing differential, causes, how to prevent it from happening, and important tips and tricks of prolonging a differential life.

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Osuagwu Solomon

Osuagwu Solomon is a seasoned automotive technician for the past 9 years, and a technical writer. He loves writing about auto professional repair guides, DIY repair guides, and buyer’s guide. After spending six years in the automotive workshop, he decided to impact his knowledge to people aside his domain, and he has achieved this by centering his Automotive writing skills on REPAIRS.

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