5 Bad Pinion Bearing Symptoms & Replacement Cost

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bad pinion bearing symptoms

If you hear a strange noise from your suspension, it could be a sign that something is wrong with your pinion bearings. This article will discuss the symptoms, causes, and how to replace them. We’ll also look at the replacement cost of pinion bearings and answer some of the most frequently asked questions related to this topic.

What are Pinion Bearings?

Pinion bearings are located at the point where your car’s driveshaft meets the differential. The differential is a gearbox that allows the driven wheels to rotate at different speeds instead of the same speed. For example, when you’re going around a corner, the inner wheel needs to rotate slower than the outer wheel. Differentials use pinion gears to accomplish this, and the pinion bearings support these pinion gears.

Over time, pinion bearings can wear out from all the friction and heat generated by differential action. If left unchecked, worn pinion bearings will eventually fail, which will usually cause catastrophic damage to your differential.

For this reason, it’s important to keep an eye (or rather, an ear) out for any signs of trouble with your pinion bearings. You can usually catch worn pinion bearings with proper maintenance before they cause any severe damage.

How Does a Pinion Bearing Work?

Pinion bearings work by supporting the pinion gear in the differential. This gear is what engages with the ring gear to rotate the driveshaft. The pinion bearing’s job is to support the weight of the differential and allow it to rotate smoothly. Like any normal type of bearing, it allows metal balls to roll between its inner and outer races. These ball bearings provide a low-friction surface that helps reduce wear on the differential gears and allows them to rotate more smoothly.

Where is a Pinion Bearing Located?

Depending upon the type of drivetrain, whether the car is forward, rear, or all-wheel drive, the pinion bearing can be located in different places. In a rear-wheel-drive vehicle, the differential is usually located near the wheels at the back of the vehicle. In a front-wheel-drive car, the differential is located near the engine in the transaxle.

All-wheel-drive cars usually have two differentials – one for the front wheels and one for the rear wheels. Each differential has its own pinion gear and bearings that support its weight and allows it to rotate smoothly.

Bad Pinion Bearing Symptoms

The most common bad pinion bearing symptoms are listed below:

  1. Whirring Noise
  2. Humming Noise
  3. Excessive Vibrations
  4. Grinding Noise
  5. Tire Damage

Let us see these symptoms in detail:

1. Whirring Noise:

Whirring noise from the differential is usually one of the first signs that something is wrong with your pinion bearings. This noise is caused by the metal balls inside the worn-out pinion bearing beginning to wear down and become damaged. As they become more damaged, they will generate more friction, and this will cause the bearing to make more noise.

2. Humming Noise:

Another symptom of pinion bearing failure is a humming noise from the differential. This noise is caused by the damaged bearings failing to support the differential weight properly. As a result, the differential will begin to wobble and make a humming noise.

3. Excessive Vibrations:

If your pinion bearings fail, you may also notice excessive vibrations coming from the differential. These vibrations are caused by the damaged bearings allowing the differential to wobble. This can cause a lot of wear and tear on other parts of your drivetrain, so getting it checked out as soon as possible is important.

4. Grinding Noise:

If your pinion bearings are completely worn out, you may hear a grinding noise from the differential. This is caused by the metal-on-metal contact between the differential and the bearings. If left unchecked, gear grinding can cause serious damage to your drivetrain.

If the noise is severe, it could indicate a serious problem that requires immediate attention. However, if the noise is more subtle, it may not be cause for alarm and could simply indicate that the bearing needs to be lubricated or replaced.

5. Tire Damage:

Another symptom of pinion bearing failure is tire damage. This can be caused by the vibrations from the failing bearings causing the tires to lose contact with the road. This can lead to uneven wear on the tires and can eventually cause a blowout.

What Causes Pinion Bearing Failure?

There are several different causes of pinion bearing failure. The most common causes are explained below:

1. Wear and Tear:

Over time, pinion bearings can wear out from all the friction and heat generated by differential action. If left unchecked, worn pinion bearings will eventually fail completely.

2. Lack of Lubrication:

Another common cause of pinion bearing failure is a lack of lubrication. Differentials need to be properly lubricated to function correctly. If the differential is not properly lubricated, the bearings will start to wear out prematurely.

Pinion bearings can also fail if the wrong type of lubricant is used. For example, using too much or too little lubricant can cause the bearings to fail.

3. Corrosion and Rust:

Corrosion and rust can also cause pinion bearings to fail. Differentials are usually filled with a special oil that helps protect against corrosion and rust. However, if the differential is not properly sealed, water and other contaminants can get in and cause the bearings to fail.

4. Overheating:

Overheating is the leading cause of pinion bearing failure. A pinion bearing overheats causes the metal to expand and distort. This can lead to premature wear, and eventually, the bearing will fail.

5. Lack of Rotation:

If a differential is not used for an extended period, it may cause pinion bearing failures. This is due to the lack of lubrication and can cause the bearings to fail.

6. Dust and Debris:

Another common cause of pinion bearing failure is dust and debris. Over time, the differential can start to accumulate dirt and other contaminants. This can cause the bearings to fail prematurely.

7. Shaft Misalignments:

Shaft misalignments or bent shafts can cause several problems for pinion bearings, including accelerated wear, reduced bearing life, bad rear axle, and increased noise and vibration. In some cases, misaligned shafts can even cause the bearings to fail prematurely. While many bearings are designed to tolerate misalignment, it is important to keep shafts as aligned as possible to prolong bearing life and prevent premature failure.

8. Incorrect Installation:

Pinion bearings are designed to support the vehicle’s weight and keep the pinion gear properly aligned with the differential. When these bearings are improperly installed, they can become misaligned and cause damage to the pinion gear or differential. This damage can lead to a loss of power or complete failure of the drivetrain.

Improper installation can also cause excessive noise and vibration and premature wear on other components in the drivetrain. In order to avoid these problems, it is important to have a professional mechanic install your pinion bearings correctly.

9. Excessive Loads:

Pinion bearings are not designed to support excessive loads. If the pinion bearings are overloaded, they can become damaged or even fail.

How to Prolong the Life of Bad Pinion Bearing?

If you have a bad pinion bearing, there are several ways that you can prolong its life:

1. Keep Bearing Clean and Well-Lubricated:

The first way to keep your pinion bearing from going bad is to keep it clean and well-lubricated. This means that you should regularly check the lubricant in the bearing, and if it is low, add more. You should also make sure that there is no debris or dirt in the bearing that could cause it to wear down prematurely.

2. Avoid Excessive Heat:

Another way to prolong the life of your bad pinion bearing is to avoid exposing it to excessive heat. This means you should not drive for long periods in hot weather and avoid parking in direct sunlight whenever possible. If you must park in the sun, try to cover the bearing with a cloth or other material to protect it from the direct rays.

3. Drive Carefully:

One of the best ways to prolong the life of any car part is to drive carefully. This means avoiding potholes, speed bumps, and other obstacles that could jar the bearing and cause it to fail prematurely. It also means driving at moderate speeds and braking slowly to avoid unnecessary stress on the bearing.

4. Have Bearing Replaced When Necessary:

Of course, eventually, all bearings will need to be replaced. If you notice that your bad pinion bearing is starting to make noise or show signs of wear, it is important to have it replaced as soon as possible. Waiting too long can result in further damage to the bearing and other parts of the car, so it is best to err on the side of caution.

If you follow these tips, you can prolong the life of your bad pinion bearing and avoid having to replace it prematurely.

How to Replace a Bad Pinion Bearing?

Here’s a quick guide on how to replace a bad pinion bearing in your car.

1. Preparation:

Park your car on a level surface and engage the emergency brake. Place jack stands under the frame of the vehicle on both sides to support it. Remove the wheels on the side of the vehicle you will be working on.

2. Unbolt differential from the yoke:

You will need a socket wrench to remove the bolts that hold the differential to the drive shaft yoke and pinion nuts. There are typically four bolts, two on each side. Remove these bolts and set them aside.

3. Remove differential cover and drain oil:

Once the bolts are removed, you can take off the differential cover. Be careful, as some oil will still be left in the differential. Use a drain pan to catch this oil and dispose of it properly.

4. Inspect bearing and gears for damage:

Now that the differential is open look at the gears to see if there is any damage. If there is significant damage, it may be necessary to replace the entire differential. However, if the damage is limited to the pinion bearing, it can usually be replaced without replacing the entire unit.

5. Differential adjustments:

While you are working on the differential, you must keep a check on the four types of adjustments involved. These include preload, backlash, ring gear mesh pattern, and pinion depth. You can readjust these by turning the adjusting screws with a screwdriver.

6. Prepare new parts:

Before you begin reassembling the differential, it is important to prepare the new parts. This includes cleaning all parts with solvent.

7. Install pinion bearing and adjust pre-load:

You must install the new pinion bearing in the pinion bearing cage with a pinion seal. Once it is in place, use a torque wrench to adjust the pre-load. This should be done according to the manufacturer’s specifications.

8. Install carrier bearings and races:

Install the new carrier bearings and races in the differential. Again, make sure to follow the manufacturer’s specifications for the proper torque.

9. Reinstall the differential cover and fill with oil:

Once everything is back in place, you can reinstall the differential cover and fill it with oil. Be sure to use the proper type and amount of oil specified by the manufacturer.

10. Test drive:

Before you put the wheels back on and take your car for a spin, it is always a good idea to test drive it first. This will help ensure that everything is working properly.

If you follow these steps, you should be able to replace a bad pinion bearing in your car without too much trouble.


Pinion bearings are an important part of your car’s differential and need to be properly maintained. By understanding the symptoms and causes of a bad pinion bearing, you can take steps to avoid this problem. If you do end up with a bad pinion bearing, don’t hesitate to replace it as soon as possible. With proper care, your new pinion bearing should last for at least 100,000 miles. Thanks for reading!

Frequently Asked Questions

What happens when a pinion bearing goes bad?

Pinion bearings are designed to keep the pressure off your transmission’s gears so they can rotate freely. When these bearings go bad, it can cause a lot of problems. You might first notice a grinding noise coming from your transmission. This is because the gears can no longer rotate freely and are starting to rub against each other. If the problem is not fixed, it can eventually lead to your transmission seizing up completely.

How often should you lubricate the pinion bearings?

It is generally a good idea to lubricate your pinion bearings every few months. This will help keep them from going bad and extend their lifespan.

How much does it cost to replace a pinion bearing?

The cost of replacing a pinion bearing can vary depending on the make and model of your car. In most cases, replacing the bearing will cost between $250 and $300.

How long can I drive with a bad pinion bearing?

You may be able to drive from a few miles to a few thousand miles before the pinion bearing fails completely. But you should not drive with a bad pinion bearing for very long. If you do, it can cause serious damage to your transmission. In some cases, it can even cause your transmission to seize up completely. If you think you might have a bad pinion bearing, take your car to a mechanic as soon as possible.

What does a bad pinion bearing sound like?

If you’re hearing a grinding noise coming from your car, it’s likely that you have a bad pinion bearing. This noise is most pronounced when making sharp turns or when driving on rough roads. If left unchecked, a bad pinion bearing can lead to serious damage to your car’s drivetrain.

How to fix a loose pinion bearing preload?

You can follow the procedure below to fix a loose pinion bearing preload:

1. If you have a loose pinion bearing preload, the first thing you’ll need to do is remove the old crush sleeve and bearings. You can do this with a few simple tools.

2. Once the old bearings are removed, clean the surfaces of the housing and shaft with a degreaser or solvent.

3. Next, install the new bearings and crush sleeve. Be sure to apply a liberal amount of bearing grease to the bearings before installation.

4. Finally, use a torque wrench to tighten the pinion nut to the proper specification. This will usually be between 30 and 35 ft-lbs. of torque.

What is the average lifespan of a pinion bearing?

A pinion bearing can last for around 100,000 miles with proper care and maintenance. However, if the bearing is not properly lubricated or if it experiences a lot of wear and tear, it may only last for 50,000 miles or less.

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