If you’re hearing strange noises coming from the back of your car, you may have a bad rear differential. This is a common problem for drivers, and it can be difficult to diagnose and fix on your own.
This article will discuss the symptoms of a bad rear differential. Stay safe on the road by knowing what to do if your rear differential goes bad!
Bad rear differential symptoms include a loud noise from the back of the car, vibrations, difficulty turning corners, and fluid leaks. If you experience these symptoms, take your vehicle to a mechanic so they can fix the problem.
Table of Contents
- What is Rear Differential?
- Understanding the Differentials
- Symptoms of a Bad Rear Differential
- What Causes a Bad Rear Differential?
- Rear Differential Replacement Cost
- Frequently Asked Question
- How long does a rear differential last?
- How long does it take to replace a rear differential?
- What are the major types of a differential?
- What happens when the rear differential goes out?
- How to fix a rear differential leak?
- What does it sound like when your differential is going bad?
- Can you drive with a bad differential?
What is Rear Differential?
The rear differential is a gearbox located at the back of a vehicle that takes engine power from the driveshaft and transfers it to the wheels.
Rear differentials allow each wheel to rotate at a different speed, which is necessary when turning corners. It also provides traction to the wheels by distributing power evenly among them.
Rear-wheel-driven cars only have a rear differential. However, four-wheel drive and all-wheel drive cars have both front and rear differentials. Each differential is responsible for delivering power to the two wheels on its axle.
Understanding the Differentials
Differentials are one of the most important parts of a car, and yet they are often one of the most misunderstood. Before we explain how they work, let us understand its construction and basic components:
Parts of a Differential
A differential is composed of seven main parts: the housing, drive pinions, differential pinion gear set, the ring gear, axle shafts or half shafts, pinion shafts or cross pins, and the side gears or sun gears. Each part plays an important role in how a differential works.
The housing is a large metal casing containing all the other parts of the differential. The housing keeps everything contained and provides a place for storing lubricating fluid.
The drive pinions are small, cylindrical gears located in the front of the differential. The pinion gears mesh with the ring gear and cause universal joints to rotate.
The differential pinion gear set is located in the middle of the differential. It consists of two bevel gears that are connected by a cross shaft. The bevel gears mesh with the side gears and allow them to rotate independently of each other.
The ring gear is a large, circular gear located in the back of the differential. The ring gear meshes with the drive pinions. This actually drives the axle shafts and makes the wheel spin.
The axle shafts or half shafts are long metal rods that come out of either side of the differential and connect to the wheels. The drive shafts rotate along with the side gears and provide power to the wheels.
The pinion shafts or cross pins are short metal rods that connect the two bevel gears in the differential pinion gear set together. The pinion shafts keep the bevel gears meshed together and allow them to rotate as a unit.
The side gears or sun gears are located in the middle of the differential and mesh with the bevel gears in the differential pinion gear set. The side gears rotate independently of each other and provide power to the axle shafts.
How Does it Work?
A differential takes power from the engine and transmission and uses it to turn the ring gear. The ring gear then turns the drive pinions, which in turn rotate the differential pinion gear set.
The differential pinion gear set then turns the side gears, which rotate the axle shafts and finally the wheels. The beauty of a differential is that it allows the wheels to rotate at different speeds.
This is necessary for the working of a differential because when a vehicle goes around a corner, the inner wheel needs to travel a shorter distance than the outer wheel.
If both wheels were forced to rotate at the same speed, the inner wheel would have to skid or slip to keep up with the outer wheel. This would cause a lot of wear and tear on the tires and could potentially lead to an accident.
A differential prevents this from happening by allowing the two wheels to rotate at different speeds. The side gears are free to rotate independently, allowing one wheel to speed up and the other to slow down as necessary. This allows for a smoother ride and helps to prolong the life of your tires.
Symptoms of a Bad Rear Differential
Several symptoms can indicate that your rear differential is going bad. The most common ones include:
- Differential Noise
- Leaking Differential Fluid
- Overheated Differential
- Losing Traction
- Excessive Vibrations
- Poor Handling
- Uneven Tire Wear
Let us understand each symptom in detail:
1. Differential Noise:
One of the most common signs that your differential is going bad is noise. If you hear a whining, humming, or grinding noise coming from the back of your car, it could indicate that your differential is not working properly.
Several things can cause differential noise, but the most common cause is worn-out bearings. The bearings are what allow the gears in the differential to rotate smoothly.
Over time, these bearings can wear out and start to make noise. This noise will usually get worse as you continue to drive on it.
Another possible cause of differential noise is a broken ring gear. The ring gear is what actually drives the axle shafts. If it breaks, it can cause a loud banging noise.
If you hear any kind of strange noise coming from the back of your car, it is important to have it checked out by a mechanic as soon as possible.
2. Leaking Differential Fluid:
Another common symptom of a bad differential is leaking fluid. Differential fluid keeps the gears in your differential lubricated and helps to cool them down.
If your differential leaks fluid, it can cause the gears to overheat and wear out prematurely. Several things can cause low differential fluid, but the most common cause is a worn-out seal.
A rear differential seal can wear out over time and start to leak. A damaged gasket or rings can also cause gear oil leaks.
Another possible cause of a differential fluid leak is a cracked housing. The housing is what holds the differential fluid in place.
If the housing cracks, it can allow the fluid to leak out. If you notice any fluid leaking from the back of your car, it is important to have it checked out by a mechanic as soon as possible.
3. Overheated Differential:
If your differential overheats, it can cause the gears to wear out prematurely. This usually happens when differential fluid leaks out.
If the fluid leaks out or if the level gets too low, it can cause the differential to overheat. Overheating can also be caused by a build-up of debris on the gears. This debris can act as insulation and prevent the heat from dissipating properly.
4. Losing Traction:
If you start to notice that your car is losing traction while turning corners, it could be an indication that your differential is going bad.
The main function of a differential is to allow each wheel to rotate at a different speed. When turning corners, the inside wheel needs to travel a shorter distance than the outside wheel.
If both wheels were forced to rotate at the same speed, they would scrub along the ground, and the car would not be able to turn.
The rear differential contains a set of gears that allow it to rotate at a different speed than the driveshaft. When it goes bad, the car will lose traction and have difficulty turning corners.
5. Excessive Vibrations:
Excessive vibrations from the back of your vehicle might indicate that your differential is failing. Though these vibrations can also result from bad sway bar links.
Differential problems can cause several different vibrations, but the most common one is a vibration in the steering wheel. This vibration is caused by the driveshaft being out of balance.
Another possible cause of vibrations is a worn-out differential gear. This gear can wear down and become misshapen over time. When this happens, it can cause a vibration that will be felt in the floorboard or seat.
6. Poor Handling:
A very profound symptom of a failing differential is poor handling. If the differential is not functioning properly, it can cause the car to handle poorly.
This feeling of instability is caused by the fact that the rear wheels are not receiving equal amounts of power. This can happen if one of the differential gears is damaged or worn out.
One way that a failing differential can cause poor handling is by causing the wheels to lose traction. Another way is by causing the car to vibrate excessively. These vibrations can make it difficult to keep control of the vehicle.
Another possible cause of poor handling is a build-up of debris on the differential gears. This debris can prevent the gears from meshing properly and cause slippage.
7. Uneven Tire Wear:
If you notice that your tires are wearing unevenly, it could be an indication that your differential is failing. When the differential gears are not meshing properly, they can cause the tires to rotate at different speeds.
This can cause the inside of the tire to wear down more quickly than the outside. Uneven tire wear is usually most noticeable on the front tires. This is because the front wheels do most of the work when turning corners.
If you notice uneven tire wear, it is important to have your car checked out by a mechanic. They will be able to tell if it is a problem with your differential or something else.
What Causes a Bad Rear Differential?
There are a few different things that can cause a bad rear differential. The most common causes are:
1. Lack of Lubrication:
One of the most common causes of a bad rear differential is lack of lubrication. The differential needs to be filled with transmission fluid in order to function properly. But also avoid putting too much transmission fluid.
If the fluid level gets too low, it can cause the gears to wear out prematurely. This can lead to a number of different problems, such as: overheating, losing traction, and excessive vibrations.
It is important to check the level of your differential fluid regularly and top it off if necessary.
2. Offroad Driving:
Another common cause of a bad rear differential is offroad driving. Off-roading is one of the most popular recreational activities for SUV and truck enthusiasts.
While it can be great fun, off-roading can also be tough on your vehicle – especially the rear differential. When you take your vehicle off-road, the differential is put under a lot of stress. This can cause it to wear down prematurely and eventually fail.
If you want to avoid having to replace your rear differential, there are a few things you can do to protect it:
- Avoid driving through deep puddles or water crossings.
- Avoid going over large bumps or obstacles.
- Take care when driving on uneven or rough terrain.
- If you find yourself in a situation where your rear differential is stressed, try to drive slowly and carefully to avoid further damage.
- You should also consider adding an aftermarket diff cover to help protect the gears from damage.
- Diff covers are available for both factory and aftermarket differentials.
3. Transmission Issues:
Another common cause of a bad rear differential is the bad transmission. The transmission and the differential are connected, so if there are issues with the transmission, it can also affect the differential.
The most common transmission-related issue that can cause problems for the differential is a fluid leak. If the seal between the transmission and differential is damaged during transmission repair, it can allow fluid to leak out of the differential.
4. Using Wrong Differential Fluid:
One of the most common mistakes people make when it comes to their rear differential is using the wrong fluid. Differentials require a specific type of fluid to function properly.
If you use the wrong type of fluid, it can cause several different problems. It can cause the gears to wear out prematurely.
When you are changing the fluid in your differential, be sure to use the correct type of fluid for your vehicle.
5. Bad Driving Habits:
Bad driving habits can also cause a rear differential to go bad. If you tend to drive too fast or make sudden stops and starts, it can put extra stress on the differential.
Over time, this extra stress can cause the gears to wear out prematurely. If you want to avoid having to replace your differential, try to drive more carefully and avoid making sudden stops and starts.
6. Accidental Damage:
Accidental damage is another common cause of a bad rear differential. If you hit something while driving, it can damage the gears or the housing.
This type of damage is usually not covered by a warranty, so it is important to be careful when driving. If you hit something, have your car checked out by a mechanic as soon as possible to ensure there is no serious damage.
Rear Differential Replacement Cost
Replacing a failing rear differential can be a costly repair. The average cost to replace a rear differential is between $1,400 and $2,200.
However, the cost can vary depending on the make and model of your vehicle. If you have a high-end car, such as a BMW or Mercedes, the cost can be closer to $4,000.
The best way to avoid replacing your rear differential is to take care of it and keep an eye out for signs of wear and tear. However, if it does fail, there are a few things you can do to minimize the cost of repairs:
Check your warranty: Many manufacturers offer warranties that cover differential repairs. If your car is still under warranty, you may be able to get the repairs covered.
Shop around: Different shops will charge different prices for differential repairs. It is important to compare prices before you have the work done.
Do it yourself: If you are mechanically inclined, you may be able to replace the rear differential yourself. This can save you a lot of money, but it is a difficult repair that should only be attempted by experienced mechanics.
If you notice any of the above symptoms in your car, make sure to have the differential checked out as soon as possible. Ignoring these signs can lead to costly repairs down the road.
On the one hand, differential problems can be difficult to diagnose because they often mimic other common car problems. While on the other, differential problems can be expensive to fix; if they are not fixed, they can cause extensive damage to your car.
It is important to catch these problems early so they can be fixed before they cause any major damage.
Thanks for reading! We hope this article was helpful. If you have any questions or comments, please leave them below.
Frequently Asked Question
How long does a rear differential last?
The rear differential is a tough piece of machinery. However, it’s not indestructible. With proper care and maintenance, a rear differential can last anywhere from 100,000 to 150,000 miles.
However, if it’s not properly maintained or used frequently in off-road driving, the lifespan can be significantly shorter.
The lifespan of a differential is also dependent upon the working temperature. If the differential overheats frequently, it will wear out more quickly.
How long does it take to replace a rear differential?
Replacing a rear differential is a fairly involved repair. It can take anywhere from four to eight hours to complete, depending on the make and model of your vehicle.
If you have a high-end vehicle with a complicated transmission design, the repair may take longer. The best way to avoid replacing your rear differential is to take care of it and keep an eye out for signs of wear and tear.
What are the major types of a differential?
There are four major types of differential: the open differential, the limited-slip differential, the locking differential, and the torque-vectoring differential. Each type of differential provides a different level of traction, depending on the vehicle’s needs.
The open differential is the most common type of differential and is typically found in passenger cars. It allows for equal power distribution to the wheels, regardless of the traction conditions. This can be an advantage on dry pavement but a disadvantage in slippery or off-road conditions.
The limited-slip differential is similar to the open differential. Still, it uses clutch packs or other mechanisms to limit the amount of power that can be distributed to a wheel with less traction. This helps to prevent wheel slip and can improve traction in slippery or off-road conditions.
The locking differential is a more extreme version of the limited-slip differential. It uses mechanical locks to prevent power from being distributed to a wheel with less traction. This can be very helpful in off-road conditions but can cause problems on dry pavement.
The torque-vectoring differential is an advanced type of differential. It uses electronic controls to manage the distribution of power to the wheels. This allows for more precise control of traction and can improve both performance and safety.
What happens when the rear differential goes out?
If the rear differential goes out, it can cause several problems. The most common problem is that the vehicle will have difficulty moving forward. This is because the rear differential helps to distribute power to the wheels.
Without it, the wheels will not get the power they need to move the vehicle. Additionally, the rear differential may also make noise when it goes out. This is usually a whining or grinding sound that can be heard when the vehicle is in motion.
How to fix a rear differential leak?
A rear differential seal leak is a pretty common issue and relatively easy to fix. The most important thing to do is to catch the leak early; if left unchecked, a small leak can quickly turn into a much larger one.
Here are some steps to take to fix a rear differential seal leak:
- Clean the area around the leak. This will allow you to spot the source of the leak more easily.
- Locate the source of the leak. It’s usually easiest to find this by following the trail of leaked fluid.
- Once you’ve found the source of the leak, clean it thoroughly with brake cleaner or another similar product.
- Inspect the gasket or seal that’s leaking. If it’s damaged, you’ll need to replace it.
- Apply a bead of RTV sealant around the perimeter of the gasket or seal.
- Install the new gasket or seal, and then tighten it down according to the manufacturer’s specifications.
- With the gasket or seal in place, apply a generous amount of grease around it. This will help to keep the area lubricated and prevent future leaks.
- Re-install any components that were removed during the repair process, and then test drive the vehicle to ensure that the leak has been fixed.
What does it sound like when your differential is going bad?
A few different sounds can indicate that your differential is going bad. One of the most common is a whining noise that gets louder as you accelerate.
Low levels of fluid usually cause this in the differential. Another common sound is a grinding noise. This can be caused by worn-out gears or bearings inside the differential.
If you hear either of these noises, it’s important to have your vehicle inspected by a qualified mechanic as soon as possible.
Can you drive with a bad differential?
If the differential is completely shot, the car will not be able to move. However, if the differential is only partially damaged, you may be able to drive for a short distance.
However, it’s important to remember that driving with a damaged differential can cause further damage to the transmission and other components. Therefore, it’s best to have the vehicle towed to a nearby repair shop as soon as possible.