The only thing bigger than the number of letters in the word “differential” is the sum you’ll spend to replace one.
This component is not only a tongue-twister, but it’s also the section of your drivetrain that allows the wheels to turn at different speeds.
Does that sound significant? Well, it definitely is!
How much do rear-differential replacements cost?
If replacing a gasket or bearing or sealing any problem areas isn’t feasible, you will likely spend between $1,500 to $4,000. Ignoring a faulty differential can not only cause further damage but can be hazardous as well.
Fortunately, this concise manual will encompass all the essential information about rear differentials, encompassing their definition, functionality, and classification.
Afterward, we will examine the indications that suggest yours is failing and what the repair options are.
Finally, we will examine in depth the exact costs of repairing or replacing a rear differential.
Note: for the sake of syllable count, we’ll often refer to the differential as “diff” (you’re welcome!).
Let’s get the basics down first!
Table of ContentsShow
What Is A Rear Diff, And How Does It Work?
Similar to runners on a track, when turning your vehicle, each wheel travels down a unique path. Since each has a different length, they need to be able to rotate at diverse speeds.
If this wasn’t feasible, the handling of your car would be erratic and dangerous.
This is where the variance comes in.
Power is supplied from the engine via the transmission to a driveshaft connected to the differential. Simply stated, the diff takes that power and then divides it between each of the wheels, allowing them to rotate at different speeds.
For a comprehensive look at how this process works, view this video.
What Are The Different Types Of Differentials?
Open Differential
This is the most basic type of diff, meaning it’s also the most affordable. It does allow the wheels to turn at different speeds, but it cannot limit power if one loses traction while the other doesn’t. This makes an open differential less than ideal on slick roads.
Limited-Slip Differential
A restricted-slip diff acts just like an open one under normal conditions.
However, a restricted-slip diff takes things a step further because it can limit the amount of power it sends should a wheel lose traction. This means that it not only provides enhanced stability but boosts safety as well.
Locking Differential
Here’s one the off-road aficionados will recognize immediately – the locking-rear differential.
In this type of immovable-axle system, clutches and discs activate a lock that causes the amount of power sent to each wheel to be identical.
With all the torque not going to one wheel and not being limited by its reduced traction, it is ideal for situations where traction is crucial.
However, if you are not off-roading or rock climbing, it is preferable to unlock it.
Torque-Vectoring Differential
Then there’s the torque-vectoring differential, the most sophisticated of them all. It combines various sensors and electronics to optimize traction based on what your vehicle is telling it.
A few of these include the surface conditions, the position of the throttle, your use of the brakes, and steering mechanism input.
This means optimal traction, regardless of the situation.
What Are The Signs Of A Bad Rear Differential?
Whining/Grinding Noises
If you notice a whining sound coming from your rear-diff (especially while turning), there’s a good chance you’re low on differential fluid. This lubricates the gears, bearings, and other rotating parts, so there’s no metal-on-metal contact.
If this problem persists, it may eventually lead to a harsh or buzzing sound, which suggests the gears have worn out.
Fortunately, replacing the diff fluid every 30,000-50,000 miles should keep this from occurring – unless there’s a leak.
Differential Fluid Leak
If the diff fluid is leaking, there’s likely a damaged seal that needs to be replaced. When this occurs, you may notice a gray or beige liquid under the rear of your car.
Tire Damage
Since the differential helps keep your tires rotating at ideal speeds, you may notice inside tire wear if it’s not functioning.
This will most likely lead to a blowout eventually if the tire threads sustain significant damage.
Vibrations While Accelerating
If rear-diff problems go untreated, they may damage other drivetrain components, like the universal joins.
When these become worn, you may notice severe vibrations (especially while accelerating). This is one of the initial symptoms that suggest your diff is going out.
Handling Issues While Turning
Evidently, if the component responsible for keeping your vehicle stable while turning decides to go out, you’ll experience a decrease in handling.
This can manifest in an exceedingly erratic way, making it hazardous to continue driving (especially while cornering at high speeds).
What Are The Repair Options For A Rear Diff?
Gasket Replacement
Most rear-diff covers are rubber or silicone, which can deteriorate and dry out over time. To prevent them from leaking, you’ll have to have them replaced. Fortunately, this is a straightforward repair that shouldn’t take more than an hour.
Bearing Replacement
There are two bearings in a differential, one for the front and one for the lateral side.
Once it begins to grind or whir, you’ll have to have one or both of them replaced. Since this requires dismantling the diff, it can take as much as 5-hours to complete, meaning it’s significantly more costly.
Sealing The Piston And Side
If you notice a puddle of fluid under your car, it may mean that the piston or the side needs to be sealed. Both require a considerable amount of time to repair, especially the latter, since the axle shafts also have to be removed.
Replacing The Rear Differential Entirely
If none of the above repairs are viable, you may have to have your rear diff replaced entirely.
This is the worst-case situation, which generally means the gears in the diff are unusable.
How Much Does It Cost To Repair/Replace A Rear Differential?
Repair
If it’s something uncomplicated, like replacing a gasket, you shouldn’t spend more than $150-$250.
However, it only goes up from there. Replacing a worn bearing with a new one will run between $200-$400, and sealing the piston or side should cost $400 to $800 due to the extra time required.
Replace
How much does it cost to replace a rear differential completely?
Depending on the make and model of your car, as well as its condition, expect to spend between $1,500 to $4,000.
The other factor is if you buy a new rear-diff or a used/rebuilt one. A used or reconstructed one will help you conserve money, but it won’t have the same warranty as a new one.
How Do You Maintain A Rear Differential?
To keep your rear-diff in excellent condition, make sure to replace the differential fluid every 30,000-50,000 miles. Also, have your drivetrain inspected each year.
Doing so will ensure that any repairs are uncomplicated rather than needing a full differential replacement.