Your rear axle differential serves an important purpose in your vehicle, and you count on it to keep functioning properly. But what happens if your rear differential starts to malfunction or cannot work properly at all?
If the damage to the rear end’s differential is too costly, you could just sell your auto as-is. Otherwise, you will need to find a mechanic you trust to make some important rear end repairs. Learn more about rear differential repairs, including their cost, to help you make an informed decision about how to proceed with your vehicle’s bad differential.
What Is a Rear Differential?
To understand the importance of rear differential repairs, you should take some time to understand exactly what this component of your car, truck, or SUV does. The rear end differential connects to the transfer case or transmission via the driveshaft. This system lets the engine power transfer to the vehicle’s rear wheels.
The rear differential is responsible for changing the direction of the power, so it is no longer along the car or longitudinal. From there, the differential directs that power to the wheels. The differential contains gears that help with this 90-degree change of direction on the rear axles. The axle shafts in the rear differential connect with the wheels and are responsible for rotating so the auto moves forward.
Servicing Rear Differentials
You need to take care of your rearend differential just like you would any other component of your auto. One important aspect of servicing rear differentials is their lubrication. The gears within the differential need to be covered in gear oil, a substance that lubricates not only the gears but also the bearings. The oil also helps keep the components cool, so they do not overheat.
This fluid will break down as time passes. Additionally, metal filings come off the bearings and gears and collect in the fluid. Between the metal filings and the breakdown of the fluid, you must change the rear differential fluid every once in a while. Your maintenance for this component will also involve changing the gear oil as a preventative measure against damaging the interior gears, which are the pinion gear and ring gear.
During rear differential service, your mechanic will take off the cover from the component. From there, they will clean any of the old fluid found in your differential cases. They will then reseal the cover and add in the appropriate amount of clean, new fluid. For most cars, you just need to change the rear differential fluid every 20,000 to 40,000 miles. Because there is some variation, you should look at the owner’s manual for your vehicle to confirm your ideal service interval. From there, you can ask your mechanic about the cost to service your rear differential.
How Do You Know the Rear Differential Is Bad?
Two main symptoms occur in the case of a bad differential sound: rear differential noise and rear or front differential leaks.
How to Fix a Noisy Differential
One of the most common signs of an issue with your rear diff is an unusual differential sound. This may sound similar to howling. This pinion bearing noise may have variations in pitch, and it may come and go. These variations will depend on the load on your differential, as well as the severity of the problem.
If you think you may hear a rear differential noise, let your mechanic know. Many people mistake it for tire noise and then just ignore it. If this happens, you may find yourself with much more serious problems and more expensive and extensive repairs.
What About a Rear Differential Leak?
Although noise is a common symptom, you are probably more likely to notice a fluid leak or just low oil for your rear differential. The leaks typically occur by the axle seals, the rear differential cover, or the pinion seal, the last of which is where your driveshaft connects to the differential.
You can tell that you have a leaking rear differential if there is grayish or light brown fluid on the ground where the rear portion of your auto was parked, as this is the most obvious of the low differential fluid symptoms. The cost of a rearend repair for leaks will depend on the extent of the damage. Just adjusting the backlash or replacing your oil seal should be quick and fairly affordable. By contrast, repairing the leak will sometimes require a rear differential rebuild or other massive repairs.
Common Rear Differential Repairs
Although every situation is different, most of the common rear differential repairs will fall into one of several categories.
Replacing the Differential Gasket
In most cases, the cover on the rear differential will be either rubber or silicone. This means that it can deteriorate over time, leading to leaks. This is among the simplest repairs, as you just need to take off the current differential cover, clean the surface for the differential seal, and then reseal the cover. This should not take more than an hour.
Sealing the Rear Differential Piston
If you look at the front of the rear end differential on your car, you will see a yoke that connects with the driveshaft. Over time, the seal surrounding this yoke may develop a leak due to aging or nicks in its rubber. To repair this problem, you will need to remove the yoke, pry out the seal, and drive a new seal into its proper place, all without causing any damage. The last step is particularly challenging, as it is easy to accidentally damage the new seal as you put it into place.
Sealing the Differential’s Side
Another common repair for leaky differentials is sealing the side of the differential. The side seals on the diff stop its fluid, so it cannot leak onto the rear brakes. This type of repair is more time-consuming and challenging than the previous two since you have to also remove the axle shafts. This process involves prying out the old seals and carefully installing the new ones. Then, you can put the entire assembly together again.
Replacing the Rear Differential Bearing
The bearings in the rear diff include the pinion bearing and the side bearing. Both can deteriorate or pit over time, which will lead to rear diff noise. If you need to replace one of the bearings, expect the process to take between three and five hours for a trained mechanic to complete. As such, it will not be as cheap as the previously mentioned repairs.
Replacing Rear Differential Gears
Another common repair is to have to replace the gears in the rear differential. Over time, the teeth of the gears may wear down badly or chip. When this happens, you will deal with noise and a higher risk of failure, unless you replace them. You do not want to have to replace the differential gears, as they are the costliest components to replace, not even counting labor.
Replacing the Entire Rear Differential
In the absolute worst-case scenario, you will need a rear differential replacement. This becomes necessary in certain situations, including when the gears “grenaded.” In that situation, the differential case may not be fixable. In this case, your mechanic will have to replace the entire rear differential, including the housing, bearings, seals, and gears.
Rear Differential Repair Cost
If you have a rear diff bad component, you will need to be prepared to spend some major money or find an alternative to repairs. Repairing or replacing a rear differential can cost as much as it would to do the same with a transmission. This means that you could spend as much as $1,500 on the repair or replacement, if not more.
Those who get lucky and only have to deal with minor rear differential problems may find themselves spending just $200 to $400. This is the average price for a couple of hours of labor and the more affordable replacement parts, like bearings and seals. As soon as the gears get involved in the equation, you will notice the price jump significantly, easily reaching $1,500 or higher.
Rear Differential Replacement Cost
What about the worst-case scenario when you need to fully replace the rear differential? This will not come cheap. Even buying a high-quality used component that still has a solid warranty will cost between $1,500 and $2,000 once you have it installed. If you prefer a new rear differential, expect to pay closer to $3,000 to $4,000. It is wise to get a new rear differential instead of a used one since this will give you more confidence in the part and it should last longer. But that is a high price to pay.
Remember that the rear- or front-end differential repair or replacement cost will depend on numerous factors, including the vehicle and its condition. For example, repairing or replacing parts in older trucks will have a very different cost than doing so in a newer Ford F-150.
Other Common Questions About Rear Differentials
In addition to all of the above information, there are also some other very common questions regarding rear differentials and their repairs.
What Causes a Rear Differential to Go Bad?
In most cases, a rear differential will go bad over time due to simple aging. Just like other components in your auto age and weaken, the same is true of the rear diff. This process may occur more quickly if you do not properly maintain the component. As such, you can avoid rear differential problems with regular maintenance, at least to some extent.
Can You Drive with a Bad Differential?
Technically, you can drive with a bad differential, but it is not wise. The problem may get worse, to the point where it leaves you stranded somewhere. It can also cause damage to other surrounding components. It is smartest and safest not to drive with a bad differential.
What Happens If Rear Differential Goes Out While Driving?
The severity of the complications if the rear differential goes out while driving with a bad pinion bearing will depend on the problem and the vehicle. In the case of chipped or broken gear teeth, there may a vibration or skip in power. Multiple broken teeth will likely cause thunks and rattling sounds. If this happens, you should pull over, as it would be very easy to lose control of your auto.
In the worst-case scenario, you may experience a full loss of power when you turn. Eventually, your car may just stop and refuse to start, leaving you stranded.
Is the Cost to Repair Your Rear Differential Too High? Sell Your Car As-Is Instead
If you are dealing with a broken rear differential and find yourself with a hefty repair bill in your future, you still have options. Instead of spending the money to repair your auto or truck, you could sell the vehicle as-is. Not only will you not have out-of-pocket costs to repair your auto in this situation, but you will actually get money in return.
When Selling Is Better Than Repairing
Ultimately, any situation where you do not feel that the repairs are worth it creates a situation where it makes more sense to sell the car. Most people will feel this way in a few circumstances.
If your car is not worth as much as the repairs would cost — or is barely worth more than the cost of the repairs — then it would not make sense to pay for them.
Or maybe you have had to make too many repairs lately and can tell that they will only continue. In this case, it probably is not worth it to keep putting money into a car in bad condition, as it will soon cost you more in repairs than its value.
If you were already thinking about upgrading your vehicle, this may be the perfect opportunity to do so.
If you cannot currently afford the cost of repairs, then selling the car as-is will put cash in your hands, so you can get a running vehicle or work out another solution.
How to Sell Your Car with a Bad Rear Diff
If you want to sell your car without repairing the bad differential, you probably will not be able to sell it to a used car lot, at least not for a good price. If the lot did buy it, the staff would subtract the cost of the needed repairs from the offer, essentially making you pay for the repairs anyway. However, it is much more likely that the lot would not even buy it.
Instead, you will need to sell your car for parts or to a scrapyard. There are a handful of individuals who will want to buy your old car to use some of the other parts, but they are hard to find.
A scrapyard would be willing to buy your car, but that would just be for scrap parts. In other words, it will likely just pay you for the cost of the metal, not any still-functional components that could be worth more. Additionally, you would have to pay for a tow or figure out how to get your auto to the scrapyard.
You could take your car apart and sell individual functional parts then scrap whatever is left, but this would be incredibly time-consuming. Additionally, few people have the skill and knowledge needed to know which parts are functional and how to price them.
The Best Option – Selling It to an As-Is Car Buyer
To make the process of selling a car with a bad rear differential or another problem easier, many companies buy vehicles as-is. These companies either make the necessary repairs then resell the cars or take them apart and sell them for parts or reuse the functional components for repairs on other autos.
The best of these companies will be able to offer you a better price for your auto than you would get with a scrapyard since they take the time to sell various components for their best value. This allows them to get more for the auto then selling it as a whole, a profit which they pass onto you. Of course, this is only true for the most reputable buyers, as some will still offer you a very low price.
We’ll Buy Your Car for Cash, Regardless of the Rear Differential’s Condition
If you do not feel like it is worth it to repair your auto’s rear differential, then let us buy your auto from you. We will buy your car as-is, regardless of the condition. We are upfront with our pricing and will offer you a quote within minutes. There are no hidden fees, and we do not charge to tow away non-running cars. Best of all, we show up to your location and give you cash in exchange for your car. This way, you do not have to bring it anywhere or worry about a check clearing.
When you work with us, you will be able to quickly get rid of the unsightly and nonfunctional auto sitting on your property. At the same time, you will get cash in hand to go toward your next auto.