The differential is an important (and costly) part of your vehicle that transfers and manipulates engine torque being sent to the drive wheels. What’s more, the differential allows the drive wheels to turn at different speeds when cornering to prevent skidding.
Generally, differentials are quite robust. But if the differential in your vehicle fails, you’ll likely notice one or more symptoms that you’ll want to address right away.
What is a Differential on a Car?
Every part of a car engine serves a purpose to keep it moving while on the road. The differential is a key component in a car that helps deliver torque to the drive wheels while allowing them to turn at different speeds during a turn. Whether the car is front-wheel drive, rear-wheel drive or all-wheel drive, the differential is necessary.
What does a differential do? The differential is a system that allows the drive wheels to turn at different speeds, which is required when the car is negotiating a turn. In a turn, the outside wheel must travel farther, which means it must rotate faster than the inside wheels.
The differential is made up of various parts, including the ring and pinion gears, spider gears, and side gears. The location of the differential depends on the drive system of the vehicle, with front-wheel drive vehicles often having a transaxle and rear-wheel drive vehicles having a separate rear differential.
There are different types of differentials, including open differentials, limited-slip differentials, locking differentials, and torque-vectoring differentials, each with its own advantages and uses. Signs of a worn-out differential include driveline noise and vibrations, grinding or clunking sounds, strange sounds when turning, whining or whirring sounds and oil leaks.
Symptoms of a Bad Differential
These are some of the most common symptoms of a failing rear differential:
#1. Grinding, Howling Or Clicking Noises.
Abnormal noises are often one of the first signs of a differential problem. A whining or growling noise from the drive axle while driving can indicate an issue with the ring and pinion gear set or one of the differential’s bearings.
If the vehicle has a limited-slip differential—a design that continuously applies power to both drive wheels—sticking clutch packs within the assembly can create a chattering noise.
Issues within the differential can also lead to clunking noises. For example, damaged spider gears can cause a clunking sound while cornering, whereas damaged ring and pinion teeth can create a clunking noise while driving in a straight line. In addition, excessive backlash between the ring and pinion can cause a clunking sound on acceleration or while putting the vehicle into gear.
#2. Vibrations And shaking.
Another early sign of bad differential symptoms are vibrations in the drive shaft. A shuddering driveshaft is the telltale sign of bad rear differential symptoms.
These vibrations are the result of excessive wear and tear in the universal joints. Just like the whining noises, the trembling increases with speeding the vehicle up. A differential fluid leak will worsen this problem.
Many drivers may not pay attention to this problem because a vehicle can vibrate for various reasons. But taking early action may save your differential from failing completely.
#3. Poor Handling
As you know, differentials help with keeping the vehicle steady during turning a corner by regulating the speed of the wheels. So, when this system goes bad, the wheels cannot readjust the speeds and you will find it harder to handle the vehicle around a corner.
This is outright dangerous since not having complete control over the vehicle when turning around a corner can lead to swerving off the road. If you want to avoid an accident, consult a mechanic after detecting the signs of difficult handling.
#4. Oil Leaks.
The differential has gear oil inside that maintains proper lubrication and temperature control while the vehicle is driving.
It is not good if the differential is leaking fluid because it will ultimately lead to significant internal damage, so get your vehicle looked at by a drivetrain specialist before it gets any worse.
#5. Excessive Tire Wear.
Premature tire wear is usually a sign of a differential that needs repair. When the differential gears are not meshing properly, they can cause the tires to rotate at different speeds. This can cause the interior of your tire to wear down faster than the perimeter.
Uneven wear is usually most visible and apparent on the front tires. This is because the front tires handle the brunt of the work when turning corners. This is often referred to as cornering.
If you notice uneven tire wear, it doesn’t always mean it’s a failing differential. It can also be caused by improper alignment, over or under-inflated tires, or a worn suspension. The best way to diagnose it is by seeing a mechanic.
#6. Gear Grinding.
When the differential wears down, the gears will start to grind. This goes along with the whining, as mentioned earlier. As you accelerate, the humming grinding nose will get progressively louder. If caught and treated early enough, all you may need is a simple fluid change.
Gear grinding and humming noises can often be confused with transmission problems since the driveshaft connects the differential and transmission. If there is a problem with one, it is likely to influence or damage the other. The complex internal gear system usually lets you know when something is malfunctioning.
#7. Overheating.
Driving your car at high speeds for a long time, or hauling heavy objects, such as a caravan or trailer, can put extra pressure on your differential, causing it to overheat. That can then cause parts of the differential to break down.
The same issue can happen if you let your car wheels spin out a lot, causing damage to the differential.
Average Differential Repair Cost
The cost of differential repair can vary greatly based on several factors, including the vehicle’s make and model, the severity of the issue, and the chosen repair shop. On average, a basic differential fluid change or seal replacement typically falls within the $100 to $400 range.
However, for more extensive repairs like fixing damaged gears and bearings, the cost can go up to $2,000 or more. In some cases, replacing the entire differential assembly may exceed $2,000. It’s worth noting that labor costs can significantly affect the overall price, as these repairs tend to be labor-intensive.
To ensure an accurate estimate, it’s crucial to consult with a reputable mechanic or repair shop. They can thoroughly assess your specific situation and provide a detailed cost estimate tailored to your vehicle’s needs. So, don’t hesitate to seek professional advice to better understand the costs involved in maintaining your differential’s performance.