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How Much Does It Cost to Weld a Diff? Prices & Guide

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person welding car diff

One of the main concerns of car owners is achieving stability and good traction on the road. Whether you drive off-road, drag, or road race, you can achieve maximum traction by ensuring that the car differential is just right.

Your car’s transmission may be able to send power to the wheels, but it needs assistance for optimum performance. If all wheels rotate at the same speed, it will put a drag on the axle, limiting your car’s ability to run. The differential prevents axle issues by controlling the speed at which each wheel rotates.

If your vehicle is making whining or grinding noises, the chances are high that the differential is inadequate. This limits the vehicle’s ability to smoothly navigate corners and turns at high speeds. The best way to handle differential issues is with diff welding. But how much will this cost you? Read on to find out.

The Importance of Welding a Diff

The main differential carrier in many vehicles is called the open carrier. It features a series of spider gears that rotate inside the carrier. These gears are designed to delegate power from the engine to the rear and front axle shafts.

This design is suitable for on-road purposes as it allows the tires to rotate at different speeds. So, when navigating a corner, the wheels do not spin at the same speed leading to dragging.

The drag is likely to create handling problems and tire damage, eventually lead to the drive train failure. To achieve stability and maximum traction on the road, differential welding comes in handy. This concept simply means forcing the axle shafts to rotate at the same speed, creating a locker.

Since differential welding prompts both the outer and the inner wheels to rotate at the same speed, the outer wheels need to spin faster than the inner wheels. By allowing both wheels to spin at the same rate, the inner wheel will lose traction and skip, which makes it easier to achieve oversteering.   

So, by welding the diff you can prevent the skipping. You can still get the same result from a mechanical 2-way LSD diff (limited-slip differential) for equal torque distribution in acceleration and deceleration. However, welding the diff is a far cheaper alternative to achieving a stable drift.

Old differential mechanism in engine oil
Image Credit: Viacheslav Life Studio, Shutterstock

How Much Does Welding a Differential Repair Cost?

Welding a car’s differential is one of the cheapest options for fixing differential failure. However, the cost depends on the severity of their condition. The average cost ranges between $500 and $2,000. This depends on whether the repair is located on the front or rear of the axle, the mechanic, the importance of the repair, your residence, the car model as well as the parts that need to be replaced.

The cost of the repair also depends on the time required. Professional non-locking differential repair takes approximately six hours, while non-locking devices typically take about 8 hours. If you factor in the labor cost of the repair and the parts required, you could end up spending close to $700 in labor fees.

For professional light repairs such as oil replacement of your front-engine rear-wheel drive, you can expect to fix the differential at a cost range of $200 to $500. The more difficult repairs, such as rebuilding the differential or overhauling, be sure to have between $700 and $1,000 at hand.

The front-engine front-wheel-drive differential repair is slightly more expensive because the mechanic must take apart the axle to sort out the underlying issue. According to diff welding experts, you could budget between $700 to $1,200 to rebuild the differential and at least $1,500 to weld a new rear differential.

Does Car Insurance Cover Diff Welding?

Insurance contracts cover various aspects of a vehicle, including the paint job, the chassis, and the windscreen, among others. However, many insurance companies only cover these expenses if a vehicle has been in an accident and the diff requires some welding.

In such a scenario, the vehicle will lose value and will not have the same worth as it had before. You can try to get paid for the loss by filing a diminished value insurance claim with your insurer. You may get compensated for the claim, but this largely depends on the state you are living in. 

Each state has different policies regarding paying diminished value insurance claims. Some states may choose not to cover the expenses, especially if you are at fault. However, if you are cleared, the insurance company is likely to pay the claim and cover your diff welding expenses.

mechanic welding car diff
Image Credit: Everyonephoto Studio, Shutterstock

Types of Car Differentials

Open Differential

This is the most standard and affordable type of vehicle differential. It lets your car wheels take a turn at varying speeds without limiting the power in case one of the wheels loses traction. The open differential is, however, not suitable for slippery roads.

Limited-Slip Differential

In normal driving conditions, the limited-slip tends to behave like an open differential. However, unlike the open diff, this one can limit the amount of power at the wheels in case a wheel loses grip. This tends to give more stability as well as improve safety.

Locking Differential

A favorite to most off-road drivers, this differential uses a fixed-axle system that activates a lock through plates and crutches to release equal power to each wheel. It is especially suitable for off-road drivers because of the reduced traction and equal torque distribution to the wheels. However, you should unlock the diff when driving on standard tarmac roads.

Torque Vectoring Differential

Torque vectoring is the most advanced differential available. It utilizes a combination of electronics and sensors to achieve maximum traction based on the information it receives from the vehicle. Sensors can detect the throttle position, surface condition steering input, and brake use to give maximum traction irrespective of the road condition.

Causes of Differential Failure

Most of the causes of differential failure arise from poor maintenance, poor assembly, and modifications. Granted, every car experiences the usual wear and tear of the differential over time. Fortunately, modern vehicles come with a sturdy differential that can withstand long mileages when properly maintained.

However, when you do not take care of your vehicle, you are likely to experience differential failure. A good example of improper maintenance is using the wrong type of lubricant and specialty lubricants.

This also applies to water because it can sip through the seals or vent, especially when driving in deep waters. When water seeps in, the differential fluid gets emulsified thus, creating rust on the bearing and gear surfaces. Thankfully, replacing the differential fluid after every 30,000 to 50,000 miles should help prevent the failure.

Also, when the gear ring fails to fit with the pinion, it can break some of its teeth or develop uneven wear. The patterns on both sides of the pinion and the ring gear must always interlock.

The other cause of differential failure occurs when the gears are excessively tightened or loosened. This creates a differential backlash, especially between the side, spider, and even half shaft gears. Eventually, the backlash will wear out the differential or even break the gear teeth when accelerating.

Signs of Differential Failure

Sometimes it’s hard to tell when your vehicle is experiencing differential failure. You don’t always hear strange noises coming from the back but suddenly find that you cannot handle your car. It takes time for the problem to develop. You can look out for the signs below.

Vibrations While Speeding

If differential failure is not fixed, it can damage the drive train, including the universal joints. When these components get worn, you will likely notice a lot of vibration from the rear end of your car. This symptom is an early warning that you ought to fix your diff.

Differential Fluid Leak

When the differential fluid is leaking, you are likely to notice brown or gray liquid sipping under the rear of your car. This is a sign that a seal is worn out and needs replacing.

Tire Damage

The main purpose of the differential is to keep the tires rotating at the best speed. When it fails, you are likely to notice tearing on the inside of the tire. If the difference is not welded, the tire will eventually blow out due to too much damage on the tire treads.

Grinding/Whining Noises

If your car is experiencing differential failure, the first thing you will notice is a strange whining or groaning noise emanating from your rear diff when turning or negotiating a corner. This is a sure sign that your car is low on the differential fluid, which lubricates bearings, gears, and other moving parts. Diff fluid prevents metal to metal contact that wears out the axle gears resulting in differential failure.

Difficult to Handle While Turning

When the parts of your vehicle designed to maintain the stability of your car fail, you will experience handling issues. These issues are unpredictable and can make driving dangerous when negotiating corners at top speeds.

Final Thoughts

Common handling issues due to differential failure can easily escalate into more serious problems if not addressed on time. It can not only compromise your safety while driving but also cause your wheels to lock up, which can be dangerous, especially in traffic.

Thankfully, some of these issues are easy to detect. The best way to prevent the deterioration of the car’s performance and avoid putting your life at risk is to fix the diff failure by welding.

There may be other methods but welding the diff is the most budget-friendly option. Diff welding helps keep both back wheels rotating faster than the inner wheels when turning. It will cost you from $500 to $2,000, subject to the factors discussed above.

Featured Image Credit: Everyonephoto Studio, Shutterstock

Cameron Dekker

Cameron grew up in Allentown, Pennsylvania, a once-proud steel town on the Lehigh River, where he got a taste of TIG welding in his high school shop class. He holds certificates for Certified WeldingEducator (CWE) and Certified Resistance Welding Technician (CRWT) from the American Welding Institute. His interests include scuba diving, sculpture, and kayaking.