SUV Driving 4x4

Expert Differential Repair to Keep Your Tires Firmly on the Road

A vehicle in need of differential repair may let you know by making clunking noises or jerking during turns. Whether you’re driving in downtown Boise or on a country lane for fresh peaches from the orchard, your vehicle’s differential has to function properly to enable wheel pairs to move at different speeds. Each time you turn the steering wheel, the wheel on the outside of the curve must move faster than its partner on the inside for a smooth turn.

As a major component of the drivetrain, the main function of the differential is to send power from the driveshaft to the wheels and tires. This flow of power must take place smoothly whether your car is driving straight or turning. It is the gears within the differential that are designed to transfer the power smoothly.

In Idaho, during winter months, road conditions are often slippery due to ice and snow. A differential also functions to keep both wheels on a two-wheel and four-wheel drive vehicle turning equally during slippery conditions. Some differentials have locking mechanisms or positive traction clutches that stop or reduce one wheel from turning more than the other when operating during slippery conditions.

Differential Service

You can be Confident in the Differential Service at AutoTranz Transmissions

Your vehicle’s differential is similar to the transmission in that it carries a heavy load by transmitting engine power to the tires. And with any load, comes heat that breaks down the lubricating properties of a lubricating fluid. Changing differential oil regularly means the lubricating properties of the oil will protect the differential and ensure optimum service and a long life.

Here’s another reason to replace differential gear oil, or fluid, at intervals recommended by the manufacturer. The wear and tear on gears and bearings that happens with normal use releases small fragments or particles of metal. These circulate as contaminants in the fluid and act like sandpaper, causing extra wear on the internal differential parts. Differential service removes the contaminated oil and reduces the amount of damage that happens.

As we provide maintenance services, like engine oil changes and transmission services, we check for other maintenance items that need to be addressed to keep your vehicle operating without problems. Our mechanics check differential fluid levels and visually inspect the oil for signs a change is indicated.

Vehicle mileage is also an indicator that it’s time to have your differential oil changed. Differential services usually fall under the manufacturer recommended 30/60/90 thousand mile change intervals. This service involves removing the old fluid and installing new fluid that meets or exceeds the manufacturer specification.

For vehicle differentials with a positive traction clutch or locking internal mechanism, special additives or fluids may be required. Some vehicles are serviced with synthetic fluids that lubricate better and last longer than standard gear oil.

If you routinely haul heavy loads, it might be a good idea to upgrade from standard to synthetic oil. The superior lubricating qualities it offers can extend the life of the internal components in your differential. While these oils generally cost more than standard oils, the extended mileage life they give balances out the additional cost.

Drivetrain Differential Repair

Entrust Your Vehicles Differential Repair to the Drivetrain Specialist

The need for differential repair is probably due to one of the following three problems:

• Leaks in the oil gasket or seal
• Noisy bearings or gears
• Clunking from loose or worn gears or bearings

Differential fluid leakage is the most common causes for a differential to fail. Gaskets and oil seals are designed to keep fluid inside the differential because lubrication is critical for internal components. If leakage allows fluid levels to drop too low, bearings or gears can be damaged. Oil leaks can be caused by a number of conditions:

• Worn bearings that allow so much shaft movement that seals can’t hold oil in
• Metal contaminants in the oil between seals and surfaces compromise the seal
• Seals and gaskets become hard and brittle over time and leak
• Excessive or improper use can overheat the fluid and cause it to blow out the vent

Ring Pinion Gear Differential

Differential noises can come in any one of three forms:

• Clunking with acceleration or deceleration
• Grinding or clunking noise on turns
• A whining noise that may vary with speed and load
• Clunking with shifting

When starting the process of repairing a differential for a noise, the first step our mechanic specialists take is to verify your complaint. That almost always requires a road test.

The next step is a visual inspection that includes assessing fluid level and quality. If the level is acceptable, but the fluid has excessive metal contamination, it is likely a bearing or gear has failed.

After providing you an initial written estimate, we will need your approval to remove and disassemble the differential for a complete inspection to determine the actual extent of damage to the differential. The parts needed to make the repair will vary depending on the damage found and an updated estimate will reflect the final cost of the repair.

If the oil contains metal fragments, all bearings would need replacement. If a gear whine occurs while driving, the ring and pinion gears, which are a matched set, will need to be replaced. If there is a clunk during shifts or on turns, the gears in the differential carrier may need replacement.

At AutoTranz our auto repair mechanics are masters when it comes to repairing front and rear differentials on 4 wheel drive cars and trucks of all makes and models from GMC, Ford and Dodge to import trucks and SUV’s. Many of today’s most popular cars with all wheel drive systems include front and rear differentials, transfer cases and CV joint axles.

These complex systems require special tools, training, and experience to be fixed correctly. You can trust AutoTranz Transmissions mechanics to keep your car’s differential operating as it should in all kinds of driving conditions.


We’ve provided a brief description of what the differential does and how it works. As with most automotive drivetrain components, the key to maximizing their performance and life is ensuring the fluid quantity and quality meets the requirements. Following the manufacturer’s recommended service intervals will go a long way to helping you avoid the expense of a differential repair or overhaul.

If you can’t remember how long it has been since your vehicle’s last differential service, set an appointment so we can check your differential fluid level and quality. At AutoTranz Transmissions, we not only provide the maintenance your vehicle needs, but we can keep track of when your next services are due.

Our goal is to help you stay within your automotive repair budget so you can spend money and time on the important things in life as you enjoy family and recreating in Boise and the surrounding Ada County area.

Avoid the need for expensive differential repair. Call us today to schedule a differential inspection or service.