Differential 101: Does My Car Have a Differential?

When it’s time for a routine vehicle inspection at your local Kennedy Transmission branch, we might tell you your vehicle requires differential service. But what exactly is a differential, and what does it do?

With front-wheel drive vehicles being so common, a standard transmission service usually takes care of the differential; most people don’t even have to think about it. Still, your vehicle’s differential plays a key role when the rubber hits the road. All drivers should know what a differential does and what goes into a standard service.

What is a differential?

Often called gearboxes, differentials have gears in them that transfer the power from the drive train to the wheels. The transfer of power prevents the tires from hopping and skipping while taking corners or lose traction in dirt or snow. It’s also why your inside wheels and outside wheels turn at different speeds when you make a turn.

Imagine cars going around an oval racetrack: cars driving in the outside lanes have further to travel than cars in the inside lanes. To correct this, the differential rotates the outside and inside drive wheels at slightly different speeds. The gears need to be very strong to handle this work, and they need to be properly protected to ensure they’ll last.

What are the most common types of differentials?

All vehicles have some form of differential. Some of the most common types include:

• Front-wheel drive: This is the most common differential in consumer cars and sits between the front wheels. This form is called a trans-axle because it combines the differential and transmission in one unit.
• Rear-wheel drive: This differential sits between the back two wheels and is commonly found in trucks and commercial vans. Because the transmission is not in the same location, RWD differentials experience less wear-and-tear during normal driving conditions so they go longer between services.
• Four-wheel (or all-wheel) drive: These vehicles have differentials in the front, the back, and in the middle. The center differential, often called a transfer case, adjusts for differences in speed between the front and rear wheels.

Why is differential service important?

Most of the vehicles you see on the road, even the smallest ones, weigh 3,000 – 6,000 pounds, and trucks weigh even more than that. To get that much weight moving, all the power from the engine directs down through the transmission, on to the differential, and then out to the drive wheels.

Differential fluid lubricates and cools the gears involved in this process. However, over time, as the chemical additives that keep the differential fluid clean and protected breaks down, the fluid gets dirty from bits of the gears grinding off.

As a result of all this wear and tear, vehicle manufacturers change the differential fluid at scheduled intervals. Contact your local Kennedy Transmission service advisor if you have questions about your recommended schedule.

If you’re driving under more severe conditions, you’ll want to service your differential more frequently. Most owner’s manuals define “Severe Service” conditions as frequent starts and stops, short trips, cold or hot weather, and towing.

All these conditions add to the stress of the vehicle and its parts. Proper service will extend the life of your differential gears and keep them running more smoothly.

Trust the Kennedy Transmission Difference with Your Differential

Differentials are hard-working mechanisms. Along with the gears in a manual transmission, they need to be serviced regularly with high-quality replacement fluid.

The expert technicians at Kennedy Transmission can give you more information about when your next differential service is recommended. You can also ask if they have a record of when the service was last completed.

Find a Kennedy Transmission shop location near you and schedule your differential service today!