When it comes time for a routine inspection of your vehicle at your local branch of Kennedy Transmission Brake and Auto Service, you might be told that your vehicle requires differential service. And you might ask yourself, what exactly is a differential and what does it do? With front-wheel drive vehicles being so common these days, the differential is usually taken care of during a standard transmission service, so most Minnesota folks don’t even have to think about it. But your vehicle’s differential plays a key role when the rubber hits the road, and it’s important for all drivers to know what a differential does and what goes into a standard service.

What is a differential?

If you paid any attention during your high school physics (or Driver’s Ed) class, you know that as you drive through a turn, your outside wheels and inside wheels turn at different speeds. It’s kind of like cars going around an oval race track – the ones driving in the outside lanes have a greater distance to travel than the cars in the inside lanes. A vehicle’s differential is what allows the outside and inside drive wheels to rotate at slightly different speeds so that the tires don’t hop or skip while taking corners, or lose traction in dirt or snow. Differentials have gears in them that transfer the power from the drive train to the wheels, which is why they’re often referred to as gear boxes. The gears need to be very strong to handle this work, and they need to be properly protected so that they’ll last.

Does my car have a differential?

All vehicles have some form of differential. Here’s a breakdown of the most common types:

  • Front-wheel drive: For FWD vehicles (the vast majority of consumer cars on the road), the differential is located between the front wheels and is often called a transaxle. This is because it combines the differential and transmission in one unit.
  • Rear-wheel drive: For RWD vehicles like trucks and commercial vans, the differential is between the back two wheels. Because the transmission is not in the same location, RWD differentials receive far less wear-and-tear during normal driving conditions, so they can go longer between servicing.
  • Four-wheel (or all-wheel) drive: These vehicles have differentials in the front and the back – and in the middle as well. The center differential (often referred to as 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 somewhere between three and six thousand pounds – trucks even more. To get that much weight moving, all of the power from the engine is directed down through the transmission, on to the differential, and then out to the drive wheels. That’s a lot of work and requires very heavy duty parts. And those parts need protection.

Differential fluid lubricates and cools the gears involved in this process. Over time, this fluid can become dirty from bits of these gears grinding off. Also, chemical additives that keep the differential fluid clean and protect the differential break down over time. Because of this, vehicle manufacturers have set scheduled intervals to have the differential fluid changed. Contact your local Kennedy Transmission service advisor if you are not sure about your recommended schedule.

As with most service intervals, if you are driving under more severe conditions, you will want to service your differential more frequently. “Severe service” conditions are defined in most owners’ manuals and include: frequent starts and stops, short trips, cold weather, 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 gears and keep them running more smoothly.

Trust the Kennedy Transmission Difference with Your Differential

Differentials are hard-working mechanisms, and 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 location nearest you to schedule an appointment today!

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