What Is a Transmission and Why Is It Important?

If you look under your Mitsubishi Outlander’s engine bay, you’ll find a large square-ish part at the left of the engine (if you’re facing the back of the vehicle). That’s the transmission. What is it, and what does it do? Read on to find out.

What is a Transmission?


Also called a gearbox, the transmission is a major part of your Outlander’s drivetrain. It looks like a square box that's about 1 to 2 feet wide.

The transmission is responsible for keeping the gear ratio optimal for the drivetrain. As your Outlander slows down or speeds up, the transmission changes the gear ratio between the engine and the drive wheels to match the speed of the car. This keeps the RPM and torque at ideal levels.

There are two different kinds of transmissions commonly used:

  1. Automatic: A transmission that automatically switches gears as you slow down or speed up
  2. Manual: A transmission that's manually managed by a stick next to the driver's seat

The transmission helps transfer power to the wheels. It works to match the power put out by the engine to the speed of which the wheels are turning.

The Difference Between a Transmission and a Transaxle

Transmissions and transaxles perform similar functions, and many people use the names interchangeably. But, while both parts serve the same purpose, they’re not the same part. A transmission uses the gear set to transfer the engine torque to the driveshaft. A separate differential then transfers that power to the axle(s). A transaxle is a type of transmission that’s situated between the wheels and has axle shafts coming out of it. It’s a more complicated part than the transmission, as the differential is inside the transaxle.

Here’s an easy way to tell if your car has a transmission or a transaxle, and it’s to answer this question: does your car have a FWD or RWD? If it’s a FWD, then it’s likely to have a transaxle. In most FWD cars, the transaxle is situated transversely right above the front wheels. If you have a RWD, then it likely has a transmission. If you have a traditional 4WD, you have a transmission. If you have an AWD vehicle, you might have either a transmission or a transaxle.

How Does an Automatic Transmission Work?

Image Credit: ClearMechanic

When your Outlander changes speeds, the automatic transmission uses mechanical parts, transmission fluid, and electrical engineering to kick the following sequence of events into motion:

  1. The engine sends power to the torque converter.
  2. The torque converter causes the central transmission shaft to spin.
  3. Depending on the gear that is selected, a set of gears within the transmission transfer power from the central shaft to the output shaft.
  4. The output shaft is connected to the driveshaft.
  5. The transmission changes gears based on a number of factors including vehicle speed, throttle position, engine rpm, and others.

The process is actually much more complicated than that, but that's the basic gist of it.

What Happens When Your Transmission Completely Fails?

When your transmission completely fails, your car breaks down. It can’t move at all. However, something like this doesn’t just happen out of the blue. Your transmission gradually fails, and during that time you’ll notice some symptoms, such as:

  • Slipping transmission
  • Clunking noise while shifting
  • Whining, buzzing, or humming noise
  • Rough shifting or lack of response
  • Transmission fluid leak
  • Check engine light coming on

If you experience any of these symptoms, it’s worth taking the time to diagnose the issue and take care of the issue before you experience complete transmission failure while driving.

You can put your Outlander back in good working order by ordering a direct replacement and then either installing it yourself or having an experienced technician install it for you. As an authorized seller of OEM Mitsubishi parts, we offer wholesale pricing for genuine OEM Mitsubishi transmissions and transaxles, including this one for 2016-2018 Outlanders.