What Will Happen If You Shift to Reverse Gear at a High Speed?

What will happen if you shift to reverse gear when driving the car at a high speed? This is one of those numerous funny questions that randomly pop up in every driver’s mind. However, no one acts on it because they fear that it will cause the transmission to explode or something worse. Is it so? Well, no more wondering what would happen. Let’s find out what will happen if you give in to your curiosity.

What Does the Reverse Gear Do?

A reverse gearwheel helps a vehicle moving backward. Its function is pretty straightforward. There’s a shaft that has teeth on it, which are used for reverse. There’s another shaft for driving the wheels. It also has teeth that help to put the car in a reverse mode. When you shift into the reverse gear, a small toothed gear gets in between the two shafts and engage them by sliding its teeth into the teeth of the shafts.

reverse gear at high speed
A reverse gear helps the car moving backward. Source: CarsCoops

What Will Happen If You Switch to Reverse Gear While Moving Forward?

Let’s say, you accidentally or intentionally switch to reverse gear when cruising through the highway at the fifth gear. It will make the lever engaged to the fifth gear to disengage and move toward the reverse gearwheel to engage with it.

It will be quite impossible since there will be no synchronization between the main shaft and the gears at such a high speed. The reverse action will set in motion when your car finally achieves the synchronization speed. To simply put, the reverse gearwheel will make Gear 1 to rotate anticlockwise (when it was rotating clockwise) and Gear 2 to clockwise (when it was spinning anticlockwise).

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This forced action will result in a number of catastrophic consequences that may even lead to the total damage of the gearbox. The issues you can face are:

  • The gears end up in a deadlocking position.
  • Breaking of the teeth of gears that have to engage
  • Stalling of the engine
  • Serious damage to several engine parts including crankshaft, connecting rod, and other components.

What Will Actually Happen?

Well, none of the dangerous things mentioned above will happen because the transmissions in modern cars are designed to avoid this situation. The automatic cars have a function called Reverse Inhibit that nulls your request of putting the car into a reverse direction. It will only activate the command when the vehicle gets down to the proper speed. Even if you try to do it at a slow speed, the gearbox will make some bizarre sounds, which seem like a warning that you have done something wrong.

reverse gear
Modern vehicles have reverse inhibitor. Source: HotCars

If you put the reverse gear command in an old stick shift, the gearbox will make an abhorrent buzzing sound. The gears will try to engage in a reverse motion but the high speed won’t let that happen. So, it will be quite anticlimactic. The car won’t stop on a dime and change the direction into the opposite or the transmission won’t explode, like what you see in a movie!