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 gear wheel helps a vehicle move 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 reverse mode. When you shift into the reverse gear, a small toothed gear gets in between the two shafts and engages them by sliding its teeth into the teeth of the shafts.

reverse gear at high speed
A reverse gear helps the car move backward. (Photo: 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. Simply put, the reverse gearwheel will make Gear 1 rotate anticlockwise (when it was rotating clockwise) and Gear 2 clockwise (when it was spinning anticlockwise).

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This forced action will result in several 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. More importantly, gears that are working at high speed and have problems shifting to R will cause them to break. When the gear in the transmission is broken, replacing the vehicle’s transmission is inevitable.
  • Stalling of the engine. If this happens when the vehicle is moving at high speed, it will be very dangerous. It can cause a series of accidents when the cars behind can hit your car if the distance between the two cars is not too far. Stopping suddenly like that is a big no-no when driving on the road.
  • 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 to put the car in 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 inhibitors. (Photo: HotCars)

In careless situations, you accidentally shift the gear lever to R or P. At this time, if you are in an automatic transmission vehicle, a position indicator light will appear on the dashboard showing that the vehicle is in reverse gear R. If you still don’t pay attention to the indicator light and don’t detect your mistake. Then the “Reverse Inhibit” function will be activated and will ignore your request to shift into reverse gear.

Therefore, even if you do not detect your error, the car will continue to move forward. Until you stop the vehicle, the vehicle’s control system will shift gears into reverse and reverse, then the vehicle will come to a complete stop. If you make a mistake and discover it immediately, you just need to return the D number and move normally. In these cases, the gearbox will not be affected much.

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 direction in the opposite direction or the transmission won’t explode, like what you see in a movie!

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To wrap up, the driver needs to be very focused when driving a car. In particular, do not let your hand rest on the gear when not necessary, and warn people sitting around not to get close to the gears when the car is running to ensure safety.