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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!

  1. Andrew Eria Kasule says

    Quite helpfull posts that I always read.
    Who ever uploads the posts is doing a great job.

  2. Devis Asiimwe says

    Wow! Thanks for the info

  3. Brian says

    Thanks ,,then ask what if the gear lever accidentally slides into parking position while driving

    1. jason larmon says

      same deal there is a strange grinding noise untill you hit a slow enough speed around 2 mph and then finaly boom park and instant stop

  4. Otieno Caleb says

    Thanks, I kind of freaked out some time back but you’ve made me understand it was just a warning. Something else, I changed my oil(synthetic oil -10000km) but have not been using the car so frequent so am left with 4000kms, its like 6 months ago when I changed it, is there need to change the oil b4 the recommended mileage elapses?

    1. jason larmon says

      no but it wont hurt

    2. EW Machu says

      Caleb, oil change should be after 10000kms or 6 months, whichever comes first. For you naona ni 6 months, just change it kaka!

  5. Peter says

    How do I press my fuel pedal to save on fuel


    please I need help with my Mazda Demio 2003 model manual transmission with a ZJ engine. it has lost pulling power and the machenic told me to buy a new pressure plate, clutch plate and release bearing but where to find them.

  7. Lwimba says

    I understand that pressing reverse gear while the car is moving foward, won’t harm the engine because a reverse gear is only activated when the car is stationary. When the car is moving, the reverse gear won’t work until the car stops.

  8. Julius Arthur says

    Your Comment , You have reminded us to be most careful while driving and knowing the exact out come if we do such a terrible mistake in driving,Thank you in advance for your description concern. I am Julius Arthur,from Tanzania East Africa.

  9. Edwinmsiska says

    I experienced this one day. I was cruising and accidentally squeezed the reverse gear. There was noise and i immediately reacted stopping the reverse gear. I knew i was on the wrong side

  10. rajab suleyman says

    Your Comment
    very grateful for the insights in fact each day am learning but I have one question when is that button written on ECT used in auto cars am always wondering its function.

  11. says

    I managed to select reverse in a old Cortina mk5 automatic I was going through the gears with my finger on the button the rear wheels locked but only for a second as I put it back into Drive

  12. Karoney says

    Have always learn from these posts thanks for the info

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