If a vehicle is moving in reverse and is shifted into drive will it damage the vehicle? If you are the type of driver who prefers a vehicle with an automatic transmission you will note that the vehicle will not shift into reverse or park unless the button is pressed on the shifter. The shifter will allow the vehicle to be in reverse and shift the transmission into drive but should you do that? The manual transmission will allow the shift as well but is there damage as a result?
Automatic Ease of Transition
According to the folks on Stack Exchange, most newer vehicles will only allow the shift to be recognized if the vehicle is moving under a certain speed. If the vehicle is moving faster than the limit the vehicle will not shift gears or will only shift into neutral, which of course slows the vehicle down because it is unable to accelerate in neutral.
The reason is that if the vehicle is moving in reverse and shifts straight to drive without stopping, you are putting stress on the drivetrain which can be felt when the vehicle slams to a stop before engaging. The faster the vehicle is traveling the more stress the drivetrain endures, and if the shift was allowed to be made at very high speeds the drivetrain would be badly damaged. At lower speeds, there is still too much stress being placed on the drivetrain and you will cause it to need replacement prematurely.
Manually Grinding the Gears
If you prefer a manual transmission you may have even more reason to avoid such a shift. There is no computer to stop the transmission from shifting, but in these vehicles, the damage is to the clutch and to the synchronizers. The synchronizers, which allow for the smooth transition between gears are not present on racing transmissions so these vehicle owners should be especially cautious. They are generally not present in reverse gears either which makes shifting from drive into reverse while in motion even more damaging.
Under five miles per hour, there is no real risk of damage, over that the potential damage increases with the speed of the vehicle. Repairing that damage can add up quickly so it is important to come to a stop, or at least a rolling stop, before shifting between reverse and drive.