There is a reason for both this sound and that harsh sound that sometimes comes out when shifting into reverse gear. In fact, at this point, everything is due to the transmission gears.
Although we see that the forward gears have a different structure, they work silently and more easily, but we see that the reverse gear does not have the same characteristics.
Why is there a strange noise when reversing in the car?
When we look at the transmission system of a vehicle, we see that the gears in the forward gear and the gears in the reverse gear have different shapes. Gears in forward gear have a curved structure called “helical gear”.
This slope allows more gears to engage during gear shifts. In addition, thanks to the slope, a smoother transition is formed and it makes it work much quieter.
In reverse gears, there are spur gears instead of helical gears. Spur gears collide directly during engagement instead of slipping like helical gears. This is the reason for that noise that occurs during gear shifting.
In addition, since it is not in a spiral structure like helical, there is more space in spur gears. This gap can also be shown as the reason for the buzzing sound that increases as the vehicle accelerates.
Why is the helical gear not used in reverse gear?
If helical gears make less noise and grip much better due to their inclined structure, you may say why these gears are not used in reverse gear. The biggest disadvantage of helical gears is that it is difficult to switch between each other.
For this reason, the forward gears always remain connected to each other, and gear shifting is possible thanks to a piece called synchromesh. For this reason, spur gears are used instead of helical gears in reverse gears.