Why does a car engine make a different noise when it reverses?

Answer 1

I suspect the noise is actually the transmission, which uses a different set of gears when moving in reverse than when moving forward. This sound can also come from the differential. Moving car in reverse puts pressure on back side of gear teeth, producing a different sound. Sound difference will normally be much more pronounced in cars or trucks with manual transmissions.

Answer 2

It's not actually the engine that makes a different noise. It is the transmission. In order for the car to back up a different set of gears in the transmission are used. Because they are only used for reverse they are not made to the same tolerances as the rest of the gears.

Answer 3

i own a repair shop,and the engine doesn't ever reverse,its the transmission that does the reversing,the engine always turns in the same direction,the noise your hearing is the transmission whining on it,good luck i hope this help,s.

Answer 4

It doesn't, but the transmission does.
Particularly on a manual gearbox, the gears for reverse are often cut differently - and certainly used less - so they make a different sound

Answer 5

Because you are moving backwards, instead of forwards. The sound waves are not compressing as they move toward you when you move forward, therefore, you hear a different pitch, also know as the Doppler Effect.

This can be equated to the sound that a train makes as it moves towards you, then passes you by. The pitch of the sound is higher before it arrives, then lowers as it passes.

See: http://en.wikipedia.org/wiki/Doppler_effect

Answer 6

New car or old car? Automatic or Manual? Gasoline or Diesel? If it an older car, automatic it is hydrolic and uses a larger gear for reverse.



>........Jimmi

Answer 7

The gear in the transmission is much smaller and quite limited, so it'll make itself heard.

Answer 8

HYYYYYYY. Because when you go backwards, you usually get in a farting position, dummy.