Car reversing noise

[emyradams]

Why do cars make the same noise when reversing?

[5029]

the same noise as what?

[emyradams]

All cars seem to make a characteristic noise when reversing. This must have something to do with the mechanism for the car to reverse (the sound is different to the sound made when going forward). Is it the gear ratio used for the reverse gear?

[quattro]

I think it's to do with the gear cog size reverse gears are lower than forward gears if you've ever been stuck and unable to get up a slope it is easier in reverse and if youve ever had to drive more than a few yards in first gear at maximum it sounds similar

[gmc2002]

I was one told that it had something to with the cogs being cut for optimal meshing for "forward" and when you go into reverse they are "a bit tight". Also you don't really "run in" the reverse gear , think how mant miles you have done in reverse !

[blackfive]

If you mean the characteristic 'snarl' sound in reverse. This is because the forward gears are helically cut. This maximises the contact between the gears to better distribute the force from the engine and also makes for quieter running. The reverse gear, which is rarely used, is normally cut as a spur gear which are far cheaper to macine but also noisier. Have a look at http://www.howstuffworks.com/gear3.htm which shows you a helical gear then click on 'spur gear' up the top to see the difference between the two.