Bought a 1997 4runner 5 speed about a month ago. It hums in reverse while moving; the faster you reverse the louder it is. I thought since it was a manual it is supposed to do this but I'm not sure. Should i be concerned?

 

That's normal many manual shift vehicles "hum" in reverse. (It's because they don't know the words )
Seriously though every stick I've ever owned (2 toyotas, 1 ford and a Miata I test drove) all hummed when in reverse. I think it's just because the gear train in the tranny/diff. is running backwards or something.
Welcome to the family
Aviator

 

Thanks aviator. It makes me feel better cause I tend to be very picky about my vehicles. Also, thanks to you or whoever for deleting my multiple "reverse hum" post. I went into the forum FAQ and looked how to delete a post. I couldn't quite figure it out what to do after I hit the edit option because i saw no delete button. Guess I just need to read up and get used to the forums....

 

Every manual car i've owned has done that too. Welcome to the forums

 

The way the gears are cut in modern transmissions makes them optimized for forward directional travel only.
Thats why they're loud in reverse.
Find a muncie rock crusher , they're loud in every gear.
Or i could just record some sounds of our camaro hahaha.
Stock muncie doesn't hold up well vs. the 454.

 

Reverse gear is a spur gear and they'll always be noisy since they're designed more for torque than speed.

 

I thought my initial reason was funnier but thanks for providing the technical answer lol..

 

no syncros in reverse, that's why it grinds if you try to put it into gear while moving. Ever hear a race car whine while it's in gear? Same deal (you have to rev match shift) Also heard them called dog tooth gears.