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reverse hum

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Old 10-20-2010, 07:36 AM
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reverse hum

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?
Old 10-20-2010, 08:11 AM
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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.
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Old 10-20-2010, 08:19 AM
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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....
Old 10-20-2010, 08:22 AM
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Every manual car i've owned has done that too. Welcome to the forums
Old 10-20-2010, 12:53 PM
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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.
Old 10-26-2010, 07:20 PM
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Reverse gear is a spur gear and they'll always be noisy since they're designed more for torque than speed.
Old 10-26-2010, 10:05 PM
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I thought my initial reason was funnier but thanks for providing the technical answer lol..
Old 10-26-2010, 10:37 PM
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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.
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