Manuel transmission whine in reverse

[necrotopsy]

I've noticed that almost ever mtx car i've drove, the transmissions whine in reverse. So i don't think this is a problem.
but i've always wondered what caused it, from a technical standpoint.

anyone have the answer?

 

[undefined0000]

I was just reading about this the other day.

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Notice how ALL of the contacts are with slanted gears, except with reverse. Theres the top gear, then in the middle is an idler gear with straight teeth, then a slanted final gear. Its because of the straight teeth that you get the noise.

 

[necrotopsy]

okay, that's pretty cool. thanks.

#themoreyouknow

 

[undefined0000]

I knew reading that article one day would pay off .

Not gonna lie, reading the title for this at first had me thinking

"Some A/T guy went and got a manual for the first time and comes here thinking that the noise is a problem"

 

[WES_393]

Notice how ALL of the contacts are with slanted gears, except with reverse. Theres the top gear, then in the middle is an idler gear with straight teeth, then a slanted final gear. Its because of the straight teeth that you get the noise.

Bingo. The reverse gear is straight cut which makes more noise than a helical gear. This is why the '90 DSM oil pump gears make so much noise compared to all the others: Straight cut vs. Helical.

 

[necrotopsy]

i asked a mechanic once and he told me "because parts are being put in reverse that normally move forward. It's because it's wearing in the opposite direction." but that never seemed like the right answer to me. glad i asked here.

is there a reason the reverse gear isn't a Helical style?

 

[xxNocturnalxx]

I wish all of my gears were straight cut, love that sound

 

[undefined0000]

Bingo. The reverse gear is straight cut which makes more noise than a helical gear. This is why the '90 DSM oil pump gears make so much noise compared to all the others: Straight cut vs. Helical.

Just imagine the terror if the forward gears weren't helical. SUPERCHARGED CARS FOR EVERYONE!

 

[necrotopsy]

just ruin a audio related ground somewhere and get "audible tach"
sounds like a super charger XD

 

[undefined0000]

i asked a mechanic once and he told me "because parts are being put in reverse that normally move forward. It's because it's wearing in the opposite direction." but that never seemed like the right answer to me. glad i asked here.

is there a reason the reverse gear isn't a Helical style?

Just look at what the idler gear is doing. The helical gears are in the same direction and a 3rd helical gear wouldn't work. I'm pushing all theory here now, but that's what I'm getting from the diagram.

just ruin a audio related ground somewhere and get "audible tach"
sounds like a super charger XD

I've got a 16g that sounds like a jet-plane. NOOO thank you. Good lord