Ever wanted to know why your car whines in reverse?

[standbackimapro]

Well Ive seen a few people ask WHY, there fwd cars whine when going in reverse, Some people Think its a transmission problem, so they bring it to my shop and i just tell them On Transmissions The reverse gear has a Spur gear,which has straight teeth so when you put it into reverse and start going, the whining noise you hear is the teeth of the spur gear slapping together, the reason you dont hear the noise in any other gear is because the other gears are called helical gears, which have like angle/beveled gears SPUR HELICAL

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[sony224422]

interesting. i've wondered that myself

[K24xCM5]

interesting indeed.

[02 accord]

I knew that already. Howstuffworks.com is great for stuff like this.

[The-Kid]

cool. ADMIN= Add this to the Accord FAQ. =P looks good.

[gianinline]

I actually like that sound!!
But yeah, it is interesting to see how little things.... can make different results of sound, performance and such.

[Centripital]

Yea, and add the reason why reverse grinds is because there isnt a syncro on it. That is why some people feel like they need to shift it into first or second before shifting it into reverse.

[HondaAccordTdR]

You must read car and driver. Good info.

[iam7head]

striaght cut gear=whine

[htekken]

good info, didnt know.

[02 accord]

Originally Posted by htekken

good info, didnt know.

Now you know.

[02 accord]

Nope. Look at worm gears. A 60:1 reduction is easy, and they don't whine. It whines because it's a spur gear. The reduction has nothing to do with it. And reverse is not THAT much lower than first. I top out in first around 35 mph, while in reverse, I can probably do 30. Not that much of a difference.

[JimBlake]

They're all spur gears. All that means is the gears mesh when the shafts are parallel to each other. The other kinds are bevel gears (in the differential), and planetary gears (really spur gears except for the ring) which are found in old-school auto trannys.

Spur gears can be straight cut or helical. Helical gears is what you're trying to describe, the teeth are 'twisted' instead of going straight across the gear. Helical gears don't whine so much since there's always some point on the gear face that's engaged with the other gear. (I know that's a sorta simplified description, so some other engineer can maybe think of a better way to describe it.)

Then there's hypoid gears which are even more sophisticated in the details of the tooth shape. They are directional, so they make more noise when going backwards. You don't have hypoid gears, they're in some RWD final-drive gearsets because of the offset shaft centerlines.

edit...
Hmmm, I just read that in howstuffworks, but I don't think they're using using the term correctly. Look at their wording under bevel gears. They talk about straight bevel gears vs. helical bevel gears. Same thing for straight spur gears vs. helical spur gears.



Modified by JimBlake at 3:07 PM 2/5/2007

[Stealthman80]

I call my car the ECHTO MOBILE, its funny as hell it sounds like a crank siren

[kulrevon]

Originally Posted by Blamm!!

you guys have no idea!! reverse whines because it is as much LOWER gear than than first! and is a different style gear. But mainly because it is lower gear!
holy smokes!!

You are absolutely wrong. And I hate people who are so confident with their wrong information. If you want to prove a point. Do some research. It whines because of the straight cut gears. not because of the low gearing.

Originally Posted by Howstuffworks.com

Spur gears are used in many devices that you can see all over HowStuffWorks. But you won't find many in your car.

This is because the spur gear can be really loud. Each time a gear tooth engages a tooth on the other gear, the teeth collide, and this impact makes a noise. It also increases the stress on the gear teeth.

To reduce the noise and stress in the gears, most of the gears in your car are helical .

[g0at357]

Something good to know.......appreciate the info...

[sir4doorking]

cool thanx for the input. but I like that noise men.

[YeuEmMaiMai]

that's funny becasue the only cars that I have had that make that whine in reverse are I4 hondas

my V6 accord didn't do it
my CL type S does not do it
None of my american FWD cars did it

Sable
Cutlass

[hurleyint]

Originally Posted by YeuEmMaiMai

that's funny becasue the only cars that I have had that make that whine in reverse are I4 hondas

Congrats on having quiet cars, but to say only I4 honda's whine in reverse is a bit much. I know for a fact I have heard toyota's, VW's, and nissans all make the same whining noise.


I read about this a few years ago, you guys are way behind.

[GhostAccord]

All of my "Manual" transmission cars have had the reverse wine to them. GM, Ford, Honda & Mazda. My 1 automatic did not make any different noise. Could that be the difference maybe????

Yeah this post was brought back to life from the FAQ's. It was a February thread.

[jamie2002]

Does anyone know how to get rid of the whine sound? Does this mean i need to get a new transmission or something? That sounds expensive

[TouringAccord]

no, thats just how it is, nothing is wrong.

[jamie2002]

Ok awesome! Thanks I hope it's not that loud on the outside! I like to try and not draw attention towards myself!

[not-a-stang]

Originally Posted by Blamm!!

you guys have no idea!! reverse whines because it is as much LOWER gear than than first! and is a different style gear. But mainly because it is lower gear!
holy smokes!!

haha! keep trying buddy. its the straight cut on the reverse gear.

Have you guys ever heard of the Muncie "rock-crusher" M22 4 speed manual? Its an old school 4-speed that came on Chevelles, camaros, etc.. that had the first three forward gears cut straight instead of the usual helical cut, man those babies whine! Sounds like a supercharger!

[Tiff_Tiff420]

ohhh