I'm rebuilding my tranny and can not figure out why cars make that wine noise when you give them some throttle in reverse. Does anyone know what's going on?
-Chris
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03:38 AM
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doublec4 Member
Posts: 8289 From: Oakville, Ontario, Canada Registered: Jun 2003
Reverse uses a different type of gear. Pretty sure they are straight cut teeth (spur gear?) I don't know transmissions that well but basically the type of gear used for reverse, and even first I think is different than the rest. They are a noiser gear because of the teeth angles and the way they mesh. The rest are helical gears if I remember correctly. Much less noise, mesh more gradually.
Someone who is more familiar with transmissions can chime in.
[This message has been edited by doublec4 (edited 04-15-2011).]
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03:58 AM
Gokart Mozart Member
Posts: 12143 From: Metro Detroit Registered: Mar 2003
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
Slightly off topic, but most built race cars also utilize straight cut gears throughout the trans. It's why in motor racing such as sports cars and Le Mans racers you hear a constant whine that gets progressively louder as the speed of the vehicle increases. It's the gears in the trans creating the whine.
The reason why common road cars use helical gears is for the noise reduction and the increased torque they provide upon the drivetrain. On a race car, while a spur gear offers a disadvantage at high speeds, spur gears work incredibly well at low speeds (that's why you can accelerate really quickly in reverse). The idea is that the advantage that a spur gears gives upon acceleration is much greater than a helical gear at high speeds, so most race cars use the straight cut gears for their trans.
[This message has been edited by Fiero84Freak (edited 04-15-2011).]
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07:45 AM
Xyster Member
Posts: 1444 From: Great Falls MT Registered: Apr 2011
Spur gears: Tooth contact is primarily rolling, with sliding occurring during engagement and disengagement. Some noise is normal, but it may become objectionable at high speeds.
Helical gear: is a cylindrical shaped gear with helicoid teeth. Helical gears operate with less noise and vibration than spur gears. At any time, the load on helical gears is distributed over several teeth, resulting in reduced wear. Due to their angular cut, teeth meshing results in thrust loads along the gear shaft. This action requires thrust bearings to absorb the thrust load and maintain gear alignment. They are widely used in industry. A negative is the axial thrust force the helix form causes.
So from my understanding it is the shaft wanting to shift under high loads (with a helical set) that drives the use of spur gears in race applications (where noise isn't a factor). Reverse is used infrequently so who cares about that small amount of noise. Also it reduces cost by enabling the use of cheaper bearings for the reverse gear. But then again I could be wrong, again.
learn something new every day! Just hearing that difference in noise, in just about any car in reverse always seemed normal to me, and never really thought about it.
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11:00 AM
TheRealShadowX Member
Posts: 1456 From: Milwaukee Wisconsin USA Registered: Mar 2010
This is the noise they were talking about. Obviously way too much for everyday commuting, but it does kinda sound cool!
Oh yeah, THIS mother effer can DRIVE!!!!
Thanks alot guys, I love learning stuff about mechanics and cars, and I never stop. I love that wine, I wish it were a bit more muffled, then it would be a cool effect on a street car. Sounds a bit like some superchargers. And RealShadow, that guy can drive, that was some Senna **** right there!
-Chris
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03:02 PM
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phonedawgz Member
Posts: 17106 From: Green Bay, WI USA Registered: Dec 2009
Slip a T-5 (Mustang + many other cars/trucks) in reverse and this gear gets slid into place to produce the reverse motion. The tranny is not in reverse in this picture. Also you can see the 'quiet' forward gears to the left here.
[This message has been edited by phonedawgz (edited 04-15-2011).]
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05:53 PM
rogergarrison Member
Posts: 49601 From: A Western Caribbean Island/ Columbus, Ohio Registered: Apr 99
Ahhhh superchargers! I love them, still but until I heard this. Richard Hammon, "Lady chattery crysis", it really does sound like a woman freaking out! Kinda wrecked it for me, but well what the hell, I love the real top gear show anyway.
