High pitch noise in race cars

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Sean24

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Can someone answer this question? What specifcally causes the whining noise in a car that changes pitch when shifting? I know if you watch any racing or own certain cars, you know what I am talking about. I have had 2 Subarus, an Impreza and a Forester, the sound is less noticable in the Forester but there is just enough insulation in to allow engine and drivetrain noise into the vehicle interior, it was really noticable in my 09 Impreza, and you can really here it when watching races on tv, in the cockpit views. I know it has to be either the transmission or perhaps the valve train right?

Anyways, I was wandering what exactly are the mechanics that cause this noise. I tried googling it, but all I got was how to troubleshoot engine noise.
 
Sean24
Can someone answer this question? What specifcally causes the whining noise in a car that changes pitch when shifting? I know if you watch any racing or own certain cars, you know what I am talking about. I have had 2 Subarus, an Impreza and a Forester, the sound is less noticable in the Forester but there is just enough insulation in to allow engine and drivetrain noise into the vehicle interior, it was really noticable in my 09 Impreza, and you can really here it when watching races on tv, in the cockpit views. I know it has to be either the transmission or perhaps the valve train right?

Anyways, I was wandering what exactly are the mechanics that cause this noise. I tried googling it, but all I got was how to troubleshoot engine noise.
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The sound you are probably hearing is straight-cut transmission. The whining noise is caused by the teeth of the gears slamming together. Its nothing to worry about and the reason why it's not audible in most road cars is that they use helical gears to keep the transmission whine to a minimum. This is the same reason (if you play racing games with a wheel) that the G25 makes a distinctive zip noise when you turn it, and the G27 barely makes a noise when you turn it.

EDIT: I don't know what crazy ideas car companies may have, but you might have "semi-helical" gears or something like that. That's why you might be hearing it quite loudly in your Subaru, but a full race transmission is going to be twice as loud as that.

EDIT 2: If you still don't understand what is meant by helical gears, here is an animation of what they look like and how they work:

 
The high pitched noises that come to mind are turbos, wastegates, and superchargers. I'm guessing turbo based on the cars that you're listing.

Edit: Good call on the straight cut transmission...
 
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It sounds to me like you're talking about gear whine, which can be very noticable on race cars.

It could also be superchargers, but to my knowledge no Subaru's have one of those. Turbos don't really whine.

An extreme example of gear whine:

 
Encyclopedia
It sounds to me like you're talking about gear whine, which can be very noticable on race cars.

It could also be superchargers, but to my knowledge no Subaru's have one of those. Turbos don't really whine.

An extreme example of gear whine:
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I love that sound.

also, quite noticeable in this video....



edit: I 🤬 love that video
 
Encyclopedia
An extreme example of gear whine:
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That guy had a pretty impressive start.

Totally unrelated to the thread, apologies. But how did that guy qualify so far back in the field, when it looks like he's just flying fast everyone?
 
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Good stuff. Thanks for the answers guys. I know it isn't a turbo/super charger noise cuz my Forester is non charged (they don't make a turbo charged version with manual anymore:( Its definitely gotta be the gear whine, but what is it specifically about the helical gears that make them whine? Is it just something inherent in the design of the transmission?

I do love that noise too. I love car noises in general. It is the best soundtrack for driving! Thats why I keep going back to Subaru I guess. They are basic and funky and the 2.5 boxer sounds great, turbo charged or not:)
 
Sean24
but what is it specifically about the helical gears that make them whine? Is it just something inherent in the design of the transmission?
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Its not the helical gears that cause whine, they actually stop the whine. The way they gradually slot together reduces the whine. Straight-cut gears (the traditional-style cogs) are the ones that cause transmission whine. They don't waste as much power as helical-cut gears, and beause noise isn't a concern in race cars, this is why they are used. Look at the video at 0:30.

 
If it changes with revs it's forced induction or something else to do with the engine, if it changes with speed it'll be the transmission and drivetrain; in a Subaru my money would be on the AWD system which is mechanical (rather than a Haldex or similar electronic clutch differential thing) and would most likely use straight cut gears for strength; that's why racing cars use them. Well that and flat shifts where you don't necessarily have to use the clutch to shift up and because of reasons. Road cars use chevron-shaped gears (think Citroen badge, which is a pair of chevrons because they were the first to use helical gears in a road car) purely so that the next gear teeth would pre-mesh and not make as much noise, there's no real benefit to them apart from that as far as I know.

This is also why cars in reverse make that whining sound, reverse gears are often straight. If you get a car up to some speed in reverse then dip the clutch the whine will continue until the car stops because it's the transmission. If it were any form of forced induction or anything to do with the engine the whining would stop as the engine returns to idle.
 
Yeah that noise is the transmission. Definitely overpowering at times, in GT5 that is, but in real life it must get annoying. However it is interesting that your Subbie is doing it.

Turbos don't produce that "eeeeee" screech, they mostly whistle. Superchargers have that whine that literally sounds like it is saying "whine" only continuously elongated.
 
If it's when shifting (coming off the throttle) it's probably the turbo or blow-off that you're hearing.

 
sumbrownkid
Yeah that noise is the transmission. Definitely overpowering at times, in GT5 that is, but in real life it must get annoying. However it is interesting that your Subbie is doing it.

Turbos don't produce that "eeeeee" screech, they mostly whistle. Superchargers have that whine that literally sounds like it is saying "whine" only continuously elongated.
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Yeah Gran turismo has always been bad with car sounds, gt5 has improved slightly since it came out, but when you start tuning a car it goes back to , as someone else described it, "a vaccuum cleaner on thick carpet"

In real life it is a wonderful component of the symphony of automotive sounds

I was surprised at how much of the engine and transmission I could hear in the Forester, I guess they keep them cheap by skimping on sound insulation, but I love it.
 
I know that straight cut gears cause the whine, but my 89 Toyota MR2 has a completely stock transmission and first, second and third gear whine like those in the videos above. Is there something about the 1980's C5x series of transmissions that make this more prominent than other transaxles?
 
That whine noise is definetly the transmission.
You can hear it in most roadcars in reverse gear, because the reverse gear is straight cut (Cheaper to produce and you don't drive backwards longer than a couple of seconds, so the noise is not a problem)
Straight cut transmissions can handle more power and torque, they are lighter, too.
Thats why you find them in race cars.
The power between the cogwheels works only in one direction, the direction the cogwheels are mounted.
In helical cut transmissions the power works in two directions, the direction the cogwheels are mounted and axial.
To handle the axial part of the force, the transmission has to be stronger, and as a result is heavier.

One possibility, why the transmission in your MR2 "whines" might be syncro wear.
But i don't think the MR2 had a straight cut transmission.

Sorry for any mistake you might find in my text, its very hard for me to explain technical things in english :)
The autocorrect on my iPhone is set up for german, that doesnt help either.
 
Thank you for all the imput, I can conclude that it is straight cut gears in the transmission of racing cars that make the whine, and although production cars use helical gears, they probably still produce a whine, and if your vehicle has insuficient sound insulation, the transmission will be audible.
 
Sean24
Thank you for all the imput, I can conclude that it is straight cut gears in the transmission of racing cars that make the whine, and although production cars use helical gears, they probably still produce a whine, and if your vehicle has insuficient sound insulation, the transmission will be audible.
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The Nissan GT-R comes to mind here.
 
SIC EM (Subaru WRX) has a similar sort of whine to it although much quieter than race cars. Personally I love it. The combo of the transmission whine, the Boxer 4 (w/modified exhaust in my case) and the turbo whistle when it spools up makes for a great sound I reckon.
 

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