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View Full Version : straight cut gears.... ok i don't want them.



ooberdoob
01-10-2007, 08:40 PM
http://www.youtube.com/watch?v=dmJH84FnQa8&NR

Superu264
01-10-2007, 08:56 PM
my speakers exploded

Wiscon_Mark
01-11-2007, 12:10 AM
duh!

You want a dogbox instead ;)

jjs316
01-11-2007, 12:31 AM
my speakers exploded


x2

Perdue
01-11-2007, 06:11 AM
Jesus that's loud. If I heard that thing coming up behind me on the street or highway, I'd be flipping out. OMG t3h aliens r 4 real!!

shazapple
01-11-2007, 12:14 PM
Your reverse gear is straight cut. Imagine that in 5th ;)

strat81
01-11-2007, 12:52 PM
i'm thinking insulation and carpeting and such would help quiet that down a bit

i'd rock them... it'd mean no broken tranny... just have to learn to perfect double clutching

deadlydave
01-13-2007, 12:35 AM
i'm thinking insulation and carpeting and such would help quiet that down a bit

i'd rock them... it'd mean no broken tranny... just have to learn to perfect double clutching

Penn. laws may be different, but in NY we have sound level restrictions...i honestly don't think anyone could drive that without getting ticketed. I'd imagine that sound is not particularly healthy for your ears either.

Wiscon_Mark
01-13-2007, 11:48 AM
Over the road noise and such, I doubt it'd be nearly as loud outside. I mean you're literally sitting right next to it when you drive, and the vibrations and noise translate through the frame of the car to you very easily.

It's like my exhaust...at a certain RPM, it tends to resonate in the cabin, but it's really not that loud outside.

And put it this way: if the cop thought it was you and pulled you over, you could turn the car on and he wouldn't hear it because you wouldn't be moving ;) (I sincerely doubt most policemen know what straight cut gears are or what they sound like).

That being said, I wouldn't drive with 'em :shock:

Reason
01-13-2007, 12:09 PM
Like Lee said, reverse is a cut gear. And only going blank miles an our in reverse, I can hear my neighbor reverse out her driveway with my windows up. If that were regular drive gears it would be ridiculous. Depending on the cop you can get away with loud exhaust on car/bikes. But any cop will pull you over doing 3rd screaming down a street.

Having a rug or standing outside of the car wont be a dramatic difference. Regardless, your car will sound like a Banshee straight out of hell.

OutbackGT
01-13-2007, 01:58 PM
What exactly are straight cut gears? How are they different from regular gears?

ooberdoob
01-14-2007, 10:04 AM
||||||||
vs
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Sarra
03-14-2007, 10:38 PM
PPG gears aren't nearly that loud, from what i've seen on Dynos.

shazapple
03-14-2007, 11:05 PM
Helical gears
https://sl-i.net/FORUM/images/imported/2007/03/gear2-1.jpg

straight (spur) gears
https://sl-i.net/FORUM/images/imported/2007/03/gear1-1.jpg

Mostly the difference is sound

Sarra
04-01-2007, 01:32 AM
Helical gears are 'stronger' because more than just one tooth is engaged at a time, whereas straight cut gears are 'stronger' because they were designed that way. :?:

Also keep in mind, that's a fully track prepped car. They removed all of the insulation between the gearbox and the cockpit of the car. In a normal, daily driven car, straight cut gears woudln't be nearly that loud, and since the transmission is in the gear tunnel, they wouldn't be that audible outside the car either.

rallysam
05-01-2007, 04:22 PM
+1 for that's louder than normal for straight cut, even with stripped insulation. Maybe his gears are tortured, maybe there's something else special about his setup. Maybe the camera was picking up the sound through the mount to the solid frame.

sheepdog
05-01-2007, 06:17 PM
Yea, I've personally ridden in a car with straight cut 1st-4th and its not nearly that loud. Its more like a supercharger whine than anything.

Rockgod
10-02-2007, 10:31 PM
OMG I would rather listen to a really fat virgin on her wedding night than drive a car with gears that loud. Want the speed but not the sound. It's like listening to a band saw on metal.

sharky nrk
10-02-2007, 11:02 PM
Helical gears are 'stronger' because more than just one tooth is engaged at a time, whereas straight cut gears are 'stronger' because they were designed that way. :?:

Also keep in mind, that's a fully track prepped car. They removed all of the insulation between the gearbox and the cockpit of the car. In a normal, daily driven car, straight cut gears woudln't be nearly that loud, and since the transmission is in the gear tunnel, they wouldn't be that audible outside the car either.

have to jump on this one as its actually not true - although that may be why the question mark it there

spur gears (straight cut gears are spur gears) have teeth that are straight and arrange parallel to the axis of the shaft that carries the gear. They feature a involute curve that allows them to mesh in a smooth manner.

a helical gear is a gear with the tooth set at an angle relative to the shaft axis. The helix angle can be almost anything but anything over 45 degrees is not really practical. anyways the helical teeth are set at an angle to allow a smoother operation that a spur gear, and are not actually stronger but the stresses are lower than in a comparable spur gear

One of the issues with a helical gear is the introduction of the axial force, the thrust force that causes the gears to create a driving force tangent to the shaft axis line. This requires bearings to be used to resist the force.

the reason for straight cut gears is simple, in a helical gearing you limited by the helix angles, tooth geometry, and thrust issues. If helical gears are to be used you are limited on sized and spacing of the gears relative to one another. A spur gear can be designed with much larger face width (thickness of the gear) and less teeth to physically make the addendum/dedendum (height of the tooth) and tooth thickness larger. This will make the gears much much stronger but at a loss of smoothness.

this doesn't include the spacing concerns when deleteing synchros and going with dogs (more space bigger gears ect ect) but you can have dog engagement helicals and straight synchro boxes as well


OK so its late and I probably just babbled for no reason - years of power transmission design classes to earn a engineering degree can do that

Wiscon_Mark
10-02-2007, 11:24 PM
No, that was very informative, thank you.

Sarra
01-31-2008, 11:12 PM
I believe that this car is so loud due to the camera being mounted directly to the roll cage, and it's transmitting sound directly from the gearbox to the camera mic. So, sitting in the car, it woudln't be that loud.

gsh
02-01-2008, 12:35 AM
If your gearbox is too loud ... your exhaust is too gentle :lol:

http://www.youtube.com/watch?v=1q8ZNkhxT04
http://www.youtube.com/watch?v=CRt0epipxQI <-- this is weird!