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Fri Mar 01, 2013 7:50 pm

kielbasa wrote: if you want a whine... slap in a supercharger,

Fri Mar 01, 2013 7:56 pm

damicotile wrote: I like everyone's opinion on what makes the noise. I don't think anyone knows for sure. My guess is it is because they are cut straight and either too close or too loose or the machined surface whether it is rough or smooth.
It could even be the center line, who knows?
1432 has it right. The noise is caused by the contact suface of the tooth. With straight cuts, only one tooth face is in contact with the other gear at a time, and when it travels to the point where it's job is done, the next tooth makes contact and takes the load. How smoothly this occurs is a function of tooth radius and lash. When you mix and match gears, there is variation in the tooth radius, and that mismatch increases noise. As mentioned, there is case variance between the crank and cam centerlines, and also variance in gear sizes due to manufacturing tolerances. A looser lash will usually be noisier, but there are situations where the mismatch in gears can produce more noise than extra lash. We have gear makers in the family going back to my great grandfather who made gears for Henry Ford, but back then the goal was to make gears quieter, lol.
The reason helical cut gears are quiet is because there is more than one tooth engaged at a time, and the pressure transfer from tooth to tooth is more linear...

Paul

Fri Mar 01, 2013 8:27 pm

I have magnums in both my 2180 and 2332. Neither are what I would call loud. The 2180s are audible and the 2332s are almost nil for noise, but that could be partially due to the IDAs;-)

Fri Mar 01, 2013 8:33 pm

Trevor P wrote: but that could be partially due to the IDAs;-)
Of the distance between the cam and crank center lines.

Fri Mar 01, 2013 8:43 pm

Glenn wrote: kielbasa wrote: if you want a whine... slap in a supercharger,

What is that, an exhaust whistle?

Fri Mar 01, 2013 8:49 pm

Yes... easy to remove when you're sick of the noise.

Fri Mar 01, 2013 9:52 pm

Here you go this is my 2276 with magnums. I like.
http://www.streetfire.net/video/drd-2275-engine-with-strait-cut-gears_94014.htm :D

Fri Mar 01, 2013 10:11 pm

When I was taking all of my mechanics courses in college, I was taught that straight gears are easier to turn than helical gears. He also added that they're louder and less favored in many applications, so if they're easier to turn, then they free up horsepower. Even if .5%, it's still something.

Fri Mar 01, 2013 10:16 pm

The power they add is not worth the headache and price. They are only needed in k800 and bigger applications. My magnums are quiet as can be. Very nice

Fri Mar 01, 2013 10:18 pm

I think im goin with the bugpack gears . Just heard a set of them and could hear them as the car drove off. Bugpack it is.

Fri Mar 01, 2013 10:19 pm

I think im goin with the bugpack gears . Just heard a set of them and could hear them as the car drove off. Bugpack it is.

Fri Mar 01, 2013 10:19 pm

Glenn wrote: Trevor P wrote: but that could be partially due to the IDAs;-)
Of the distance between the cam and crank center lines.

It's that for sure. The 2180 measured out with tighter backlash. I was just joking in regards to the beautiful loud music the IDAs create.

Fri Mar 01, 2013 11:00 pm

Glenn wrote: You all know that straight cut gears on a street car serves no purpose. Unless you're running K800 or triple springs they are just "tits on a bull".

Totally agree, but there are some things that just tickle my fancy. :lol:

It used to be all the rage in my area for blokes to drill a 1/16" hole in each cooling vane on the alternator pulley. At high RPM, they gave a rather annoying whistle, which some were convinced sounded like a turbo. Now that's tits on a bull! :wink:

Sat Mar 02, 2013 7:29 am

Or.....since it is just "tits on a bull" and serves no purpose.......just a sound.....you could just record someone else's and play it loud over the stereo.

Sat Mar 02, 2013 7:48 am

It seems like this is the VW equivalent of sticking cards in the spokes of your bicycle?

Sat Mar 02, 2013 8:03 am

Had a set of Magnums in a street 2332 with big valves held by K800 springs. Nice and loud. :)

Sat Mar 02, 2013 11:16 am

I have Magnums in my 2165. You can't even tell I have straight cut gears.

Sat Mar 02, 2013 12:48 pm

raygreenwood wrote: you could just record someone else's and play it loud over the stereo.

Then you would just be listening to the sounds of someone else's engine. What's the fun in that?

Sat Mar 02, 2013 12:58 pm

Q-Dog wrote: It seems like this is the VW equivalent of sticking cards in the spokes of your bicycle?

Kinda. When I was a kid in the 60's I used to hitchhike up to Sears Point. I hitchhiked before dawn on the race days and often as not got a ride in an entered car up the curvy road to the track and right into the pits if the driver and I got along OK on the way. Hitching before dawn often meant a free entry along with a pit pass.

I came to love the sound of the solid lifters and straightcut gears the Vettes and Mustangs ran, and the high pitched sound of the 356 Porsche's high RPM fan too. those old Porsches whistled stock or modified.

Straightcut gears, aside the relative freedom from cam thrust bearing loss, reminds me of the sounds of those old days at Sears (and Sometimes Laguna Seca too). I don't need any more justification than that.

Sat Mar 02, 2013 2:22 pm

Altema wrote: Glenn wrote: kielbasa wrote: if you want a whine... slap in a supercharger,

What is that, an exhaust whistle?

I work with a guy that every sound his car makes, he freaks out. Im' thinking that slapping one of these in his exhaust would keep him up at night and he'd never find it. classic prank tool.