Helical vs Straight Cut 5th Gear
Road Warrior
Joined: Nov 2006
Posts: 1,462
Likes: 121
From: Northern Illinois
The 5 speed tranny was straight cut for all gears. OL whining is definitely more annoying than any 5th gear whine!!
Tourer
Joined: May 2009
Posts: 332
Likes: 0
From: Smithfield, NC
Mine makes a little noise, but not much. I have stock pipes, so I hear a lot of mechanical noises, but that 5th gear noise is really not intrusive at all. Maybe I'm lucky and don't have a loud one, but I probably never would have even thought about it if I hadn't read about it here. Just ride!
That being said, I would guess that a helical gear is not going to weaken things enough to start seeing any failures either.
That being said, I would guess that a helical gear is not going to weaken things enough to start seeing any failures either.
Cruiser
Joined: Aug 2008
Posts: 162
Likes: 3
Did a little research and here is what I came up with.
In short, helical gears operate quieter than straight cut. Straight cut will 'whine' the faster they go but offer both:
A. More directional application of force allowing for less power loss.
B. Higher acceptable loads until failure. Basically making the transmission stronger and more efficient. However though, like noted before, car manufacturers don't use straight cut due to the noise the transmission will produce.
A good example of this is that the reverse gear in most cars is straight cut.
Racing transmissions also differ from street transmissions by running straight-cut gears. Straight-cut gears are stronger than diagonally cut helical gears found in most street transmissions because engine torque is spread out over a larger contact area between the teeth. The downside to straight-cut gears is they generate a lot more gear noise than helical gears.
Conclusion: The whine that we all have in 5th gear is a beautiful sound. I have an 08 and still love it, but I believe that you guys that bought the 09’s have a better bike than the 2010’s. Plus the 2010’s have the Cat in all the head-pipes and I hear that the 09’s can be had for 1K to 2K below MSRP.
In short, helical gears operate quieter than straight cut. Straight cut will 'whine' the faster they go but offer both:
A. More directional application of force allowing for less power loss.
B. Higher acceptable loads until failure. Basically making the transmission stronger and more efficient. However though, like noted before, car manufacturers don't use straight cut due to the noise the transmission will produce.
A good example of this is that the reverse gear in most cars is straight cut.
Racing transmissions also differ from street transmissions by running straight-cut gears. Straight-cut gears are stronger than diagonally cut helical gears found in most street transmissions because engine torque is spread out over a larger contact area between the teeth. The downside to straight-cut gears is they generate a lot more gear noise than helical gears.
Conclusion: The whine that we all have in 5th gear is a beautiful sound. I have an 08 and still love it, but I believe that you guys that bought the 09’s have a better bike than the 2010’s. Plus the 2010’s have the Cat in all the head-pipes and I hear that the 09’s can be had for 1K to 2K below MSRP.
Road Master
Joined: Feb 2007
Posts: 990
Likes: 0
From: Trinity Al
I had a whine until I change the trans oil the first time . I now have 52000 miles and ride it like i wasgoing to die the next day. Drag race and get 8.6 in the 1/8 mile at least once a month. Will have her 3 yrs in November. A set of plugs and 11 rear tires and no problems yet. Harleys have the best soul over the others.
Intermediate
Joined: Nov 2006
Posts: 42
Likes: 0
From: Bartlett, IL
Not really wrong, more correctly - not preferred construction for a transmission gear (1st gear not included). It's just cheaper to produce a spur gear, and by it's design will be noisier than a helical.
The angled teeth of the helical gear engage more gradually than do spur gear teeth. This causes helical gears to run more smoothly and quietly than spur gears.
The angled teeth of the helical gear engage more gradually than do spur gear teeth. This causes helical gears to run more smoothly and quietly than spur gears.
Tourer
Joined: Aug 2007
Posts: 429
Likes: 1
From: California
It's simple. Harleys always used straight cut gears in their trannys. The camshaft was always geardriven too. Listen to old car trannys, they whine in lower gears. Listen to a knuckle, pan or generator shovel, they whine too. I remember the school bus whining in low every morning. In years past Harley riders understood their bikes, most could work on them, and had grease under their fingernails. A little whine running through the gears sounded cool. Now days a lot Harley riders, not all, can't even ride their bikes (they trailer them to rallies) let alone work on them or understand what makes them tick. Read this forum if you think that's not true. Grease under their nails, heaven forbid! If it don't sound like a Lexus or whatever it's atrocious. "Screw 'em" I say, but Harley depends on these guys to buy bikes. These guys have more dough than guys like me, and are more easily seperated from it. So, to cater to the ignorant uninformed public they changed the tranny to a less durable more expensive design. It's all about sales! Imagine that, and the yuppies will post about the "improvement".
dude---- friggin' well-said
Road Captain
Joined: Aug 2008
Posts: 687
Likes: 2
From: Wisconsin
I am with you there, I dont have a problem with it at all.
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Club Member
Joined: Feb 2007
Posts: 5,335
Likes: 0
From: Tidewater
My guess is they were running out of things to change and this seemed logical since they got so many complaints over it..Like others, I never noticed it..Music and engine are louder than any dam whine..lol
