How-To: Detect-Avoid Harmonics

Sven

Well-Known Member
This is a basic how-to avoid creating a new pattern on moving parts. When two parts mesh together over and over, they have a matching footprint between themselves. These parts can be described as:

1. Chain to sprocket.
2. Belt to pulley sprocket.
3. Primary chain to crank sprocket.
4. Primary chain to clutch basket.
5. Clutch basket gear to crank gear. [diff engine design]
6. The transmission's gear to gear.
7. Cam sprocket to hi-vo chain. [h-d eng design]
8. Crank sprocket to hi-vo chain...

... Are a few of the moving parts that can be detected to create a new harmonic: if the mesh is assembled out of time. However, the list can be mismatched without a catastrophic occurrence happening. Only think that may happen is a new wear pattern to begin again, a buzz, or a harmonic may show up.

The 4x4 transfer cases in a GM Suburban use hi-vo chains. A bulletin came out about harmonic complaints coming from under the floorboards > after a transfer case was rebuilt. The engineers answer was to mark the hi-vo chain to the opposing gears so they would mesh as before.

If you apply this type of marking before removing the rear tire to change out, it would be a smart way to avoid an induced harmonic that is just one tooth away from hearing one come down the road in a waaa-waaa sound the chain makes [belt may buffer that however]. Still, a tooth is a tooth and that begins a new wear pattern if mismatched.

If you think taking your bike in for service will have this sort of attention to replacing a tire, I doubt most places do not go thru these steps with the engine tear down, so I do not expect it with a belt/chain to sprocket. The only way to avoid this is to do it yourself.

Signed,

NOLTT (no one listens to turtle)

[ame=http://www.youtube.com/watch?v=jKwN2X03xNc]Classic quote from movie "North Shore" - YouTube[/ame]
 

kickstart

Well-Known Member
It's a process used in industry called Match Marking, really helps while putting things back together.
 
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