Counter balance shaft side clearance

[cuong-nutz]

Is the side clearance for the counter balancer crucial? The 250 and 300 FSMs did not mention anything regarding it? There is a good amount of axial movement of the countershaft in the 300 case. The bent weight on the 300 balancer cut a groove in the case.

[Motofool]

Originally Posted by cuong-nutz

.........There is a good amount of axial movement of the countershaft in the 300 case. The bent weight on the 300 balancer cut a groove in the case........

Normally, in order to reduce friction, a thrust washer between a step of the shaft and the case is used for any shaft that transfers some axial load.

In such a case, limiting hitting other parts is all the designer takes into consideration.

I don't know how the countershaft in the 300 is; however, if a shaft is powered by a gear which teeth have certain angle (helical), then there is a lot of axial force or thrust being exerted as a result of that angle.

Copied from:
http://en.wikipedia.org/wiki/Gear#Helical

"A disadvantage of helical gears is a resultant thrust along the axis of the gear, which needs to be accommodated by appropriate thrust bearings, and a greater degree of sliding friction between the meshing teeth, often addressed with additives in the lubricant."

[cuong-nutz]

The 250 and 300 share the same design except it has heavier weights

[tubarney]

If there is supposed to be movement (which I doubt); there isn't supposed to be that much.

Machining error. Could be crank (that sprocket is almost impossible to move), balance shaft itself or cases.

[mgentz]

My shaft did not move side to side at all.