Vibration When Shifting Kansaki (yanmar) KM3 Transmission

[F10]

Originally Posted by Matsubob

Thanks for your comments, F10. Without getting into technicalities, I may have overstated a bit, but my point was that the damper plate on a boat has much lighter duty than on a car. (and, technically, it is the flywheel and "harmonic balancer" that balances out the pulses on a multicylinder engine; the damper plate absorbs shock when applying power to the drive train).
All of that aside, the damper plate seldom fails, unless something inside, like a rivet or spring has broken. Based on the post, something of that nature would not cause the engine to not stop and begin running roughly, so I was simply saying that the symptoms point more to fuel/firing or other engine related issues
Sorry for the confusion.

I am no expert on damper plates and harmonic balancers, although I have been learning a lot in the last few weeks. However damper plates do absorb impacts of the explosion effects on the piston, apparently they are used on both boats and land vehicles:
Vibratech Heavy Duty Diesel Dampers

Harmonic balancers serve a different purpose, they take care of torsional harmonics of the crank shaft:
https://en.wikipedia.org/wiki/Harmonic_balancer

You also say damper plates seldom fail. Well the space shuttle seldom fails, but some times it does, so not really sure how useful that statement is. And the fact a failed damper plate (cracked plate, or broken or loose, or missing spring) will be most noticeable when first engaging into gear was similar to what I was seeing. I may still have a problem with my damper plate, perhaps the springs have become week and if I have a fouled prop, that is enough to take the damper plate to its limits, time will tell.


Here is more interesting reading:
http://www.alberg37.org/Project%20DB...te_Install.htm

[F10]

Final update. Took boat out yesterday and had no vibration issues. Shifted in all gears smoothly with no vibration. Engine is idling between 850-900 rpm (as per spec). So problem was probably fouled prop (barnacles) and also maybe lowering idle rpm helped with damper plate vibration.
Regards.