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Balance problem after flywheel relocation

Started by veggie, May 01, 2010, 11:11:06 PM

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veggie


After locating my flywheel further from the engine to accommodate an inboard belt drive, the side with the new drive is bouncing more that normal.
Enough to cause the normally well behaved unit to start walking across the floor.
Perhaps the flywheel is out of balance and the condition was accentuated by moving it 3" further away from the engine. :-(

or....perhaps I should have moved both flywheels the same amount ??
the sketch below shows the current placement of the wheels.

One more thing....the crank has counterweights and the flywheels have drill holes on the inside faces (balancing ?)

veggie

Crofter

Veggie, if your engine has the counterweights bolted to the crank as the compensation for the rod and piston, then the flywheels should not have any individual eccentric weight factor. That said, the lumps on the crank opposite the throw are an imbalance in the fore and aft direction so should be in the center of lateral mass, not off to one side; having one flywheel considerably farther out will induce some oscillating effect viewed from above. Occillation viewed from front or rear would be induced to a lesser extent but still theoretically affected by having the flywheel positions off center to any great amount.

In the event that there was any imbalance in the particular wheel that you moved out, it would then have a greater effect from being further away from the center of mass. The same discrepancy in flywheels positions will have more effect on a single than on the greater mass and wider distribution of the twin setup. I am not suggesting that you move the other wheel out (except as a trial) but it might restore the composure of your engine ;D Best keep the weight as close to the supports as possible and as near to the power pulses input.

This is splitting hairs a bit really, as the imperfections of individual castings and combinations could be enough that your engine actually ran smoother with one or the other wheels offset: in a perfect world though, symmetry rules.
Frank


10-1 Jkson / ST-5

billswan

Veggie

Don't give up have sent PM.

Billswan
16/1 Metro DI at work 900rpm and 7000watts

10/1 Omega in a state of failure