Balance Shaft

[thomas94]

Remember all 4-cylinder engines lack inherent balance in one plane. They vibrate at particular RPMs, depending on stroke, piston, rod weight, and other factors. Since the 1970s at least, Mitsubishi has installed balancer shafts to combat these harmonic vibrations.

because of the way 4-cylinders are imbalanced, there is no way to cancel all of the vibrations produced by the engine, except just those that occur in a particular range of engine speeds. Also, balancer shafts are carefully designed to combat vibration occurring in one particular engine- if you change pistons or rods to a different part or stroke the engine, or bore it larger the balancer shafts become less effective.

[bikrama]

That's very interesting info man. Let me ask my friend who re-bored his old pajero engine to get more hp.

[joseo]

Does that happen in six cylinders Pajero as well? I recently noticing the slight vibration (extra one, more than normal) on idle rpm. Might need to check this balancer issue. Any idea where its is located?