No engine vibrates when it’s shut down, so how does crankshaft RPM turn into vibrations and how can we ‘unwobble’ them? The first and most familiar shake comes from the effect of a sequence of power strokes: as the piston pushes the connecting rod down to turn the crankshaft, the connecting rod and the engine load in turn push the piston sideways against the cylinder wall, cushioned by a thin layer of oil.