As your engine wears over time, so does the reciprocating parts that keep it running. Rebalancing your engine requires ensuring that all its working parts are oiled, weighed, smoothed, and operating correctly. If the rotating components of your engine (crankshaft and the lower half of the connecting rods) aren’t correctly counter-balanced, the crank cannot spin smoothly on its axis, which damages its function.
Although essential, engine balancing is not a huge priority for a vehicle with factory parts. It is more intended for drivers looking to optimise performance. When adding customised parts to your vehicle, you use parts not explicitly designed for its make and model. Therefore, it is of the utmost importance they are balanced correctly with the other components in the engine.
Imbalanced engines produce noise vibrations that can be felt through the chassis and drivetrain, regardless of whether you are pushing the car to its limits or not. Eventually, the effects will wear on your engine and engine mounts. As previously mentioned, engine balancing is not an immediate concern for street vehicles unless you want to maximise performance or are concerned about prolonging the life of the bearings and crankshaft.