Static balance refers to weight-matching individual parts. Dynamic is "moving" balance, the vibration caused by spinning a part that has a heavy spot somewhere.
In the case of wheel balancing, a static imbalance can be corrected by finding the heavy spot and installing a compensating weight directly opposite it. Dynamic balance comes in when the heavy spot is off-center, and induces a shake as the wheel turns. A static-balanced wheel and tire (bubble balancer) can still shake when it's in motion due to dynamic imbalance. Compensation of dynamic wheel imbalanced is done by installing the weight diagonally from the heavy spot. Modern computer balancers figure static and dynamic balance at the same time, and compensate with only one weight on each side of the wheel. Ditto for weight-matched engine parts when the crankshaft is out of balance, weight has to be added or removed to cancel out the shake after the parts are weight matched. The 120 degree separation of weight masses on an inline six make it much more likely to be in balance from the factory.
Jerry
Last edited by Hotrod Lincoln; 08/28/2010 5:15 PM.
