Category Archives: Balancing

Balancing the crankshaft and entire rotating assembly can reduce engine vibration and improve durability.

Engine Balancing

In an internal combustion engine, the crankshaft must rotate at high RPMs. As this rotation occurs, vibration can become more profound. Vibration will not only reduce horsepower in high performance engines, but it can cause internal engine components to prematurely fail. Because of this, engine balancing is necessary.

Bobweight SetBalancing an engine requires simulating the weights of the pistons, piston pins, rings, connecting rods, engine bearings and even the oil with what is known as a bobweight (set pictured left). The bobweight accepts individual weights and is secured to connecting rod journals before the crankshaft is spun in a balancing machine. To calculate these weights, and create a bobweight, we must first look at the connecting rods and the components that appear on each end. The large end of the connecting rod, which is affixed to the crankshaft with bearings, is the rotating end. The small end of the connecting rod actually uses a reciprocating motion when the engine is operating. In calculating the weights for balancing, the rotating and reciprocating weights are used in the formula. Continue reading