how do you balance a crankshaft?

Question

what is the concept of balancing crankshafts.I know they have machines to do it but whats the concept?

Answer 1

It is not just the crank that is balanced. The machine shop will balance the entire rotating assembly. Crank, rods, pistons, flywheel, pressure plate, harmonic balancer. Everything needs to be within a certain tolerance. It is the same concept as balancing your tires, anything that rotates needs to be balanced otherwise there will be horrible vibration. Have you ever been in a car that has horribly unbalanced tires? Same concept

Answer 2

You seem to be leaving something out but yeah, an off balance crank will cause a crank to fail

Answer 3

It's sort of like balancing a tire.If it is a little too heavy at one point it causes vibration or worse.They do this at the factory

Answer 4

the crank is spun and holes are drilled to remove material to balance it
in some cases a crank shaft balancer is installed instead of drilling

Answer 5

well they do that to have a smoother running motor with more power less friction

Answer 6

http://en.wikipedia.org/wiki/Engine_balance

http://members.aol.com/pullingtractor/balance.htm

maybe this will help