|
|
On 8/2/2011 5:05 AM, David Leonard wrote:
... I am starting to think that the whole science of balancing is just a gimmick. Despite the old balance hole being mostly drilled away, the new balance holes are on the opposite side of the flywheel. !??
Dave,
Balancing is a procedure that falls right on the edge between science and black art. At high RPMs, changes "out of plane" can become critical.
As an example, when I started balancing wheels all we had were bubble (static) balancers, and - because the weights had to go on the rim edges - we would find the amount of weight, then split it, e.g. two half ounce weights, one on the inside and one on the outside. ~Most~ of the time it would put give good freeway speed balance. Sometimes, though, we'd still get an out-of-balance wobble in the wheel due to the imbalance being off center of the c.g. plane of the wheel.
Then affordable (for a small shop) dynamic balancers came along, and we discovered that, most of the time, less weight was required on one side of the wheel than the other, often not even opposite each other, to bring the center of balance the same as the center of rotation.
Drilling balance divots on only one side of something like a wheel can create a similar situation - where the static balance is correct but the center of balance is no longer the same as the center of rotation. It takes sophisticated equipment and an equally sharp operator to get it right.
BTW, FWIW ... For an average car tire with 25" diameter at the tread, at 60 MPH, the wheel is turning ~7950 RPM.
--
Dale_R
Cozy MKIV #497
|
|