Gentlemen
I'm sure that in this august group there is someone with theoretical and
practical knowledge of wheel balancing.
I think I understand the difference between static and dynamic balance. A
freely pivoted wheel which is in static balance will remain in any position to
which it is rotated. However, the weight may not all be in the same plane:
that is a heavy point on the out-facing rim of the wheel may be
counterbalanced by a heavy spot diametrically opposite, but on the in-facing
rim of the wheel.
If this is the case, when the wheel spins the heavy points will act together
to twist the wheel at right angles to its axis of rotation, and it will
wobble. It is not in #dynamic# balance, and will require appropriate balance
weights added to the in- and out-facing rims to achieve this and stop the
wobble.
As I understand it, the difference between static and dynamic balance is small
for large diameter, narrow wheels/tyres (MMM and TABC) and absolutely crucial
for small diameter, wide tyres (most more modern cars).
I've just watched a friend balancing the 19" wheels for our J2. He was using
an old (but I believe reliable) wheel balancing machine: it has a setup rather
like a front stub, so that an unbalanced wheel causes a considerable wobble in
the shaft. A mechanical indicator guides the operator on where balance weight
is required.
Each wheel had weights progressively fitted until it spun true on the machine,
but in most cases the wheel in not in #static# balance at the end, and I don't
see how this can be.
Would our experts please enlighten me?
Regards
Dave Dwyer
J2 - I havn't had a chance to try the wheel balance on the road yet!
TA, TC
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