"Xeno" wrote in message
...
On 4/5/19 1:05 am, Arlen G. Holder wrote:
On Fri, 3 May 2019 20:02:29 +1000, Xeno wrote:

On a modern car it's a waste of time.

Hi Xeno,

Most people who posted to this thread, IMHO, have proven that they own
completely imaginary belief systems, where the logical proof is that
their
ludicrous excuses instantly failed the simplest of the simple tests of
any
belief system, which is the three words when someone declares an opion
o Name just one FACT from which that belief system is based upon.

Given these vehicles I'm working on are all about two decades old (give
or
take), can you name just one FACT that supports your belief system stated
above?

I'm not saying your belief system is correct, nor am I saying it's not
correct, since you stated your belief system clearly, but you didn't
state
even a single fact that backs up that strongly held belief system.

What FACT is your strongly held belief system actually based upon?

A number of *facts* prime among them being my training and involvement in
the automotive industry as a mechanic since the 60s. First and foremost,
it's clear from what you have written that you do not understand the
concept of *dynamic unbalance* and the ramifications it has for anyone
doing a *static* balance. You make too many assumptions based on your
*limited* experience and minimal training.

First, assume a tyre with a heavy spot central to the centreline of the
tread. this tyre is only in static unbalance. This will cause only wheel
tramp, ie. the bouncing of the wheel and tyre assembly up and down and
should not have any effect on the steering (shimmy). This type of
imbalance can be statically balanced but it requires a little common sense
when applying balance weights. If you apply balance weights incorrectly
you can remove static unbalance but create dynamic unbalance.

Not something likely to be seen with a new tire and no ****ed wheel.

Second, assume the same tyre but with the heavy spot over to one side of
the tread and away from the centreline. This tyre is not only in static
unbalance but it is also in *dynamic unbalance*. It will cause wheel tramp
but also steering shimmy.

Again, not something likely to be seen with a new tire and no ****ed wheel.

The issue here is that a static balancer will not tell you which side of
the tread area the heavy spot is, only that it is on that side of the
wheel/tyre assembly. That means that when you add balance weights to the
opposite side of the rim, you need to add weights to both sides. You look
at the counterweight needed, then halve it and add half to each side of
the rim opposite the heavy spot. Might add, when carrying out a static
balance you need to always use balance weights on both sides of the rim at
the light spot, even in cases that are clearly only statically unbalanced,
else you will potentially end up with a dynamically unbalanced wheel. This
type of dynamic unbalance can only be reduced, on average, by 50% even if
the static balance is corrected 100%. The point here is that your steering
joints will be affected by the unbalance

Third, now assume a wheel that has two heavy spots, one each at opposite
points on the wheel diameter.

Again, not something likely to be seen with a new tire and no ****ed wheel.

To a static balancer, this wheel assy. will be balanced producing no wheel
tramp. However, assume one heavy spot is located at the *outside* of the
tread centreline and the other on the opposite side located on the
*inside* of the tread centreline. The wheel is, if both heavy spots are of
the same mass, will evince no tramp but will show up as steering shimmy,
the severity of which will depend on the amount of imbalance and the
distance it is located from the tread centreline. It is caused by the two
masses attempting to alternately get to the centreline. Note too that the
type of suspension system and the steering geometry can play a significant
role in the sensitivity to unbalanced wheels.

So, of the 3 imbalance situations, a static balancer can fully address the
first and only partially address the second depending on the mass
location.

But not something likely to be seen with a new tire and no ****ed wheel.

In the case of the third imbalance situation, the static balancer is
totally useless. So, to ensure correct balancing over all situations, a
dynamic balancer is the only choice to be made.

As to the situation where, in the past, static balancers covered most
bases, what has changed today? It's simple really, older cars had narrow
tyres fitted to large diameter rims so less prone to dynamic unbalance
effects. Today's cars have much wider tyres so accentuating the
possibility of dynamic imbalance.

In theory. In reality even the cheapest new tires are unlikely to be a
problem.

Road speed with respect to wheel assy. diameter plays a role in this. That
brings me to truck wheel balancing.

He is talking about car tires, not trucks.

Given the large diameter and relatively narrow section width of truck
wheels, static balancing is Ok for most cases. In these cases, on vehicle
balancing, usually of front wheels only, is carried out using equipment
like this;
https://www.bigwheels.net.au/on-vehicle-wheel-balancer

I have done this task many times since the late 60s when I first entered
the trade and I can attest to the efficiacy of this type of balancing for
truck wheels. That, however, was in the past and trucks now travel at
relatively high speeds so dynamic unbalance with consequent steering
shimmy has become an issue with truck wheel balancing. In this case you
*need* an off vehicle dynamic balancer like this;
https://www.bigwheels.net.au/off-vehicle-wheel-balancer

I must add too, just because you feel no vibration or shimmy from the
wheels doesn't mean no imbalance exists. What it means is that the effect
is not being transmitted through to you, the driver. The steering and
suspension may well be feeling the effects and this could cause aggravated
wear in suspension and steering joints. Power steering, for instance, has
an effect on nullifying road feedback. After all, manufacturers adopted
power steering on FWD vehicles in order to reduce or nullify the effects
of unwanted feedback, in this case torque steer.

They actually did it to make the parking forces less of a problem.

What would you do if you had a vehicle that had a vibration in the front
through the suspension akin to wheel tramp?

Not something likely to be seen with a new tire and no ****ed wheel.

Let's assume you static balanced the wheels with no luck. You checked the
tyre for runout, the rim for runout and the tyre to rim concentricity -
all perfect. A spin up on the dynamic balancer shows the wheels are
perfectly balanced both statically and dynamically yet that vibration in
harmony with road speed persists. Where do you go now? Balance is perfect,
runout is perfect, concentricity is perfect, what is left?

Not something likely to be seen with a new tire and no ****ed wheel.