On 4/5/19 7:18 pm, Rod Speed wrote:


"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.

Seen on new tyres including those fitted to new vehicles.

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.

Seen on new tyres including those fitted to new vehicles.

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.

Seen on new tyres including those fitted to new vehicles.

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.

Seen on new tyres including those fitted to new vehicles.

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.

Seen on new tyres including those fitted to new vehicles.

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.

Balance a car wheel or a truck wheel, it's all pretty much the same
deal. The exact same principles are involved.

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;
Â*Â*Â* 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;
Â*Â*Â* 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.

They actually did it to make torque steer less of a problem with the
universality of PS on all FWD cars.

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.

Seen it in new cars under factory warranty - when warranty was 12/12
and/or 12/20. The dealership in which I was working at the time had a
specific diagnosis method for it which isolated the issue immediately.

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,Â* concentricity is perfect,
what is left?

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

Seen it in new cars under factory warranty - when warranty was 12/12
and/or 12/20.



--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)