Xeno wrote:

>> If a vehicle shudders while braking, people intuit that their rotors
>> warped, and, I don't blame them for thinking that any more than I blame
>
> I, for one, know that warped rotors do not necessarily *shudder*. What's
> more, I can differentiate between *shudder* and the myriad other
> symptoms that manifest themselves from brake faults.

Hi Xeno,
I respect your experience, where I am never afraid to admit when I don't
know something since there is an almost infinite amount of knowledge that I
don't have. You have much of that knowledge that I do not have.

I respect you for that.

One thing that always confuses me is "other people's terminology".

For example when my wife explains the taste of wine, and I can never
understand what she means by the "bouquet of slight hints of pear and
lavender", etc., where the problem is the far more simple and more
scientifically descriptive words I tend to use are "sweet, salty, sour,
bitter, and umami" (which is pretty much all our tongue _can_ taste).

Likewise when she talks of colors, where she has an almost infinitely
vibrant vocabulary whereas I only have RGBIV type color descriptions.

Which brings me to shudder, shake, judder, and vibrate in terms of braking.
*Brake Judder In Detail* by Jurid (who makes my OEM BMW rear brake pads)
<https://www.jurid.com/technical-support/light-vehicles/technical-tips/brake-judder.html>
"Brake judder is the vibration felt through the steering wheel
and suspension when the brakes are applied at certain speeds
and pressures. It can vary from a barely noticeable vibration
to a violent judder - experienced either through the brake
pedal or steering wheel."

If that's "judder", then what's "shudder"?
*Brake Shudder: Why Your Car Vibrates When You Brake*
<https://www.sundevilauto.com/brake-shudder-why-your-car-vibrates-when-you-brake/>
"You step on the brake pedal and you feel a vibration coming
from the brake pedal or worse, through the steering wheel.
You hold on tight to the steering wheel as you come to a stop.
You've just experienced brake shudder, also known as brake judder."

And then what's "shake" while braking?
*Why does my car shake when I brake?*
<https://www.tiresplus.com/blog/brakes/car-shakes-when-i-brake/>
Where at least this guy put "warped rotors" in quotes. :)
>> The only difference with me is I don't trust my intuition.
>> Most people trust their intuition well neigh more than they do the facts.
>
> Intuition, for the most part, *develops* from experience.

I agree even more than you realize, because intuition is _only_ from
experience, where that's why I keep harping on the fact that we own the
innate intuition of a monkey, where, luckily, monkeys needed good depth
perception and the ability to calculate whether or not they could get to
that next branch without it cracking under the combined weight of their
body and the added force their momentum based on weight & speed incurs.

There are _many_ things I've intuited that turned out to be wrong, Xeno.
An example is I intuited (like everyone else) that cellphones are a
distraction (they are) and they're a _big_ distraction (which they are),
and that they're a big _added_ distraction (which they are), so, duh, of
course the accident rate must have shown something of an effect between the
times that cellphones didn't exist, during the times that they skyrocketed,
and then plateaued.

And yet... the accident rate didn't even change by a blip.
That's just a fact. A decidedly non intuitive fact. But still a fact.
A fact in _all_ the reliable USA (and Australia) data sets.

The accident rate only seems to change in the bullshit data sets, almost
all from those who politically and financially benefit from stating that
they go up, such as from lawyers, police, and insurance companies.

Those are the datasets that the bullshitters (like Steve) always use.

Given I agree with you that intuition _develops_ from experience, I'm not
saying intuition is always wrong. But people who trust more in their
intuition than in facts are _often_ wrong because intuition itself is
limited.

I already said even Einstein was wrong as much as he was right, and he was
one of the most intelligent intuitive observers of physics who ever lived.

It's intuitive that brake rotors could warp just as it's intuitive that
we're moving at different speeds through spacetime, but the fact is that
brake rotors can't warp (the physics won't let them) and that we can't move
at any _other_ speed but the speed of light (the physics won't let us).

People who trust their intuition _more_ than they trust facts to the
contrary are often wrong (trust me, I am well aware the iKooks do just
that).

>> My intuition says that rotors should get hot and start "warping"; but the
>> facts say otherwise, just as my intuition says that cellphones must be
>> causing increased accident rates; but the facts say otherwise.
>
> You tell that to the warped rotors I have discarded.

If the rotor met thickness, cracking, gouging specs, then you wasted a good
rotor.

Wasting rotors _always_ solves what people think is warp.
But the "warp" will come back simply because the cause of the warp is your
foot.

What people call "warp" is explained on gory detail in my half dozen
respectable references, but mostly it's simple TV which can be solved two
ways:
a. Remove the TV
b. Junk the rotors

Your choice.

HINT: If "warp" was truly a wavy rotor, then why does rebedding often work?

> FWIW, when you machine rotor, you can actually *see* the warp right up
> until they clean up.

If the experts tell me that a rotor can't warp, and if you tell me not only
can they warp, but you can _see_ the warp, then we have a conflict of data.

Rest assured, I'm extremely well educated in some of the most complex
fields of endeavor, so I'm rather familiar with conflicts of information.

When there is a conflict of information such as you presented, you have to
weigh the discordant information based on a myriad set of ancillary data
points, one of which is what you say happened is what the most experienced
racers on this planet say can't possibly happen.
*The 'Warped' Brake Disc & Other Myths of the Braking System*
<https://www.ipdusa.com/Articles/528/The-Warped-Brake-Disc-and-Other-Myths-of-the-Braking-System>

When it's inconsonant, whose mutually exclusive opinion should I believe?

>> If marketing gold plates the letters on the marquee, people "think" it's
>> better, or, more to the point, if a car simply has DTV caused by pad
>> deposition, the shop tells them they need new rotors and pads (and maybe
>> even new calipers and a few other things too).
>
> I grew up and did my apprenticeship in a relatively poor area. You
> couldn't suggest such expensive fixes to people , they couldn't afford
> it. You were forced to do what was necessary to make the car serviceable
> and *safe* to use.

Trust me on that. I have an income of zero for the past 10 years, so I keep
my expenses low and one of the ways I do that is to repair my own vehicles.

What I do NOT do though, is hold down on the brake pedal after a long hard
stop, so as to avoid (as much as I can) the TV that can occur due to a pad
footprint.

Often I'm asked to 'fix the brakes' of my wife's car or those of my kids
though, where I take it for a nice fast and hard rebedding procedure, which
almost always 'fixes' the "warped" rotors in about a dozen 60 to 10
applications on the highway at night.

Some people actually put (supposedly) more abrasive pads on temporarily, to
scrape off the TV; but I don't know where the heck they get them. Do you?

>> "By declaring a customer's brake pedal pulsation complaint is caused �by
>> warped rotors is like saying the earth is flat. Both are cases where
>> �the observation of the person is based on a tiny piece of evidence
>> �that is false in nature and application."
>
> I never say that! Pedal pulsations can be caused by *hard spots* on
> rotors. Warped disks are more likely to cause symptoms akin to a
> *shimmy* in the steering under braking.

Bearing in mind I mount and balance my own tires at home, I'm well aware
there are a billion causes of "vibrations" while driving, where only some
of those causes are even related to the brakes (see this chart for others).
*Vehicle Vibration Diagnosis Chart - Tire Rack*
<https://www.tirerack.com/images/tires/vibechart.pdf>

>> Doesn't matter if the rotor is solid or not, if they're sold in the USA,
>> they meet a spec that makes it impossible - as the fluid would boil well
>> before the rotor could get hot enough, and the rest of the brake system
>> components would disintegrate well before the rotor ever got hot enough.
>
> Hmmm, I only needed to replace my periphery melted rotor. Everything
> else worked just as well as before and I didn't even get *brake fade*.
> My intuition is telling me something.

We all have intuition, which, you and I agree, is borne of experience.

The problem is that companies take advantage of that intuition, e.g., many
people "might" intuit that a tire worn to flat rubber has "less dry
traction" than a tire with treads.... because they "think" the treads
themselves, somehow "grip" the pavement (like fingers grasping the sand).

You, I'm sure, realize that the tire tread doesn't "grip" the road, even as
advertising would have you believe that it does (we're talking macadam).

Intuition is borne of experience.
But intuition is often wrong as a result.

In fact, I'd wager that in these contentious "what oil" arguments about
cars, intuition is almost always wrong... simply because _marketing_ has
swayed people's intuition where they don't remember _where_ they got the
"experience" that they believe they have.

Why else would an iKook think that an iPhone could do half of what they
claim it can do, when it simply can't for obviously well known reasons?

Marketing tells people that their brand of API-whatever SAE-whatever oil is
"better" than the other brand, and, for some reason, people believe the
marketing because that brand costs more than the other brand (yes, I know,
some _are_ better even with the same specs, but not because marketing told
them they were).

Marketing preys on people's intuition.

Hell, you know as well as I do that I can find a billion web pages from
brake outfits saying your rotors have "warped" and the solution is their
brand of rotors... which is just marketing preying on people's intuition.

Intuition, even as it's borne of experience, is a terrible thing when it's
wrong.

Me? I don't trust my intuition more than I trust facts to the contrary.
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