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Why can't people figure out warp versus runout versus disc thickness variation



 
 
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  #1  
Old August 7th 18, 03:05 AM posted to alt.usage.english,rec.autos.tech
Arlen Holder
external usenet poster
 
Posts: 98
Default Why can't people figure out warp versus runout versus disc thickness variation

Why, for Christs' sake, can't people figure out the difference in the
English language between warp versus runout or disc thickness variation?

There has been a perennial argument since the 70's when someone got the
notion that brake rotor (aka disc) "warp" is the same as "dtv" (which it's
not), where it can't be shaken out of their heads that they are two
completely different things. Likewise with "runout".

Witness this reference posted in good faith to the home-repair group today:
<https://groups.google.com/d/msg/alt.home.repair/mIcLF2bSnU8/3sE9Wi1ODgAJ>

Which referenced this paper:
<https://link.springer.com/article/10.1007/s11665-012-0397-7>
Titled:
The Effect of Residual Stress on the Distortion of Gray Iron Brake Disks

In that paper, the Asian authors *continually* appear to callously abuse
the English language by confusing the term "warp" with "disk thickness
variation (DTV)", which is completely different from warp (as in a potato).

For example, you can have a warped sheet of metal where the thickness
variation is zero, and you can have a thickness variation without warp.

If this was a high-school kid equating the two, I'd shrug it off as
ignorance; but this is an engineering paper, for heaven's sake.

Here is the first sentence where they appear to abuse the English language:
"It is known that disk warping or uneven disk thicknesses
induce pulsation during brake applications."

Clearly it is well known that "warp" (as in potato) and "uneven thickness"
are two completely different things - which means that this particular set
of Asian authors (M. W. ShinG. H. JangJ. K. KimH. Y. KimHo Jang) are likely
ignorant of what "warp" actually means - or - they simply assume that it
means something that it doesn't mean (i.e., warp and thickness variation
are completely different things - they just are).

They then compound their abuse of the English language in a sentence not
far from that last horrid sentence, saying:
"When the disk temperature is increased by friction heat during braking,
the heat often causes dimensional instability of the disk,
permanently modifying the runout or disk thickness variation (DTV)
of a disk and producing brake judder."

This sentence clearly appears to indicate the authors have no clue how to
use the English language because it's a fact that runout and DTV are also
two completely different things.

============ terms below ==============
Stop the ¡Warped¢ Rotors Myth and Service Brakes the Right Way
http://www.brakeandfrontend.com/warped-rotors-myth/

BTW, if you skim the paper, these two definitions may be useful:
Gray Iron
<https://www.merriam-webster.com/dictionary/gray%20iron>
"pig or cast iron containing much graphitic carbon which causes
its fracture to be dark gray"

Residual Stress
https://en.wikipedia.org/wiki/Residual_stress
"Residual stresses are stresses that remain in a solid material after
the original cause of the stresses has been removed."
Ads
  #2  
Old August 7th 18, 03:31 AM posted to alt.usage.english,rec.autos.tech
Paul in Houston TX[_2_]
external usenet poster
 
Posts: 201
Default Why can't people figure out warp versus runout versus disc thicknessvariation

Arlen Holder wrote:
> Why, for Christs' sake, can't people figure out the difference in the
> English language between warp versus runout or disc thickness variation?


> <https://link.springer.com/article/10.1007/s11665-012-0397-7>
> Titled:
> The Effect of Residual Stress on the Distortion of Gray Iron Brake Disks
>
> In that paper, the Asian authors *continually* appear to callously abuse
> the English language by confusing the term "warp" with "disk thickness
> variation (DTV)", which is completely different from warp (as in a potato).


To be sure of their meaning, you will need to be fluent in Korean
and read the original paper in its native language, Korean.
https://www.boredpanda.com/funny-chi...slation-fails/


  #3  
Old August 7th 18, 03:46 AM posted to alt.usage.english,rec.autos.tech
Arlen Holder
external usenet poster
 
Posts: 98
Default Why can't people figure out warp versus runout versus disc thickness variation

On 6 Aug 2018 19:31:14 GMT, Paul in Houston TX wrote:

> To be sure of their meaning, you will need to be fluent in Korean
> and read the original paper in its native language, Korean.
> https://www.boredpanda.com/funny-chi...slation-fails/


I'm not sure the paper is actually written originally in Korean, are you?

The authors seem completely ignorant that the word "warp" has two different
meanings, one of which is the colloquial abuse of the word, while the other
is the technical use of the word.

Given that it's a technical paper, I'm astounded that they used the
colloquial term, and even more so astounded that we can assume that's a
peer reviewed paper, where one wonders how it got accepted given the horrid
abuse of the English language.

Given the paper equated "warp" with DTV & lateral runout, this description
is apropos to describe what those two latter terms mean, technically
speaking:
Stop the ¡¥Warped¡¦ Rotors Myth and Service Brakes the Right Way
<http://www.brakeandfrontend.com/warped-rotors-myth/>
Where that author advises:
"Starting today, remove ¡§warped rotor¡¨ from your vocabulary. Instead, you
should be both looking for and educating your customers about these terms:
Lateral Runout & Disc Thickness Variation (DTV)"
  #4  
Old August 7th 18, 04:08 AM posted to alt.usage.english,rec.autos.tech
Paul in Houston TX[_2_]
external usenet poster
 
Posts: 201
Default Why can't people figure out warp versus runout versus disc thicknessvariation

Arlen Holder wrote:
> On 6 Aug 2018 19:31:14 GMT, Paul in Houston TX wrote:
>
>> To be sure of their meaning, you will need to be fluent in Korean
>> and read the original paper in its native language, Korean.
>> https://www.boredpanda.com/funny-chi...slation-fails/

>
> I'm not sure the paper is actually written originally in Korean, are you?
>
> The authors seem completely ignorant that the word "warp" has two different
> meanings, one of which is the colloquial abuse of the word, while the other
> is the technical use of the word.


Odds are the authors are not fluent in English and they had a grad student
translate for them. There is no telling what they orginally meant.

"The Effect of Residual Stress on the Distortion of Gray Iron Brake Disks"

Authors
Authors and affiliations

M. W. Shin
G. H. Jang
J. K. Kim
H. Y. Kim
Ho JangEmail author

M. W. Shin
1
G. H. Jang
1
J. K. Kim
2
H. Y. Kim
2
Ho Jang
1
Email author

1.Department of Materials Science and EngineeringKorea UniversitySeoulRepublic of Korea
2.R&D DivisionHyundai Motor Company and Kia Motors CorporationHwaseong-siRepublic of
Korea


  #5  
Old August 7th 18, 04:10 AM posted to alt.usage.english,rec.autos.tech
Jack[_34_]
external usenet poster
 
Posts: 3
Default Why can't people figure out warp versus runout versus disc thickness variation

On Tue, 7 Aug 2018 02:05:46 -0000 (UTC), Arlen Holder
> wrote:

>Why, for Christs' sake, can't people figure out the difference in the
>English language between warp versus runout or disc thickness variation?
>
>There has been a perennial argument since the 70's when someone got the
>notion that brake rotor (aka disc) "warp" is the same as "dtv" (which it's
>not), where it can't be shaken out of their heads that they are two
>completely different things. Likewise with "runout".
>
>Witness this reference posted in good faith to the home-repair group today:
> <https://groups.google.com/d/msg/alt.home.repair/mIcLF2bSnU8/3sE9Wi1ODgAJ>
>
>Which referenced this paper:
> <https://link.springer.com/article/10.1007/s11665-012-0397-7>
>Titled:
> The Effect of Residual Stress on the Distortion of Gray Iron Brake Disks
>
>In that paper, the Asian authors *continually* appear to callously abuse
>the English language by confusing the term "warp" with "disk thickness
>variation (DTV)", which is completely different from warp (as in a potato).
>
>For example, you can have a warped sheet of metal where the thickness
>variation is zero, and you can have a thickness variation without warp.
>
>If this was a high-school kid equating the two, I'd shrug it off as
>ignorance; but this is an engineering paper, for heaven's sake.
>
>Here is the first sentence where they appear to abuse the English language:
> "It is known that disk warping or uneven disk thicknesses
> induce pulsation during brake applications."


Are you assuming that the 'or' means they are equating 'warping' with
'thickness variations'? Maybe they just mean that either condition can
cause pulsations.

>Clearly it is well known that "warp" (as in potato) and "uneven thickness"
>are two completely different things - which means that this particular set
>of Asian authors (M. W. ShinG. H. JangJ. K. KimH. Y. KimHo Jang) are likely
>ignorant of what "warp" actually means - or - they simply assume that it
>means something that it doesn't mean (i.e., warp and thickness variation
>are completely different things - they just are).
>
>They then compound their abuse of the English language in a sentence not
>far from that last horrid sentence, saying:
> "When the disk temperature is increased by friction heat during braking,
> the heat often causes dimensional instability of the disk,
> permanently modifying the runout or disk thickness variation (DTV)
> of a disk and producing brake judder."


Again, maybe they mean that 'dimensional instability' can modify
either runout or DTV, causing brake judder, without equating the two
distiortions.

>This sentence clearly appears to indicate the authors have no clue how to
>use the English language because it's a fact that runout and DTV are also
>two completely different things.


{trimmed}.

--
John
  #6  
Old August 7th 18, 05:08 AM posted to alt.usage.english,rec.autos.tech
Arlen Holder
external usenet poster
 
Posts: 98
Default Why can't people figure out warp versus runout versus disc thickness variation

On 6 Aug 2018 20:10:51 GMT, Jack wrote:

> Are you assuming that the 'or' means they are equating 'warping' with
> 'thickness variations'? Maybe they just mean that either condition can
> cause pulsations.


I fully agree that the "or" is confusing in and of itself, but I read the
entire paper, so I know what they *measured*, where they did NOT measure
warp.

Warp is easily measured since anyone who checks a head, for example,
measures it for warp. You use a known-straight surface and then you use
feeler gauges to see the variation in "flatness" to that known flat
surface.

From the word "or", I agree with you the authors' intent is ambiguous - but
from their measurements, they clearly measured DTV and lateral runout.

> Again, maybe they mean that 'dimensional instability' can modify
> either runout or DTV, causing brake judder, without equating the two
> distiortions.


I think they intended on proving that *heat treating* caused less lateral
runout and/or less disc thickness variation - which I'm sure they did
accomplish.

But that's not the same thing as warp, which is not only the word they used
repeatedly, but which was the reason that the person referred me to that
paper, since *he* thought the paper had something to do with warp.

It didn't.
It just used the word.
But they abused the English language in using the word (IMHO).

That boggles the mind that people are _that_ sloppy using that technical
term, particularly because disc rotors can't warp (as in potato chip)
because the temperatures required are impossible to achieve according to
the reliable references I've seen.

Raybestos says:
"Brake rotors do not warp from heat..."
<http://www.hendonpub.com/resources/article_archive/results/details?id=1787>

This says:
"Rotors are cast in extreme heat three to five times greater than
the most aggressive braking situation. Physically, warping a rotor
would require a similar application of extreme heat, which is
impossible."
<http://www.brakeandfrontend.com/warped-rotors-myth/>

This says:
"...the temperature required to make metal that resilient soft enough to
simply bend would be tremendous."
<https://www.yourmechanic.com/article/why-do-brake-rotors-warp>

This says that there are adverse effects starting at 1200dF:
"When this local temperature reaches around 1200 or 1300 degrees F.
the cast iron under the deposit begins to transform into cementite
(an iron carbide in which three atoms of iron combine with one atom
of carbon). Cementite is very hard, very abrasive and is a poor heat
sink. If severe use continues the system will enter a self-defeating
spiral - the amount and depth of the cementite increases with
increasing temperature and so does the brake roughness."
<https://alconkits.com/technical-info/brake-tech/56-the-myth-of-warped-brake-discs>

This says:
"in more than 40 years of professional racing, including the Shelby/Ford
GT 40s, one of the most intense brake development program in history
- I have never seen a warped brake disc."
<http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths>

These say the myth of warped rotors started in the 1970's:
<http://www.brakeandfrontend.com/brake-tech-feature-8-myths-that-could-be-holding-you-back-from-performing-the-best-brake-job/>
<https://www.onallcylinders.com/2017/05/19/6-biggest-brake-rotor-myths-debunked/>

This non-scientific thread, which we can quickly assume isn't scientific so
let's just take it as a reasonable point of view only, says that the
surface may get to 600dF but the rest of the rotor is at a lower
temperature than the surface.
<https://www.reddit.com/r/cars/comments/3dxoli/the_myth_of_brake_rotor_warping/>

It's pretty clear from this (and other references) that the authors abused
the term "warp" - but since the long term solution for a warped rotor is
completely different than the long term solution for a rotor with lateral
runout or disc thickness variation, it's *important* the distinction.

NOTE: A compounding factor is that the short-term solution to warp is the
*same* for disc-thickness variation (but not for lateral runout) - which is
why you consistently get guys implementing the short term solution for
brake judder instead of the long-term solution, simply because they *think*
their rotors warped (as in potato chip).

Hence, use of the wrong terminology has many dollars of unintended
consequences (likely hundreds of millions of wasted money every year,
IMHO).
  #7  
Old August 7th 18, 06:41 AM posted to alt.usage.english,rec.autos.tech
Peter Moylan
external usenet poster
 
Posts: 1
Default Why can't people figure out warp versus runout versus discthickness variation

[Followups set to a group that might find this interesting.]

On 07/08/18 12:05, Arlen Holder wrote:

> In that paper, the Asian authors*continually* appear to callously
> abuse the English language by confusing the term "warp" with "disk
> thickness variation (DTV)", which is completely different from warp
> (as in a potato).


Bad translations by non-native speakers will always be with us. When
you're using a language that's not your own, it's not always easy to
find le mot juste.

Using the wrong technical term in a technical paper is a problem, of
course, but it hardly amounts to an abuse of the English language.

Now, if the disk had capsized, ...

--
Peter Moylan http://www.pmoylan.org
Newcastle, NSW, Australia
  #8  
Old August 7th 18, 08:50 PM posted to alt.usage.english,rec.autos.tech
Jack[_34_]
external usenet poster
 
Posts: 3
Default Why can't people figure out warp versus runout versus disc thickness variation

On Tue, 7 Aug 2018 04:08:25 -0000 (UTC), Arlen Holder
> wrote:

>On 6 Aug 2018 20:10:51 GMT, Jack wrote:
>
>> Are you assuming that the 'or' means they are equating 'warping' with
>> 'thickness variations'? Maybe they just mean that either condition can
>> cause pulsations.

>
>I fully agree that the "or" is confusing in and of itself, but I read the
>entire paper, so I know what they *measured*, where they did NOT measure
>warp.
>
>Warp is easily measured since anyone who checks a head, for example,
>measures it for warp. You use a known-straight surface and then you use
>feeler gauges to see the variation in "flatness" to that known flat
>surface.
>
>From the word "or", I agree with you the authors' intent is ambiguous - but
>from their measurements, they clearly measured DTV and lateral runout.
>
>> Again, maybe they mean that 'dimensional instability' can modify
>> either runout or DTV, causing brake judder, without equating the two
>> distiortions.

>
>I think they intended on proving that *heat treating* caused less lateral
>runout and/or less disc thickness variation - which I'm sure they did
>accomplish.
>
>But that's not the same thing as warp, which is not only the word they used
>repeatedly, but which was the reason that the person referred me to that
>paper, since *he* thought the paper had something to do with warp.
>
>It didn't.
>It just used the word.
>But they abused the English language in using the word (IMHO).
>
>That boggles the mind that people are _that_ sloppy using that technical
>term, particularly because disc rotors can't warp (as in potato chip)
>because the temperatures required are impossible to achieve according to
>the reliable references I've seen.
>
>Raybestos says:
> "Brake rotors do not warp from heat..."
> <http://www.hendonpub.com/resources/article_archive/results/details?id=1787>
>
>This says:
> "Rotors are cast in extreme heat three to five times greater than
> the most aggressive braking situation. Physically, warping a rotor
> would require a similar application of extreme heat, which is
> impossible."
> <http://www.brakeandfrontend.com/warped-rotors-myth/>
>
>This says:
> "...the temperature required to make metal that resilient soft enough to
> simply bend would be tremendous."
> <https://www.yourmechanic.com/article/why-do-brake-rotors-warp>
>
>This says that there are adverse effects starting at 1200dF:
> "When this local temperature reaches around 1200 or 1300 degrees F.
> the cast iron under the deposit begins to transform into cementite
> (an iron carbide in which three atoms of iron combine with one atom
> of carbon). Cementite is very hard, very abrasive and is a poor heat
> sink. If severe use continues the system will enter a self-defeating
> spiral - the amount and depth of the cementite increases with
> increasing temperature and so does the brake roughness."
><https://alconkits.com/technical-info/brake-tech/56-the-myth-of-warped-brake-discs>
>
>This says:
> "in more than 40 years of professional racing, including the Shelby/Ford
> GT 40s, one of the most intense brake development program in history
> - I have never seen a warped brake disc."
> <http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths>
>
>These say the myth of warped rotors started in the 1970's:
><http://www.brakeandfrontend.com/brake-tech-feature-8-myths-that-could-be-holding-you-back-from-performing-the-best-brake-job/>
><https://www.onallcylinders.com/2017/05/19/6-biggest-brake-rotor-myths-debunked/>
>
>This non-scientific thread, which we can quickly assume isn't scientific so
>let's just take it as a reasonable point of view only, says that the
>surface may get to 600dF but the rest of the rotor is at a lower
>temperature than the surface.
><https://www.reddit.com/r/cars/comments/3dxoli/the_myth_of_brake_rotor_warping/>
>
>It's pretty clear from this (and other references) that the authors abused
>the term "warp" - but since the long term solution for a warped rotor is
>completely different than the long term solution for a rotor with lateral
>runout or disc thickness variation, it's *important* the distinction.
>
>NOTE: A compounding factor is that the short-term solution to warp is the
>*same* for disc-thickness variation (but not for lateral runout) - which is
>why you consistently get guys implementing the short term solution for
>brake judder instead of the long-term solution, simply because they *think*
>their rotors warped (as in potato chip).
>
>Hence, use of the wrong terminology has many dollars of unintended
>consequences (likely hundreds of millions of wasted money every year,
>IMHO).


I bought a 97 Contour in 2001, and it had brake pulsation. I called it
warped rotor, not caring much what was the precise distortion that
caused the pulsation. I replaced all four rotors myself for $105. Not
really big money. It's been a long-term solution: I still keep the car
for pulling a trailer, and the problem has never returned.
Maybe they weren't 'warped', or maybe they were, by careless lug nut
tightening.

Another sort of physics/language problem -

"Rotors are cast in extreme heat three to five times greater than the
most aggressive braking situation."

I don't think it makes sense to speak of multiples of temperature
unless you are referencing to absolute zero.

--
John
  #9  
Old August 7th 18, 10:43 PM posted to alt.usage.english,rec.autos.tech
Arlen Holder
external usenet poster
 
Posts: 98
Default Why can't people figure out warp versus runout versus disc thickness variation

On 7 Aug 2018 12:50:55 GMT, Jack wrote:

> I bought a 97 Contour in 2001, and it had brake pulsation. I called it
> warped rotor, not caring much what was the precise distortion that
> caused the pulsation.


Agreed that the abuse of the word "warp" has zero negative effects ... if
.... if ... if ... if ... if .... if ... if ... if ... if...

Remember the Spartan's response to the "if we attack you" diplomatic
'cable' way back in the days of the Greeks? The keyword is if.

If you actually *act* on "warp", you'll do the most insane things, and, in
the end, you'll *still* have your vibration.

Thats' because the long-term solution for warp is *different* than the long
term solution for, say, lateral runout or disc thickness variation.

The short term solution is the same - but the long term solution is
completely different.

That's the main reason it matters.
  #10  
Old August 7th 18, 11:21 PM posted to rec.autos.tech
dsi1[_11_]
external usenet poster
 
Posts: 331
Default Why can't people figure out warp versus runout versus discthickness variation

On Tuesday, August 7, 2018 at 9:51:00 AM UTC-10, Jack wrote:
>
> I bought a 97 Contour in 2001, and it had brake pulsation. I called it
> warped rotor, not caring much what was the precise distortion that
> caused the pulsation. I replaced all four rotors myself for $105. Not
> really big money. It's been a long-term solution: I still keep the car
> for pulling a trailer, and the problem has never returned.
> Maybe they weren't 'warped', or maybe they were, by careless lug nut
> tightening.
>
> John


It doesn't matter what you call it. The fix is still the same. My guess is that the warping problem is caused by hard braking and the resulting transfer of friction material from the pads to the rotor surface. This occurs on a molecular level and results in the rotor surface acquiring areas of differing friction coefficients. This can cause hot spots on the rotor when braking. To that effect, I try not to clamp down too hard on the brakes after coming to a stop when going down a hill. That's pretty the only thing that can be done to protect your rotors.
 




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