The scientific question is how do we correctly interpret why EE pads seem
to outperform FF pads in this police cruiser study done in 2000?
https://www.justnet.org/pdf/EvaluationBrakePads2000.pdf
https://www.justnet.org/pdf/Copy-of-...port-Draft.pdf

In another thread today, the topic was discussed on how to intelligently
select friction materials for replacement brake pads and shoes.
https://s18.postimg.org/wqilqasdl/to...n_material.jpg

That discussion hinges on a scientifically valid interpretation and
understanding of the utility of the "friction codes" printed on every brake
pad and shoe in the USA:
AMECA Compliance List of Automotive Safety Devices:
Friction Material Edge Codes(TM), May 2011
http://safebraking.com/wp-content/uploads/2013/02/AMECA-List-of-VESC-V-3-Brake-Friction-Material-Edge-Codes-May-20112.pdf

A general summary of which is listed below:
http://faculty.ccbcmd.edu/~smacadof/DOTPadCodes.htm
https://netrider.net.au/threads/unde...ratings.88551/
http://www.hotrod.com/articles/hrdp-...ad-technology/
etc.

The scientific question is how do we correctly interpret why EE pads seem
to outperform FF pads in this police cruiser study done in 2000?
https://www.justnet.org/pdf/EvaluationBrakePads2000.pdf

On Thu, 11 Jan 2018 02:47:38 -0000 (UTC),
Mad Roger wrote:

The scientific question is how do we correctly interpret why EE pads seem
to outperform FF pads in this police cruiser study done in 2000?
https://www.justnet.org/pdf/EvaluationBrakePads2000.pdf

Here is the original response to that thread where it was said that SAE
J866a Chase Test EE pads outperformed FF pads.
https://groups.google.com/d/msg/rec.autos.tech/_SSZmTXS5kk/87MU4e1JAAAJ

I can't run my own tests like the police did he
https://www.justnet.org/pdf/EvaluationBrakePads2000.pdf

And those tests showed the EE pads CONSISTENTLY outperformed the
FF brakes pretty well across the board - with the FF brakes
SEVERELY underperforming in most cases.

The Dana Ceramic family was the only FF to outperform OEM, while
HawkHead outperformed on both Chevy and Ford - and Raybestos and
Carquest alsooutperformed on Ford in the panic stop test.

Across the board, EE brakes, on the whole, outperformed the FF
and even the EE/GG combination - so what does your friction
rating tell you????????????

What it tells ME is if I buy Raybestos, NAPA, CVarquest, or Dana
(all major OEM suppliers) brakes, I will equal or excede OEM
performance - doesn't make a bit of difference to me WHAT rating
they have.

If I want slightly superior hot panic braking, at the expense
of poorer cold and medium temperature braking I should buy
ceramics - and this is STRICTLY for braking performance.

Now, from REAL WORLD experience, both myFord Aerostrs went
through rotors like crazy - untill I put on NAPA's Carbon
Metallics a set of pads destroyed a set of rotors at about
half of pad life - and I mean TOTALLY DESTROYED, here in
Southern Ontario. That came out at just over a year.

When I went to NAPA Carbon Metallics, the same rotors lasted
for TWO FULL SETS of pads - and over 5 years - and I was able
to actually lock the front wheels on dry pavement (rear ABS only)
- which NONE of the other brakes were capable of doing.

Never looked at the friction rating - never needed to,
because friction rating doesn't tell the whole story
(as your reference so elegantly proved)

You can have 5 different FF pads - and one will be noisy as hell, one
will eat rotors for lunch, onde will corrode as soon as it SMELLS
salt, and another will turn to gravel the first time you get it hot -
ALL FF rated (or ef, or ee. or FE )

The fact it met the test requirements ONCE in the lab means NOTHING
about quality

On 1/10/18 8:47 PM, Mad Roger wrote:
The scientific question is how

He's back with a new name.
Hopefully this means the end of the Apple thread.



--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

On 11/01/2018 2:09 PM, Fox's Mercantile wrote:
On 1/10/18 8:47 PM, Mad Roger wrote:
The scientific question is how

He's back with a new name.

In spades!

Hopefully this means the end of the Apple thread.



But the start of a new, and useless, thread.

--

Xeno

On 11/01/2018 1:47 PM, Mad Roger wrote:
The scientific question is how do we correctly interpret why EE pads seem

The scientific results are back! You are certifiably insane!

to outperform FF pads in this police cruiser study done in 2000?
https://www.justnet.org/pdf/EvaluationBrakePads2000.pdf
https://www.justnet.org/pdf/Copy-of-...port-Draft.pdf

In another thread today, the topic was discussed on how to intelligently
select friction materials for replacement brake pads and shoes.
https://s18.postimg.org/wqilqasdl/to...n_material.jpg

That discussion hinges on a scientifically valid interpretation and
understanding of the utility of the "friction codes" printed on every brake
pad and shoe in the USA:
AMECA Compliance List of Automotive Safety Devices:
Friction Material Edge Codes(TM), May 2011
http://safebraking.com/wp-content/uploads/2013/02/AMECA-List-of-VESC-V-3-Brake-Friction-Material-Edge-Codes-May-20112.pdf

A general summary of which is listed below:
http://faculty.ccbcmd.edu/~smacadof/DOTPadCodes.htm
https://netrider.net.au/threads/unde...ratings.88551/
http://www.hotrod.com/articles/hrdp-...ad-technology/
etc.

The scientific question is how do we correctly interpret why EE pads seem
to outperform FF pads in this police cruiser study done in 2000?
https://www.justnet.org/pdf/EvaluationBrakePads2000.pdf



--

Xeno

On Thu, 11 Jan 2018 02:47:38 -0000 (UTC), Mad Roger
wrote:

The scientific question is how do we correctly interpret why EE pads seem
to outperform FF pads in this police cruiser study done in 2000?
https://www.justnet.org/pdf/EvaluationBrakePads2000.pdf
https://www.justnet.org/pdf/Copy-of-...port-Draft.pdf

In another thread today, the topic was discussed on how to intelligently
select friction materials for replacement brake pads and shoes.
https://s18.postimg.org/wqilqasdl/to...n_material.jpg

That discussion hinges on a scientifically valid interpretation and
understanding of the utility of the "friction codes" printed on every brake
pad and shoe in the USA:
AMECA Compliance List of Automotive Safety Devices:
Friction Material Edge Codes(TM), May 2011
http://safebraking.com/wp-content/uploads/2013/02/AMECA-List-of-VESC-V-3-Brake-Friction-Material-Edge-Codes-May-20112.pdf

A general summary of which is listed below:
http://faculty.ccbcmd.edu/~smacadof/DOTPadCodes.htm
https://netrider.net.au/threads/unde...ratings.88551/
http://www.hotrod.com/articles/hrdp-...ad-technology/
etc.

The scientific question is how do we correctly interpret why EE pads seem
to outperform FF pads in this police cruiser study done in 2000?
https://www.justnet.org/pdf/EvaluationBrakePads2000.pdf


The engineer's enigma.

And that's with "genuine" parts (we will "ass u me")

Now google "counterfeit brake parts" - or just "counterfeit auto
parts" - and you will see how big a problem parts counterfeiting is
world wide, and why those ratings stamped onthe brakers do not
NECESSARILLY mean ANYTHING.

That's why I say buying known brand parts from a trusted supplier is
the FIRST step in getting good parts.

Assuming coefficient of friction IS the main quality you want in
brakes - which for me it most definitely is NOT.

I want quiet brakes that respond smoothly both hot and cold, last for
a good length of time, and do not destroy my rotors/drums.
On disc brakes I want pads that don't dust excessively, and the dust
does not attack the finish on my alloy rims or wheel covers.
I want brakes that do not fade excessively, and that willprovide more
than adequate braking in real world conditions.

When I installed oversized tires on my Ranger, brake effectiveness
deteriorated significantly - with the same brake pads and rotors.
I'm no engineer - but it was not hard to determine the problem was a
problem of leverage - the big wheels were exerting more foot-lbs of
torque to the brake - and the answer was bigger rotors - NOT different
brake pads - or even bigger brake pads. Just move the brake pads 10%
farther from the axle, like the larger wheels moved the road contact
area about 10% farther from the axle, and the brake force was
re-ballanced.

On Wed, 10 Jan 2018 23:07:18 -0500,
Clare Snyder wrote:

The engineer's enigma.

This is a difficult question to answer, where *Xeno the troll* clearly
isn't capable of answering it, but neither am I, which is why I asked for
scientific help.

We're talking about EE and FF pads as determined by the SAE J866 Chase Test
http://standards.sae.org/j866_201201/

And, we're talking about EE/FF pads being tested in the *same vehicle*,
where one must note the friction coefficient of E is marginally above that
of steel on steel (i.e., no pad at all).

Hence it is an enigma if the EE lower-friction coefficient friction
materials can outperform FF higher-friction coefficient materials in
real-world tests.

However, it is true that the link above says, very clearly:
"Due to other factors that include brake system design and
operating environment, the friction codes obtained from this
document cannot reliably be used to predict brake system performance."

So the only scientific question here is why would EE outperperform FF?

And that's with "genuine" parts (we will "ass u me")

Now google "counterfeit brake parts" - or just "counterfeit auto
parts" - and you will see how big a problem parts counterfeiting is
world wide, and why those ratings stamped onthe brakers do not
NECESSARILLY mean ANYTHING.

While counterfeit parts "could" be the problem, do you really think that a
state-run test posted and published nationally, would fall prey to them?

I think that fails Occam's Razor for logic (unless you have proof).

That's why I say buying known brand parts from a trusted supplier is
the FIRST step in getting good parts.

But we can assume the police did that - where it's just not reasonably
logical that they would fall prey to a plethora of counterfeit parts,
especially since the parts were *supplied* by the manufacturers, I believe.

(We could fall prey to "ringers" though...)

Assuming coefficient of friction IS the main quality you want in
brakes - which for me it most definitely is NOT.

I have to openly admit that I think the coefficient of friction is one of
the critical factors in brake friction materials, other than fit and
"reasonable" everything else (longevity, noise, dust, etc. in the Bell
Curve).

I want quiet brakes that respond smoothly both hot and cold, last for
a good length of time, and do not destroy my rotors/drums.
On disc brakes I want pads that don't dust excessively, and the dust
does not attack the finish on my alloy rims or wheel covers.

Everyone wants that, so we all agree (except trolls like Fox's Mercantile).

But how do you know that from the numbers printed on the pad?
(Rhetorical question - as I know there's no way to know that.)

I want brakes that do not fade excessively, and that willprovide more
than adequate braking in real world conditions.

Why wouldn't fade be covered in the SAE J866 Chase Test, which tests their
friction coefficient at a variety of temperatures?

When I installed oversized tires on my Ranger, brake effectiveness
deteriorated significantly - with the same brake pads and rotors.
I'm no engineer - but it was not hard to determine the problem was a
problem of leverage - the big wheels were exerting more foot-lbs of
torque to the brake - and the answer was bigger rotors - NOT different
brake pads - or even bigger brake pads. Just move the brake pads 10%
farther from the axle, like the larger wheels moved the road contact
area about 10% farther from the axle, and the brake force was
re-ballanced.

I agree that there are *many* factors in the act of slowing down a vehicle
with brake friction material heating up causing a loss of the energy of
momentum.

However, the cold & hot friction coefficient, logically, must be a primary
factor, where there's a reason if lower coefficient EE pads (which have
just barely better a coefficient of friction than no pads at all) could
outperform FF pads (which have appreciably higher friction coefficients) in
the same vehicle under standard tests.

All I ask is how this can happen (where counterfeits are not logically the
reason).

On Thu, 11 Jan 2018 14:46:34 -0000 (UTC), Mad Roger
wrote:

On Wed, 10 Jan 2018 23:07:18 -0500,
Clare Snyder wrote:

The engineer's enigma.

This is a difficult question to answer, where *Xeno the troll* clearly
isn't capable of answering it, but neither am I, which is why I asked for
scientific help.

We're talking about EE and FF pads as determined by the SAE J866 Chase Test
http://standards.sae.org/j866_201201/

And, we're talking about EE/FF pads being tested in the *same vehicle*,
where one must note the friction coefficient of E is marginally above that
of steel on steel (i.e., no pad at all).

Hence it is an enigma if the EE lower-friction coefficient friction
materials can outperform FF higher-friction coefficient materials in
real-world tests.

However, it is true that the link above says, very clearly:
"Due to other factors that include brake system design and
operating environment, the friction codes obtained from this
document cannot reliably be used to predict brake system performance."

So the only scientific question here is why would EE outperperform FF?

And that's with "genuine" parts (we will "ass u me")

Now google "counterfeit brake parts" - or just "counterfeit auto
parts" - and you will see how big a problem parts counterfeiting is
world wide, and why those ratings stamped onthe brakers do not
NECESSARILLY mean ANYTHING.

While counterfeit parts "could" be the problem, do you really think that a
state-run test posted and published nationally, would fall prey to them?

I'm discounting conterfeit parts as being the problemin these tests -
just going back to your "trust" in "government mandated markings" from
your previous thread.

I think that fails Occam's Razor for logic (unless you have proof).

That's why I say buying known brand parts from a trusted supplier is
the FIRST step in getting good parts.

But we can assume the police did that - where it's just not reasonably
logical that they would fall prey to a plethora of counterfeit parts,
especially since the parts were *supplied* by the manufacturers, I believe.

(We could fall prey to "ringers" though...)

No, I'm just saying - again - that depending on the government
mandated friction rating markings will NOT get you the best brake -
which has been my thesis from the beginning and has been proven by TWO
law enforcement vehicle tests you have provided to support your
position.

I'msorry, but your thesis does NOT stand the test of proof using the
scientific method. You are an engineer. What does that tell you???

If it was just a case of FF pads on a dodge undeperforming the same
pad on a Foprd, you could put it down to bake design - but that is not
the case here., There is NO LOGICAL EXPLANATION other than the FACT
that the markings are NOT a reliable predictor of brake performance -
muchless quality.

Assuming coefficient of friction IS the main quality you want in
brakes - which for me it most definitely is NOT.

I have to openly admit that I think the coefficient of friction is one of
the critical factors in brake friction materials, other than fit and
"reasonable" everything else (longevity, noise, dust, etc. in the Bell
Curve).


I puit more weight on the other qualities,as they are readilly evident
- while the friction grade of the material is not - as proven by the
tests.

I want quiet brakes that respond smoothly both hot and cold, last for
a good length of time, and do not destroy my rotors/drums.
On disc brakes I want pads that don't dust excessively, and the dust
does not attack the finish on my alloy rims or wheel covers.

Everyone wants that, so we all agree (except trolls like Fox's Mercantile).

But how do you know that from the numbers printed on the pad?

You don't.

Now another thing that affects HOT braking is the attachment of the
lining to the shoe/pad. Does the "glue" adequately transmit the heat
or act as an insulator?? Personally,I'm a BIG fan of rivetted linings
and pads, rather than bonded.

They are generally quieter,and in my experience exhibit less fade.
They also generakky speaking have a smoother engagement.
(Rhetorical question - as I know there's no way to know that.)

I want brakes that do not fade excessively, and that willprovide more
than adequate braking in real world conditions.

Why wouldn't fade be covered in the SAE J866 Chase Test, which tests their
friction coefficient at a variety of temperatures?

Because the damned tests are either faulty or improerly performed
(the material does not meet the spec) OR the method of mounting does
not properly mitigate the heat.

When I installed oversized tires on my Ranger, brake effectiveness
deteriorated significantly - with the same brake pads and rotors.
I'm no engineer - but it was not hard to determine the problem was a
problem of leverage - the big wheels were exerting more foot-lbs of
torque to the brake - and the answer was bigger rotors - NOT different
brake pads - or even bigger brake pads. Just move the brake pads 10%
farther from the axle, like the larger wheels moved the road contact
area about 10% farther from the axle, and the brake force was
re-ballanced.

I agree that there are *many* factors in the act of slowing down a vehicle
with brake friction material heating up causing a loss of the energy of
momentum.

However, the cold & hot friction coefficient, logically, must be a primary
factor, where there's a reason if lower coefficient EE pads (which have
just barely better a coefficient of friction than no pads at all) could
outperform FF pads (which have appreciably higher friction coefficients) in
the same vehicle under standard tests.

All I ask is how this can happen (where counterfeits are not logically the
reason).


Failure of the testing/certification process to reflect real world
conditions.

Sorry, but you engineers devise the tests. There is definitely
SOMETHING wrong with either the design of the test, the implementation
of the test, (application) or the theory applied.

Which is why I put very limited weight on the stamped/published
friction ratings.

They have been proven time and again to be pretty close to useless.

Now, if you take a, for instance, BRakebond pad with ee, another of
their pads with ef, and another eith ff - there MIGHT be a displayable
progression between them - all other factors being the same (which
they seldom are). Or you may find an ee or ef pad or shoe STILL
outperforms an ff in the real world.

There is a lot more involved in brake performance - particularly hot
performance, than simple coefficent of friction.

gassing from the friction material, and how it is vented, being one
issue. Simply cross-cutting a pad, or chamfering the edge of the pad -
while marginally reducing the active braking area CAN improve hot stop
performance significantly.

In this case, the test using a one square inch sample of pad material
TOTALLY misses the mark - meaning the test design is faulty from the
start.

I'm no engineer - but I know that much!!

When you combine government beaurocrats and engineers with no "real
world" experience to implement ANY program, the chances of failure to
perform get exponentially higher than tests performed under "real
world" conditions.

And as for not using EE friction materials - SOME of the cruisers
used in thase testa use ef or ff material in the
persuit special" vehicles, while civilian and even taxi (heavy duty)
use may have EE from the factory.

The whole CAFE situation, requiring the lightening of all components,
has resulted in a generation of vehicles that are (or have been)
SEVERELY underbraked - and this deficiency has been hidden by the
universalimplementation of antilock brakes - the small brakes canNOT
provide enough braking force to lock the wheels on dry pavement
because, by and large, they do not have to.

As long as the braking action of the brake assembly matches the
friction betweenthe tires and the road, it is accepted.

If I shut off the antilock function of my brakes, I want them to be
capable of throwing the vehicle into a complete slide - on command -
whether hot or cold.

With the oversized brakes (same pads as stock) with ee friction
material on my ranger- I CAN lock all 4 wheels - on command - with
antilock dissabled. - so why would I insist on FF pads, which, by the
results of the tests YOU provided, may very well underperform the "low
grade" ee pads I have installed?????

On Thu, 11 Jan 2018 11:44:01 -0500,
Clare Snyder wrote:

I'm discounting conterfeit parts as being the problemin these tests -
just going back to your "trust" in "government mandated markings" from
your previous thread.

I agree with you that it's unlikely that the police in Michigan were
testing counterfeit parts, especially as they apparently received the
friction material directly from the manufacturer, according to their
summary paper.

(We could fall prey to "ringers" though...)

No, I'm just saying - again - that depending on the government
mandated friction rating markings will NOT get you the best brake -
which has been my thesis from the beginning and has been proven by TWO
law enforcement vehicle tests you have provided to support your
position.

I'm not disagreeing with your contention that the EE pads, in those police
tests, somehow worked better than the FF pads, even though E is a friction
coefficient only marginally higher than steel on steel.

I'm only asking why.

I'msorry, but your thesis does NOT stand the test of proof using the
scientific method. You are an engineer. What does that tell you???

I'm an electrical engineer; so I believe in friction, but if the lower
friction coefficient pads are working better than the higher friction
coefficient pads, the precise understanding of that is out of my league.

That's why I asked here, where I was hoping the s.e.r intelligentsia might
help us rationalize a reason that stands the test of logical analysis.

If it was just a case of FF pads on a dodge undeperforming the same
pad on a Foprd, you could put it down to brake design - but that is not
the case here., There is NO LOGICAL EXPLANATION other than the FACT
that the markings are NOT a reliable predictor of brake performance -
muchless quality.

I agreed with your assessment, and I even quoted the Michigan police
cruiser test warning saying that the markings don't necessarily conform to
real-world practice.

I'm only asking here WHY an E coefficient pad (which is basically no pad at
all) performed better than an F coefficient pad (which has an appreciably
higher cold & hot friction coefficient)?

I puit more weight on the other qualities,as they are readilly evident
- while the friction grade of the material is not - as proven by the
tests.

I'm going to have to somewhat reluctantly agree with you, unless we get a
good reason, that no pad at all (i.e., just metal on metal) is "just as
good" and "maybe even better" than a high friction coefficient pad.

Pretty much that says "all pads work", does it not?

But how do you know that from the numbers printed on the pad?

You don't.

Again, I'm going to have to somewhat reluctantly agree with you, from a
logical standpoint, that if essentially no pad at all (i.e., an E
coefficient pad which has a coefficient of friction marginally better than
steel on steel) is better or about as good as having a pad, then almost
nothing printed on the side of the pad is going to make any difference.

Now another thing that affects HOT braking is the attachment of the
lining to the shoe/pad. Does the "glue" adequately transmit the heat
or act as an insulator?? Personally,I'm a BIG fan of rivetted linings
and pads, rather than bonded.

It seems there *must* be other *major* factors in braking performance,
other than the friction rating of the pads themselves.

That's a hard logical pill to swallow, for me, which is why I asked here,
hoping the s.e.r folks can enlighten us as to why.

Failure of the testing/certification process to reflect real world
conditions.

Well, the friction coefficient is a "real world" measurement.

It just doesn't seem to matter in braking performance, based on that police
cruiser test I unearthed.

That's too bad, because it means you can't compare pads easily other than
to note the material, type, and manufacturer, which the DOT CODES printed
on each pad and shoe do tell you.

So at least we can tell three pads with three different marketing
strategies (e.g, Axxis, PBR, & Metal Masters) are the exact *same* pad, and
we can tell when a pad is rebranded (I think Centric only does rebranded
pads, for example, but I'd have to check the numbers to be sure).

That indicates there is some utility in the mandated information that is
printed on the side of each pad.

But it's just sad that the friction coefficient means so little to a
friction material!

Sorry, but you engineers devise the tests. There is definitely
SOMETHING wrong with either the design of the test, the implementation
of the test, (application) or the theory applied.

Friction is friction.
It's a mathematical beast.

I don't think the SAE J866 Chase Tests lie about the friction of a 1"
square piece of the friction material.

They just don't predict real-world performance, it seems.
(As noted in the Police Cruiser report.)

Which is why I put very limited weight on the stamped/published
friction ratings.

Again, I must reluctantly agree with you, as hard a pill as it is to
swallow, that friction coefficients are NOT an important factor in the
performance of brake friction materials.

Sigh.

I just want to know WHY?

They have been proven time and again to be pretty close to useless.

Well, as I said, the *numbers* printed on the side of every pad/shoe sold
in the USA are *useful* in that they tell you the manufacturer, the
material, and, the friction rating - so even if we discount the friction
rating, it's nice to know when you can tell that two pads sold and marketed
at two different prices, are the same pad.

Now, if you take a, for instance, BRakebond pad with ee, another of
their pads with ef, and another eith ff - there MIGHT be a displayable
progression between them - all other factors being the same (which
they seldom are). Or you may find an ee or ef pad or shoe STILL
outperforms an ff in the real world.

I'm gonna have to reluctantly agree with you, yet again.
I don't ever dispute fact.

There is a lot more involved in brake performance - particularly hot
performance, than simple coefficent of friction.

It must be the case that friction isn't a *primary* determinant of brake
performance, hard a pill as that is to swallow.

In this case, the test using a one square inch sample of pad material
TOTALLY misses the mark - meaning the test design is faulty from the
start.

You'd think the SAE would know how to design a friction test though...

And as for not using EE friction materials - SOME of the cruisers
used in thase testa use ef or ff material in the
persuit special" vehicles, while civilian and even taxi (heavy duty)
use may have EE from the factory.

I know. I know. You don't have to rub it in.
I apologize for chastening you for using EE pads and shoes.

I still think my Toyota OEM shoes are FF so I'm gonna get FF.
Can you summarize again the short list of brands you'd recommend?
I want to do the work for the owner this weekend.

Thanks.

On Thu, 11 Jan 2018 20:09:25 -0000 (UTC), Mad Roger
wrote:

On Thu, 11 Jan 2018 11:44:01 -0500,
Clare Snyder wrote:

I'm discounting conterfeit parts as being the problemin these tests -
just going back to your "trust" in "government mandated markings" from
your previous thread.

I agree with you that it's unlikely that the police in Michigan were
testing counterfeit parts, especially as they apparently received the
friction material directly from the manufacturer, according to their
summary paper.

(We could fall prey to "ringers" though...)

No, I'm just saying - again - that depending on the government
mandated friction rating markings will NOT get you the best brake -
which has been my thesis from the beginning and has been proven by TWO
law enforcement vehicle tests you have provided to support your
position.

I'm not disagreeing with your contention that the EE pads, in those police
tests, somehow worked better than the FF pads, even though E is a friction
coefficient only marginally higher than steel on steel.

I'm only asking why.

I'msorry, but your thesis does NOT stand the test of proof using the
scientific method. You are an engineer. What does that tell you???

I'm an electrical engineer; so I believe in friction, but if the lower
friction coefficient pads are working better than the higher friction
coefficient pads, the precise understanding of that is out of my league.

That's why I asked here, where I was hoping the s.e.r intelligentsia might
help us rationalize a reason that stands the test of logical analysis.

If it was just a case of FF pads on a dodge undeperforming the same
pad on a Foprd, you could put it down to brake design - but that is not
the case here., There is NO LOGICAL EXPLANATION other than the FACT
that the markings are NOT a reliable predictor of brake performance -
muchless quality.

I agreed with your assessment, and I even quoted the Michigan police
cruiser test warning saying that the markings don't necessarily conform to
real-world practice.

I'm only asking here WHY an E coefficient pad (which is basically no pad at
all) performed better than an F coefficient pad (which has an appreciably
higher cold & hot friction coefficient)?


Elementary, my dear Watson. There is a HECK of a lot more to brake
pads than just the coefficient of friction - as Ihave been stating
time and time again. Steel on steel is noisy. Steel on steel has no
"feel". Steelon steel makes TERRIBLE brake dust, and steel on steel
would have terrible pad and rotor or shoe and drum life.

The coefficient of friction isn't all that bad - and the difference
between e and f, I would postulate, is not so "appreciable" as
"measurable"
and the difference in fade bertween ee and ff pads is laughable. At
600 degrees an ee can suffer from 0 to 25% fade, while the
"appreciably better" FF suffers from 0-22% fade - which means there is
EVERY possibility that an EE pad would hac WAY less fade than another
FF pad.

The STUPID thing is an fe can suffer 2-44% fade - doesn't make ANY
logical sense, but that's straight from
http://faculty.ccbcmd.edu/~smacadof/DOTPadCodes.htm



Friction material consists of a cobination of the following
components:
Fibers, such as fiberglass, kevlar, arimid, stainless steel, and
aluminum maintain the heat stability of the pad. These fibers have
various binding strengths and can be organic or metallic. Friction
Modifiers such as graphite adjust the friction level and fine tune the
performance characteristics of the pad at specific cold and hot
temperatures. Fillers take up dead space in the pad. These are
generally organic materials with some low frictional effect such as
sawdust. Finally, Resins are used to hold the elements of the pad
together so they don't crumble apart.

I puit more weight on the other qualities,as they are readilly evident
- while the friction grade of the material is not - as proven by the
tests.

I'm going to have to somewhat reluctantly agree with you, unless we get a
good reason, that no pad at all (i.e., just metal on metal) is "just as
good" and "maybe even better" than a high friction coefficient pad.

Pretty much that says "all pads work", does it not?

All pads work at least once. The life of the pads is not taken into
account

But how do you know that from the numbers printed on the pad?

You don't.

Again, I'm going to have to somewhat reluctantly agree with you, from a
logical standpoint, that if essentially no pad at all (i.e., an E
coefficient pad which has a coefficient of friction marginally better than
steel on steel) is better or about as good as having a pad, then almost
nothing printed on the side of the pad is going to make any difference.

Dropping a railway tie into a post hole will stop you faster than a
GG pad will = guaranteed!!!

Now another thing that affects HOT braking is the attachment of the
lining to the shoe/pad. Does the "glue" adequately transmit the heat
or act as an insulator?? Personally,I'm a BIG fan of rivetted linings
and pads, rather than bonded.

It seems there *must* be other *major* factors in braking performance,
other than the friction rating of the pads themselves.

That's a hard logical pill to swallow, for me, which is why I asked here,
hoping the s.e.r folks can enlighten us as to why.

Failure of the testing/certification process to reflect real world
conditions.

Well, the friction coefficient is a "real world" measurement.

Yes, but the assininely simple test procedure is FAR from "real
world". The behavior of a 1 square inchchunk of friction material does
not come CLOSE to the effect of 2 30 square inch arcs of pad material
in a 3 inch wide enclosed drum, or 2 10 square inch pads rubbing on an
open disk - simple things like pad vibration can reduce the EFFECTIVE
friction of a disc pad SIGNIFICANTLY (by cutting the "duty cycle" of
the pad basically in HALF (A vibrating pad is only in full contact
with the rotor roughly half the time)
An off-gassing pad only 1 inch square is not going to "float" on that
gas layer like a 10 square inch patch is under the same pressure. The
"micro-ball-bearings" of brake dust will have virtually no effect on a
1 inch piece of friction material, but may have a SIGNIFICANT effect
on 10 inches of brake shoe (which is why , partly, a grooved pad can
significantly outperform a solid pad.

There are WAY too many contributing factors that have WAY more
influence on brake performance than the relatively SMALL difference
between an e and an f pad. You could have an E pad at .34 and an f at
..36. You tell me there is a quantifiable difference between the
two????
Not in my world - where the rubber hits the road.

It just doesn't seem to matter in braking performance, based on that police
cruiser test I unearthed.

That's too bad, because it means you can't compare pads easily other than
to note the material, type, and manufacturer, which the DOT CODES printed
on each pad and shoe do tell you.

So at least we can tell three pads with three different marketing
strategies (e.g, Axxis, PBR, & Metal Masters) are the exact *same* pad, and
we can tell when a pad is rebranded (I think Centric only does rebranded
pads, for example, but I'd have to check the numbers to be sure).

Well over half of the "brands" are rebrands - not manufacturers.
particularly the "boutique" brands the enthusiasts and boy racers wet
their pants over

That indicates there is some utility in the mandated information that is
printed on the side of each pad.

VERY limited utility

But it's just sad that the friction coefficient means so little to a
friction material!

Sorry, but you engineers devise the tests. There is definitely
SOMETHING wrong with either the design of the test, the implementation
of the test, (application) or the theory applied.

Friction is friction.
It's a mathematical beast.

"Figures don't lie, but liars figure"
You can make math give you any answer you want - ask an accountant.

I don't think the SAE J866 Chase Tests lie about the friction of a 1"
square piece of the friction material.


They don't lie, they just, by their very nature, CAN NOT tell the
whole truth
They just don't predict real-world performance, it seems.
(As noted in the Police Cruiser report.)

Which is why I put very limited weight on the stamped/published
friction ratings.

Again, I must reluctantly agree with you, as hard a pill as it is to
swallow, that friction coefficients are NOT an important factor in the
performance of brake friction materials.

Sigh.

I just want to know WHY?

Because the initial friction co-efficient, as measured by the test in
question, is only one of a miriad factors involved in brake
performance - and a relatively MINOR one in the grand scheme of
things.

They have been proven time and again to be pretty close to useless.

Well, as I said, the *numbers* printed on the side of every pad/shoe sold
in the USA are *useful* in that they tell you the manufacturer, the
material, and, the friction rating - so even if we discount the friction
rating, it's nice to know when you can tell that two pads sold and marketed
at two different prices, are the same pad.

Now, if you take a, for instance, BRakebond pad with ee, another of
their pads with ef, and another eith ff - there MIGHT be a displayable
progression between them - all other factors being the same (which
they seldom are). Or you may find an ee or ef pad or shoe STILL
outperforms an ff in the real world.

I'm gonna have to reluctantly agree with you, yet again.
I don't ever dispute fact.

There is a lot more involved in brake performance - particularly hot
performance, than simple coefficent of friction.

It must be the case that friction isn't a *primary* determinant of brake
performance, hard a pill as that is to swallow.

In this case, the test using a one square inch sample of pad material
TOTALLY misses the mark - meaning the test design is faulty from the
start.

You'd think the SAE would know how to design a friction test though...

And as for not using EE friction materials - SOME of the cruisers
used in thase testa use ef or ff material in the
persuit special" vehicles, while civilian and even taxi (heavy duty)
use may have EE from the factory.

I know. I know. You don't have to rub it in.
I apologize for chastening you for using EE pads and shoes.

I still think my Toyota OEM shoes are FF so I'm gonna get FF.
Can you summarize again the short list of brands you'd recommend?
I want to do the work for the owner this weekend.

Thanks.


Well, if I was doing the job, I'd be heading over to my neighbourhood
NAPA store and pickingup a set of their Napa Ultra Premium rear shoe
kits for $57.28 CANADIAN (about $35 US??)and be done with it.
Or possibly over to Canadian Tire for a set of Brembos if they have
them 20% off (they did this week - but their coverage is limited -
they might not have shoes for a 'runner) or Wagners.

Let's face it - they are REAR brakes - and they do less than 30% of
the actual braking. A whole lot less in many cases due to the action
of the load sensing brake proportioning valve that cuts preasure to
the rear brakes when the rear axle us "unloaded" to prevent the rear
brakes from locking and the ABS from activating.

ABB (Brakebond) and Dana are generally predictable performers as
well.

On 2018-01-11 12:09, Mad Roger wrote:

It seems there *must* be other *major* factors in braking performance,
other than the friction rating of the pads themselves.

That's a hard logical pill to swallow, for me, which is why I asked here,
hoping the s.e.r folks can enlighten us as to why.


Whats the stupid fixation with the coefficient of friction anyway?

As any fule kno, friction is notionally independent of contact area, and
force due to friction is determined by the coefficient of friction *and
the applied force* so if you want more frictional force, you just need
to press the pedal harder, or have more servo assistance.

Simply ignoring all of the other (engineering) considerations which have
been cited, relating to brake performance in the real world, will not
help you be enlightened about anything. It just makes you look like a
dumb **** trying to be cleverer than your brain permits.

On 2018-01-11 06:46, Mad Roger wrote:
I agree that there are *many* factors in the act of slowing down a vehicle
with brake friction material heating up causing a loss of the energy of
momentum.


Bollox bollox bollox.

Momentum and energy are quite different quantities, if you want to play
properly at being a scientist.

On Thu, 11 Jan 2018 02:47:38 -0000 (UTC),
Mad Roger wrote:
The scientific question is how do we correctly interpret why EE pads seem
to outperform FF pads in this police cruiser study done in 2000?
https://www.justnet.org/pdf/EvaluationBrakePads2000.pdf

I called Centric at 626-961-5775 where I'm told the Centric parts for this
vehicle a
* Rear shoes: 11105890 ceramic
* Front pads: 10504360 ceramic

I spoke to Centric tech support multiple times today, who knew all about
the Michigan police cruiser studies, SAE J866 Chase Test, and SAE J2784
compliance, and the AMECA Edge Codes (aka DOT Edge Codes).

They gave me the DOT Edge Codes after calling the warehouse:
* CENTRIC 11105890 shoes = 111AA9101FF30N17 which is CEN 111AA9101 FF
* CENTRIC 10504360 pads = 15AA2256FE48A17 which his CEN 15AA2256 FE

The rear shoes have a registered material of #161379 which matches:
* CEN 111AA9101 FF
* CEN 112AA9101 FF

There is a large discrepancy in the front shoes since they match to #161583
* CEN 15AA2256 GF (this is not EF which is what is printed on the pad)
* CEN 15AA8241 GF

After multiple calls to Ameca and to Centric (I've left out the engineer's
names from this and all my reports on purpose), there must be a mistake
which they'll iron out between themselves.

I asked CENTRIC what "OEM Quality" means, and the engineer told me "mostly
marketing". I asked if there was a spec of clay in the pad if they could
call it ceramic, and he agreed.

He told me a lot of other stuff also, such as the fact they don't sell to
Rock Auto nor to Amazon, so if you get Centric parts there, it's through a
reseller of some sort.

The technical engineer did tell me that Centric puts all brake shoes on a
dyno and tests them thoroughly to assure they meet OEM Quality, but it's
not like a manufacturer gives them a spec. They just know how brake shoes
and pads should work.

If you do not believe any of this, I don't blame you because it goes
against all your intuition but intuition is almost always wrong on highly
marketed items because it's not intuition that drives the thought process
anymore - it's marketing.

But all you have to do to confirm is make the same phone calls I did.
Just ask for tech support when the operator answers the phone.

AMECA +1-202-898-0145
CENTRIC +1-626-961-5775