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?
In another thread today, the topic was discussed on how to intelligently
select friction materials for replacement brake pads and shoes.
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
A general summary of which is listed below:
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?
On Thu, 11 Jan 2018 02:47:38 -0000 (UTC),
Mad Roger wrote:
Here is the original response to that thread where it was said that SAE
J866a Chase Test EE pads outperformed FF pads.
>I can't run my own tests like the police did here:
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
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
On Thu, 11 Jan 2018 13:20:56 -0800 (PST),
Here's just one example to help answer that on-topic question
bearing in mind that brake pads are highly marketed items.
If you are comparing three pads that fit your vehicle spec:
a. $50 Axxis performance
b. $30 PBR midline
c. $20 Metal Masters economy
And you look at the code printed on the pads, you'll find they are
*exactly* the same numbers (since they're all the same pads/shoes, just
In addition, the code printed on the pads tell you the material is exactly
the same, even if they're not the same pads (so you can more easily compare
And it will tell you the coefficient of friction, even if those two things
are different still, so you can compare across lines and brands for
Why would you deny a vehicle owner that useful comparative information?
On Thu, 11 Jan 2018 02:47:38 -0000 (UTC), Mad Roger
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
On Wed, 10 Jan 2018 23:07:18 -0500,
Clare Snyder wrote:
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
We're talking about EE and FF pads as determined by the SAE J866 Chase Test
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
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?
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).
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...)
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
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.)
Why wouldn't fade be covered in the SAE J866 Chase Test, which tests their
friction coefficient at a variety of temperatures?
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
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
On Thu, 11 Jan 2018 14:46:34 -0000 (UTC), Mad Roger
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.
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
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 -
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
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.
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.
Failure of the testing/certification process to reflect real world
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
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
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
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
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 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
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'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.
I agreed with your assessment, and I even quoted the Michigan police
cruiser test warning saying that the markings don't necessarily conform to
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'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?
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.
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.
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 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.)
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.
I just want to know WHY?
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.
I'm gonna have to reluctantly agree with you, yet again.
I don't ever dispute fact.
It must be the case that friction isn't a *primary* determinant of brake
performance, hard a pill as that is to swallow.
You'd think the SAE would know how to design a friction test though...
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.
On Thu, 11 Jan 2018 20:09:25 -0000 (UTC), Mad Roger
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
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
The STUPID thing is an fe can suffer 2-44% fade - doesn't make ANY
logical sense, but that's straight from
Friction material consists of a cobination of the following
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.
All pads work at least once. The life of the pads is not taken into
Dropping a railway tie into a post hole will stop you faster than a
GG pad will = guaranteed!!!
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
Not in my world - where the rubber hits the road.
Well over half of the "brands" are rebrands - not manufacturers.
particularly the "boutique" brands the enthusiasts and boy racers wet
their pants over
VERY limited utility
"Figures don't lie, but liars figure"
You can make math give you any answer you want - ask an accountant.
They don't lie, they just, by their very nature, CAN NOT tell the
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
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
On Thu, 11 Jan 2018 16:55:12 -0500,
Clare Snyder wrote:
I found out the DOT Edge Code for the OE Toyota shoes which is
NBK LN508 FF
which is made by "Nisshinbo Automotive Manufacturing, Inc.".
It turns out that you were completely correct where I was hoping this
number would be a "holy grail" where I could use it to better compare two
brake shoes in my hands.
To get a better handle on how to interpret the numbers, I called the main
number at AMECA.ORG in Maryland at 202-898-0145 and spoke to the engineer
in charge of that "AMECA Edge Code Markings" cross reference.
It was a long discussion, the net of which is that this code isn't really
for the consumer.
The engineer said it's kind of like the so-called "serial number" on a
tire, or on a package of baked beans, where if something goes wrong, the
government has a way of tracking down whose fault it is. In addition, he
said that the SAE J866 Chase Test is really a quality metric, and not a
performance metric, even though friction is an outcome of the Chase Test.
The engineer did give me all sorts of personal insight into how to buy
brake pads but overall, he said you can't extrapolate very much real-world
decision-making data from the DOT Edge Code.
Of course, if you miraculously find two pads with the same DOT Edge Code,
then there's a 100% chance that it's the same friction material.
Or, if you find any pads with any of the 19 DOT edge codes that cross
reference to the same AMECA registration number 160426 then they too are
exactly the same friction material.
NAC D9011 FF
NAC LN508 FF
NAC N2009 FF
NBK D9011 FF
NBK LN508 FF <==== this is the OE Toyota brake shoes DOT edge code
NBK N2009 FF
NSA D9011 FF
NSA LN508 FF
NSA N2009 FF
NSC D9011 FF
NSC LN508 FF
NSC N2009 FF
SABC D9011 FF
SABC LN508 FF
SABC N2009 FF
SAC D9011 FF
SAC LN508 FF
SAC N2009 FF
SABC LN508 FF
That's because the AMECA registration number 160426 is for a specific
1-inch square piece of friction material that can be used on any brake pad
But that's really as far as a consumer can go with the edge code, he said.
He knew about all three of the Michigan police studies of EE and FF brake
pads, where those in-depth police cruiser tests also said it's hard to
extrapolate real-world performance from just the EE or FF friction code
The AMECA engineer said that there are from 10 to 30 compounds in a brake
friction material, where he opined that Toyota spends enormous energy with
what he called the Tier 1 companies (e.g., Nisshinbo for Toyota) optimizing
the compound for each vehicle; but the engineer said that the aftermarket
suppliers (e.g, Centric, Wagner, Akebono, Axxis, etc.) centralize on about
a half dozen formulas for all their offerings.
In summary, the AMECA Edge Code is only "slightly" useful to a consumer, as
it tells the consumer the most information only if numbers match, but if
they don't match, the only three things it tells the consumer are the
manufacturer, the friction coefficient, and the registration number for the
specific friction material.
BTW, I was tempted to call the Nisshinbo senior principle engineer himself
(Tsuyoshi Kondo, +1-586-997-1000, firstname.lastname@example.org) who submitted
the 1-inch squares for our particular friction material on October 31st
2017 for repeat testing, but I didn't have the nerve to call him for more
information, especially after the AMECO engineer told me this information
is mostly for law enforcement and government use, and not really intended
for consumer use.
The one thing the AMECA engineer told me over and over again though, is
that what we'd want for comparative purposes, has been studied and studied
by the "smartest guys on the planet", and nobody can agree because of
So he sympathized with our needs.
Xeno the troll.
How much on-topic technical value have you added to *any* thread.
In your *entire* life?
Xeno the troll can't comprehend the topic.
Nor can Xeno the troll add any technical value.
Xeno the troll is too stupid to add any value to any topic whatsoever.
Just watch. Xeno the troll proves he's incapable of even *comprehending*
the technical topic by his every response.
Xeno the troll will respond with more non-technical worthless blather.
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 fuck trying to be cleverer than your brain permits.
On Thu, 11 Jan 2018 09:37:21 -0800 (PST),
With respect to "stopping distance", in the Michigan Police Cruiser study,
they controlled for identical deceleration (thus identical stopping
distance) and measured pedal force.
This is a different test than applying a uniform pedal force and measuring
I'm not sure how to extrapolate that information to stopping distances.
On Sun, 14 Jan 2018 01:30:23 -0800 (PST),
Thanks for that observation as I'm trying to derive as much real-world
benefit from the police cruiser report as is possible given Clare's astute
observations about EE and FF pads faring differently, but not because of
their coefficient of friction.
There were 3 police tests over the decade, where only the penultimate test
aimed for uniform pedal pressure.
The middle test is the one that aimed for a given pedal pressure:
a. 45-to-15mph at 10ft/s/s (approximately ~10 foot pounds +- a few)
b. 70-to-30mph at 22ft/s/s (approximately ~20 foot pounds +- a few)
c. 90-to-0mph at 22ft/s/s (approximately ~30 foot pounds +- a few)
Fundamentally, they said pedal pressure is, effectively, what a human does
all day every day - hence pedal pressure is, arguably, more important in a
well-used "cruising" vehicle that doesn't do panic stops consistently.
A targeted deceleration rate where pedal force is proportional to pad temp.
The other two studies were different.
1. Mostly stopping distance
2. Mostly pedal pressure
3. Mostly driver perception
In the end, the DOT edge code (AMECA edge code) is only slightly useful to
a consumer, I think. I wish it were more useful, but I've gleaned out of it
what I can, and that's the best any of us can hope to do.
I was hoping to get more insight from the scientific and mechanical folks
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