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Clare Snyder Clare Snyder is offline
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Default Need help INTERPRETING these test results police cruiser SAE J866a Chase Test

On Mon, 15 Jan 2018 14:19:44 -0000 (UTC), Mad Roger

On Sun, 14 Jan 2018 18:05:29 -0800 (PST),

Sigh. It's just sad.

if they all work ok it's not sad, it's a nonissue

I think you hit the reluctant nail on the head!

The only way this can make sense is if all brake pads work. Period.

Because if people were getting into accidents due to bad brake pads,
someone would step in and stop that (we hope).

Notice even the police report, which is the only scientific study we have,
never said any pad was better or worse - they just required more foot
pounds or fewer foot pounds of pedal force for the same deceleration value.

They never said anything about not being able to decelerate at the desired
deceleration value.

The tests were limited - addressing the use a cruiser puts the brakes
to. If you know how to read the information, it tells you a LOT about
the brakes - but you are correct - there is no "best" brake material -
it depends onthe use they are being put to, and what YOU want from
them. There may well , however, be " WORST" brakes.

If brakes require higher pedal pressure to stop in a longer distance
(and decellerate at a lower rate) both when cold and at normal
temperature, and fade significantly on the second and third
application - they are pretty crappy brakes.

If they require low pedal pressure to decellerate quickly to a stop in
a short distance when both cold and at normaltemperatures, AND do not
fade appreciably on the second and third (panic) stop - they are
pretty darn good brakes - anlness they squeal like a stuck pig, only
last for a month of driving, and/or destroy brake rotors - and/or coat
the wheels with nasty corrosive brake dust - - -

So, I very belatedly am getting the lesson that, in terms of stopping a
typical passenger vehicle, all pads sold are just about the same in terms
of performance.

No, not at all - you are TOTALLY missing the point.
The different brake PAD materials are mission specific.
A ceramic pad will outstop a economy organic pad when hot - hands
down. Every time.
A metallic pad will usually stop better after several panic stops, or
when towing a heavy trailer down a longhill - than either the organic
or the ceramic. Both the semi metallic and the organic will stop
better on a cold stop than a ceramic.

Another way of saying that is that no matter what the price is, you can't
get a bad pad (nor a good pad). All you get is a pad.

No. a $85 Thermoquiet Ceramic will stop better than a $20 no-name
organic pad - and you can be pretty well assured you will not get a
$20 ceramic pad unless Rock Auto has something on clearout.

Price is not a sure predictor of quality - but can be a pretty darn
good indicator.

Also, a high iron semi metallic WILL wear out your rotors faster than
either the organic or the ceramic unless the organic causes the rotor
to blister because of uneven pad material transfer, and abuse.

What you TOTALLY do NOT understand is how disc brakes, in particular,
work - and how the co-efficient of friction changes.

When you "bed in" pads, you are burnishiung a thin coating of pad
material into the finish of the rotor.. The stopping power of the
brake depends on the co-efficient of friction between this burnished
in friction material and the pad - not between the pad and bare metal.
How this coating is applied, and maintained, dictated the braking
charachteristics of a disc brake as much as anything. If you stop hard
and fast and keep your foot onthe pedal at a stop untill the brake
cooles,there will be a heavier deposit on the rotor at that point -
UNLESS the padmaterial deposited on the rotor does not adhere properly
and it pulls away with the pad. Either way you will end up with uneven
braking - either a "thump" or a "skip" on the next brake application.

A "quality": pad will transfer evenly and bond reliably to the rotor
during the perscribed "bed-in" and will not cause uneven transfer
under "normal" driving conditions. It will also not cause or promote
corrosion between that pad mnaterial and the rotor steel (which causes
"scabbies" and pitted rotors (often mistaken for the less common, but
sometimes "real" "warped rotor".

Inferior brake friction material performs more poorly in these ways
than premium materials.

A worn, glazed, or grooved rotor will not "bed in" reliably because
the surface will heat and cool unevenly - with uneven pressure across
the brake surface -

So brake friction material quality AND the installation affect brake

Also, the brake mounting hardware - the shims and springs either
provided with the new pads, purchased separately, or salvaged from the
prior installation (whether OEM or aftermarket or totally missing)
alsohave effects on the performance (and life) of the brakes. Heat
transfer, Vibration, and freedon to move in the caliper, are all
effected by the quality and presence of the proper mounting hardware -
which is designed/modified by the pad manufacturer to matvch the
characteristics and requirements of their particular pad and friction
material - which is why "premium"brake kits are supplied with the
proper hardware to install the brakes for their best performance.

All this assumes that you can't afford to run your own scientific tests,
because the one scientific test we do have, concludes as much anyway in
that there's no way to tell unless you run the test yourself, which you
can't do.

More paranoid bull****.

For actual racing, those guys can spend the actual immense time comparing
two different pads, but the consumer is left to realize, as sad as this
conclusion is for me to state, that all consumer-available brake pads are
pretty much exactly the same in terms of stopping ability.

Total bull****. The friction rating doesn't tell you much, but the
difference in required pedal pressure, and the difference in stopping
distance - notto mention the difference in pad temperature between the
best and worst in the test is VERY significant.
What is NOT significant is the predictabiklity of the results based
on the frictionrating of the pads under test. (almost totally useless)

Sigh. It's sad. I didn't want to conclude that. I really didn't. But it is
what the science tells us it is. The rest is just marketing bull**** and
fear mongering from the butt-dynos that think if they paid $157 for a pad,
then it must be better than if they paid $20 for the same pad.

And do your friend a favour and send them to a REAL mechanic to have
their brake work done. I fear you are DANGEROUS.