- [Bart] Picture this, it's a beautiful day and you're
cruising down the road.
Happy to be out of the office.
And you're hugging the turns and you're gaining speed
and you're going down hill.
Now you're going so fast that you can't
go, slow down, somebody stop me!
(exhales)
Brake Pads!
(fun music)
Some people say brakes are just as important
as your engine.
There I said it.
Geesh. It feels good to get that off my chest.
Without brakes, you don't just crash into
each other all the time.
Well it sounds pretty fun.
Doesn't make much sense if you're trying not to be dead.
Most of us have disc brakes on the car.
But the disc is only half of what's needed to stop your car.
The other half is the pad.
So as technology advances, the materials we use for
brake pads changes drastically.
Bertha Benz, Mercedes Benz fame gets credit
for inventing the first brake pads and they were leather.
That was in 1888.
The first disc brakes used in production were
in a car made in 1902 by the Lanchester Company.
It had thin copper pads that wore down quickly
from dust and dirt and really they were pretty useless.
The idea didn't really catch on 'till 50 years
later when the Jaguar team won the 1953 Le Mans.
Demonstrating the superiority of disc brakes
over drum brakes.
So, the brake pad or shoe as it's sometimes called
is made up of the a solid metal backing with
a brake lining.
Which is relatively soft, but tough material
with high coefficient of dynamic friction.
The job of the brake pad is to convert
the kinetic energy of the vehicle
to thermal energy through friction.
When the driver presses on the paddle,
two brake pad contained in the caliber
are hydraulically clamped around the rotor.
Nope.
Think of a crab, pinching a spinning quarter.
When the pads come into contact with rotor,
they create heat.
And that results in an small amount of
residual material being left on the disc.
This material allows the pads and the rotor
to stick together.
Brakes create friction in one of two ways.
Abrasive friction and adherent or adhesive friction.
Thinking about abrasive friction, let's move
away from brake pads and think instead about sand paper.
You know why sand paper is abrasive,
it's because it wears down what it's rubbing.
On the other hand when the brake pad comes into
contact with the rotor, that abrasive friction
causes a lot of heat and is pretty destructive.
It gradually wears down the rotor.
Adherent friction is what happens when a
thin layer of the brake pad bonds to the rotor
through the process of heat and friction.
When the brake pad presses on rotor,
it essentially sticks to the residue that is
left on the surface.
Higher end brake pad, use more adherent friction
because it's less destructive and the rotors last longer.
Alright, dynamic friction coefficient is measurement
of how effective a brake is.
We talk about the forces on the pad and then
the force on the rotor.
The force on the rotors called brake force.
To figure out the dynamic friction coefficient,
we're gonna compare the two.
If the brake puts a force of a 1,000 newtons
on the pad and the resulting brake force
is 400 newtons then the dynamic friction coefficient
or DFC is .4.
A normal commercial brake pad has a dynamic friction
coefficient around .35 to .42.
Some high end racing brake pads can achieve
a DFC of of .62.
And that's keeping a lot more force.
Most consumer brake pads have a cool feature
called a warning tang.
And as we know, the warning tang clan ain't
nothing to mess with.
So if your break pad's worn down,
these little metal strips will scratch against
the rotor and let you know in the most annoying
way possible that you need new brake pads.
Materials used to make linings on brake pads
have evolved to be the most durable, most efficient,
most brake paddy.
The materials must be able to withstand extremely
high temperatures and tons of friction in order
to function properly.
Asbestos used to be used in brake pads for a long time
because of it's ability to dissipate heat extremely well.
It's since been discontinued due to it's
harmful effects on health.
Asbestos has harmful effects on health?
Now you tell me.
(cough)
Modern day break pads come in many different types,
depending on how durable you need them to be
or how much you wanna spend.
There's four common categories of brake pad linings.
Organic.
Semi-Metallic.
Full metallic.
And ceramic.
Some are so expensive there usually only reserved
for race cars, or DJ Khaled.
So, you got an old car that needs brakes.
And you don't really feel like sinking a lot
of money into it.
Organic brake pads.
Sound great.
These brake liners are made of materials like
glass, kevlar, fiber, rubber, and resin.
Because all those compounds can withstand high heat
and they're relatively inexpensive to produce.
The heat actually helps the materials bond
together tighter.
You wanna know the coolest thing
in a lot of organic break pads?
Cashew.
Cashew containing friction dust has the ability
to absorb the heat created by friction
while retaining breaking efficiency.
Organic break pads were designed as an
alternative to asbestos pads.
They're quiet, they're easy on the brake rotors,
and one of the softer break pad materials.
They don't need much heat to generate good friction
and they produce a minimal amount of break dust.
There's a couple of downsides, but that's life
get used to it!
Organic brake pads wear more quickly than other brake pads.
They also have a high compressibility, because of
their softness, which can cause a mushy feeling
while braking.
It's gonna lose some of that brake force.
And that's why its got a lower dynamic friction coefficient.
But for normal use you still get a pretty good brake
for your buck.
- [Man] You suck! - [Bart] It's a funny joke.
Alright, now let's cut one open to see what it's made of.
- [Man] Uh, we didn't get the pad yet.
- [Bart] Hey, what I gotta do everything around here?
- [Man] Sorry.
- [Bart] (chuckles)
(swoosh)
(typing)
Hey, what's up Buddy? How you doing?
- [Anthony] Oh, hey. You know I watch one of your shows.
- [Bart] Yeah? What'd you think?
- [Anthony] Eh, you spelled Diesel wrong.
- [Bart] (sighs) I know.
- [Anthony] Anyway, what could I do for you?
- [Bart] Can I get a brake pad please.
- [Anthony] Okay, what kind?
- [Bart] I'm gonna cut it open, so.
- [Anthony] Oh okay, I'll be right back.
Got your brake pad for you right here.
- [Bart] Wonderful.
- [Anthony] That's spelled B-R-A-K-E.
- [Bart] Thank you.
- [Anthony] Welcome. - [Bart] See you in a week.
- [Anthony] Alright.
(swoosh)
- [Bart] Okay, So Anthony just sold me
some organic brake pads.
We're gonna cut it open and see what it looks like.
And how long it takes to do so.
(electric saw)
We're almost there.
- [Man] Drill baby drill!
(electric saw)
- [Bart] So again, it's a mix of a bunch of
different stuff.
But we got through it pretty quickly.
I'm excited to see how the speed at which we cut
through the pad is gonna compare with the
other two types of pads we're gonna cut into.
So if you've never seen a brake pad, you've probably
noticed that there's a little angle on the edge.
Zack get out of the lab.
That's a chamfer, let's talk about that.
If the surface of the brake lining is not
perfectly aligned with the surface of the rotor
it could cause some problems.
And that could be because of debris or maybe
it was installed improperly.
The extra vibration usually translates into more noise.
One way engineers deal with this when the design
the brake pad is through chamfers.
A chamfer is an angled cut on either end of the
pad that controls how the edge of the pad reacts
when it's pressed against the rotor.
This cut ensures the largest amount of surface
area touching the rotor, cutting down vibration.
And in turn, cutting down noise.
Okay, so you got rid of your old beater.
You traded up for a nice midsize luxury car.
Good for you!
You got a good deal, but it needs new brakes.
You wanna spend a little more on your pads.
So you go with semi-metallic.
These brake pads are made up of anywhere between
30 to 65% metal.
Like steel, iron, these are tough metals that
can handle a lot of heat.
And the rest is made up of friction modifiers.
Like fillers and resins as well as graphite lubricant.
These are materials that bond together and
dissipate heat well.
These are arguably the most versatile of brake pads.
They last a long time and provide better
performance than organic pads.
They do however, produce a little more noise
and a little more dust.
Wait, now let's cut one open.
Eddy! Give me the semi-metallic brake pad.
- [Eddy] Uh. - [Bart] I swear to God!
Eddy, If I gotta go back,
this guy is gonna think I'm an idiot.
(swoosh)
Hey, me again Anthony.
I'm hoping I can return this, I'm looking for something
a little bit more high performance.
- [Anthony] Oh, totally.
Returns are easy and simple.
- [Bart] Sure feels like no one.
- [Anthony] You know, I had get these out of the back.
- [Bart] Thanks man, I appreciate it.
- [Anthony] You're welcome.
(whoosh)
- [Bart] Sure feels like no one, doesn't it?
Think he's got a brother?
Anyways, Anthony give me this semi-metallic
brake pad.
This type of brake pad got a little bit higher
level of metallic components, so we're gonna do what we do.
So I got a new blade and and a new pad, let's see
how it does.
(electric saw)
Got it!
This is a semi-metallic, and it did take
a little bit longer than the organic to get through,
this top part 'till we got to the sparks.
You can see a slight difference.
Down here, that's the tang, so if you hit that
it's gonna squeal, by design.
That means you need new brakes.
It's cool man, pretty sick.
Somethings that are unavoidable when it comes to
any type of break pad are dust and the gas
produced by super heated pads.
There's no way around it.
Like your mom in an hallway.
These things can be detrimental for brake pads,
causing a drop in efficiency and lopsided wear.
If too much gas builds up, the pads aren't gonna
get a solid contact with the rotor.
Remember, we're turning kinetic energy into thermal energy.
And if the brakes can't dissipate the heat,
then they get too hot, they can't stop the kinetic energy.
(slot machines)
Slots in the break pads lets the dust and hot gases
escape with out causing pressure or extra heat.
They can also relieve some friction and reduce
vibration and that means,
quieter brakes!
And now wouldn't you know it, you get bored
with that luxury car.
You trade it in for a high end sports car.
Boy! That thing is fast.
But the mechanic says, "It needs new brakes."
(chuckles)
Can't catch a break!
Am I right? Alright.
This time you decide to shell out some serious cash
for some brake pads.
So you go with ceramic.
Ceramic just means a solid inorganic compound.
Like a brick or porcelain.
This type of pad has a longer life than organic
and semi-metallic pads.
It's also pretty quiet and the dust they produce
is light and doesn't stick to wheels.
The downside is that ceramic pads are super expensive.
Let's cut one of those open!
Eddy! So help me gosh, if there isn't a ceramic break pad
in this office I'm gonna be upset!
- [Eddy] (growns)
- [Bart] Oh man, oh man!
(grunts)
(whoosh)
- [Man] Do you actually think he's mad?
- [Eddy] Yeah, I think he's mad I've never seen
him like this.
- [Man] No, he's not mad, Bart doesn't get mad.
- [Eddy] How was I supposed to know?
- [Man] I don't know.
Eddy I think you really dropped the ball on this.
- [Eddy] Oh, you know what? I just found it.
I have the ceramic pad.
- [Man] He's gonna be pissed!
- [Eddy] (grunts) What do you want me to do?
- [Man] Get rid of it! - [Eddy] (grunts)
(shatters)
- [Man] Just be cool, act normal. (whoosh)
- [Bart] I'm sorry guys, that wasn't that big of a deal.
I kind of flew off the handle.
No harm, no foul.
So this is a higher performance, ceramic brake.
It's a little bit different composition.
I got a new blade, new brake pad, let's see--
(phone ringing)
Hold on.
Hello?
It's Pep Boys.
Anthony, how you doing?
Oh, yeah I, no I, I forgot I actually cut that in half.
Okay.
Same card, just put it on the same card.
Yeah, alright.
Well, see you soon buddy.
(electric saw)
See it looks like there's actually a little bit
more copper.
So as you can see, cutting into it,
I think it came apart pretty quick.
'Cause all these brakes are designed to wear.
You want the brake to wear not the rotor.
Brake pad.
There are of course, other type of brake pads
that we didn't cover.
Full metal brake pads are just that.
They're fully metal, but as you can imagine
they're not very good for daily use.
Imagine metal on metal, you know that's bad.
Right?
Oh, but then we can't finish an episode
without talking about the holy grail of brake pads.
Carbon ceramic.
These pads are the best when it comes to
performance, weight, and the ability to handle heat.
They comes standard on very few high end production cars.
But, they're common in drag racing and aviation.
When things are going so super fast that they need
to stop even super-er more quick.
I'm not gonna cut one open because I can't afford
one of the dang old things.
Carbon fiber brakes can upward cost upward of 10,000.
That's more than my house.
I live in a shipping container.
This button is a subscription button.
You know where you don't need brakes?
Drag racing in a desert.
What a dumb idea.
Check out this video, it's rad.
We got new stuff coming out, if it's the holidays
you need to go to shop.donut.media, follow us on
Twitter and Instagram @donutmedia.
And follow me @bidsbarto, I take pictures of stuff
and tell stories.
Don't tell my wife I forgot to pay for that
stuff at Pep Boys. (laughs)