(ambient music)
- For your car to operate the way it's all mighty engineer
intended it to.
Its individual systems got to be in the Goldilocks zone.
Not too hot, not too cold.
That goes for the engine, the tires, even the driver.
But one component that often gets unnoticed are your brakes.
Too cold, you get this, too hot, you get this.
So today, we're gonna figure out why temperature
is so important for your brakes.
And to do that,
we're taking a little field trip to Wilwood engineering,
to see how engineers manipulate brake components
to maximize their stopping power.
You can manipulate brakes, but you can't manipulate me.
I'm unmanipulatable.
- [Eddie] Glad you decided to grow out that mustache Jerry.
- Thank you, Eddie.
That compliment gave me the confidence to grow it out.
Let's go.
(upbeat music)
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Now let's boom, back to the show.
I'm gonna take this here, we don't need this anymore.
This is how I carry products out of the office.
Oh, what do you got in your jacket?
Nothing.
Heat is the enemy of braking.
Even though most brakes don't work great
when they're extremely cold,
brakes have no trouble making heat and a hard time
getting rid of it.
When brakes get overheated,
they don't stop well and they can fail completely.
That's more of a problem on high performance and racing cars
than a typical road car,
but almost all cars use braking systems
that operate the same way.
To understand why temperature matters so much.
We first need to see how brakes work
and they're not that complicated.
For a typical braking setup.
There are three main parts at each wheel.
There's the disc, the caliper and the pads.
The disc or rotor as people call it
is attached to the hub or axle
and rotates along with the wheel.
As it rotates, the disc passes through a stationary caliper
that holds the pads.
When you step on the brake pedal,
this increases hydraulic pressure in the caliper
pushing a piston into the backside of the brake pad,
which presses it against the face of the disc.
Manufacturers of road cars, especially electric cars
have recently introduced electronic braking system.
We did a whole B2B about those.
So check that out over here
if you want to understand the differences,
but those still rely on disc calipers and pads
and despite their name, they'll still use hydraulic pressure
to create braking force.
So, the heat problem applies to those systems as well.
The biggest difference though is in the pedal
because in an ordinary hydraulic braking system,
the resistance you feel with your foot
is actually the pressure in the hydraulic fluid.
In an electronic system
pedal feel is simulated with a separate hydraulic
or electrical system.
But for today, we're gonna stick with the juicy stuff
because that's what you'll find on most performance cars
and at the racetrack.
The fluid that takes the paint off your car
if you ever spill it on there, been there brother.
How your brakes work is pretty simple
friction between the disc and pads slows the wheel.
And that friction is produced by an increase
in hydraulic pressure.
But the two physical principles that make brakes work
friction and pressure,
both create heat and heat is what makes brakes stop working.
Friction is just the force opposing motion
between two surfaces and your brakes work
by using frictional force
to convert kinetic energy into heat energy.
With greater friction, more kinetic energy
can be converted into heat,
but you already understand this.
It's why we rub our hands together when we're cold.
When a brake pad and a disc really love each other,
they make friction baby.
(Jeremiah groans)
The amount of kinetic energy is based on the speed at which
the two surfaces are moving relative to each other.
So the faster you move your hands,
or the faster the brake disc is rotating
the more kinetic energy it has.
Not a lot of kinetic energy.
A lot of kinetic energy.
The amount of friction is determined by the materials
the two surfaces are made of.
Any two materials have a specific coefficient of friction.
A number of usually represented by the Greek letter mu.
Mu is like u, but with a little tail,
it's a u with a droopy neck.
That's why brake pads are sometime described
in terms of their mu factor or mu level.
The higher that number is, the more friction they produce.
But the total amount of friction between two surfaces
also depends on how much force is pressing them together.
In physics, that's Amonton's first law,
the force of friction is directly proportional
to the applied load.
So if you rub your hands together gently,
there's not much friction and they don't produce much heat,
but if you really put some muscle into it,
you can feel the heat in no time.
The muscle in your brakes depend on the hydraulic pressure.
And you already know about the direct relationship
between pressure and heat.
It's how a pressure cooker works or a diesel engine,
or even why a can of soda left in a hot car can explode.
As temperature increases, so does pressure
and as pressure increases so does temperature.
It's why I get hot when I'm forced
to release these episodes.
(tense music)
For a hydraulic system like brakes,
which uses pressure to generate force.
Every time you step on the pedal and increase that pressure,
it also increases the temperature of your brake fluid.
Stopping an object completely requires enough friction
to turn all of its kinetic energy into heat.
And in the case of a car, that can mean a lot of heat.
Kinetic energy is 1/2 mv squared.
It's directly proportional to mass.
So the heavier a moving car is, the more energy it has,
but kinetic energy also increases as a square of speed.
So a car moving 40 miles per hour
has four times the kinetic energy as it does
when it's going 20 miles an hour.
At 60 miles an hour,
the same car has nine times as much kinetic energy
as it does at 20 and so on and so forth.
All that kinetic energy being turned into heat by the brakes
is absorbed in the discs, pads, calipers
and even hydraulic fluid.
In a road car under normal driving
that heat dissipates into the air.
And you're unlikely to notice any problems,
but in performance applications
that require repeated hard braking, heat is a major concern.
Excessive heat can work discs
as the metal softens and deforms
reducing the contact surface with the pads.
A pads mu factor also changes with temperature.
And at a certain point, they won't produce enough friction
to stop the car.
Overheating the brake pads can crack the material
or cause it to glaze,
meaning it turns smooth and glassy
no longer able to produce enough friction,
even once it's cooled.
Heat can damage or rupture the rubber seals in the caliper
causing leaks that reduce hydraulic pressure.
And heat can boil the brake fluid, turning it into a gas.
So we understand that heat is the enemy of brakes.
So to find out how engineers manage brake temperatures,
we went to Wilwood engineering where one of the major tasks
when designing high performance brakes
is getting rid of all of that heat.
(upbeat music)
So I'm here at Wilwood engineering in Camarillo, California.
They've got production, they've got manufacturing.
They've got it all.
We're gonna walk around and I'm gonna ask questions
and figure out how these guys
engineer better braking systems.
Let's go, come on, come on, Grant, let's go.
I hear you're the man
who's gonna give me a show of this place.
- What's up man? How are you?
- I'm doing well, thanks.
- Good to have you here man.
- This is Mike.
Mike, why don't you tell us a little bit about
what you got going on here.
- What we've got going on is
this is where all of the R and D is done.
We bring cars in, we test fit stuff.
We design new brake systems.
And then from here,
we're gonna walk you through the shop
kind of show you like the progression of how stuff's made,
but primarily calipers
'cause that's our primary stuff.
- Okay, cool.
- Cool? - Yeah, let's do it.
- So, primarily, caliper manufacturing,
but like that caliper is our Dynalite.
You've probably heard of that caliper.
- Yes, sir.
- So that one machine with one operator
will do 250 inboard and outboards in an eight hour shift
- Oh thanks.
- And very few failure rate.
This is like the most common caliper that we sell
on a lot of our street applications,
but also some race applications.
- Okay, all right, cool.
- [Mike] So over here, there's one last thing
that I think you'll kind of trip out on.
So, this is like where we used to get all of our dyno
information and we're talking from 35 years ago.
- Okay, the OG set up.
- This is super OG.
In fact, when I started here, it was still running on dos.
- [Jeremiah] Oh nice.
- [Mike] But there's no reason now for us
to change any of this.
- [Jeremiah] It works.
- Well, we bad brake pads now with it.
So we're not extracting any data from it anymore.
Basically what we're doing is pre-bedding
for race applications, brake pads, and rotors,
and really even do it together for a race team.
- So can you explain what betting and brakes means?
- So, the betting procedure is super important
when you're talking about high coefficient of friction,
high temperature applications,
what happens is it's kind of tough to take your race car
and drive it up and down the street here
and even get it hot enough
to get all of the saturation in the system
so that the binder that's inside the brake pad
gets onto the face of the rotor.
- [Jeremiah] Okay.
- [Mike] We don't want just the face of the rotor
or the face of the brake pads to be 'hard'.
- Right.
- We want all of the system to get hard.
- The entire rotor, right or just the entire system.
- 7175 are the forgings that you saw out there.
- Yeah.
So before, when we were in the diner,
you were talking about saturation temperature
and how all the individual components, when they get up,
they need to get up to temp to perform optimally, right?
- Correct.
- What happens when you pass that threshold?
What happens?
- That's when you start experiencing fade.
- Okay.
- So when you start to experience fade,
one of the first things that'll start to happen is
maybe you don't have the right brake fluid.
You might have like a DOT three brake fluid,
and you really need to step up to a DOT four
something that has a higher boiling point.
So the next thing is, rotors are very important.
This is one of our premium spec, 37 race rotors,
and it's not only directional vein, it's also staggered vein
What we learned from testing was
if we were to close this stagger,
there wasn't enough air getting flown.
So now we've got way more capacity.
We can cool off the rotor a lot better, super important.
- Okay, so here we have two different types of brake pads
and you said two different ways that they were manufactured.
Okay, so how was this made right here?
- So, this backing plate you can see is flush.
- Right. - Right.
There's no holes in it, that one's got holes.
- Right.
- So anything that we're gonna do for racing,
we don't want holes
because that's gonna add deflection in the pad.
All right.
The other thing about this pad is it was made with NRS.
So feel that. - Gotcha.
So that's what's getting that to grip onto this
piece of metal right here, right?
- I hate to say the word, but it's almost like Velcro,
right? - [Jeremiah] Okay, yeah.
- [Mike] So when we manufacture
this particular type of setup
under super high heat and pressure,
we press the material onto this backing plate.
- You know, obviously the material pad composition
is a huge influence or the factor
when it comes to the coefficient of friction of the pad
temperature range as well.
Is there a specific compound in particular
that higher temperature pads have in it
that allow for that ability to take that much heat?
- So all the pads that we're talking about today
are gonna be what we sell, which are semi-metallic.
- Semi-metallic, okay.
- So, here's the thing that I don't even know
is the ratios for different pad formulations.
Some might have more nickel, more copper, more beryllium
different things that cause the pad to do
what you're asking it to do.
- Right, so different secret formulations
of metals in this pad determine the temperature range
and the coefficient of friction.
- Absolutely. - Okay.
- And in a lot of cases, like I joke around, but.
- [Announcer] Sergio 709, Sergio, 87609.
- Sergio, 07.
All right, I was hoping you were gonna be able to tell me
the secret formula.
- No. - It's cool, you don't have to
- No, I'm not going to.
So, all of our engineering staff is here
in building number one.
So we do all of our dyno testing
when we've got a new project,
when we've got friction materials that we want to try
or test. - Right.
- So, this is our link.
Now this is pretty much state-of-the-art
dynamometer for doing brake systems.
- [Jeremiah] Okay.
- [Mike] It's all electric.
It has the capacity to be able to give you the inertia
of 30,000 pounds.
- [Jeremiah] Oh wow.
So you can do calipers, pads, rotors
all in this one machine.
- Yes.
- Okay, great.
We're gonna get to run it.
- Yeah.
- I get to hit the big button over there.
- That's the turn off button.
You don't want to hit that.
- You don't know that.
(upbeat music)
A brake dynamometer or dynamometer or brake dyno
is often used to measure the amount of power
a car is transmitting to its axle.
But it can also be used to measure the force
of a braking system.
Advanced brake dynos like the one at Wilwood
could even be programmed to run simulations
of specific racetracks to determine the conditions
the brakes will face over the course of a race,
helping engineers choose the best braking setup.
Wilwood engineering has been designing and building
performance brake components for 45 years.
They make everything from high performance pads,
big brake kits for road cars
to fully custom setups for racing.
I got to set of Wilwood brakes on the old catfish Camaro
They get me out of the jam when I'm going too fast.
But I drive with the speed limit.
Most brake discs are made from iron.
These are cheap and effective, but they're also heavy.
So some race cars will use steel, which can be made thinner,
lighter and has greater thermal connectivity.
Meaning they dissipate heat faster,
but steel wears quicker and is more prone to warping
than iron.
Aluminum dissipates heat better than steel,
but it also has a lower melting point.
So it's only used for lightweight applications
like motorcycles or as the hub component
of a two piece rotor
with a disc made of iron, steel or carbon ceramic.
That's what's used on some of the most expensive
performance cars in the world,
like the Bugatti Chiron and Rimac Nevera.
Because the two-piece carbon ceramic brake disc
can be made large, lightweight and heat resistant
at a cost of course.
Carbon brakes, they can be as much as 21 grand.
If you want the option then for your Porsche 911 turbo,
for example, that's like a car.
You buy a whole car for that. Keeping a brake this cool
isn't just about the material
size and construction matter too.
Big brake kits like the ones designed by Wilwood
use larger discs, larger disc means heat is spread out more
and their greater surface area means more disc
is exposed to cool air.
All of which helps dissipate heat.
Engineers will also design discs with vents
wave patterns, slots, grooves, dimples, and holes
to increase surface area and create passages
for hot gases to be channeled away from the disc.
Pads have a huge impact on braking performance.
Like tires, each pad has a unique compound.
That's the mixture of materials it's composed of
and just like tires, the compound
determines the amount of grip or friction it can produce.
And the temperature range at which it works.
Like tires, brake pads don't work well if they're too cold
or too hot.
Pads fall into three general types.
You've got organic, ceramic and metallic.
Organic pads are made from materials like glass, rubber
and Kevlar bonded together with resin.
A lot of road cars come with organic pads
because they're quiet,
but they also don't create a lot of friction
and wear quickly under hard braking.
So they are a poor choice for performance application.
Ceramic pads are made from ceramic fibers.
They're incredibly durable and good at dissipating heat,
but like carbon ceramic brakes,
they're incredibly expensive.
So they're the least common of the three types.
Most performance pads are metallic
made from a combination of metal shavings and resin.
Metallic pads can include copper, steel, graphite, brass,
but the exact mixture of any specific pad
is a closely guarded secret
like Kentucky fried chicken's recipe.
By varying the materials in the pad compound.
Engineers can dial in pads to work
at just the right temperature for different application
and to avoid brake fade.
That's when the pads get too hot to work
and the amount of friction it produces drops off.
In the quest for speed, many enthusiasts add power,
and they don't spend much time thinking about brakes.
But when engineers think about speed,
brakes are an essential part of that equation
and maintaining the right brake temperature is vital
for hard stops and fast laps.
On a racetrack, speed on the streets.
It doesn't do you any good
if you can't get rid of it before the next turn.
- Ho-ho-ho. - Happy holidays Donut fans.
- We want to personally let y'all know
it's your last chance to order donut swag
before the holidays.
- Get your orders in before December 10th.
- And never forget 'cause we're Island boys.
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♪ Shout out to Donut media fans. ♪
- I want to thank everybody at Wilwood engineering
who helped out with this episode.
Those guys are great over there.
If you want more information about them,
we'll put a link down in the description below.
You want to see more videos about the catfish.
Watch this video over here.
Man, I think it's looking sick, isn't it?
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