(energetic music)
- We here at Donut enjoy four-wheel drifts.
We like rally pedigree and we love
station wagons that can embarrass super cars.
So that means we're really into Audi quattro,
but more than one all-wheel drive system bears that name,
and those can be as different as and Camrys and Koenigseggs.
So today we're gonna look at all the current versions
of quattro and figure out how they work.
Quattro means four in Italian.
I know two words in Italian.
One of them's quattro and one of them's cinco
and that last one's Spanish.
Let's go.
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Hi, I'm junk car, Jimmy.
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So get it at DonutMedia.com today.
I'm junk car Jimmy and we'll pay you
a of money for that junk car,
depending on the year, though.
Nothing too new, nothing too old.
It's gotta be just right.
- Quattro is what Audi calls all-wheel drive.
But that originated with a single car
called the Quattro back in 1980.
Now at the time all-wheel drive was common
in trucks and military vehicles.
But the idea to put it in a sports car was revolutionary.
The Quattro, it dominated the World Rally Championship
and Pikes Peak Hill Climb, solidifying Audi's reputation
for all-wheel drive performance.
So to commemorate that success,
all of Audi's all-wheel drive systems
now carry the Quattro name.
but with a lower case Q to distinguish them
from the car that started at all.
The current lineup includes five different types
of all-wheel drive systems,
and there's some pretty big differences between them.
The one that's most different from the rest
that we're gonna talk about is the quattro used
by fully electric vehicles, like the RS e-tron GT.
We're not gonna get into it
but that system is designed to take
on the Tesla model S and the Porsche Taycan.
These systems are drastically different
from what's used with internal combustion.
So that's a subject for its own episode.
At least maybe, I don't know, you guys don't
really like EV stuff,
but if you do leave a comment down below
and we'll do a whole episode on it.
Now a more common system is transverse quattro,
often described using the original
manufacturer's name, Haldex.
That's for optional all-wheel drive systems
in front wheel drive cars, where the engine
is mounted perpendicular to the car
like in the Audi A3 NTT.
It relies on a multi plate clutch
mounted at the rear differential,
instead of having a center differential
like their original Audi Quattro.
Because of that design, older Haldex systems
could only send half the power to the rear.
So some critics say this isn't real quattro
and they even call it faux wheel drive.
Oh, you clever, clever journalists.
How funny with words you are.
We just make YouTube videos.
(recorded applause)
But transverse systems are found in some
serious performers like the TTRS and RS3,
even if it's not what most people think of
when they hear quattro.
Half of the Audis sold today use quattro Ultra
paired with a longitudinal engine like the original Quattro.
Having the engine mounted parallel to the car
keeps things simple when using a drive shaft
which is why it's also the most common configuration
for rear world drive cars.
But to add power for the front wheels,
most all-wheel drive systems use a
center differential to divide power
between the front and the rear.
So in old Audis like the original Quattro.
The center differential always sent
some power to both axles.
That's permanent all-wheel drive.
Ultra is different and Audi calls it
permanently available all-wheel drive,
and that's not the same.
Permanently available, huh?
Oh.
Oh, that's funny, look who's calling.
Quattro Ultra spends most of its time
sending power to just the front wheels,
and when the system was first announced
not everyone was super happy about that.
Remember what people said about their old Haldex systems?
Well, pretty much the same things were said
about the front bias Ultra.
It's not real quattro.
Frickin' haters.
But here's the thing, you may not actually
want permanent all-wheel drive.
Audi engineers discovered something which was
a bit worrying for a company that
built its reputation on all-wheel drive.
During 90% of ordinary driving,
all-wheel drive is not only unnecessary, it's wasteful.
Sending power to all four corners consumes more fuel
because the engine has to rotate greater mass
than if it only had to power two wheels.
And don't I know that.
I get like 12 miles to the gallon in my GX 470.
It's terrible.
And I only go off road like once every month.
That's like 90% of the time.
(explosion sound)
So Audi engineers designed a
new version of quattro that eliminates that waste
but retains all-wheel drive functionality
for the 10% at the time when you actually need it.
Pretty freaking smart.
And of course, Audi isn't the only company that knows this.
A typical all-wheel drive crossover
or family sedan with all-wheel drive
is engineered so that most of the time
power is only going to the front wheels.
Power only gets sent to the rear wheels when necessary
to make up for a loss of traction, for example.
That's accomplished by having a clutch
at one end of the drive shaft
either at the transmission or rear differential.
So when power needs to be sent to the rear wheels
the clutch engages and it disengages
when it's no longer needed.
But there is still a source of waste in that system.
And that's the drive shaft itself.
If the clutch is at the rear differential
the drive shaft spins, even when it's
not powering the rear wheels.
That consumes engine power and fuel.
And if the clutch is at the transmission,
well the drive shaft is still turned
by the rotation of the rear wheels
even when it's disengaged,
and that extra rotating mass of the drive shaft,
even when it's disconnected
still consumes power and fuel.
It'd be the equivalent of having just
extra heavy wheels in the rear end.
So according to Audi, a spinning drive shaft
decreases driveline efficiency by 20%,
stealing power and burning more fuel.
So to avoid this, Ultra disconnects
the drive shaft at both ends.
(man makes popping sound)
So on the back end of the transmission
Ultra uses a clutch pack
like you'd find in a motorcycle
that sends power only when needed
and disengages so the drive shaft
can float when it's not.
At the rear, a second clutch is used
to fully disengage all-wheel drive,
but it's not where you'd expect.
The right rear axle is split in half,
and the second clutch is between those two halves.
That's a dog clutch, which uses two
gear-like plates that mesh together
instead of pressure plates.
So when the front and rear clutches are both open
the drive shaft is disconnected from the wheels
and the engine, and it doesn't spin.
To switch from front-wheel drive to all-wheel drive,
the front clutch pack engages to spin up the drive shaft.
The drive shaft is always connected to
the rear diff, but because that's an open diff
and power follows the path of least resistance
all of that rotation is going to the
disconnected half axle on the right, not to the wheels.
Once that dog clutch on the axle engages,
the drive shaft's rotation is transmitted
to both wheels and you've got all-wheel drive, baby.
And if you wanna know more about how
an open differential makes that possible
we explained how these work in our episode
we did on torque vectoring.
Click right here.
It'll be somewhere.
Is it up here?
So by using two clutches, the process of
engaging all-wheel drive is incredibly smooth
and it happens in 200 milliseconds.
But to make Ultra work perfectly for most drivers
and in most situations,
Audi engineers paired the mechanical system
with sophisticated programming.
Ultra works with onboard sensors,
the ECU, and three different criteria
to engage all-wheel drive.
Proactive, predictive and reactive, PPR.
Oh, I have another PPR.
P P really big.
(bell dings)
Proactive engagement uses vehicle sensors
to make predictions about what is going to happen.
But Ultra uses sensors in other clever ways,
like checking the temperature and engaging
all-wheel drive if it's cold and
you're more likely to encounter ice.
Predictive engagement takes into account the driver.
The ECU builds up a profile on how you drive.
So if you drive your car a lot harder,
all-wheel drive will engage more often.
It adapts to make sure you have the
power delivery best suited to your driving style.
Reactive and engagement is response to
detected changes in traction.
Ultra transfers power when it detects a wheel has lost grip.
The same thing that's done by traction control
or limited slip diff.
Quattro Ultra is engineered to be the
all-wheel drive solution for the majority of drivers.
The rear wheels are only engaged when necessary
and they aren't a leech on the system
the rest of the time.
Because it's designed around longitudinal power trains
in a center differential,
it's an evolution of earlier quattro systems,
but it acts a lot like transverse quattro
and the system found in kind of boring crossovers
available for many other companies.
That's turned out to be a bit of a problem,
because to a lot of people,
Ultra doesn't seem very Audi-like.
Audi built a reputation for high performance
all-wheel drive on their roots and rally.
Because it's not permanent all world drive,
the Ultra system isn't very rally.
It isn't very sporty at all actually,
and some fans have expressed disappointment about that.
Ultra isn't meant to offer maximum performance.
It's engineered for how most people
use their car most of the time.
For the truly thrilling stuff they make
Torsen based quattro with sport differential,
and that is what you'll find in
most of the S and RS cars, like the RS6 Avant.
Avant is a fancy word and it just means
station wagon for British people.
And the RS6 Avant is the tippy-top
pinnacle of station wagons.
It's got 591 horsepower.
It goes zero to 60 in 3.1 seconds.
It goes 190 miles per hour, in a station wagon.
That's **** cool, man.
You got the kids in the back and they're
screaming like, Dad, why are you going so fast?
And he's like, I'm just trying to outrun my past.
And they're like, well we're part of your past Dad.
And you're like, get out the car,
and then you toss them.
Don't do that.
Even though it can go fast in a straight line,
the RS6 is all about grip when going around corners.
And that is where quattro comes in.
Up front is a relatively normal open differential.
Power delivery to the left and right wheels
is managed by a brake-based system.
We talked about these in our torque vector episode
and I called them the 99 cent store torque vectoring.
Now by itself, that's not all that special,
but the way it works with the rest of the system
is pretty clever.
At the rear is Audi's sport differential.
That is a true torque vectoring system.
It uses electronically actuated clutch packs
on the left and right axles
to distribute power independently to each wheel.
That maximizes your grip, it reduces your under steer
and it improves cornering speeds.
Now in the middle is a torsion
or torque sensing center differential.
That sends 60% of the power to the rear wheels,
but it can go all the way up to 80%
if it senses a loss in traction.
And the real heart that pumps and feeds
Audi's all-wheel drive system
is its all-wheel drive torque vectoring
which integrates all three differentials,
vehicle sensors and the ECU to predictively
manage power to all four wheels.
It even has rear wheel steering to
maximize cornering ability.
Audi claims that by combining braking at the front diff,
the torque vectoring rear diff and the
torsion center diff, the RSX can send
a hundred percent of the power to the rear wheels.
But the pinnacle of quattro performance
is in the R8 supercar.
And guess what Audi fans?
It's nothing like an Audi rally car.
(upbeat music)
That's okay, it's the only car
in the Audi lineup with a mid engine layout,
so it needs its own quattro system.
The R8 supercar quattro system can send
a hundred percent of the power to the front or rear axles.
And it does that first through a trans axle
mounted to the rear of the engine.
That combines the gear box, the rear diff,
the rear axles and the center diff into one complete unit.
And under most circumstances that sends
about 85% of the power to the rear wheels.
But like all modern quattro,
the exact distribution varies based
on road conditions and how the car is being driven.
So to get power to the front wheels
R8 quattro has a multi plate clutch
mounted at the front differential.
That's pretty much transverse quattro,
which we talked about at the very beginning of this episode.
With the axle switched, meaning the
quattro that Audi fans love to hate
is integral to the R8.
We'd love to do more on the R8 quattro
and maybe we'll do a whole episode
after Audi sends me one.
You can have a dream car when you're an adult, right?
You're never too old for that.
That, and a punch buggy.
Beep beep.
So there it is.
Audi quattro isn't just one system, it's freaking five.
If maximum speed is what you want,
well, you need quattro with torsen
and the sport diff or an R8 if you got the cash.
On the other hand, quattro Ultra
may not be that rally inspired quattro you want,
but it does the job it was designed for.
Saving money and fuel while still
providing that sweet all-wheel drive stability.
All right, how about this?
Count how many times I say quattro in this **** episode.
Count how many times I said quattro.
If you got the correct number,
leave it in the comments and I'll send you a shirt.
Whatever shirt you want that's on the Donut website
in your size, I'll find it,
if you can name the number of times I say quattro.
That includes the time I just said right now.
Thank you guys so much for watching
this episode of B2B.
We freaking love you.
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and until next week, bye for now.