January 28, 2014 5:02 AM
Ross Bentley <[email protected]>
To: Ross Bentley <[email protected]>
Speed Secrets Weekly 39
Hi Ross. "Driving fast is all about how you use the
brakes, isn't it?!"
One of my coaching clients had that epiphany during a
race weekend, when he finally began to run at the front
of the pack. His revelation was followed up by, "And it
has little to do with how late I brake…"
Yep.
The awesome thing with data is that you can track
every nuance of how you use the brakes, as Matt
Romanowski illustrates so well in his article below.
Following his advice, it's possible to "draw the ideal
brake trace" with your foot. If you know exactly what
the brake pressure trace on the data acquisition
system should look like, you can work at replicating the
line with how you apply and release the pedal.
With Matt's article and screen grabs of data, you now
have a target to shoot for. Enjoy the article - and
drawing the brake trace with your foot!
Oh, and even if you don't have data acquisition, you
can imagine the application of the brake pedal that it
would take to create the traces that Matt shares.
"Braking" Down The Data
ISSUE #39
"Bring your foot off the brake pedal
gently and progressively. The whole
sequence should be one gentle,
sensitive, flowing movement. You
want the nose of the car to come up
gently and undramatically." - Jackie
Stewart
How and when you release
the brakes will have more
effect on your lap times
than where you start
braking.
I'm not saying that late braking isn't a
good thing. I'm not saying that by
braking later, you can't improve your
lap time. What I am saying is that it's
an over-used method of trying to go
faster.
Ask a driver how he is going to
by Matt Romanowski
When we analyze data, we do it in a number of
ways. One of the most popular is to compare the
data from two different drivers (often using a
professional driver as a baseline), to see where one
person is faster. We also look at how proficient and
consistent a driver is in basic skills such as braking,
throttle application, and steering inputs. In fact,
fellow SSW contributor Peter Krause is often heard
telling people that the single biggest differentiator
of drivers is the consistent and correct execution of
these fundamental skills. Without a solid foundation
of the basics, none of the advanced techniques will
help.
improve his lap time, and the most
often given answer is "brake later
for…"
If you're braking very early, then
braking later is going to help, for sure.
But if you're close to braking as late as
anyone else, then my suggestion is to
focus more on how you release the
brake pedal… when you start releasing
it, and how quickly you release it.
When you do that, you'll find that
you're able to carry more speed
through the turn, while still be able to
begin accelerating as early as before
(and maybe even earlier because
you've been able to rotate the car
early in the turn, meaning you've got a
better line exiting the corner).
So what are these skills?
They include what you learn in your driving schools
and HDPE events. The basics are:
Driving the line
Applying the throttle smoothly and
consistently while exiting a corner
Hitting apexes precisely
Braking aggressively
Looking far enough ahead
There are more, but if you nail these basic skills
every time, you will be amazed at how quickly you
can drive and how effortless it will be.
Let's look at braking. Most people can gain
significant amounts of time just by braking
correctly. I think braking is one of the skills most
often done incorrectly; it can easily have the most
influence on lap times.
If you've been driving for a while and are familiar
with data analysis, you will have heard that you're
supposed to apply the brakes quickly, then slowly
reduce the pressure. Depending on the type and
speed of a corner, the tailing-off should coincide
with the turn-in and the first phase of the corner.
While it's easy to say all this, an illustration might
help you to understand what I'm talking about. I've
put together a series of graphs, so you can see
what a good brake application looks like, along with
those in which the drivers have room for
improvement. I hope that these will provide you
with a bit of a cheat sheet to check your own
But Wait, There's More...
I use the term "rotate the car" often.
And some drivers are not exactly sure
what I mean by that, so let me
explain.
The simplest way of defining the term
is like this: Imagine looking down on
your car from directly above (almost
as if you're driving on one of David
Beattie's slot car tracks featured a few
weeks ago). As your car changes
direction from a straight line and into
the corner at the turn-in point, think of
how quickly it changes direction,
almost as if it's turning or rotating
around a single point in the middle of
the car. And think about it rotating in
degrees...
graphs and be able to recognize the patterns in
your driving, to see where you can improve. All of
these graphs are brake pressure-on-a-distance
basis, though longitudinal G-force-versus-distance
would look very similar and is something that
everyone with data acquisition has!
Let's say your car changes direction,
or rotates 70 degrees, rather than just
60 degrees. And it does that in the
same length of time. That means the
car has rotated more.
Okay, but how do you do that? How do
you make a car rotate more? Well, you
may begin the process by turning the
steering wheel, but the real cause of
the rotation is how you change the
balance of the car.
If you make a fairly crisp, quick turn of
the steering wheel, while having a
large percentage of the car's weight
still transferred onto the front tires
(meaning the rear tires are relatively
unweighted), the car will be more
inclined to rotate more quickly.
The first graph shows a good brake application and
decline. Notice the graph has a steep slope up and
then a slow slope down. Cars with lots of downforce
(Formula Continental, Sports Racers, etc) will have
a steeper graph, while older or non-aero cars will
have a less-steep graph. The release of the brakes
will also change, based on the speed and trail
braking that the corner requires. Corners that allow
trail braking will have a longer, slower brake
release versus higher speed corners, which will
typically have a quicker, steeper release.
So, while rotating the car is typically
started with the steering wheel, it's
when and how you release the brakes
that will continue it. Time your release
of the brakes just right, and you'll
change how quickly and how much you
rotate the car.
And that's a useful technique to learn
and use. As a very general rule, you'll
want to rotate the car more in tighter
corners than you will in long, fast
corners.
The blue line in the illustration below
demonstrates a line where the car was
rotated more, allowing a straighter line
for acceleration exiting the turn.
What Do You Think Of SSW?
The braking in the second graph we see could use
improvement, though. It's what I call the "double
hit." It's a case of braking a little early, realizing
you were early, releasing some pressure, then
braking again. It shows up with this characteristic
double peak shape. The fix is easy to talk about,
but harder to practice: brake later! If you see this
in isolated instances, it can also be a release of
pressure to stop a wheel from locking up. Talk to
your driver (or yourself!) to find out why the double
hit occurred.
Join the conversation on
the DriverCoach Facebook page & let
me (and others) know what you think
of Speed Secrets Weekly.
Looking Ahead...
In next week's issue of SSW:
We welcome a new-to-us guest
author, David Ray, the founder and
Group Leader of Hooked On Driving.
He recounts a true story that
happened to him when instructing
from the right seat - one with a
powerful and insightful message.
Got a Question?
The next graph is "the plateau." In this case, the
brakes are depressed to a certain level and held,
then released. In fact, most cars have better
braking capabilities than you think - you just have
to get yourself to brake harder initially, then tail off.
By braking in the correct way, you will be able to
accelerate a little longer and be just a bit faster.
If you have a question that you'd like
answered in Speed Secrets Weekly,
send me an email at
[email protected].
Sharing
If you want others to enjoy what you get
from Speed Secrets Weekly, go ahead
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suggest they sign up for themselves by
going to http://speedsecretsweekly.com.
But don't get in the habit of sharing it
because that's against the copyright
rules - plus, it would be a big pain in the
butt to do that every week. Let them work
for it!
The fourth graph to look for is "slow application."
This shows where the brakes can be applied more
quickly than they were actually applied. As I said
before, the speed that every car will accept brake
input will be different, but a tell-tale sign that it was
a "slow application" is the two slopes in the graph.
The final area where many people have room for
improvement is in "heel-and-toe" braking. In this
graph, there will be many valleys in the release
portion. These correlate to a reduction in brake
force, as the foot rolls over to blip the throttle for a
downshift. If you have a throttle position sensor,
you will see the dips in the brake pressure line up
with the increase in throttle position. The fix for this
mistake is easy - more heel-and-toe practice.
I hope these graphs of common mistakes will help
you analyze your own driving to see where you can
improve your braking performance. Now instead of
just looking at data that shows your driving can be
improved, you'll be able to identify your
weaknesses, work on them, and turn them into
strengths.
- Matt Romanowski
Twitter: @trailbrakematt
Website: www.trailbrake.net
Copyright Ross Bentley, 2014
Opinions expressed here are entirely mine and/or of the contributing author(s), and are meant to be used at your own
risk... and all that other legal stuff that usually goes at the bottom that no one tends to read anyway. But it's here, right?
So it's all up to you now. You're responsible, okay?
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