Braking broken down

I once drove in a Lemons race where the car builder put a Ford 5.0L in a Toyota Celica. It was a fun car on the straights but a nightmare in the corners. Sadly, he used OEM brake pads, and they were fading on me before the end of the first lap. Buttonwillow has 7 braking zones, and in order to keep them cool I had to limit myself to braking twice per lap. In the other zones I had to coast, downshift the automatic transmission, and scrub speed with excessive steering. After getting over how much I hated the car, I actually had fun solving the puzzle of how to drive it fast.

At a more recent Lemons race at Sonoma I was nearly in a similar situation. We were working on the car before the race and the car owner brought out some $12 brake pads. No fucking way was I driving with those. Luckily, he also had some EBC Yellowstuff from the previous owner. When novices think about track driving, they focus on acceleration, not deceleration. That’s why when random people you meet ask about your racing activities, the first question they ask is “how fast do you go?” More important is how fast you stop. And more important than that (eventually) is how little you turn the steering wheel. Stopping and turning are the domain of the brake pedal. If you didn’t know that the brake pedal is the turn pedal, you had better keep reading. So let’s talk about the braking progression from novice to alien.

Level 1 – Novice

Description: If there’s one word to describe how novices brake, it would be tentative. Novices often exhibit a lot of coasting before applying the brake pedal. When they finally press it, they do so softly and then gradually increase the pressure. By the time they release the brake, they are going quite slow and the technique of the release hardly matters.

How to improve: The key to graduating out of this stage is just confidence. For some, that happens in 1 track day. For others, it may be years. If fear was easy to get over, it wouldn’t be fear.

Level 2 – Low Intermediate

Description: Intermediate braking is firm braking, but inconsistent. Gone are the fears of high G-forces. Intermediates can stop so fast their sunglasses fly off their faces. What they lack is any kind of finesse. They may brake too late and overshoot the corner. Or brake so early that they are confused about when to add throttle. Or brake in the middle of a corner and spin. Seeing how much better they are than novices makes them think they are fast, but this is just a manifestation of the Dunning-Kruger effect.

How to improve: Braking becomes less of a panic, and more consistent the more you do it. So this is mostly a matter of training. To snap someone out of the D-K effect, compare lap times in the same car.

Level 3 – Intermediate

Description: The hallmark of the intermediate driver is “in slow out fast” with an emphasis on slow. That comes from very aggressive braking. This is usually followed by very quickly jumping off the brake and onto the throttle. The car tends to pitch fore and aft with this driving style, and the car is often understeering as the weight gets thrown to the rear. In a high power car with nannies, this level of driving can be pretty quick, even if it’s not very skillful.

How to improve: This driver needs to work on being smoother because their style is reducing the grip available in the corner. Until they see lap times or telemetry traces from another driver in the same car, they may believe they are driving correctly.

Level 4 – High Intermediate

Description: The high intermediate has learned to used trail-braking to extend the braking zone into the corner. Not only does this lengthen the straight, it also keeps the suspension quiet on turn in. This is a relatively fast and safe way to drive, and lots of HPDE regulars and coaches drive like this.

How to improve: The next stage isn’t so easy because it requires both oversteer recovery skills and the confidence to use them. Lots of people get stuck here and may require some coaching to move on.

Level 5 – Advanced

Description: The advanced driver confidently uses the brakes to rotate the car at the entry. After all, the faster driver is the one who turns less. Steering with the rear wheels is the key to speed, but the key pedal is the brake, not the throttle. Some people understand this. Few actually do it.

How to improve: What holds the advanced driver back from progressing further is precision. All the skills are there, but the edges are rough. Like in any other sport, improving technique requires many hours of deliberate practice. There is no shortcut to expertise.

Level 6 – Expert

Description: The expert is able to balance the grip of the car to such a fine degree that all laps fall within a couple tenths of a second. They have worked very hard to attain this level of mastery and may not recall how difficult it was, leading to the other side of the Dunning-Kruger effect.

How to improve: Be born with unnatural ability and work harder than everyone else.

Level 7 – Alien

Description: They seemingly break the laws of physics and human ability. It would be easier to accept if they were cheating, but they aren’t. We all just suck in comparison.

Intermediate Topic #2: brake pressure

This series of posts is aimed at you, the intermediate driver. Let’s identify and fix some common errors. If you’re not an intermediate driver, just know that you can become one if you try hard enough.

If there’s one defining flaw of the intermediate driver, it’s too much emphasis on the phrase in slow, out fast. This leads to several related problems, which I’ll be discussing in the next couple posts.

The problem with threshold braking

Remember those days when you were afraid to hit the brakes hard? Probably not. Your mind was so full of the track that you were barely aware of what your limbs were doing. There was no spare attention for self-assessment. I’m guessing that like a lot of novices, you coasted into your braking zones. We all did at one point. But not anymore! Your car brakes so well it feels like your eyes are going to pop out of their sockets. Once you get a little experience, you start to feel the fun in braking. There are more Gs in braking than there are in accelerating or cornering. While threshold braking is a skill that is important to master, it may also be holding you back. We all know that exit speed is the key to a corner. But what you might not appreciate is that the entry speed determines the exit speed. However, that comes with some risk.

Exiting a corner on the limit is like tightrope-walking; entering a corner on the limit is like jumping onto a tightrope while blindfolded –Mark Donohue

There is an ideal speed at the entry that maximizes the exit speed. Too slow and the corner is ruined. Too fast and you may end up off track. Most drivers recognize that too slow is a lot safer than too fast and therefore drive too slow. Now let’s imagine you have a blindfold on and there is a rope in front of you and you are forced to walk it. Are you going to jump blindly or inch forward to feel where it is? The more time you take to inch forward, the more likely it is you’ll find the rope and have some success walking it. And so it is with entry speeds. The more time you give yourself to feel the entry speed, the more you’ll be able to maximize it without going too far over. The problem with aggressive braking is that it robs you of the time you’re allowed to probe. To get more experience in optimizing your entry speed, you need to spend more time sensing it, thinking about it, and adjusting to it.

The exercise: triangular brake pressure

In the figure below, I’ve loaded up some demonstration laps from Assetto Corsa into Race Studio Analysis. The blue line is hard braking while the red line is soft braking. Note how much higher the blue traces are than the red. They are also much more rectangular in shape. That’s not only because the top is flat, but the sides are vertical. This is using the brake as an on/off switch. For the exercise, I want you to make your brake pressure triangular. Build it up and then trail it off. Yeah, this is exactly what some instructor told you not to do at one point. Go slowly enough that you can spare the attention to your braking foot.

Try to build up your entry speed by braking less and less. However, the goal isn’t to stop braking but to stop over-braking. Drag your brake through the corner entry and you will feel the steering wheel start self-centering. This is a kind of tactile speedometer that your hands will learn to read. My favorite reason to trail-brake isn’t rotation but speed-sensing. A relaxed grip will help you in this endeavor.

U-shaped speed trace

If you’re rolling more speed through the corner entry, your speed traces will have U-shaped bottoms (red) rather than V-shaped bottoms (blue). A V-shape indicates an abrupt change in speed. That typically happens if you mash one pedal and then the other. If you’re holding speed, the speed trace is much more gradual in descent.

But wait, there’s more

In the graph above, one thing you may notice is that the red laps are more consistent than the blue laps. It’s easier to drive when the car isn’t being yanked fore and aft. The red laps are also faster by about 1 second. If you counted up how many lines there are, you would also observe that there are 10 blue lines and 11 red ones. That’s because soft brakes increased fuel economy by 10%. Can it really be true that braking softer results in faster laps, less wear, increased economy, and more consistency? Yes, but don’t take my word for it, try it yourself.

So when do you go back to threshold braking? Is never okay? Yes, I think it is. By giving yourself more time to set the ideal entry speed, you’re on the path to advanced driving techniques (like zero steer). Mashing the brake pedal leads to flat-spotted tires, understeer, bad decisions, and remaining an intermediate driver forever.

Coaching Report (-ish)

Last week I posted about the Lucky Dog sim racing series I attended. In the post-race FB chat, I offered to help a slower driver get faster if they were willing to look at telemetry with me and didn’t mind me blogging about it. The only person who took me up on that offer was actually one of the faster racers. The next race on the schedule was Summit Point, so that’s what we would work on. I haven’t run Summit in ages and I’ve never driven the ND MX-5 there. Sometimes I wonder why I keep an iRacing subscription. My laps wouldn’t be ideal, but I logged a couple sessions to get some telemetry for comparison. One expected difference is our setups. He downloads setups from aliens whereas I drive the baseline like a rookie. Setups are critical when looking for tenths of second, but not 1.6 seconds, which was the gap between my fast lap and his. My goals were (1) to figure out why he was 1.6 seconds off and (2) to see if I could offer some advice that would help him get faster. In a perfect world, I’m such a good teacher that he ends up faster than me. I can dream.

Telemetry

The “student” has done some racing in the real world and has been on iRacing for a little over a year. Good, that means we could dive right into the data without troubleshooting rookie problems like how to set up controllers or drive the typical racing line. In the telemetry traces below, you can see panels for Brake, Speed, Steering Angle, Throttle Position, and Time Lost. iRacing reports over 100 channels, but you don’t need more than 4-6 to figure out what’s going on. The image is a screen capture from TrackAttack. One of the things I like about TrackAttack is that it is available on PC and Mac, imports a variety of data formats (e.g. iRacing, AiM, Apex Pro), and stores its data on the cloud. Viewing and sharing telemetry data has never been so convenient. Click on the image to view it full size.

The student trace is yellow and mine is purple. Let’s look at the obvious things first: brake and throttle.

  • He brakes a little later and a lot harder than I do
  • He gets to 100% throttle sooner than I do

In a lot of peoples’ minds, the formula for speed is braking as late and hard as possible followed by accelerating as early and hard as possible. But if that worked, why are my speeds higher pretty much everywhere on track? It’s certainly not the setup. Given that I’m using the baseline and haven’t even bothered to move some weight to the right side of the vehicle, he should carry more speed in the right hand corners, which is most of them. The clue to this mystery comes from the steering angle: he turns the wheel more than me. So when we struck up a FB Messenger conversation, that’s where I started the dialog.

Conversation

I looked at your traces… the more you turn the wheel, the more speed you scrub. How does one get around a corner without steering as much?

Better racing lines. Lol.

No, it’s not the line.

Oh?

(At this point I sent him a TrackAttack screen cap showing the steering angle trace).

Wow!¬†Minimizes the sudden weight transfer by being smoother and only turning as much as necessary….

We both have to turn the same amount at the end of the day. My car is turning just as much as yours believe it or not. The difference is that I’m not using the wheel to do it.

Ahhhhhh….gotcha. Skinny pedal. Lol.

Middle pedal.

Earlier brake? Or trail brake?

Yeah and yeah.

Both. Roger that.

Your current style is to brake late and hard. When you do that, you can’t rotate the car.

Little earlier on, later off, but less overall pressure.

Earlier on, less pressure, earlier off actually. You can move the whole braking sequence earlier in the corner and carry more speed through the corner.

Oh gotcha. Makes sense. That’s probably why I struggle with a real car that way as well…

The harder and later you brake, the less time there is to set up the ideal corner speed. The less time there is to feel the balance of the car. There’s nothing wrong with threshold braking. But it takes away your time to sense speed. So until your speed sensing skills are exquisite, it’s better to give yourself more time at the corner entry to find the optimal entry speed.¬†I brake pretty softly in real and sim life.¬†I haven’t figured out how to threshold brake and sense speed.

I see. So by braking earlier, you can rely more on the momentum of the car and the suspension instead of sending it in hot and praying that the tires can soak up the forces.

Braking too hard will also see you below the optimal corner speed. The natural reaction to that is to stomp on the throttle. But if you do that, all the weight goes to the rear and the front starts understeering. So if you find yourself pushing, it’s probably because you’re also using a lot of throttle. And that’s because your corner speed was too low.

Got it. That’s exactly what I feel like I am doing, too….

So next time try braking a half marker earlier and trail off the speed to keep as much momentum as possible. It takes a while to change driving style. Don’t expect miracles. Things get worse before they get better sometimes.

Misconceptions

The student knows a lot about driving and is a pretty fast driver. It’s great that we can have a conversation about racing line, weight transfer, understeer, etc. without having to define terms. What’s holding him back are some misconceptions about the fast way around a track. He’s probably had these misconceptions for a while and has a driving style that optimizes them. In order to get faster, he’ll have to unlearn some of what he currently knows and re-train himself to drive differently. Let’s talk about his misconceptions in a little more detail because everyone goes through this.

  • Brake as late and hard as possible
  • Get to 100% throttle as soon as possible
  • Oversteer is generated via the throttle pedal

On the surface, all of these are correct in their own context. If you’re trying to get as much out of the straight as possible, you should brake as late as possible. And if you’re trying to slow the car, you should be using all the traction you have available, not part of it. The reason we drive the typical racing line is to maximize the exit speed. So it makes sense that you want to get on throttle as soon as possible. It’s also true that you can initiate and control oversteer with the throttle. So if all of these things are right, what’s wrong?

I think there are 3 phrases in common usage that improve the novice driver and shackle the advanced.

  • In slow out fast
  • You should always be on throttle or brake, never coasting
  • Whoever gets to 100% throttle first wins

All of these phrases emphasize the speed of the vehicle. By any objective criteria, I’m doing the speed things worse than the student. I brake softly. I’m late to brake and throttle. I coast. What am I doing right that makes up for all that I’m doing wrong?

  • The winning driver is the driver who turns less

So how does one get around a race track by turning less? It starts by learning how to control oversteer with the brake pedal. That’s it. Just one little thing. The brake pedal. And fuck all if I’m not still working on it.