Why did I wait so long to try the pedal dance

[autoracer86]

Nice to know it works with the haltech. You know just in case I ever k swap lol

[kodasaurus]

Wow, this thread came back with a vengeance.

Trail braking has been brought up a few times. In my experience, there's actually two adjacent braking techniques that people call "trail braking", which can cause confusion. And I think I see that disconnect happening here a bit.

Absolutely no trail braking is obvious. That is just only braking while the car and steering wheel is straight, coming fully off the pedal, and then turning the steering wheel. This seems to actually have been the method of driving a racecar waaaay back in the day, but unless you are Stirling Moss, you probably dont do this.

The first thing that tends to be called "trail braking" is the intial part of the brake release while entering a corner. This usually gets taught in the racing world with the string analogy - when you are hard on the brakes, imagine a taught string between the brake pedal and the steering wheel, and as you increase the steer angle, you need to decrease the brake pedal. I've noticed that in the amatuer racing/coaching/trackday/enthusiast world, this is wht most people consider trail braking. I've also noticed that many normal people tend to do this naturally when driving, even sublimit driving on the street, without any instruction, because it reduces the jerk that you feel in the car. My wife drives like this. Your mom probably does this too. Most amatuer racers/enthusiasts/etc are probably doing this, although not everyone is doing it smoothly or to the full potential of the car. The goal of this technique in racing is to maximize the time spent at the maximum acceleration capability of the car, which means you are going through the corner faster. In racing, you pretty much have to do this well in every corner that requires braking, if you want to be competitive. On data logs, this is characterized by looking at the G-G diagram and seeing your little dot for your combined accel move up to your desired decel (or max decel for hard braking), and then arc its way around the friction circle to the max lat accel.

The second thing that tends to be called "trail braking" is the final part of the brake release. This is basically where you apply or drag (or...trail...) a tiny amount of brake pressure (like 1-5Bar) midcorner, somewhere before the apex, just before you are fully off the brake pedal. I've noticed that many drivers/engineers/coaches in the professional racing world tend to call just this brake dragging technique in the final part of the brake release, "trail braking." The best way to feel this technique is to drive on a skipdad, get to or near your peak lat, and then just graze the brake pedal lightly and feel the nose of the car point inwards and feel the car drive a tighter arc. The goal of this "trail braking" is also different - here the goal is to rotate the car. IE, to make an understeery or neutral car more neutral or oversteery. The reason why this is faster is a bit confusing, because it isnt always faster. IE, this technique isnt always necessary. You're more likely to need it for low speed corners that require a lot of direction change. Some cars dont need the technique at all to be fast. Some cars are actually slower when you use the technique. I find that in the amatuer world, this technique is less known, less understood, and less utilized, although there are still lots of guys doing it.

So when Kyle asks Bubba in the pits, "are you trail braking turn 13?" it can get pretty confusing if they are not on the same page.

I'm not a jacket wearing, championship caliber autoxer like some of you guys - in fact i dont really like autox. But I think I am a decent racer (previously B Spec, open wheel, sim racing, any many many years of karting), and when I'm not busy lighting my hard earned cash on fire, I do get to work in the field of vehicle dynamics. So just my .02.

For the record...when I started tracking my purely stock BRZ on all seasons, I spent some time evaluating all the modes I could put it in at the track. The push and hold method and the pedal dance make the car feel totally different. I could not understand what the car was doing and how to get it to rotate when I did the push and hold. After the pedal dance, the car behaved exactly like I wanted it to. I repeated this process at a few different tracks with the same results. So currently I only do the pedal dance. However, with my new setup and sticky tires...I have noticed that my car is unable to reach the same long g as lat g. 1.3g in lat, but only 0.8g or so in decel. Currently, I am suspcious that with the pedal dance (without EBD), the base brake bias in the car is too inefficent for me to hit 1.3g in decel. Planning on testing this at the track this weekend by giving the push and hold method another shot.

[RedReplicant]

Hehe, the magical braking matching or exceeding lateral basically not happening is the subject of much complaining on the internet...

[kodasaurus]

Originally Posted by RedReplicant

Hehe, the magical braking matching or exceeding lateral basically not happening is the subject of much complaining on the internet...

Can you elaborate? Do you see the same thing but just drive around it?

[RedReplicant]

Originally Posted by kodasaurus

Can you elaborate? Do you see the same thing but just drive around it?

I don't know the reasoning behind it, but most street tire / street tire adjacent people are not seeing nearly as much peak or sustained inline braking force as they are seeing laterally, even though the usual idea is that a car should be able to generate a bit more or at least equal force under braking as turning.

If you look around serious track tinkerer groups you will see that a lot of people don't really see higher than 1.15 - 1.2g decel even though they see 1.3-1.4g lateral... this crosses over to ABS swapped or even motorsports firmware flashed ABS unit swapped cars.

When you do see logs of 1.5-1.8g+ under braking its cars on slicks or Hoosiers.

There are a lot of ideas floating around and it is a super common question to which I have not gotten a straight answer even from some super knowledgable people.

[ZDan]

Originally Posted by kodasaurus

I've also noticed that many normal people tend to do this naturally when driving, even sublimit driving on the street, without any instruction, because it reduces the jerk that you feel in the car. My wife drives like this. Your mom probably does this too. Most amatuer racers/enthusiasts/etc are probably doing this, although not everyone is doing it smoothly or to the full potential of the car.

True story: At a Zcar convention a long time ago, a friend asked me to go out on the autocross with his wife driving his 350Z, as he and another friend were having difficulty getting her to get around the course efficiently. I went out with her and after the first turn which she trail-braked for she said "sorry, I was supposed to 'brake in a straight line'"! I told her she was doing fine and she went 2s faster around the course with minimal other input. I am *genius* instructor!

[GrandSport]

Originally Posted by RedReplicant

I don't know the reasoning behind it, but most street tire / street tire adjacent people are not seeing nearly as much peak or sustained inline braking force as they are seeing laterally, even though the usual idea is that a car should be able to generate a bit more or at least equal force under braking as turning.

If you look around serious track tinkerer groups you will see that a lot of people don't really see higher than 1.15 - 1.2g decel even though they see 1.3-1.4g lateral... this crosses over to ABS swapped or even motorsports firmware flashed ABS unit swapped cars.

When you do see logs of 1.5-1.8g+ under braking its cars on slicks or Hoosiers.

There are a lot of ideas floating around and it is a super common question to which I have not gotten a straight answer even from some super knowledgable people.

Or uphill.
Reality is you're not going to get these high G's, sustained, without serious tires, aero and track geometry helping. Peak is another story.