How To Brake?

[beez]

To me, the fastest way around a circuit is the compromise between covering the least amount of real estate while turning the steering wheel the least. if you can accomplish that, then the very fastest way through the turns, will be self-evident. this will set you up to give you the longest possible time on the throttle in the straights.

[Larry Herman]

Momentum. The fastest way through a circuit is with the highest average speed. If I can brake longer & more gently to allow my car to have better balance and therefore more lateral grip, I can keep my overall speed higher, resulting in a faster corner and ultimately a faster lap. There are some corners where this technique yields higher mph at every point in the corner segment. There are other turns where it may not. The skill is in knowing the requirements of each corner, not applying a blanket driving style across the board. That is why we coach using data; to figure this out.

[NickW]

Hmm... kind of a loaded question...

I touched upon this at rennlist- http://forums.rennlist.com/rennforum...ds-help-2.html

But the issue isn't even as simple as keeping momentum up.

As a driver's experience progresses, car setup changes. A beginner will probably prefer a tighter car- one that pushes. That way the worst possible thing he can do is just push off the track if he holds the throttle too long. As the driver gets better with actually controlling the car, the setup will get looser, and become more pointy. How the car is driven changes.

In general, as the movie quote goes, loose is fast. But just because loose is fast doesn't mean everyone can drive such a setup. A tight car won't want to "dance" but a loose car will quickly tell you you're not in charge if you're not on top of it.

If you're really intent of improving as a driver, making setup changes throughout the day will really help you understand chassis dynamics. Get outside your comfort zone, but don't drive beyond your ability. In general, when I see someone off the track or looping it, I think- driving beyond ability.

EDIT-

I attached a pic of me at Road America, T5. You can see the cone on the gator strip, and my tires within 3 feet (probably less) of that edge. In addition, you can see by the way my car's weight is jacked to the rear right corner that I am accelerating through the corner- all braking finished way beforehand. That is what they mean when they say "slow in, fast out."

[Larry Herman]

Originally Posted by NickW

Get outside your comfort zone, but don't drive beyond your ability. In general, when I see someone off the track or looping it, I think- driving beyond ability.

This is probably getting off-topic, and maybe worthy of another thread, but I see plenty of people looping it and going off-track due to poor technique and lack of car feel. It's not that they are being too aggressive as much as how they are driving causes the car to go from 8/10ths to 11/10ths instantly, and beyond their ability to recognize it. I am firmly convinced that barring an improperly setup car, there is no such thing as a snap-spin that "just happened". The situations that can result in that type of car behavior are predictable and recognizable. Then again, maybe that is precisely what is defined as "driving beyond ones ability".

[NickW]

Originally Posted by Larry Herman

This is probably getting off-topic, and maybe worthy of another thread, but I see plenty of people looping it and going off-track due to poor technique and lack of car feel. It's not that they are being too aggressive as much as how they are driving causes the car to go from 8/10ths to 11/10ths instantly, and beyond their ability to recognize it. I am firmly convinced that barring an improperly setup car, there is no such thing as a snap-spin that "just happened". The situations that can result in that type of car behavior are predictable and recognizable. Then again, maybe that is precisely what is defined as "driving beyond ones ability".

Well, I think part of the problem is how HPDE teaches people how to brake- usually an A/X brake zone exercise. That does nothing to actually promote feel of the braking, although it teaches the student that they have powerful brakes. If anything it teaches students they can be hamfisted in their input.

Skill requires sensitivity. If you can't sense it how can you react to it? I had a related issue with a friend recently- he insisted on turning up the radio in the car, and I kept telling him I couldn't drive the car properly without hearing the engine (manual trans). He doesn't drive stick. Can you see the problem- we can't relate because our POV is so different- and that's part of the problem with a lot of beginners- they want to go fast on a track, without the associated learning and experience. As for my friend, I told him he needs to stick to his Lexus...

[Skypalace]

Saying that the fastest way around a course is the highest average speed is a bit of a tautology - average speed is of course course distance divided by time, the shorter the time the higher the speed. Course distance is (relatively) fixed.

Any of these fine suggestions above are rules of thumb, but are never perfectly correct. The fastest way around a course depends on a lot of variables, and is extremely car-dependent, as well as course dependent.

The best line through a particular corner very much depends on what's after the corner. If there's a long straight, then the best line will likely have a very late apex so that you can get on full throttle as quickly as possible. But if there's another corner immediately thereafter turning the same direction, you might do a very early apex to be able to get you to the outside edge of the track as quickly as possible to set up for the following corner, which might be more important.

Then there are corners with a broad range of lines, turn 7 at the (repaved) Portland International Raceway is an example, it's 6 or 8 cars wide, but leads onto a the long back straight. Sure you want a late apex in order to maximize exit speed onto the straight, but it's SO wide on entry that I see many people enter too wide, adding material track distance at the slowest corner on the course, adding time that they don't need to add as it's not actually improving their exit speed. Also, as with many corners, the line through there is very different on a momentum car (944 or Spec Miata) than in a car with significant power, as you normally need a later apex in a higher-powered car so that you can be on full throttle without rear tires getting loose (ie. you have less available grip for lateral acceleration). With a lower powered car, there's less traction required for acceleration on full throttle, and thus more available for lateral grip (turning), so you can apex earlier and continue turning but still have full throttle through the exit.


And of course, on almost any corner a 911 wants a later apex than a Vette with equivalent power, because of the rearward weight bias, and a late turnin works because trail braking allows you to rotate that big pendulum behind you, whereas a car with 50/50 weight distribution won't react to trailbraking the same way.

I completely agree with Nick on sensitivity. It's one reason I've been having braking problems with the new Cup - the brakes are rock-hard, like pushing against a brick wall, and have very little travel, and virtually zero feedback through the pedal. I'm basically having to calibrate how hard my quads are pushing the pedal, rather than feeling the pedal travel through the side of my foot through my driving shoes, like in the 996 that has a softer pedal and much more pdeal travel during braking. I'm developing the feel, but I'm not fully there yet (or I wouldn't have spun under braking twice in my last race weekend :-))

I like to drive with my bottom seat cushion removed, as it gives me better feel of the car - literally improving the feedback through the seat of my pants. The biggest difference in being able to sense yaw (esp. rear of the car moving out) as quickly as possible. With hard engine and tranny mounts, there's enough engine & tranny noise in the car (plus I have earpieces in) that it's difficult to hear the tires, which are a ton easier to hear in a street car.

I also have a seat with very high side (thigh) bolsters, in a seat that most people would probably consider to be one size too small, but I like to have zero movement in the seat so that I can feel the car as much as possible. I like to think it's one reason I'm much better in a real car than in video games. As Nick says above, loose is fast, I definitely prefer a car a little on the loose side, but it requires high sensitivity (but it's SOOO fun when it's working!). I spin fairly often in video games because I can't sense the yaw movement of rear getting loose, in a game the only way to sense yaw is through the front windshield, but that's definitely not how I sense it in a real car. Or so I like to think :-)

I have full Motec data in my cars, and spend a very bit of time analyzing it, to see exactly what works and what doesn't. Often it's counter-intuitive. I've seen many times where I've changed a line to make up .3 sec on corner entry, only to lose .5 second through to the next corner. I've also seen the other way, lost .3 sec on corner entry, and made up .5 second along the next straight. Data is very helpful, but it takes some practice to figure out how to use it properly, and to actually help yourself rather than confuse yourself with so much information.

I find video even more useful, I will never pass up an opportunity to have someone look at my video and make comments. I've had many pros and fellow competitors (most helpful if they're in a different class so not directly competitive :-)) willing to look at video of a lap and make comments. Usually it works, occasionally it doesn't - I had one pro insist that I was taking a particular corner in too short a gear (I should roll through in 3rd rather than downshift to 2nd). I must have done a dozen laps in my next session, and it never felt right. My data showed that I was losing launch speed out of the corner every single time, and lost more time on the next straight than I gained. It was probably gearing/grip difference (I was in the 996 and he had been in a 2010 Cup, which has both slightly different gearing, as well as quite a bit more mechanical grip esp. in the back), but could have been me trying his gearing advice, on perhaps the wrong line.

[csmarx]

Originally Posted by Skypalace

I also do a visualization exercise - think of a string tied between your toe and the steering wheel. When you're on full braking, string is all the way tight from the bottom of the wheel to your toe. As you turn, turning the wheel will lift your toe on the brake. As you press the accelerator after exit, think of it pulling the outside of the steering wheel back down, so that you have to accelerate.

I think that many novice and intermediate drivers are scared of getting too close to the trackout, as they're worried about getting onto (or over) the exit curbing. After all, their instructors have told them numerous times about bad things happening when they drop a wheel off the outside of a curb on exit. So in response they're staying away from track out, but their mechanism for doing so isn't doing a trackout to a lesser point, it's to keep full steering input in while exiting the corner, which at best delays their throttle input until they're pointed straight (killing their corner exit speed), or at worst adding throttle with full input, potentially causing spins or worse (exiting track when overcorrecting after attempting to catch a spin for example).

Jim

I've also used the "string theory" with students to good effect, but I quite like your phrasing of "releasing traction." It's a good image that gets the point across really well." I'll make sure to use that in the future!

As to your last point, I think most of us here on this forum are quite experienced and in some cases experts. So it's easy to forget that a novice often has no idea where his car is going to wind up on the exit of a turn. So it's no wonder they are nervous about going off the track and try to pinch it a bit. But I also think a lot of novices just go too fast for their skill because they are exited to go fast on a track.

I think the best advice an instructor ever gave me was that if you start making mistakes, just slow down to where you are making clean laps. Only then start to speed up - slowly. Repeat as necessary. By the end of the day you will be going much faster than if you just keep pushing and making mistakes. I still use that for my self.

-Christian

[TRAKCAR]

I think the best advice an instructor ever gave me was that if you start making mistakes, just slow down to where you are making clean laps. Only then start to speed up - slowly. Repeat as necessary. By the end of the day you will be going much faster than if you just keep pushing and making mistakes. I still use that for my self.

+1. So often I have to back up even an intermediate student. Somehow their previous instructors just let them go faster mistakes and all.

Different brake points, turn in, missing apexes, wrong gears prevents getting in a rythm and increases potential for spins or worse.

I make them back up to 7/10 (Their 7/10th) and tell them I want carbon copies of every lap after I take out their worst no-no's. I give them small adjustments that should not disturb the rythm. If they can do it, they already carry much more speed and lower laptimes then when they where going ragid 10/10th.

I am just after a rythm (Smaller mistakes and all), if they can do lap after lap without forgetting what to do you can go and continue to work on improving their driving.

[Gator Bite]

Originally Posted by csmarx

I think the best advice an instructor ever gave me was that if you start making mistakes, just slow down to where you are making clean laps. Only then start to speed up - slowly. Repeat as necessary. By the end of the day you will be going much faster than if you just keep pushing and making mistakes. I still use that for my self.

-Christian

I recently applied this at Watkins Glen. During my last visit there I had some pretty fast laps, but my consistency left something to be desired. This time I consciously broke earlier and found my consistency in the turns went way up. Then I could push a little deeper, a little faster per lap. My times were good. Not as good as last time, but more consistent. That's a win to me. With practice I should get the 1 or 2 seconds back and be consistent.

[Trackrat]

Not sure how I managed to not read this thread since it's inception. My loss, that's for sure. Pure gold. Thanks to all for the superb comments.

1. Balance
2. Sensitivity
3. Work up to the limits of the car incrementally
4. Comparing video and data with my track pals

Things that have come to mean a lot to me as I have pushed harder and gotten faster. I very rarely have an off (once a year on average) and very rarely scare myself while lap times decrease and are more consistent almost every single time I visit the same track. Must be some validity to that formula?

Braking technique in my world: no one size fits all, it is different for every corner for every track I run. But as a generality I have really been striving for a smoooooth release. For me, easing that transition from brake to throttle (even though the transition itself can be quickened or slowed, depending upon the situation) has meant a lot to my lap times.

Thanks to all for the fantastic food for thought!