The basics of Braking

Ahh... I haven't written anything in eons... X-p

I do have a lot of materials to write upon, since we were brimming with activities the last time Ryosuke came back from war-torn Iraq :-p but i haven't found the time to divest the necessary creative juices to actually pen any worth mentioning literary pieces :-p

Anyway, what I am about to post is not about our recent activities.. :-p that'll have to wait, since i am still trying to find the time (and correct software) to come up with a nicely composed video collection ^^ maybe not as poetic as the videos edited by Ryosuke, but at the least something worth spending the next 5 minutes of one's life... :-p

I have always been thinking about braking techniques... I have read many articles on it, from cadence braking, to full-lock braking, to threshold braking etc... However, I have come across something so basic, that i feel it's fundamental to read and reflect before one tries any of those advanced braking techniques.. which unfortunately we did not practice as we had immediately jumped to trying it :-p a trial and error way of doing things, one finally learn something, but at quite an atrocious cost X-p

We have always instinctively known this basic concept of braking (and i am sure many are) however, this article, i believe, is great in the sense that it is able to articulate on that basic concept so well :-)

After so long driving at the touge, I notice that one of the most important aspects of driving technique is, for want of any better word, 'weight management' :-p and i am not particularly referring to my growing waistline (which is, quite frankly, also a cause of alarm X-p) but to the understanding and manipulation of the dynamics of the car and its shifting weight... this is particularly so when driven at the limit, and even more so in a downhill run... with an oversteer happy rear wheel car :-p

Aryton Senna was famous for being uncannily good at knowing where the 'grip' is...
and to me, Weight management is the holy grail of controlling when and where the 'grip' of the car is... by manipulating the weight of the car, one can control how much grip goes to which wheel and etc... of course i am not here to talk about weight management (considering my not so graceful growing physique, i certainly am not the most appropriate person to talk about it :-p) but about braking...

One of the most basic and important technique in this 'weight management' concept is braking... proper braking helps the car to settle in on its suspension, to take a 'set' (as they would call it) before turning in... more advanced drivers would do 'trail braking' by braking deep in the turn, manipulating the weight of the car using the brakes rather than the throttle (which is, speaking from experience, a really difficult feat to accomplish...)

Braking, if done properly, is not only to 'slow down' the car, but make the car take the turn faster... Jackie Stewart (particularly famous for being a super-smooth driver) used to say that his advantage over his opponents is how he 'eases' off the brakes... thus, eventhough braking is the most fundamental aspect of driving, mastering it can be considered one of the most difficult (for me at the least :-p)

Well, enough with my rant... This article was found at http://www.racingschools.com/drivingtips.php, a really good site to check out :-)

"BRAKING - Slow It

Virtually all of the braking that a race car driver does is done in preparation for or in conjunction with cornering. One of the first lessons that every racer must learn is that the most efficient way to slow a car is in a straight line, with the car's weight evenly distributed side-to-side. The "standard" turn on a race course is made under power, with all slowing having been done before the car is turned.

In the last article I noted that braking transfers weight from the rear of the car to the front, and that your braking system is designed to accommodate this. Cornering transfers weight from one side of the car to the other -- from the inside to the outside of the cornering direction. The braking system is not, with rare exceptions, designed to adapt to this weight transfer. The driver has to adapt instead.

Any time we turn our car's steering wheel we compromise braking efficiency. When we turn left, for example, some of the car's weight transfers to the right side; the left side of the car gets lighter. If we brake (or, for that matter, even slow down) at the same time, the car's weight is transferred forward as well. Now the car is unbalanced; the braking and tire adhesion forces on all four corners of the car are different. In all likelihood, each of the four wheels is either bearing too much weight to brake efficiently or too little weight to stick to the pavement optimally.

At the very least this condition will make the car uncomfortable for its passengers and difficult to steer. At the worst, it can cause the driver to lose control of the car entirely. The solution? For comfort or for safety, whenever possible, don't brake and turn your car at the same time. If you have to do so, be aware that it will neither brake nor turn as well as it would if you were doing one at a time.

While absolutely correct braking and cornering may not be a matter of safety at street driving speeds, they can be a matter of increased comfort. Next time you drive on the street try slowing down for corners before you turn the steering wheel to negotiate them. Turn at a constant (but not too fast) speed, and as you start out of the turn, accelerate gently. If that's different from the way you usually drive, you'll feel the difference immediately and so will your passengers.

The same braking technique will make driving a curvy road much easier: concentrate on slowing down for each corner while the steering wheel is straight. If the corners are esses, slow during that brief time when the wheels are straight as you turn from one direction to the other. Do this as smoothly as possible. Accelerate lightly coming out of the corner. Assuming you've judged your cornering speed correctly, slowing in a straight line and not braking while turning will make a dramatic difference in the ease and comfort with which your car negotiates a curvy road. And it will let you make better time without having to drive any harder.

Ideally all braking should be done before the wheel is turned for a corner. At the very least, 70% of your car's braking should be done before turning, and all of it should be completed by one-quarter of the way into the turn.

The cornering/braking tradeoff is dramatically illustrated in a highway emergency situation we've all seen or experienced. The car in front of you stops abruptly. You brake as hard as possible and swerve into the breakdown lane simultaneously. If you're lucky, this works, but it's only because you weren't stopping as quickly as you could have. If you're less lucky, you're suddenly sliding sideways toward the car you'd hoped to avoid or you're in a spin.

That shouldn't be a surprise now that you know your car can't brake and turn optimally at the same time. If you've mastered the technique of "instantly" squeezing your brakes to the limit, you'll brake at the limit first, then ease off your braking slightly to turn to the side; or, if getting out of the lane is more critical, brake lightly to preserve turning capability.

Copyright © 1998 by Tim Moser of Silhouette Racing. All rights reserved.


BRAKING - Stop It

Of all the skills that a race car driver must master to go quickly around a road or street course, none is more complex or more critical than braking. In fact, braking is important enough and complicated enough to discuss that I plan to devote two of these articles to it, and I'll do a third article, later in the series, on the unique characteristics of antilock braking systems (ABS).

No racing skill is harder to execute perfectly or to learn than is slowing a race car at the limits of its braking performance. It occurs dozens of times each lap on the race track. Slow down too much, too slowly or too soon and you've lost critical lap time; slow down too little, too quickly or too late and you've lost your race car or more.

There are three factors that make braking so complex. First, virtually all braking during a race is done at the absolute limits of the car's performance -- at the limit of the brakes' ability to convert the car's kinetic energy into thermal energy and/or at the limit of the tires' ability to adhere to the track surface. Second, the car's braking characteristics are never the same for two stops in a row. Third, the act of braking induces changes in the race car's posture, its weight distribution and its handling characteristics, all of which make braking more difficult and complicated.

Because race braking is done "at the edge," race car drivers have plenty of opportunity to experience and to practice braking for maximum performance. The everyday driver rarely experiences braking at the limits. When we do, it's an emergency, and one for which too few of us are prepared. I'd like to see every driver have the chance to practice braking at least twice a year, coming to a full stop as fast as possible, without skidding, from 30, 45 and 60 miles per hour. If all of us knew exactly what that feels like and how much time and distance it takes, the streets and highways would be safer places to drive.

There's a television commercial on these days that says something to the effect that your brakes stop your wheels; your tires stop your car. That's actually a profound statement, for all that it's technically flawed. Tire characteristics such as pressure and tread depth have a direct impact on a car's ability to stop. Race cars are checked for tire pressure and condition dozens of times during a race or practice session. Do you know the ideal tire pressure for your passenger car? Do you know how to measure it? What's the tire pressure of your car right this very minute? If you can't answer these three questions, you are in increased danger of not stopping in time when you need to. Tire pressures should be checked every time you put gas in your tank, and you should take a conscious look at the tread on your tires every time you get into your car.

When you step on your car's brakes, whether gently or firmly, some of your car's weight transfers from the rear of the car to the front. You experience this in the front end's dipping down. Your front brakes and tires experience it by having to do more of the work of slowing. That's why your front brakes are probably larger than your rear brakes and why they will probably need maintenance before the rear ones will. Weight transfer happens as a result of the laws of physics and your car is designed to accommodate it.

However, if you "grenade" your brakes -- if you stomp on them -- it is possible, even likely, that your more powerful front brakes will lock before that weight transfer occurs. Your tires will be skidding well before your brakes have dissipated any energy, and most of your braking effectiveness will be lost. The race car driver learns, and every passenger car driver should learn, to squeeze the brakes on (rapidly) rather than to stamp or slam them on, and to maintain pedal pressure right at the brakes' limits. The panicky "Oh no....STOMP!" stop has no place on a track and no place on the streets or highways; when it occurs either place it's likely as a prelude to a crash.

Copyright © 1998 by Tim Moser of Silhouette Racing. All rights reserved."

Though ABS is not really relevant to Old Kate (being stripped of that system long ago :-p), however, for the benefit of modern day drivers, i suppose there's no harm done in posting an extra article on ABS braking ^^

"ANTI-LOCK BRAKING

In my first braking article, earlier in this series, I promised a separate article on antilock braking systems (ABS). A recent report by the Insurance Institute for Highway Safety (IIHS) has raised questions about the effectiveness of antilock brakes and prompts me to follow up with this article.

Strictly speaking, antilock braking isn't a racing technique, since most race cars don't utilize antilock braking. There are two primary reasons for this: 1) It isn't entirely clear that antilock braking will reduce stopping distance for the skilled driver; and 2) Antilock brakes add system complexity, cost and weight to the race car, the disadvantages of which outweigh any possible advantages.

The IIHS report, issued December 10, 1996, notes that in single-vehicle accidents, cars with antilock brakes are as much as 44% more likely to produce fatalities than are cars without the antilock system. While the Institute declines to give a reason for this, it seems to me that the reason is simple and obvious. I don't believe that it indicates that antilock brakes are ineffective or dangerous in and of themselves. The problem is that stopping with antilock brakes, in an emergency situation, requires an entirely different braking technique than the one used with conventional brakes, and virtually no drivers have had or taken the opportunity to learn this new technique.

Different ABS systems work and react differently under extreme braking. While they all prevent the brakes from locking up, many of them generate pedal feedback -- pulses or bumps -- when they're working. They may seem to be pumping themselves; they may alternate between feeling firm and feeling soft; they may feel as though the pedal is going to the floor. The instinctive reaction for most drivers when they feel this strange brake pedal action is to reduce brake pressure, which deactivates the ABS, increases stopping distance and can actually cause a loss of control by upsetting the car's balance.

I said earlier that it isn't entirely clear that ABS will reduce stopping distance for the race car driver. It is very clear that it will reduce stopping distance for the everyday driver -- except perhaps in loose gravel or loose snow -- but that's not its primary purpose. The primary function of ABS is to enable the driver to steer the car while braking at maximum effectiveness. But steering in an emergency stop is itself a new technique. Abrupt or severe steering movements under these conditions will, again, unbalance the car and may cause a loss of control.

If you have a car with ABS you must learn to use it. ABS works and works well when you apply maximum braking pressure and HOLD it. DO NOT pump or ease off on ABS brakes in an emergency braking situation, no matter what they seem to be doing. If you steer while in an ABS stop, do it smoothly, but don't, under any circumstances, release or lighten your pressure on the brake pedal until your car is stopped completely. None of the above, by the way, applies to pickup trucks with rear ABS only, which should be driven as though they have no ABS at all.

It behooves every driver of an ABS-equipped car to unlearn his or her old braking habits and to learn the new ones that work with ABS. To do that, take your car to a safe location such as a completely empty and obstacle-free parking lot or a completely unoccupied street, preferably when the pavement is wet, and practice hard braking. Don't "slam" on your brakes, but press firmly, as hard as you can, with the force that would definitely lock up conventional brakes. Start at 15 - 20 mph and try to lock the brakes up while driving in a straight line. Your tires may screech or even skid or slide momentarily, but they should not lock up. If you can lock your brakes up, your ABS is not functioning properly. Stop your practice immediately and get your brakes checked and repaired.

No matter what the car or the brake pedal does in this practice, don't let up the braking pressure. Get used to what your ABS feels like when it's working; then do the same thing from 30 - 35 mph. At each speed, once you are comfortable with the feel of the car in a straight line, practice turning smoothly but positively while under maximum braking. Repeat this exercise several times, particularly at the higher speed, until you are completely comfortable with the way your car will react to a maximum braking situation and are confident that it won't surprise you.

ABS technology is expensive, and the more expensive the car the better the quality of the ABS system it is likely to have. There is a world of difference between, say, the ABS in a relatively low-cost Chevrolet and a top-of-the-line Mercedes. Both, however, require learning new driving habits.

Learn your car's ABS braking, what it feels like in your car and how it's different from what you have learned in the past. It is an exercise that can save your life in an emergency.

Copyright © 1998 by Tim Moser of Silhouette Racing. All rights reserved."

Anyway, hopefully this article helps refreshes my memory on proper driving technique ^^ sometimes we get lost in the minute details of trying to push the limit even further, that we stray from the most basic of concepts :-)

After a hiatus of driving on the limit for so long (due to that rather unfortunate accident :-p) driving fast again feels pretty much alien to me, and I do feel that I have to re-learn everything again, from the ground up X-p that crash really shattered everything inside of me :-p from my self-confidence, to my courage and even to my understanding of the most basic of concepts... It's great to finally able to drive again ^^ but the dread is still hanging over every turn :-p

Ryousuke is certainly over it (as is his post earlier), but i still got quite a hill to climb X-( well then, nothing wrong with a spirited hill-climb attack then X-p haha... Until then, drive safe ^^ one hardcore touge enthusiast once said (whom shall not be named for security purposes :-p) "drive safe, not slow... but safe" :-)