Breaking the code.

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Breaking the code.

BHP! Brake Horse Power! That’s what we want! Is there ever is too much of the stuff? Obviously not. I know this because in all of my years of driving fast, I have never once stepped out of a car and uttered the words… ‘I think it would be better if it had less power.’ Never. Not even an awful car with really bad, vindictive handling. One that, you assume, has been designed by an evil genius with some kind of Darwinian like plan, engineering in chassis characteristics that are so bad it would kill off anyone stupid enough to attempt to drive it quickly.

Now, you see, here’s the clever thing about power- you have a throttle, an accelerator or, for our American friends, a ‘gas’ pedal. Despite what has apparently been taught to some track day drivers I have encountered in my time, the throttle is not a digital switch. There is indeed an ‘off’ setting, along with an ‘on’ setting. But, there are lots of other positions the throttle can be placed in as well. These other settings are massively beneficial and will help you make swift and safe progress through and out of a corner. If you haven’t already, I suggest you try them some time, you may surprise yourself, and it really will open up a whole world of options.

If then we do find that the car has too much power for A) the chassis or B) the driver (obviously it’s going to be A), one can adjust the amount of power being delivered to the driven wheels. Whether that happens or not is a function of our own ability to control what our right foot is doing. So fundamentally, we have a choice. And it’s obvious that more power is better. Just look at who makes cars. Every single car manufacture with a tendency towards producing sporty motors is giving us more power with each engine or model variant that comes out. In the world of modification, there are only car tuners not car de-tuners. So it’s not outrageous of us to assume BHP has got to be the most important aspect of a performance car, right?

Well maybe…OK so, power is king, but what about handling? The chassis is also pretty high on the list ,surely? But, with our ability to be able to control even the biggest skids imaginable, we can overcome any flaws in the chassis or indeed any laws handed down by ‘physics’ by just trying a bit harder. Also, it’s well known that all of those quick guys passing us out on track throw money at new tyres, so we’d be as quick as them if we did the same. We can buy dampers with knobs on as well. Anything you can adjust is good. Even if you don’t really know what a damper does or how it works, I’m sure you’ll find that by twiddling the knob left or indeed right, it will make it better.

In conclusion then, I think we can all agree that if you want to be a better (faster) driver, we need to find a way of screwing more BHP out of our motor, buy new tyres and throw some adjustable suspension on it. Simple!

Stop a moment (big clue) and think about it though. Is that all there is to driving? What are the fundamental component inputs we make to a car in order for it to go around a track?

1) Turn the wheel to guide the car around bends.

2) Accelerate to make the straights as short as possible.

3) Brake to slow the car down to the correct pace so we can do No. 2) without crashing.

So points 1) and 2) are easy. I’m sure we have all gone around a corner on the limit of the grip that is available to us from the tyre. We can tell this from the way we have the car dancing on the end of our fingertips, an incredibly slight slide, with almost neutral steering, a magical, near Zen like experience.

Then, we’ve accelerated as hard as we can out of the corner, burying the throttle through the bulkhead. And frankly, once the pedal has made its way partially into the engine bay, there really isn’t an awful lot else to do with it.

But what about point 3)? Do we brake properly? Honestly, ask yourself, have you ever really actually totally 100% nailed a brake zone? And then did you do it again at the next corner, then for the next 12 laps at every brake zone on the 11 bends which require centre pedal application of the Silverstone GP circuit? That’s 132 perfect stops. I can tell you that you haven’t. No one has.

We don’t talk about braking because it’s not one of the coolest bits of driving that we can do. We all know fine well that your mates will be impressed that you can do big skids round bends and then accelerate away leaving big smokey black lines on the floor. However, no-one has ever said “this is my new car, look at the brakes! I’m not sure what engine it has and I haven’t got a clue what tyres it’s got on, but just look at those cross drilled and ventilated discs!”. It is also a very well researched and documented fact that no girl on this planet that has ever knowingly been impressed by floating discs. The only way by which we rate how good a cars’ braking system is, is by the colour of the callipers. Red = good. Yellow = much better.

Carbon composite/ceramic braking systems are a perfect marker of our understanding and knowledge as to what brakes do, why they are important and indeed, how they work. There is so much misinformation about them it’s unreal. Even the car salesman flogging these incredibly expensive, yet if used correctly, effective bits of technology generally don’t know how they work and what the true benefits of them are. If they don’t, how on earth are you, the customer going to know?! All we do know for sure is that they are made of carbon and so are F1 brakes, therefore they must be great and well worth the £10,000 price tag. And why are we talking about slowing down anyway!? We want to go fast!

The thing about braking is that to do it properly is really hard. It’s honestly one of the toughest elements of driving. Don’t just take my word for it. A decent chap called Jackie who used to race cars in the 60’s and 70’s said that it was the last of the skills he mastered. Sir Jackie Stewart won 3 world championships in F1, he was a bit handy. Braking is so important, it’s totally vital to the cornering process.

Think about a corner like a mathematical equation; B= Braking. C= Cornering. A= Acceleration. However, the cornering process isn’t made up of digital actions. You don’t flick a switch and apply 100% brake pressure then flick the switch back off, only to flick another switch to turn the steering wheel to 100% of the required steering angle to then flick that switch off and do the same with the accelerator. No, there are stages in each of these processes. Let’s keep it simple and just say there are 3 elements each to braking, cornering and accelerating. For example, the 3 component elements to braking are;

 

X = initial pressure

Y = maximum required retardation

Z = pressure release.

So, X+Y+Z= Braking and so forth for cornering and accelerating. Got that? Good.

B= Braking. C= Cornering. A= Acceleration

So, we have an equation. (X+Y+Z) = B + (X+Y+Z) = C + (X+Y+Z) = A = Yes! Nailed it!

What happens if we get the first part of the equation wrong though?

(X+H+Z) = S + (X+Y+Z) = C + (X+Y+Z) = A = Oh. I’ll get it right next time/I didn’t expect tyre walls to be quite so firm.

I’ll leave you to work out what S stands for.

The thing about braking is that because it’s the first process of the corner/equation, if you do get it wrong, you are no longer able to get the rest of the corner/equation right. It doesn’t matter how well you do the remainder of the corner/equation, it can’t work.

If we look at all three parts of an average corner (braking, turning, accelerating), in terms of time, we will typically spend the least amount of time braking when compared to the other two parts. But, in comparison to accelerating, we’ll be having a greater effect on the speed of the vehicle while we are there. Think about it. With the obvious exception of those crazy American Top Fuel dragster chaps, any car will be able to take more speed off, much more quickly than it can put speed back on. And you’ll almost certainly spend more time applying some degree of turning angle with the steering wheel than you will pushing the centre pedal in a brake zone. So, percentage wise, you have a lot to do in a little amount of time. What a complete nightmare. You’ve got the most important job, with the least amount of time and if you get it wrong, you can’t get the rest of the bend right. Pressure is indeed an appropriate word when talking about braking.

So how should we brake? Sweeping statement time… We should brake harder. When coaching a complete novice on track, the most common term to come from any instructor’s mouth is ‘BRAKE HARDER!’ Your average driver just has no concept of what kind of force is required when driving on a track. A great demonstration of this is when coaching in a Nissan GTR, which is frankly a rocket ship in every sense. The GTR has a centre console screen, the contents of which have been designed by the clever chaps that create the somewhat epically successful Gran Tourismo racing game series. Somewhere on one of the 48 pages of critical information, among the turbo inlet pressures and gearbox lubricant temperatures is something actually useful. Brake pressure, measured in %. During an appropriate session on track with an appropriate cross section of the driving community, I did a very unscientific experiment. When briefing my drivers, I didn’t focus very heavily on how hard to brake, saying no more than you’ll have to brake harder than you would on the road. They intelligently reasoned that this makes sense and would indeed do their very best to follow my instruction if asked to brake harder. Off we pop, out onto the circuit. Arriving at the first big braking zone, despite hitting the brakes at roughly the right point, as expected we sail past the clipping point. After being guided that not enough pressure was applied to the pedal and that it needs a lot more, we tried again. A bit better, but ultimately, the same result. Despite being fully aware that missing the clipping point continuously is a fairly clear signal that too much pace is being taken into the bend, it carried on throughout the session.

Approaching a big brake zone, I asked the driver to hit the pedal as hard as possible, don’t hold back, and give it everything. They did their best.  On the way back into the pits and on an appropriately empty track, I pointed to the readout of the brake pressure dial on the info screen. I then asked the driver to replicate that braking force again, while keeping one eye on the reading. Boom. 50%. They looked a bit confused. How come they were braking as hard as possible but the little dial on the display only rose to 50%? We swapped seats. First brake zone, my passengers did try to spot the break pressure readout, but they were too busy peeling their face off the dashboard. Next brake zone, they knew what was coming, and braced. That’s when they managed to spot that the little dial does indeed reach 100%. Big uncomfortable lesson time. It must be something they’re doing…

So, if they knew, by their own admission that they missed the clipping points because they were taking too much speed into the bend, why didn’t they just slow down more? There are a few answers. A novice just simply isn’t used to ever using the brake pedal in that way. It’s all new to them so they can be forgiven for taking some time to get used to it. You will never use the brake in the same way while driving on the road. Often some track ‘instructors’ compare it to an emergency stop. Although in some respects the ultimate pressure may be similar, it’s not a great comparison so avoid trying to replicate it. The fear of skidding is huge as well. Very few drivers are truly aware of ABS and how it works. So they think that hitting the brakes that hard will just send the car in to an uncontrollable skid. There are also physiological barriers to deal with. You’re on a race track, in a performance car and you want to go fast. Braking hard is literally the opposite of what you’ve turned up to do. Add to this the fact, modern race tracks are incredibly wide so ones perception of speed is greatly diminished, plus you’re in a sports car that’s really good at going around bends… we have a recipe for things not quite working out so well.

It’s not just novices that struggle with this though. In relative terms, even very experienced track day drivers and racers struggle to get it right all the time. If you brake early, you’ll definitely make the bend, so you can make up for the less than ideal start to the bend by trying harder in the other bits (this is obviously not correct but you’re welcome to think that if it makes you feel better). Pushing it to the limit is really hard because you’re trying to brake as late as absolutely possible. But once you start that braking process, you can’t go back. You’ve hit a bell that can’t be un-rung. You’ve committed. If you realise that you’ve braked too late though, you’ll invariably react in a blunt fashion and apply an un-considered force, probably locking a wheel/activating ABS. At best, in a car without ABS, this normally ends in just about staying on the track with potentially flat spotted/square tyres, or more likely, an off….. with flat spotted/square tyres.

Learning how to brake properly is a case of trial and error. When I am coaching a client specifically on braking techniques, I often base the training at a strip of tarmac and when appropriate we use their race car, or any car without ABS. We’ll spend all day driving up and down in a straight line and also initiating the start of a turn, using techniques which allow us to focus on the foundations of threshold braking.

Ultimate braking can only be learnt though feel. Explaining how to brake on a page simply using written words is almost impossible. But, because we push the boundaries of conventional journalism here at Track Driver…. here goes:

Think back to that mathematical equation we covered earlier and the three stages of Braking – X, Y and Z.

Initial application of pressure should be assertive but measured. This is X. What you’re trying to do at this stage is transfer weight onto the front tyres but not grab or shock the breaks. Think of this as giving the car a bit of a heads up as to what’s about to happen. Of course, it’s all done in the blink of an eye.

Then, once you’ve initiated the weight transfer, we can move onto Y. The pressure can now increase firmly. At this point you’re right foot or indeed maybe the left foot for those with paddle shift cars, is on heightened alert for incoming signals from the brake pedal, clues as to what might be happening to the rubber currently in contact with the tarmac. Add into this the feedback from the steering wheel and the signals it’s giving to the palms of your hands. For the benefit of those that aren’t too up on the mechanics of cars, thanks to the wonders of weight distribution and momentum, the front wheels, which are connected to the steering wheel, are also the wheels which will be doing most of the braking. These are the ones that will be giving some of the biggest signals. What few people realise is that it’s actually really hard to lock a tyre when traveling at high speed in a well set-up car. It’s only when the speed starts to drop into the zone of 70mph and bellow that locking a wheel is more likely. This is especially true for cars with big aero given the amount of down force on the tyre when travelling at speed. One of the reasons for this is simple and can be explained through the use of a kitchen appliance. The next time your washing machine is running and it’s on the final cycle of its wash programme, the spin cycle, take a look at what’s going on there. The energy it’s developing is pretty impressive. The whole thing moves and shakes, which is astonishing given how much those things weigh. What you’re seeing is the gyroscopic effect. If your pants, socks, T shirts and jeans can have a big enough impact to move 80kg of washing machine around your kitchen floor, just imagine what a brake disc, wheel and tyre can do! At this point I think it’s prevalent to have a think as to why carbon discs are an attribute….

Typically, if the wheels do start to lock, you’ll feel the steering start to go light, even in a straight line. If the car you’re driving has road or “track day” tyres on, you can sometimes hear a squeal of protest from the tyres when they are right on their grip limit, if you are running slicks, you won’t. In this phase, there is constant modulation taking place. You’re responding to the bumps in the brake zone, the car kicking around and moving and of course, you’re adjusting and reducing the pressure as the car is sheading speed.

So next comes a really tricky bit, Z. When the appropriate amount of speed has been removed, we need to start the process of relieving the pressure from the brake pedal, freeing up some energy for the car to be able to start to turn into the bend. This is where a ‘pro driver’ comes into their own. A pro is able to consistently judge the amount of grip the tyre has available for it to be able to slow down but also start the turn at the same time. This allows them to keep the brake on a little, while initiating the steering angle. The benefit of this is that it keeps weight over the front tyres (but not too much) and it kind of blends one action into another, meaning there is no pause, or down time between braking and turning. Efficient.

What a novice tends to do once they’ve done with braking, is move straight onto the next bit. Invariably this is carried out with all the finesse of a toddler playing a xylophone. The issue with this is that coming off the brake pedal quickly has the immediate effect of launching the front end of the car in the air, thanks to those springs coiled around the fantastic adjustable dampers. This effectively removes grip from the front tyres. Anyone experienced understeer as you turn into a corner??? By holding onto the brake pedal a little as the car is turned into the corner, we are no longer trying to greatly slow the car down, more that we are managing the weight of the car. Too much brake force at this stage will either cause a front wheel to lock, or lead to dramatic corner entry oversteer. This is key and why jumping from Braking to Cornering to Accelerating is not a digital exercise, it’s done with finesse and feel. Truly a case of physics meets art.

The above example was a typical explanation of normal braking for an average corner. Only thing is, there is no such thing.  Every corner is different, some are similar, but they are not the same. What I’ve described is an example of technique. If this technique is applied and adjusted for each car, corner and weather condition then you’ll have the right tools in your box to be able to get the most out of every brake zone, every lap.

I hope that it is now a little clearer why braking is one of the most important things we as drivers need to focus on. We need to keep practicing and we need to keep learning how to slow the car down. If we do, we’ll be on our way to breaking the code of truly fast driving.

March 23, 2016 / Coaching Corner

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