When you come to one of our advanced driving courses you will find we spend a lot of time and effort helping you to understand how to maximise your potential to control your car. Our aim is for you to learn better car control skills so as not to get into sticky situations, such under–steer, over–steer, or any other skid or slide, but what happens if you do get into one? How do you deal with it? Come to that, what causes the car to skid in the first place?

Usually, and this is said with absolutely no disrespect to anyone who may be reading this page, a tricky situation is made worse by doing the wrong thing, doing the right thing wrongly, or doing it at the wrong time. Hopefully, after reading this edition of the Ride Drive advanced driving tips and advice series, you will be less likely to get into a skid, be more able to cope with skidding if you do get into a skid situation, and to be more effective at coming out of it in better shape than perhaps otherwise would be the case.

Skidding can be defined as the involuntary movement of the vehicle due to the grip of one or more of the tyres on the road becoming less than a force or forces acting upon that vehicle. In other words, a vehicle skids when one or more of the tyres loses normal grip on the road.

There is nothing controversial about that, but what may amaze you is there are actually only four official causes of skidding, and these can occur either singularly or in combination.

The above four items are perhaps best summed up by saying that a skid occurs where the driver has expected more from the vehicle than it was capable of delivering under the conditions at that time. The vehicle only has so much performance that it can give to you, and if you demand more than that, you are exceeding its capability.

Tyre Grip Trade–Off

There is a term that you may well not have heard of, and that is, Tyre Grip Trade–Off. If you think of all four tyres on your car, and then say that each has 100% in potential grip to offer, for every task that you set for that tyre, it has to use up some of its grip allocation in order to complete that task. Therefore, if it takes 80% of the available grip whilst under heavy braking, that only leaves 20% for steering. However, if you don't brake whilst steering, then the tyre will give you a lot more of its available grip with which it can complete that task. If you expect full grip for cornering whilst braking, that is an occasion where you are expecting too much, the car will not cope with what you ask of it and that is when something will go wrong.

Working on the principle that if you know what causes a skid it is easier to avoid one, or to deal with one if it was not so avoided, let’s now look at each of the four causes in turn.

1 – Excessive Speed for the Conditions

This means that you are trying to do something, such as drive a 40mph bend at 50mph. It just ain’t going to happen, because like it or not, when you drive a car you will always be bound by the rules of physics relating to moving bodies.

If you have read the chapter within this driving tips and advice series covering cornering forces you will remember we talked about how, when making a vehicle steer around a bend, you are asking it to do something unnatural. We used the analogy of a conker (horse chestnut) tied on a piece of string to demonstrate this, by whirling it around like a helicopter rotor, saying that the conker represented the car and the string was the grip of the tyres on the road. The point was to say that if the string broke, or is released, the conker will cease to orbit your hand, but immediately will assume a straight line course at a tangent to the circular path from which it just came. The same goes for the car, in that when the tyres let go, the car, or part of it (front or rear), will slide at a tangent to the curvature of the bend. Unfortunately, and according to another unbreakable law (sod’s law), this will normally involve contact with a tree, another hard object, such as another vehicle, or entry to a ditch.

Staying with bends just for a moment, if the tyre grip at the front lets go when trying to negotiate a bend, this is called under–steer. If it is the rear end of the car that is affected in this way, this is called over–steer, and we will deal with how you tackle each individual situation a little further on.

2 – Coarse Steering in Relation to a Speed, Which in Itself is Not Excessive

This means that you are still entering your 40mph bend, but at 35mph, and yet you still get a skid situation. In this scenario your skid will most likely be that of under–steer, and this will have happened, because instead of feeding in the steering progressively, you have grabbed a big armful of steering wheel and thrown it around aggressively, and certainly with no empathy for the car. To illustrate the effect of this we have another analogy.

Fred and George are twin brothers who work in a warehouse. They are both of the same build, level of fitness and height. Fred is carrying a heavy box that he needs to pass over to George. If Fred stands holding the box steady, and allows George to take hold of it by bearing the weight in his own time, George is able to take the box from his brother and carry it equally as well. However, if Fred had thrown the box, George would drop it, only because he is being asked to cope with too much too quickly and too soon in terms of bearing its weight. The same applies to steering. Throw in too much too quick and the tyres won’t cope, but feed it in progressively and the car will respond up to its full cornering potential.

3 – Harsh, Excessive Acceleration

You can apply the above heavy box story to this one as well, because if you are harsh with the loud pedal, or when releasing the clutch, the tyres at the driven wheels may not cope. This is where you may encounter wheel spin under power.

We at Ride Drive actually believe there is a fifth cause of skidding, and would include harsh or inappropriate deceleration here, as in the abrupt releasing of the accelerator, or if you down-change a gear without matching engine speed to road speed, so inducing the loss of grip between tyre and road surface due to the drag of the engine. There’s more on this a little later on.

4 – Excessive or Sudden Braking

This compares very well to the heavy box story again. Brakes, like the accelerator and steering, are a variable device, and not an on/off switch. Apply the brakes gently at first, then ease in the pressure smoothly and progressively, and you will get the best stopping power available at that time. Give the pedal a poke, or stamp on it, and you will get a poor response.

Notice how none of the causes of skidding are given as ice on the road, for example. This is because it isn’t the ice that makes you skid as such. Ice is just another variation in road surface, and is a temporary surface condition on a piece of road that would more normally provide better grip. The reason you slide here is because you are not taking into account the low coefficient of friction properties of the frozen road when you apply your acceleration, braking or steering. Therefore you are doing this in a manner that is inappropriate for the conditions and by asking more of your car than it is capable of coping with.

Correcting Skidding Under Braking

If you get into a skid situation, how you deal with it has one generic answer – remove the cause.

If you have applied your brakes and your wheels lock into a skid, to remove the cause you need to lift off the brake pedal and then immediately go back on to it again, but this time a little more gently so as to try and avoid the lock–up of wheels.

Always remember that if you are driving a car that is not equipped with Anti–Lock Brakes (ABS), and you brake heavily enough to lock up your front wheels, whilst they are skidding along the road you can spin your steering wheel from lock to lock and you will go nowhere else but straight on. If this happens when you are heading for the back of another vehicle stopped in front, and there isn’t enough room for you to pull up before hitting it, you will have to go against all those instincts, that keep you rooted to your brake pedal, and get your foot off so you can then steer away from the obstruction.

When you come to Ride Drive there is a particular point we try to get across to you, and that is you do not brake and steer at the same time. Completing an emergency lane change, for example, will require initial application of the brakes, release of the brakes, steer away from the obstruction, and re–apply the brakes once you have straightened up.

Correcting Under–Steer

Under-steer is what the name suggests. It is where you apply steering, perhaps to negotiate a bend, and the response from the front of the vehicle is disproportionately less to the amount of steering applied.

You will probably have induced under–steer by putting in too much steering, or by putting in too much too soon. To counter this you will have to take some or all of it out again before re–applying the steering more sympathetically.

Straightening the steering in a bend is not easy. It takes real courage, so it is most important that you don’t get to that stage to begin with. In our experience, customers find it almost impossible to take steering out when in an under–steer situation, even on an open expanse of aerodrome where there is nothing in front of them. It goes against every human instinct there is, but it does work if you can do it.

Correcting Over–Steer – Rear Wheel Drive Cars

Over–steer is where the amount of direction change that takes place, following steering input, is disporoportionalely greater than the amount of input. This is the one where the tail swings out and we have deliberately left this next one to last, because this is where the standard suggestion of always removing the cause of a skid can actually get you into more trouble. We are talking here of over–steer caused by harsh or excessive application of power (acceleration).

Particularly with rear wheel drive vehicles, and those without any form of traction control equipment, if you apply sufficient power to cause the rear tyres to lose their grip on the road, and that loss in grip occurs when you are driving anything other than a straight line, the rear end of your car is going to head off–course. Remember what we said about conkers on strings in relation to cornering forces? Excessive power being applied whilst cornering can cause over–steer and for the reason given above.

When this happens the normally recommended method by which to regain control is to immediately counter the direction of the slide by steering in that same direction. So if the back of the car swings to the right, you have to steer to the right to try and catch it. You may have heard this referred to before as Opposite Lock, and to apply it at this point is good advice. You also have to remove the other part of the cause of the slide, which in this case is the excessive or overly aggressive application of engine power. This will involve you lifting off the gas pedal to cut the power. However, for rear wheel drive power induced over–steer, if you use opposite lock and lift straight off the accelerator pedal, the chances are you will actually make matters far worse, and here’s why.

What can happen if you snap your foot off the accelerator is you convert the power induced over–steer into power–lift over–steer, and due to your new direction in steering, the opposite lock you used to counter the slide, the tail of the car will now swing in the opposite direction. Yes, you now need to steer into that slide by reversing the steering input you had already given, but unless you do something drastic about the pendulum effect you are creating at the rear, it is most likely to spin you completely around.

How to Neutralise the Skid

To deal with this situation effectively you need to understand what is going on within the car.

If you experience power induced over–steer in a rear wheel drive car, what is actually taking place is the driven wheels are driving at a speed greater than the speed of the rest of the car (the vehicle speed here we refer to as Road Speed). If this occurs, and you take your foot off the gas pedal, the driven wheels will slow until they again match the road speed of the car. When this moment is reached we shall call this is the point of stabilisation.

Particularly if the car you are driving has a high–compression high performance engine, and⁄or where there is no damping system to the throttle (making engine to throttle response instant), it is possible you can pass through that point of stabilisation from driven wheels rotating in excess of vehicle road speed, to driven wheels rotating at a speed that is less than road speed. In other words, power driven wheel–spin is reduced to power–lift drag.

The problem here is that when at that point of stabilisation the tyres will regain their bite onto the road surface, and just for that fleeting moment, full grip is restored. This is the point where the back of the car kicks round in the opposite direction, according to where you have the front wheels pointing, and when this happens the effect is even more violent than the first slide. This is so because the tail of the car has begun that second phase slide from beyond a central point and so has a bit of a run up at it and that is the one that normally throws you off the road.

What you have to do is find another method by which to reach the point of stabilisation, and then remain there if you are to neutralise the skid. You will have to do it very quickly too. Yes, if the rear end steps out of line you still need to steer in the direction of the slide (opposite lock), but don’t just snap your foot straight off the accelerator. Instead, feather the power back slightly and gently until the driven wheels have slowed down to the point where they have again matched the road speed of the car. Once you have achieved this stage of stabilisation the tyres can again grip the road properly and stay gripped, and by keeping your accelerator foot steady at that point, you can smoothly re–adjust the steering back to your intended course. It is vital that you do not make any change in power setting here, at least not until the car has been fully stabilised.

The other option, which is a whole lot easier to complete, and which is very effective, is to do exactly the same with the steering as suggested above, but this time just slam the clutch pedal down to the floor. The effect this has is to instantly create the situation where the driven wheels will become neither driven nor dragged, but will return to a pure rolling action that matches the road speed of the car. Immediately you should be able to straighten the steering and recovery will be swift.

When we allow customers to demonstrate this for themselves on an airfield they are usually flabbergasted at how quickly the car will change from being an unruly wild animal into a state of obedience. The change in vehicle attitude really is very quick.

Power Lift Over–Steer

Power lift is actually a far more common cause of over–steer on bends than powered over–steer, and is more of a danger, because people are so much less aware of it. If you talk to those who drive powerful rear wheel drive cars they will only be too happy to tell you in a sage–like manner that you should never accelerate in a bend, least of all when the road is wet.

Power lift over–steer is cause by a driver lifting off the gas pedal whilst negotiating a bend, and as a consequence, the rear tyres lose grip on the road causing the back of the car to break out of the curve. This will happen due to the drag of the engine compression against the rotation of the drive wheels. This will affect front wheel drive cars as well as rear wheel drive, but in a different way, but we will come that that later. Putting aside power lift over–steer for a moment there is an even bigger threat, and this one is what we at Ride Drive call, Clutch Drag Over–Steer, and is the one that we say makes the number of causes for skidding up to five.

To explain clutch drag over–steer we need to show you a couple of diagrams as we go.

Power Applied – Engine Driving The Drive Wheels

When a car is being propelled by its own engine power, that drive, or energy, is being transmitted from the engine to the road surface through the drive wheels. However, if the driver lifts off the accelerator, does the engine immediately die to idle speed? No, of course not, as it will continue to register rpm that matches the road speed of the vehicle. This is so because during deceleration, or over–run, the drive wheels are transmitting the road speed back through the drive train to the engine. So, to simplify that, when under power the engine drives the drive wheels. Lift off the power and the drive wheels then drive the engine.

Deceleration (Overrun) – Drive Wheels Driving The Engine

If you can imagine a driver travelling at 60mph in 5th gear, lifting off the accelerator and then disengaging the clutch, the car will be coasting. Whilst coasting, and with no input through the accelerator, the engine speed will reduce to idle speed, or tick–over, which is at a RPM very much lower than the vehicle road speed. Imagine then the driver re–engaging the clutch without using the accelerator. This will force the engine back up to the road speed of the vehicle through the drag of the clutch and from the rotation of the drive wheels being driven by the momentum of the car still travelling along the road. This transfer of energy will again accelerate the engine until both vehicle speed and engine speed are again matched?

The demand for grip from the tyres of the drive wheels, in this case, will be considerable, and if the this occurs when the car is cornering, and where the road surface has a low grip factor, perhaps due to being wet, those tyres may well break traction. If you think about it, this is like completing a hand brake turn, but without using the hand brake

This scenario, for a high percentage of drivers, is close to happening day in and day out. People going about their everyday business on the road will be blissfully unaware of what is going on beneath them, or of the potential consequences that lurk just below the surface. Think about it, where are drivers most commonly braking and changing down gears at the same time? Cornering or course.

This is where the danger of spinning is at its most acute, and where the resulting spin will happen far more violently than ever it will through applying too much power in a bend. This is one of the reasons that we train our customers to complete all gear changes prior to the bend, so by the time they enter the bend, they are travelling at the right speed and with the right gear engaged to complete the bend. We also train people to match their engine speed with the road speed whilst changing down to a lower ratio, so as to eliminate any drag at the drive wheels.

Correcting Over–Steer – Front Wheel Drive Cars

Over–steer when driving a front wheel drive vehicle, unless you have pulled on the hand brake, or there is some other issue such as incorrect tyre pressures, the condition will most likely be caused by lifting off the accelerator in a bend, and here’s why it causes such a problem.

When in motion a vehicle is in its most stable state travelling in a straight line and at a constant speed. This is because the loading on each wheel is as evenly spread as possible. Under acceleration the situation changes, as there is now an apparent weight transfer to the rear of the car. Bearing in mind that tyre grip is created through the tyre being pushed onto the road surface by vehicle weight, under acceleration the available grip offered by the front tyres is now decreased, whilst it is increased at the rear. Under braking the situation is reversed, as it will be the rear tyres that have less grip. All of this is not too much of an issue whilst the car is travelling straight ahead, but during cornering, the vehicle tyres have to use a lot of available grip to pull the vehicle off course, so as to follow the line of the bend.

Given that under braking the rear tyres become less heavily loaded, passing on their lost down force to the pair at the front, there becomes an imbalance in the amount of available grip front to rear. Mix this with some steering input, having less grip than the front, the rear tyres are the more likely to break grip with the road. If that happens, the back of the car will do what comes naturally, as in take off at a tangent to the curve, creating over–steer.

This can also occur where the car is under high–cornering stress and the driver releases the accelerator pedal. This does not involve braking, but is power lift over–steer again, and when this occurs by this manner of driving, and in a front wheel drive vehicle, it is exceedingly more difficult to recover.

This over–steer situation for most it will be the beginning of the inevitable end to a bad situation, and there will be very few who will get out of it. The best that you can hope for is that you have lightening quick reactions, because if this situation starts to develop, unless you can counter it in a nanosecond, the moment of redemption will have passed.

If the car breaks away due to braking whilst cornering, the old remedy of removing the cause is still good advice to use, but in this case it isn’t going to be enough. Bearing in mind that over–steer with a front driven vehicle can be induced by lifting off power in a bend as well as braking, when releasing the brakes you are still in power lift off mode, so therefore may still have to do more.

Now you have two options, to either go for power–on (if you have the room) or a de–clutch option. The power–on option gives you the opportunity to make the front of the car catch up again with the wayward rear, whereas the de–clutch option will allow all four tyres to resume a pure rolling action, with them being neither driven nor dragged, and therefore allowing the restoration of normal grip. However, for the public motorist, it is most likely that recovery will not happen.

The Value of Skidpan Skid Control Training

There is generally a great misunderstanding among the motoring public concerning the benefits attached to skid tuition on a skid pan, and hopefully we will now set the record straight for many.

A skidpan driving experience is good fun, and in that environment you can learn to control various different skidding scenarios quite well. However, you are only able to perform as well because to do skidding is the reason why you are there. When you skid on a skid pan you are expecting it to happen, and in fact, the majority of your slides will be self–induced. When it happens for real on the road, the reason it does so is that you are not expecting it, otherwise you wouldn’t, or shouldn’t, have skidded in the first place.

Another factor to consider is that of speed, as when you are driving on a skid pan, in all probability the maximum speed you will achieve will be no more than 15mph, and look at how much room that takes to correct it! If you were to get into a skid for real, when driving on the public road, what speed do you think you will be travelling when that happens? 40, 50, 60mph – more? When you factor that into your thinking, do you honestly believe you are going to have the space on the road that situation will demand to sort it out?

Always remember that skidding is the result of something else that has gone wrong further back up the road, and as we have said before on this page, we can sum up that cause as being that of a driver asking more of the vehicle at that point, and under those conditions, than the vehicle is able to deliver. You can say the skid is a traffic accident, even if you are lucky enough not to hit anything, and if you skid for 50–metres before hitting a tree, your road accident has covered 50–metres of road, culminating in making contact with a tree.

Soon There Will Be No Need For Car Control Skills

Another point to consider, when talking of the usefulness of skid pan driver training, is that of technology. The sorcery built into cars is becoming ever more sophisticated. Traction control, vehicle stability control and other electronics made all the more confusing by manufacturers not referring to their systems by the same names. Especially in the more high–end market vehicles there are systems that are so advanced they will actually override some of the errors made by the driver in order to keep the vehicle from harm. It won’t be long before lower–end budget vehicle will be so equipped and you can take one of these so equipped cars to a skid pan and get a great deal of assistance from the electronics, as they even help prevent you skidding on a skidpan.

What this means, however, is that when driving one of these cars badly, the safety features will look after you to a point, but when they have to let the car go, and the car is out of control, you are going to be travelling at a much faster speed than if you were to lose control in a not so well equipped vehicle. This speed difference will not be measured as one or two miles per hour either, as that gap will be wider. That being the case, where the safety systems will protect you to a point, after that there is a chance the technology will play a part in bringing about your crash.

As automotive technology advances, so the need for skid correction and skidding control training will disappear. Also, because of this by–product of improved car control and safety systems, the need to drive with an understanding of the vehicle, as well as the need to have good control skills, becomes almost superfluous.

Ride Drive provide advanced and high performance car driving courses that include skidpan driving sessions, but the emphasis we put on skid pan driving is different to that of the standard skidding lesson.

Have a Better Road Crash

Hopefully you will appreciate, through reading this page, that having the odds of you being able to rectify a skid without harm on the public road is pretty minimal. However, whilst you may not prevent yourself from crashing, you can look at improving a skid situation in terms of damage limitation. When losing control on the road, if you have the ability to alter the attitude of the car just a little, you could have a crash with a better outcome. Confused? Well, don’t be, because this is important.

If you hit a tree, for example, and whilst travelling sideways you are probably going to die. However, if you can hit it head on, or even with the rear end, you will probably survive. If you hit a kerb whilst travelling sideways the car will most likely flip over, but hit the kerb head or tail first, the car will remain upright. The difference between head–on and side–on can be as little as a few degrees, so if you can learn enough control to make that much of a difference, you may well be able to do enough to save your life.

Another way to think of the value of a skid pan driving session is to not look at it as a skid control and correction course at all, but as a car control course. If you can drive around on a low grip surface, and by ‘feeling’ the car, you can avoid sliding. If you can achieve this, you will have fine–tuned your car control skills, because in that environment you really do have to develop a close working partnership with the car. Every little movement of the wheel, every adjustment of the accelerator has to be completed with all the finesse and care of a bomb disposal expert defusing a hair trigger device. When you can do that, you are really working with the car.

By putting you through a series of exercises such as this on a skid pan you will not only build a closer bond with the vehicle you are driving, but you will realise that by coaxing it to do what you want of it, you can get a whole lot more performance out a car in terms of improved agility.

To sum up this page, and when looking at all these different remedies for skidding, wouldn’t it all just be so much easier if you could drive in a manner whereby you didn’t get into a skid situation in the first place? The best rule that anyone can follow is that prevention will always be far better than cure – every time. The best professional advice that we can give to our readers is, know your car, know your road environment, know your own limitations and never drive in a manner by which you expect more than any one of them can deliver.