Skid Control

Now we get to talk about something I REALLY enjoy, sliding a vehicle. For most people however, when a car slides it's a scary thing. And the reality is, in the real world, out on the public roads, it's not something you want to have to deal with, not even me. But this does not mean that you shouldn't KNOW how to deal with it.

Most of us will drive in some sort of bad weather climate at some point in our driving careers, rain, snow, ice, sleet, dirt road whatever it may be, these are all conditions that can easily result in dealing with a sliding vehicle. Can it happen on a dry paved road?, sure it can and it does, just not as frequently as it happens when there is inclement weather.

So first we will discuss a couple of different and typical types of slides, why they happen and what you as a driver can do to control them as well as possibly prevent getting into the situation to begin with.

The first type of slide we will talk about is UNDERSTEER

Understeer, when relating it to a skid, is when the front tires of your vehicle lose grip and start to slide, typically as you are entering a corner. (see image1)

In the image above you see a car that is attempting to make a left hand turn. The driver has steered the car to the left, but the vehicle is not turning at the rate the driver would like it to, it's taking a straighter path which leads to the edge of the road.

What are the typical reasons for this situation to occur? Well, the number one reason is speed. The driver has typically gone into a corner faster than the front tires ability to maintain grip and make the car change directions at the angle requested.

If you have ever driven in snow or ice this is something you have likely dealt with, however, it can happen on any surface.

Another reason this may have happened is a surface change. Possibly the driver was going at a speed that was perfectly acceptable until they got to the portion of the road that had sand on it, or wet leaves or some sort of fluid. This change in the surface changes the available grip level of the front tires.

So what would a typical driver do in this situation? Well let's see, first, panic. This would be the OMG moment where you either take a deep breath and hold it, or you don't breath at all. This is typically followed by the desire to turn the steering wheel MORE to the left. Why? well, because we are trying to make a left hand turn, and if we have turned the steering wheel left and the car isn't turning the way we want it to, we must not have turned the wheel enough, right? All the while, we are staring at the edge of the road looking at the ditch we are about to end up in, thinking to ourselves, no! no! no! no!  If you've ever been in this situation in the real world, you know what I am saying is true, and it doesn't fell good.

What SHOULD we do about this situation? Well, the good thing id that understeer is the easiest type of skid to deal with. In fact, all vehicles are engineered and designed to understeer as their first type of loss of traction because its easier to control than an oversteer (we'll get to that) and typically a less significant crash should you not be able to fix it.

So what do we do for understeer. the obvious first thing would be to say, plan further ahead. Get your eyes up and look further into the corner so that you have a better idea how sharp the corner is, this way you will slow the car down to the appropriate speed for the corner. I have talked about eyes and how important vision is with respects to driving and skid control is no exception to the EYES UP rule. One of the most common places that you can see where people have understeered is on off ramps. Typically a driver will exit the freeway where they have been traveling 70mph +, then they approach their exit. As most drivers, they are not looking far enough ahead and don't realize that the off ramp is a decreasing radius corner (meaning the corner gets sharper the further you drive into it) so they don't slow down enough and by the time they do realize they are going too fast, it's too late. This would be why you see a lot of the scratches on the concrete barrier at your local off ramp. If you have never noticed it, take a glance the next time your on your local ramp.

Now let's say that you are in the situation, now what? first, keep your eyes on your intended path, through the corner. Remember, your eyes tell your hands where you want to go, so if you are looking at the ditch, you significantly increase your odds of getting there. So eyes on your intended path.

Next, release the throttle. By getting off the accelerator you get two benefits from one reaction. The first benefit is that you slow the car down. Speed was likely the cause of the problem, so let's not complicate things by adding more. The second benefit is weight transfer. When you lift off the accelerator it will cause a weight shift to the front of the vehicle. This weight shift puts more down-force on the front tires therefore giving them more grip, this is a good thing.

After the above, the next part is the hardest, don NOT turn the wheel more! You will instinctively want to turn the wheel more, its just the way we are wired. Turning the wheel more can actually make the situation last longer and be significantly worse.

Think of it like this; if at X speed, you turn the wheel say 5˚ and you are going too fast and the car starts to understeer. At the same X speed, if you turn the wheel MORE, let's say to 15˚, the tires are just going to slide more. See, no matter what the angle, if you are in an understeer, you are already trying to make the car turn at an angle sharper than it can. So with the steering wheel you either, do nothing with it and just hold the angle that you already have and wait for the vehicle to slow down to a speed that the tires can regain traction and make the car change direction or, if there is enough road space available, you could try to reduce the amount of steering you have requested. On the public roads, the latter option is not very common. Public roads a pretty narrow and don't often allow room to reduce steering angle.

Once you have done these steps;

1-eyes on intended path

2-off the gas

3-don't turn the wheel more, reduce steering input if possible

The rest is kind of a waiting game. You have to wait for the car to slow down to a point at which the front tires regain grip. Another option that you have, but it has to be done with some delicacy, is braking. You can use the brakes to help this situation, but not in a panic, stomp the heck out of it kind of way. Remember, you have already lost grip with the front tires due to steering angle, so also asking the front tires to slow the car down can complicate things and make the situation worse, much like adding more steering. However, if you can "lightly" apply the the brake, you can accentuate the effects of getting off the throttle. You can slow the car down more and you can also create a larger transfer of weight. Both of these will help the situation.

So that's understeer and it's the EASY one, now let's discuss oversteer.

Oversteer, this is likely the most difficult skid for people to control or deal with. Oversteer is when the rear end of the car is sliding around. 

Basically, the rear of the car wants to pass the front of the car. 

A term you’ll hear a lot, especially in snowy climates is “fishtail”. You may hear someone say something like; “ I was doing ok and then all of a sudden the car started fishtailing down the road.” A “fishtail” is basically a series of oversteers that have not been dealt with correctly.

So, what causes oversteer? Well, several things. Oversteer can actually be a result of fixing an understeer situation. When you lift off the throttle to slow down the vehicle due to an understeer, you transfer weight to the front of the vehicle, which is what you wanted to do. However, this weight transfer has lightened the load on the rear of the car therefore reducing the grip of the rear tires. In this situation it is easier for the rear tires to start sliding.

Another way to induce oversteer is by accelerating too aggressively, especially if you have a high horsepower vehicle or you are driving on a slippery surface. Let’s say for example you are coming out of a corner and the road is wet. You step on the accelerator too hard and start to spin the rear tires. (rear wheel drive vehicle of course) Well, the spinning tires mean the tire is not getting good grip with the road and it will now slide.

You could also find yourself oversteering due to locked rear wheels. Maybe you are driving a manual transmition and you were downshifting in the middle of a corner (something you shouldn’t be doing unless absolutely necessary, but that’s another topic) and during the downshift you don’t rev-match the engine speed to wheel speed (also another topic) there is a good chance you will get a “chirp” from the rear tires. This chirp is the tires locking for just a second. This brief lock up can put you in oversteer.

Basically, any time you spin or skid the rear tires, you can place the vehicle in oversteer. So how do you deal with it?

Most of us have heard it said that when the rear of a vehicle slides, “steer into the skid”, and this is true. However, over the years I have found that many people have no idea what this means. In a lot of cases they can't even tell you which way the vehicle is sliding and by the time they figure it out (if they do) it’s too late to fix it.

But let’s say for the sake of argument that the driver does recognize the direction of the slide and they do “steer into the skid”, then what? ………………………. exactly, crickets. If you ask an untrained driver to tell you what to do AFTER they have steered into the skid they don’t know what to tell you. Better yet, even before that question, simply ask them “how much should you steer into the skid?” Again, you’ll get some guesses, but they really don’t know.

Why is it that people don’t know how to deal with this? Because they haven’t been properly educated. Sure, maybe they have seen a diagram in a manual or maybe even seen a video, but as I’ve said before, you cannot learn how to drive from a book. The driver’s education system in this country doesn’t really have the means to train drivers how to deal with this and a lot of people will not invest in their own driver training. Most think "it will never happen to me." Well, this mentality and lack of training is what has gotten us to the point of about 6000 teens a year being killed in motor vehicle accidents. 

So, what is the proper way to deal with an oversteering vehicle?

In most driving schools you will hear a term CPR, this stands for Correct, Pause, Recover. This is a great, easy method of remembering how to deal with oversteer. I will step you through the process of CPR.

Correction

For whatever the reason, the back of the vehicle is starting to slide. There are a few things that need to happen almost simultaneously as part of the "correction". 

first, keep your eyes on your intended path! this is HUGE. Remember from earlier posts, your eyes tell your hands what to do. If you are looking at the ditch your vehicle is headed for due to oversteer, you are going to significantly increase your odds of getting to that ditch. Be sure to give yourself GOOD information, keep your eyes up and on your intended path. Also, keeping your eyes on your intended path will help calm you down a bit. If you are looking at a ditch or a tree or whatever, as your vehicle is sliding toward it, nothing in your path of vision is a solution. Its all negative information and you panic. If you keep your eyes on your intended path, you can see a clear path and a means of escape or a solution. This alone can help keep you more calm. 

Along with keeping your eyes on your intended path, release the accelerator. Once again, there is a good chance that the accelerator was part of the problem to begin with, so lets get our foot away from that pedal. There are SOME instances in which MILD throttle application can reduce or help fix oversteer, but these are not the norm for an everyday driver. However, as an example of when adding throttle may help, let's say you are driving a rear engine vehicle and you get whats called a TTO (Trailing Throttle Oversteer) this means you lifted off the accelerator in a corner and it caused the rear end to start sliding. A mild reapplication of the throttle can help plant the rear end again. Its simply a matter of putting the weight back on the rear tires. Old Porsche drivers are well aware of this phenomena.

Finaly, as part of this combined sequence that is called the Correction, turn the steering wheel in the direction that the back of the vehicle is sliding. Now, I say it like that because saying "steer in the direction of the skid" tends to leave room for an interpretation. See, I can show you a site where a professional driver made the statement "To fix oversteer reduce speed and turn the steering wheel in the opposite direction of the skid." see how it can get convoluted. I know what the instructor that wrote this article means, but it can make thing confusing. When dealing with oversteer DO NOT OVER THINK THINGS. Whatever direction you feel the BACK of the car sliding, that is the direction you steer. If the back of the car, as in our diagram above, is sliding to the right, then you steer to the right.

Now the question becomes "How much do I steer in that direction?" Well I cant give you an exact answer on that. In fact, no one can. You steer as much as it takes to stop the rotation of the vehicle. I don't mean you stop the skid, I mean the rotation of the vehicle, two different things. It may only take a small steering input to stop the rotation or it may require steering all the way to the end of the steering rack. It all depends. When you feel that the vehicle has stopped rotating around, you can stop giving steering input. If when you stop it feels like its coming around more, get another handful of steering. 

So all of the above was the C part of CPR. If you have done all of the above correctly you will now be at P. Pause. 

Pause

The Pause can be VERY short lived or it can last for quite some time. How long the Pause lasts is dependent on several factors but the reality is, you are waiting for one thing. GRIP. If you have done everything else properly up to this point, then you have nothing else to do at this time but to wait for your rear tires to start to regain adhesion with the surface.

Once the tires regain their adhesion, the most important part of the sequence comes into play, RECOVER. This is also unfortunately the least educated portion of oversteer skid control. See, in driver's Ed you are lucky if you get taught to "steer in the direction of the skid". But even if you do get that information, that's pretty much where it ends. Well as you can see, that's only about a third of the required information needed to fix the problem. Only steering into the skid is what will have you "fishtailing" up the road. A fishtail is just a series of "steering into the skid."  Back and forth, steer to the right, whoa!, steer to the left. I got it, I got it. Whoa! Steer to the right again. I got it, I got it, Whoa! ........ And so forth and so on. As in the words of Metallica, You know it's Sad but True!

Recover

The Recovery means you have to take out all of the steering you put in to stop the rotation. If you do not take out this corrective steering, hold on! your going for a ride. 

Look at the oversteer example above. If the rear tires regain grip, where is the vehicle going to go? To the right, and in a BIG way. And where is your intended path? To the left. So definitely not a good scenario. 

Taking the Corrected steering out typically is going to require you to move the steering wheel faster than you did when you put the correction in. This is NOT always the case, but it certainly can be. 

So when you feel the rear end of the vehicle start to regain grip you need to start taking out the corrected steering input. This is also the reason you need to keep your eyes on your intended path. If you are not looking toward your intended path, your hands don't know where to steer to. 

So, if done correctly, in the diagram above, you would get off the accelerator, steer to the right, wait for grip, take out the amount of steering you put in. All the while keeping your eyes on your intended path. 

As I said many time before, this stuff cannot be taught in a book, or blog as the case may be. I can help give you a head knowledge of what you are “supposed to do. But unless you try this and practice it you will likely not fully understand it. I would strongly encourage everyone to attend some sort of driving school that teaches car control so that you can feel what these situations are like. If you would like to attend a school and are not really sure where to go, contact me and I’ll be more than glad to point you in the right direction. 

JM