|Driving Tips Number #3
Understeer & Oversteer
For most people, driving on the street, getting into a skid is about the scariest thing that could happen. Losing control of a car is not something you want to do, especially on the streets where things to hit are so close. But really, skids arent that scary, especially if you know what causes them, and then what to do if you do get in a skid. You do need to understand the concept of weight transfer, so hopefully you have read that.
Lets start with understeer.
Understeer is basically a skid where you are turning the steering wheel, but the car keeps going straight, or is not turning as quickly as you would like. Understeer is the characteristic that engineers build into most cars, particularly front wheel drive cars. The reason for this is that your fear response is the correct one. Ill get to that in a second.
Remember that for most cars, with the engine being in the front, as you get to a corner, all of that weight will not want to change direction. One of Newtons laws explains this , a mass in motion wants to stay in motion in the same direction, unless another force is acting upon it
or something like that ! Hey, Im a race driver..not a scientist. Anyway, as this mass is over the front tires, you need some weight transfer to help those front tires stick. So lets say you get to a corner
you turn the wheel
but the car isnt turning as quick as you need. You get afraid like anyone would, and the first thing you do is lift off of the gas. This is good, as by doing that, you are transferring weight to the front tires giving them grip. But lets say you are still scared
so you go to the brake. In doing this you add even more grip to the front tires, and will most likely be correcting your understeer skid.
The only tricky thing about understeer is making sure you dont lock up the front tires. Once you do this, you might as well throw the steering wheel away as you can turn it forever, but as long as those front tires are locked up
you are going straight. One of the best things technologically speaking that you can get in a car is ABS. Its great because it allows you to aggressively brake and still turn your car. If you have never tried the ABS on your car, you should find a parking lot, make sure it is safe, and then get some speed, you dont need a lot, and then slam on the brakes. This will let you know how they perform, and what the feel is like. Pretty important thing to do with your car as you want to know what the feel and performance is like so that should you get in a situation where you need to use the ABS, you dont want to get scared when it kicks in.
OK, now oversteer.
This is the scary one for most people. First, lets look at why it happens. Generally speaking, speed has a lot to do with it, but not always. Its better to think of it as a balance problem then a speed problem. That said, lets look at an example.
Lets say you are running down a road at 50 mph. All of a sudden a dog runs out in front of you. Dont want to hit that dog, so the first thing you usually do is hit the brakes. This of course gives a ton of grip to those front tires, and takes a lot of grip away from your rear tires. Now when you did this, you totally unbalanced your car. SO what is the next thing we usually do? Yep, turn the wheel. By doing this we have basically told our car to spin.
Now mom and dad were a little bit right when they told us should you start to spin, steer in the direction of the skid. Unfortunately there is more to it then that.
Remember weight transfer. As the rear is out of control, it would be a bad thing to go the brakes, as this would just take more grip away from the rear tires. So it is best to just release the brake
and sometimes it helps to apply at light throttle, especially if your car is front wheel drive. This will add some grip to the rear tires, and make the fronts less sensitive. Make Sense ???? Good. But there is still more.
When I was teaching at Bondurant we used to teach a thing called CPR. The letters represent the moves you need to make as a driver to catch oversteer. The C stands for correct, meaning to steer in the direction the rear of the car is going. Thus if the rear is going to your right, steer right. Rear going to your left, steer left. Just like mom and dad told you. But here is what they left out.
Once you have steered into the skid, and corrected enough, there is a moment, a distinct pause, where the back end stops going one way and gets ready to come back. A lot of energy is stored up in the tires and suspension at this point, so you have to look for it. This moment is called the P pause.
Now the moment you get the P pause, you immediately do R, which is recover. This means you bring the steering wheel back to straight. This has to be done quickly. So putting it all together
Correct, Pause, Recover.
Its a funny thing, but with what mom and dad told us, most drivers do catch the initial skid. But then what happens is the counter skid ( because they dont know about the Pause /Recover stage ) gets them spinning in the opposite direction of the initial skid. Maybe this has happened to you ? And if not that, then you might have really had to catch a couple of skids when you got oversteer, and this means that you missed the pause.
Finally, one extremely important thing
.that no one ever tells you. ALWAYS look where you want to go, and not where you are going. I remember a friend of mine in high school
.wrote off his father car. Happened to be a BMW and he totally got in mega trouble. Anyway, when we all asked him on Monday what happened
he said he hit the only damn tree on the whole street. Now I never asked him
but I would bet that while he was losing control, he was looking at the tree saying to himself dont hit that tree ! From experience I know, that if you look at it, odds are you are going to hit it !!
Now I am a firm believer in practice. If you live in a place where it snows, or sometime when it is raining, go to the local high school parking lot, make sure no one else is there, that it is a safe environment, and get yourself into some skids. Try and feel for the pause, and really focus on looking where you want to go, not where you are going. Also, I would love to hear feed back on this. What might have happened to you, and if this makes sense or you have questions. This whole driver tip thing is to make drivers better, and Im always happy to help.
Finally, as in all of my previous tips, remember that I never ever think that you should drive fast on the streets. It is far too dangerous. If you want to drive fast, go to track days at a race track, join the SCCA, do some go-karting
.but keep the speeding off of the streets.
Back to Most Recent Tip
Driving Tips #1 Driving Position
Driving Tips #2 Weight Transfer
Driving Tips #3 Understeer & Oversteer
Driving Tips #4 Braking and Shifting
Driving Tips #5 Street Techniques
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