The intellect knows the mere act of the sun going behind a cloud or a small, undetectable amount of oil or dirt can change the track condition enough where the margin of safety is lost. Consequently, the race driver’s next time through the corner the driver increases his speed a mere 100-rpm and suddenly he is spinning out of control. I did not even mention that handling characteristics of the race could change too! Changing fuel loads, tire air pressure, etc. and of course driver fatigue all contribute to the need for a safety margin.

It is well advised not to practice “sweepers” as directed here until all of the proceeding chapters have been mastered. Your familiarity of yourself as a driver and your practice car must achieve a high comfort level.

High-speed sweepers feel like they are not going fast enough and will go out of control at any moment. Their mastery is dependent on keeping your intellect in command and working up to speed while gaining confidence as well. Every increase in speed must be planned out well in advance of the corner. Under no circumstance should an increase in speed be made just before the corner.

Remember this well and during the heat of battle, in an actual race, this habit may very well save a crashed car or bruised bones! Many years ago, while attending a race drivers school at willow springs raceway in Southern California, a fellow student, who had been inactive for many years as a race driver, fell victim to over-confidence and rolled his rented racecar into a ball of junk going through Willow’s high speed sweeper. This poor guy was embarrassed since he was having difficulty getting up to speed since because of his long layoff of race driving.

There are three types of sweepers:

1.  The simple continuous radius

2.  The small radius at the beginning, then the radius increases.

3.  The larger radius at the beginning, then the radius decreases.

First off find suitable sweepers to practice on. Freeway off and on ramps work very well, especially the kind that are two lanes wide. Find all three types too. Practice on the symmetrical type first. As explained before the apex locations are determined by where the straight aways are. Note that it is not necessary to exceed the peed limit to practice. Set up your tire pressure in a comfortable mode. Begin by picking out a braking point and note your RPM.

At this point set up the car to hit the correct apex, late apex for corners followed by another corner and early apex when the corner is followed by a straight. Again note your RPM. At apex, “set” the car and apply the gas to maintain a constant radius through the corner, always remembering to keep the car away from the loose gravel, etc. on the outer edges of the corner. Leave yourself a margin of error between your car and the loose stuff.

Apply more gas or reduce the gas a little to feel the car’s reaction but, mostly keep a nice steady rate of speed through the corner. Next pick out an exit speed point and note your RPM and note what gear you are in.

Proceed to write in your logbook what the tire pressure is, as well as the braking point RPM, apex RPM and the exit point RPM. Again go through the corner and increase your speed to a level high enough that you are driving at 6/10 of the corner again at the same speed as before. Once you are going through the continuous radius increase and reduce the speed a little. If you feel no difference when you change speeds through the radius then put more rear tire pressure until you can. What you are looking for is oversteer.

As explained before, oversteer is the tendency for the rear tires of the car to lose grip with the road. We use oversteer to position the car in very tight slow speed corners. You will experience oversteer when the rear tire pressure is too high in a sweeper, most notably when reducing speed in the continuous radius of the turn.

The reduced speed lessened the centrifugal force of the car to maintain a direction. It is the same principle as a marble following the rim of a tin can because of speed and centrifugal force created by speed.

Once you have experienced oversteer and can induce it with tire pressure and gas pedal response return the rear tire pressure back to normal, or to your starting point. Now increase the front tire pressure and again and again.

Go through the turn to feel the front cause understeer. It reacts to reduced speed, the opposite of oversteer. Lifting the gas pedal reduces speed and that increases the front tires’ grip to the road. So, when your practice car feels a little out of control because of understeer, just lift the gas and it will regain its stability.

Next find a suitable corner where the radius or curvature increases, gets larger as you go through it. Begin in the same way as the symmetrical corner. Pick your braking point and apex and maintain a steady rate of speed, but as you feel the radius increase, increase your speed to take advantage of the added curvature, which will tolerate a high speed through the first part of the corner. As in the symmetrical corner, practice increases in speed, tire pressure and the sensations of understeer and oversteer.

Lastly, there are the decreasing radius corners. These are the most challenging of all and caution must be adhered to! In this corner the radius or curvature gets smaller. This results in the speed for the tighter section to be reduced from your speed through the larger part of the corner. Begin by memorizing a point on the track where the corner starts to tighten up. Let’s call this the “ease up point”.

Go through the corner hitting your braking point and apex, don’t worry about having any speed here. (It is a matter of going through the motions to develop discipline to follow the proper sequence of events in corner taking). Then mentally hit your “ease up point” and back off the gas a tad and note your RPM at this point. Again go through the corner and keep your RPM (speed) the large and small part of the radius (less braking and “setting” sections) at the same speed. Increase the speed each time not worrying how slow it feels through the large section.

Concentrate on getting to 6/10 of your driving skill and car ability. Once this has been reached, note in your logbook the RPM at the “ease up point”. Next raise your speed in the open section of the corner a hundred RPM, then drop it down to the planned “ease up point” RPM. Increase your speed over and over in this open section of the corner until it too is at 6/10 skill level.

As you can see, we have figured out the maximum speed through the tightest section first, then we do the larger corner in a series of compromise. The decreasing radius corner is the most frustrating corner of all because it takes discipline of the highest degree.

Chapter 12- Passing and Being Passed

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