From the GRM Vault: Learning to Race in the Rain


Story by Peter Argetsinger

Rain driving is something many drivers approach with fear and trepidation, but with a few tricks of the trade, it could be something to look forward to. Remember, the challenge of negotiating a wet and slippery track is not yours alone. Solve the problems of traction and visibility better than your fellow competitors, and you may find that elusive advantage not available in the dry. The rain is recognized as the great horsepower equalizer; because grip is diminished, driving skill suddenly plays a bigger role than inequities created through better equipment and bigger budgets. To consider the challenge, let’ s look at three major ares of concern:

1) Visibility: This may seem obvious enough, but lack of visibility can be a major problem.
2) Setup: What can we do to enhance the performance of a car in the wet?
3) Technique: How should we alter our driving style? In particular, what changes should we make to our line, braking points and accelerating?

Visibility

If you can’t see where you’re going, it’s hard to keep your foot in it. I raced a 600 hp GTS Camaro for a private team in the 1993 IMSA 12- hour race at Sebring, which was red-flagged for torrential rain and flooding. Nobody else on the team liked driving the car in the wet, partially because it was a handful in the rain, but mainly because there was no blower system to defog the windshield. I was pressed into service because I remembered how a Skip Barber colleague, Walt Bohren, won the GTU championship using a gas station squeegee on a stick. I held one on my lap and did several wipes on every straight until the red flag came out, giving us a chance to rig up a proper defrosting system. Being able to see changes your whole perspective, not to mention your attitude. So be careful about gutting that blower system in your racing sedan to save a few pounds.

If you drive open-wheel cars and wear a full-face helmet, it is easy for the inside of your visor to become fogged during wet conditions. Since it’s hard to hold your breath for the duration of most races, experiment with commercial no-fog devices and solutions applied to the shield. These can be either chemicals, like the types that are available at many dive shops for scuba masks, or coverings like the Fog City Fog Shield. I found that the fatty emulsifiers in lanolin hand cleaners work pretty well in a pinch; rub the cleaner on the inside of your visor, then wipe clean. Of course, it’s best to test your solution prior to actually racing with it. One of my colleagues wears his helmet in the shower to simulate the wet conditions on track. Be careful, though—you could look pretty silly showering with your helmet on.

Unfortunately, you can’t foresee everything. Many chemical products wear off during the race, or you may start a race in the dry that turns wet. In those instances, cracking the visor on your helmet a bit can help clear the way. To avoid getting soaked, though, we recommend you use a piece of racer tape to just prop one comer of the shield open. This will provide enough fresh air to keep the shield mist-free, but since the front of the Visor won’t be wide open, you won’t get a wet face.

Try to avoid getting your hair wet, as this just adds to the rain forest environment inside the helmet. Also, don’t keep the helmet inside the air—conditioned motorhome until the last minute. Introducing it into radically different ambient temperature and humidity will fog things up quickly. Drivers with eyeglasses should also be wary of a potential fog situation. In this case we recommend a no-fog chemical. Contact lenses are probably a better solution, but they aren’t for everyone. And if your contacts fog up, you have cataracts—we can’t help you there.

One other wetness tip—having less to do with visibility than com— fort—is to try and keep your shoes dry. Your feet will slip off the pedals less, and wet feet just feel ooky.

Setup

Racing engineers and designers spend vast sums of time and money working out ways to limit roll, dive and squat in race cars in order to maximize the car’s contact with the road. In the rain, cornering speeds are reduced, and we are in search of traction and grip. Suddenly, softening the car and actually promoting some roll helps to transfer weight and enhance traction. It also helps the driver get more feel, or feedback, and a softer car is therefore more forgiving and easier to drive.

There are numerous ways to achieve this softer car, but the easiest way is by softening anti-roll bar settings. Other methods include softening the adjustable shocks, moving pick-up points and installing softer springs, but it’s usually a good idea to just change things than can be changed back quickly when it starts to dry out.

A word of warning: Don’t arbitrarily make changes without first testing them. The general rule of thumb is that if you make a change at one end of the car, you’ll have to make a corresponding change at the other end to preserve the balance. How much to change and what changes to make come from experimenting and keeping good notes. A lot of teams won’t test in the rain because they don’t want to risk equipment, or they feel that there’s nothing to gain on their setup. Maybe there’s nothing to gain on the dry, setup, but there’ s plenty to be learned about what works—as well as what doesn’t—in the wet.

In my first season racing Formula Ford in England, I went to a wet test day at Mallory Park and found myself alone as everyone else went home. Sure enough, it rained in qualifying later in the week—and I found myself on pole in a field of 90 cars by a sizable margin when generally hundredths of a second separated the field. I had found that disconnecting my rear sway bar gave me enough added traction to gain 200 rpm at the exit of the hairpin. When it rained on race day, I had a plan; I knew exactly what would work on my car, at that track, in those conditions.

Not all cars are easily adjustable, but everyone can adjust tire pressures. A slightly over-inflated tire helps create a V shape, like the hull of a boat, which cuts through the water more efficiently than a normally-inflated tire. While some folks run under-inflated tires in hopes of generating some tire temperature, they’re opening themselves to the possibility of overheating the sidewalls and creating a pocket in the center of the tire which can promote aquaplaning.

If you race with slicks or shaved street tires, be prepared to put on wets or fully—Headed street tires when the rain falls. Slicks have a nice large contact patch for dry traction, but make no pro visions for displacing water. A true wet-weather racing tire has grooves to shed the water and is made of extremely soft rubber to promote good heat buildup. This is great in the rain, but if the track dries out, these super—soft tires are very prone to chunking apart. Ifthe track starts drying out and you don’t have time to duck into the pits for a tire change, do whatever you can to keep the tires cool. Find puddles to drive through (even wet grass will work, but be careful, it’s slippery) to keep your soft rains cool.

If you’re lucky enough to be driving a car with wings, crank in as much wing as you can when it rains. You’re looking for grip, not straight line speed, and downforce is a wonderful thing in these instances.

Finally, brake bias adjustments are often forgot- ten. Since we don’t brake as hard in the wet, there is less weight transfer to the front tires. Consequently, it is important not to transfer too much braking force to the front. We want to keep the brake bias a little toward the rear. This is easy to do in a car with a bias bar, but nearly impossible in many race cars.

Technique

The most important change you must make as a driver in wet conditions is that you should View the circuit as a totally new place—no matter how many dry miles you have there. We tend to get locked into driving “the line” which is fine in the dry, but in the wet, turn radius becomes less important and grip becomes all important. Therefore, Our usual method of driving the circuit simply won’t work. How successful you are in the rain is usually a product of your ability to quickly adapt to the changing situation.

As a kid growing up near Watkins Glen, I was fortunate enough to be privy to some advice that Grand Prix driver Jochen Rindt gave to my brother Michael. Rindt was a brilliant wet-weather driver and demonstrated his skill, I remember, during practice on those wet autumn mornings at the Glen with a style and flair wonderful to behold. “You can drive just as fast in the wet as you can in the dry—as long as your hands are straight,” he said. It’ s apiece of advice that I will never forget.

At the Skip Barber racing school, we tell our students that hand position dictates foot position. If the hands are straight, we can use all of the tires’ available grip in either braking or acceleration. If the hands aren’t straight—if we are cornering—that leaves a smaller proportion of grip available for accelerating or braking. Tire engineers tell us that a tire’ s ability to brake and accelerate in the wet has been diminished by about 18% compared to dry conditions. Conversely, a tire’s ability to corner has been reduced by about 40—45%. Jochen Rindt was right: minimize your time tuning and get those hands straight! What this tells us is that we should look for long, straight brake zones and long, straight drag strips, and spend the least possible amount of time cornering.

Before we look at what might be a proper wet line, based on what we know about the tire’s grip, let’s also factor in the pavement’s relative grip functions.

The usual racing line is a highly polished surface due to the cars constantly pounding over it and grinding away the rough edges. When it rains, these areas become as slick as an ice rink and should be avoided like gray beef. On the other hand, the outside of a corner, where no racer dares tread, is covered with rough, porous pavement which is excellent for wet traction.

Add to this the fact that most road surfaces are designed with some camber to aid drainage, and we can generally expect puddles to appear at the apex. The brake zones and approaches to a comer are not immune to the polishing effect, either. Some may even develop “wagon ruts” similar to the ones that develop on highways with heavy truck traffic. This is a recipe for puddles and slipperiness.

Based on this information, our wet-weather line might look a little like the one in the diagram. As we can see, we move the car away from the edge of the road in the brake zone to find grip and avoid standing water. We lengthen our brake zone by braking deeper than our usual turn—in point and turn the car out on the “rim.” Here on the rim, we find more grip and also spend less time turning, our goal being to straighten our hands so we can get the power down and accelerate out in a straight line.

Everything we experience in the dry in terms of slip angle we also experience in the wet, only at a lower speed. Drivers who trail brake excessively will experience lock—up and the resultant loss of steering much more readily in the wet. Developing good habits like releasing brake pressure to regain steering control become vital survival tools.

Likewise, our relatively low horsepower car suddenly feels as though we gained an additional 200 hp as we quickly experience wheel spin at anything more than a judicious application of throttle.

Wet-weather driving forces us to be smoother with our throttle and brake applications. We also develop heightened tactile senses as the lack of grip magnifies the impact of our inputs. Pressing on the gas has been likened to stepping on eggshells, but anything resembling an abrupt transition to the gas or brake will result in sliding or spinning tires. Conditions like power-induced understeer or oversteer may never be experienced in the dry in some cars, but in the wet we have to educate our bodies to accept these conditions.

A good racer always pushes the performance envelope—the rain simply allows us to find those limits of adhesion earlier.

Good luck and have fun.

This article is from an old issue of Grassroots Motorsports. Get all the latest how-tos and stories for just $20. Subscribe now.

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Comments

View comments on the GRM forums
Shaun
Shaun HalfDork
12/8/16 4:13 p.m.

Apparently Max Verstappen read this article when he was a wee tike.

iceracer
iceracer PowerDork
12/8/16 5:43 p.m.

Sounds just like ice racing.

We have a couple Spec Ford racers that excel in the rain and fog. They credit yearly racing on ice.

HapDL
HapDL New Reader
12/11/16 9:23 a.m.

Did my best racing in the rain. Loved that outside line! Still kills me to see people racing in the wet doggedly sticking to the traditional line.

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