# Dale Earnhardt Jr. cleared to resume race activities, says Roger Diez

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I had to drive from my house in Dayton to Reno on Thursday. The slippery conditions once again reminded me of the similarities between driving a race car and driving on snow and ice. In both cases the connection between tires and road is significantly reduced. The main difference is the speed of the vehicle when adhesion is lost. But even though loss of adhesion occurs at much lower speeds on snow and ice, the techniques used to control your vehicle are very similar. Understanding the underlying reasons for this are helpful in avoiding tow trucks and auto body shops all winter.

Let’s start off with a little basic physics.

Say you’re driving a 4,000 pound vehicle at 30 mph — that’s a considerable amount of mass and inertia. This collection of steel, aluminum, glass and plastic is tenuously connected to the road by four small tire contact patches. Your requests for a change in speed or direction must be transmitted through those patches. Anything that detracts from the tires’ adhesion to the road, snow or ice for instance, tends to limit their ability to respond to your commands. Tires can transmit only three things from the vehicle to the road: acceleration, deceleration and change of direction. There is a limit, determined by road surface, temperature, and other factors, of just how much of these inputs the tires can transmit before they lose grip. And when the tire receives multiple inputs, such as braking and steering simultaneously, there is a vector of the two forces, which reduces the absolute limit of either force.

OK, let’s put theory into practice. Say your vehicle can stop from 30 mph in 100 feet on dry asphalt pavement. On snow or ice, that distance will be double, triple, quadruple, or quite possibly infinite. Remember to slow down in slick conditions, and to increase your distance to the car in front of you. Drafting is definitely not recommended. Also remember the reference to vectors in the last paragraph. If you try to brake and turn at the same time on a slick surface, both your braking and turning performance will suffer. You will immediately experience what the race driver calls “push” and you will plow straight ahead with your wheels cranked to the right or left. Similarly, if you accelerate too hard while turning, you will be confronted with the condition racers call “loose”. You will notice this when the rear of your car passes you.

The bottom line is that on slick roadways you have to use gentle inputs on all the controls. Brake early and progressively; turn slowly and smoothly, don’t jerk the steering wheel; and accelerate smoothly, gently pressing the gas pedal as if there were an egg under it. You also need to stay more alert in slick conditions. Get “up on the wheel” as Darrell Waltrip is fond of saying. Unfortunately, the level of concentration most people bring to their daily driving is just above comatose. In slippery conditions, that can lead to a trip to the body shop or worse yet, the hospital. Don’t be that guy.

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Dale Earnhardt Jr. fans will be delighted to hear the he has been cleared to drive again. He was evaluated during a five-hour test session at Darlington Speedway last Wednesday and pronounced fit by the medical director of the UPMC Sports Medicine Concussion Program, Dr. Micky Collins. Dr. Collins consulted with Charlotte neurosurgeon Dr. Jerry Petty, who supervised Earnhardt’s rehabilitation. Junior will race at the Daytona 500, but his #88 Chevy will be piloted in the Clash by Alex Bowman, who earned that honor with his pole position at Phoenix Homestead in November.

Four-time Cup champion Jeff Gordon also will be at Daytona next year, but not in a stock car. Gordon will co-drive the Wayne Taylor Racing #10 Konica Minolta Cadillac Dpi-V.R prototype in the Rolex 24 at Daytona. Gordon’s only previous Rolex 24 outing was in 2007 with the same team. Gordon will put the new car through its paces during a test session next week.

Finally, we bid a bittersweet farewell to newly crowned Formula One champion Nico Rosberg, who recently announced his retirement.