Tech Article Title Author Date
Winter Driving "Quattro Cornering & Stopping Tips" Ned Ritchie 1999

On slippery surfaces there is only a limited amount of grip that is available for the tires. The grip can be used for turning, braking, acceleration, and possibly a combination of them. However, on slippery surfaces using a combination of braking, turning or acceleration is only asking for a skid or slide. If you feel your vehicle begin to slide through a turn, you are likely experiencing "understeer." Understeer is usually caused by entering a corner too fast, or by braking while trying to turn, or from excessive acceleration while cornering. To most effectively control your car on a slippery road, and prevent understeer, lower your speed, and only use one aspect of grip control at a time. The proper way to negotiate any curve is as follows:

  1. Brake on the straightaway before the curve, adjusting your speed.
  2. Coast and steer through the turn.
  3. Accelerate only when the road becomes straight again.

In other words while cornering, you should be off the brake and off the accelerator, coasting through the turn and using all available grip for steering. Please note that excessive acceleration in a quattro except when very slippery or with very high power will always create understeering, but you can accelerate a little harder than front or rear wheel drive cars because of the extra acceleration grip available from two more tires. The "unfair advantage." If you're already in a corner and your quattro is not responding to your turning input, (steering seems light) you are understeering. The only way to stop under steering is :

  1. Get off accelerator (Transfers weight to the front tires)
  2. Reduce the amount of steering input. (Straighten the wheels)
  3. Wait, and wait again, for the front wheels to grip again before turning into the corner again.

If you're in that corner and the back end of the quattro seems to be coming around faster than the front is turning you are oversteering. To stop oversteering:

  1. Immediately and quickly input a counter steer (Steer into the direction of the slide)
  2. Add a burst of acceleration (I worry about putting this here as this is only for experienced drivers)
  3. As the car begins to correct it quickly counter steer the other way for 1/2 a second and
  4. Immediately and quickly steer straight or you will be over steering the other direction in a heartbeat
  5. It is better to counter steer twice than to counter steer too long.

Generally on ice and snow quick steering does not have much effect on turning. Therefore when steering you must begin each turn slowly and progressively increase the speed at which you turn the steering wheel as the car begins to turn. The only time to turn the wheels quickly is when correcting for an oversteering situation. I've just described how to negotiate curves safely but perhaps a bit slower than you want to go. What then? The trick is to never allow the car to understeer by creating continuous oversteer and negotiate curves and corners with the throttle and brake.

Stopping and reducing speed in an emergency with ABS

To stop or reduce speed in a straight line get on brakes very hard. Don't wait. The first few feet are very important. Use your leg muscles. Your ankle is not strong enough! You have to press on the brake pedal with at least 88 pounds of pressure. If you press with less that than 88 pounds you may feel the ABS working, but it is only working on the rear wheels. You have not reached the maximum braking with the front wheels yet. This minimum brake pressure is absolutely required for maximum stopping power! Simultaneously disengage the clutch so that you do not have to stop the rotating mass of the transmission and drive train. Keep pressing hard and steer. Audi's new version 5 ABS is better than the previous three channel systems. The new version 5 has a quicker pulsing action, front to rear and lateral loading detection, plus 50 percent of the braking is now applied to the rear wheels instead of the 30 percent in earlier systems. Just nail the brakes and the clutch, hang on, and steer.

When do you turn off ABS?

On some quattros you can turn the ABS off. For those who can there are only two times when you should turn the ABS off:

  1. There is compact snow or ice with fresh slippery snow on top
  2. A loose gravel-covered road in contrast from simply a gravel road

If your quattro is without ABS keep the clutch engaged to possibly keep the wheels from locking up. However, with the clutch engaged you could kill the engine and loose your power steering. Remember you must come off the brakes to turn. In other words only when you are going straight ahead brake as hard as you can. Hold the brakes on to the last moment, come off the brakes, turn the steering wheel with progressive increase in speed to change direction, immediately correct the counter slide you created, come back to straight, and nail the brakes again when going straight.




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