The accelerator or gas pedal isn’t an on-off switch. You will get the most out of your vehicle’s handling if you step on the gas pedal gradually in certain situations.
This gradual application is called feathering the accelerator, an important form of throttle control. Proper application of this technique could even save your life.
How does this concept work, and when is it needed? Here are some driving techniques and situations that involve feathering the accelerator.
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The Concept of Weight Transfer
Before we can talk about feathering the accelerator, we must understand the concept of weight transfer and how vehicles maintain traction as they move.
Your vehicle touches the ground at four points where the tires touch the ground. The contact patch of each tire is about the size of your hand, and the entire weight of the vehicle is distributed across these four points. The more weight you have over a given tire, the better traction it will have and the larger the contact patch will be.
When you accelerate, decelerate, or turn, the weight of the vehicle is transferred from one side of the vehicle to the other. As you accelerate, the contact patch of the tires in the front get smaller, and the contact patch of the tires in the rear gets larger as weight shifts toward the rear of the car. The same is true from left to right as you turn.
When you feather the accelerator, you gradually shift the weight to the rear of the vehicle rather than shifting that weight suddenly. Sudden changes in weight distribution are far more likely to break traction, which is the fundamental reason that feathering the accelerator is important in situations where you might easily exceed the limits of traction.
When to Feather the Accelerator
Each of the following situations boils down to not upsetting the car when you’re near the limit of traction. Here are some specific situations where you should feather the accelerator for better throttle control.
1) Mid Corner
You don’t want to lose traction in a turn. Accelerating too hard in a turn can easily make the car understeer or oversteer. Understeer is when the front tires lose grip, and oversteer is when the rear tires lose grip.
Front or All Wheel Drive
If you mash the gas mid corner in a front wheel drive vehicle (or most all wheel drive vehicles), you are likely to understeer. Understeer will push the car toward the outside of the road. This is because one or both of the front tires loses traction as the driven wheels spin freely.
When you experience understeer, it will feel as if the car can’t turn tight enough no matter how much you turn the steering wheel. To counteract understeer, try straightening the wheel slightly. If that doesn’t help, you can ease off the gas or apply a very slight amount of brakes to increase weight over the nose of the vehicle.
Too much weight over the nose will cause snap oversteer, also called lift-off oversteer, where the rear of the vehicle will swing violently in the opposite direction.
Rear Wheel Drive
If you mash the gas in a rear wheel drive vehicle, you are likely to oversteer. One or both rear tires lose traction and your car will continue to rotate in the direction of the turn far more quickly than you intended.
When you experience oversteer, it will feel like the car is turning way too quickly. Keep the front wheels pointed in the direction you want to go and ease off the gas (that’s how drifting works, by the way). Don’t dump the gas entirely or you could experience snap oversteer.
2) Driving in the Rain
Driving in the rain makes it much easier to lose traction, particularly if you encounter standing water. If you drive through standing water, feather the accelerator to keep the tire from spinning freely.
If you start to hydroplane, back off the gas slightly and point the front wheels in the direction you want to go. It is best to drive in a straight line if you encounter large amounts of standing water at speed.
3) High Horsepower Rear Wheel Drive Vehicles
Rear wheel drive vehicles made the list twice? Yes, because the concept of throttle control is particularly important for folks with rear wheel drive, especially if you’re driving a sports car that makes over 300 horsepower.
High power rear wheel drive vehicles can spin even if you’re trying to drive the car in a straight line. You can’t simply mash the gas to accelerate, especially in first and second gear. Doing so will likely break traction in the rear and cause you to spin the car like a misbehaving Mustang owner leaving Cars and Coffee.
As you feather the throttle, weight will transfer to the rear. This creates a positive feedback loop where the increased weight allows you to apply more throttle, and you can continue doing this until you reach full throttle.
The purpose of traction control is to limit how much you can accelerate to whatever the tires can handle, essentially helping you feather the accelerator appropriately. Don’t disable this feature unless you’ve had some sort of high performance driving education and you know what you’re doing.
Each car will behave differently depending on tire compound, suspension setup, and how much horsepower you have. Get to know your vehicle before you try to accelerate hard in a rear wheel drive car without traction control.
Related: How to Get Started in Autocross
4) Driving on Ice
Driving on ice is a lot like driving in the rain, but turned up to 11. Driving on ice further limits the available traction and makes it far easier to slide. Increase your following distance, brake way earlier, and squeeze the gas very carefully when you pull away from a stop to avoid breaking traction.
5) Low or Rough Idle
If you have a mechanical problem with the vehicle that causes it to stall or idle roughly, you can sometimes keep the vehicle running by adding a small amount of gas to raise the RPM. This is good to know if you need to limp the vehicle home or to the shop to repair the issue.
Feathering the gas to keep the engine running should be seen as a temporary measure. If you need to do this, there is something wrong with the car and you should have a mechanic diagnose the issue.
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