Welcome to part two of this racing concepts series. Remember: the most dangerous words in the English language are “I already know that.”
Let’s jump right in. Vehicle dynamics are the foundation of driver knowledge.
Without understanding how various forces act on a racecar, you’ll never be able to make logical adjustments that result in being faster.
The physics involved with vehicle dynamics are astounding.
These are the same concepts that I applied to my driving which led me to repeated success.
I strongly encourage you to continue learning beyond the scope of this program, as there are many interesting “Ah ha!” moments to be gained within this extensive topic.
Many drivers, especially new ones, make the mistake of believing that going faster is all about guts.
They think that white-knuckling the wheel, braking later, banging off rapid shifts, and taking risks are the keys to being the fastest driver–and they couldn’t be more wrong.
Randy Pobst says it best.
“Your primary job as a driver is weight management.”
Going faster is all about being smooth. One of the most basic concepts of faster driving is weight transfer.
If you can control how weight is shifting around the vehicle, you will be faster.
So many concepts directly relate to weight transfer, as it is affected by almost every force. This makes weight transfer the foundation of high performance driving.
A vehicle is only capable of producing a finite amount of traction. Any time the driver makes inputs (through the brakes, throttle, and steering) part of the vehicle is losing traction.
To be fast you must know how to keep weight transfer to an absolute minimum.
Simple Examples of Weight Transfer
At rest, a vehicle’s weight should be equal. On a perfectly balanced vehicle, each axle should carry 50% of the vehicle’s overall weight. Each tire should carry 25% (Figure 1).
On a car weighing 2000 lbs, each axle should carry 1000 lbs. Each tire should carry 500 lbs.
Everyone has experienced the way a vehicle’s weight shifts during various conditions. There are three main ways a vehicle’s weight can shift:
- Acceleration (Figure 2) – During an application of throttle, a vehicle’s weight will shift toward the rear, due to inertia.This makes the rear of the car heavier and the front end lighter.During acceleration there is more traction available at the rear wheels because there is extra weight over them.Conversely, there is less traction available at the front wheels because there is less weight over them, meaning that cornering potential has been reduced.
- Braking (Figure 3) – When a vehicle is slowing down, weight will be transferred to the front end, due to momentum.Being the opposite of acceleration, braking results in a heavier front end and a lighter rear end. This provides more traction to the front tires, and less to the rear.
- Steering (Figure 4) – Steering causes a lateral weight transfer toward the outside corner.During a left hand turn, weight will shift to the right. This results in extra weight (and traction) on the outside tires. The opposite is also true.Weight can also be transferred in various combinations.For example: You’re headed down a straight leading into a long right corner that becomes progressively tighter as you near the apex.The fastest way to navigate this corner is to begin braking down the straight and continue braking as you enter the corner.In this situation, when you begin turning, you are creating a combination weight transfer of braking and steering. This will cause weight to shift forward and to the left.Managing this type of weight transfer is much more complicated, so we discuss that later.
A General Rule
More weight transfer reduces a vehicle’s ability to perform.
When a vehicle is stable (when all its weight is even distributed on its four tires) it has the highest potential for traction. While weight is transferred to a different part of the car its overall weight remains unchanged, but its overall traction potential can be significantly reduced.
The closer a vehicle is to being stable, the more traction it can produce. This means that a racecar which is experiencing less weight transfer has the potential to be faster than a racecar with more weight transfer.
Through this concept you can see that the driver plays a key role in creating the least amount of weight transfer possible and increasing the vehicle’s potential for speed.
- Weight Transfer is the foundational concept of speed.
- Inputs (throttle, braking, and steering) always have an effect on vehicle balance.
- Weight transfer decreases potential grip. If a driver causes less weight transfer, he will be faster.
NEXT WEEK: Understeer and Oversteer
The next part in this series is only a week away. Go back and read through this again. Make sure you truly understand what you just saw, because the series progressively builds as it continues.