Your Friend, The Throttle Pedal: Use It For Car Control

The loud pedal, the go pedal, trigger, throttle, gas . . . we have many names for that right pedal. From an early age, we gearheads quickly understood the long thin plastic piece on the right made things fun. It makes the Countach sing, the Skyline beat the piss out of the competition, the neighbor’s supercharged Camaro shred the tires away from the stop light. By the time we were 16 and a few months, we had already figured out burnouts. Not long after, donuts, and then more donuts. And then the odd attempt at drifting, which often ended with a bit of curb rash.

Years after I started driving, I took my first car control clinic through the BMW Car Club of America (CCA). It would become the gateway drug that put me into autocross. Eventually, through many track days, it led into getting my racing license and the all-consuming addiction of racing that now conspires daily to distract my focus from work, and steal all my money.

As some of you already know, and some of you will soon come to know, the entire trick behind driving fast is the management of weight transfer. — Kasra Ajir

It was at this very first clinic that I recognized the actual “power” of the throttle pedal. It was on a wet, soapy skid pad at Burbank airport where I learned I could affect the angle of the car mid-turn, simply by adding or reducing throttle, all while holding the steering wheel at a constant degree. It’s really quite simple…drive the car in a single-radius large circle. Keep the steering wheel in the same position – now add throttle. As your speed increases, the radius of your turn will increase.

Too much throttle, and the car does a straight tangential line right out of the circle. We know this as “pushing” or “understeer.” Too little throttle, and the nose will tuck in. If you are near the limit of grip and pop off the throttle abruptly enough, the backend will come around and the car will “drift” or “oversteer.” Pretty cool right? That’s part of what is referred to as “steering with the throttle.” But there’s more than that to the loud pedal. It, along with your brake pedal, are superior tools used to control the entire attitude of the car via controlling weight. Let me explain.

Weight Management

(Note: While I am basing the following examples on a rear-wheel drive car, the basics behind weight transfer and the traction circle are universal. Driving styles and lines through corners do change depending on which wheels drive the car, but for this article, I’ve selected fairly standard turns that will showcase the usage of weight transfer to control the car, not necessarily the fastest LINE through the corner.)

As some of you already know, and some of you will soon come to know, the entire trick behind driving fast is the management of weight transfer. The driver that can smoothly and quickly change direction and transfer weight from one corner of the car to the other (or from the front to the back) without upsetting the car’s overall balance, will have the most overall traction. This means they will carry more speed through turns and will see their lap times improve.

The driver that cannot do so will see their lap times drop. The very heavy-footed will see the car maybe spin, understeer, go off track, or hit walls. Tires will groan in agony and brake pads will scream in defeat. You can learn more about this in numerous racing and car control books. Just look up The Traction Circle.

So where does all of this theory apply to real life, and how can it make you a better driver? Well, I can give you some examples where it’s made a difference for me.

My little BMW Spec E30 that I wheel during NASA and CCA events.

Turn 2 — Willow Springs International Raceway

For our first example, we will focus on using the throttle to get the car to turn in where a steering input would not make any difference. So, let’s go to Willow Springs International Raceway in Southern California. “The Fastest Road in the West”, WSIR has a very cool mix of high-speed, long sweeping turns, off-camber sequences, and a couple of major-pucker-factor turns that will test all of your driving skills. It’s awesome. Turn 2 is the one we want to focus on for this example, and we will use the basic line through the turn.

Turn 2 is a long, uphill right-hander that is taken in Fourth gear in a Spec E30 (160-ish WHP, 2,700-pound minimum – so, momentum car). The apex of the turn is very late, almost as you crest the top of the climb. You enter Turn 2 flat (or almost flat) out, depending on what you’re driving, and stay about a car width from the inside of the turn. Playing with the throttle you will focus on maximizing traction and speed through the duration of the turn. Your steering input is almost constant throughout the duration of the turn (steering angle remains the same). Since you are almost at the limit of adhesion in the front tires, turning the steering wheel inward to the apex will net you almost no results. You’re only going to push, aka understeer.

As you near the end of the turn and want to bring the nose of the car into the apex, you simply lift on the gas a touch. Not abrupt, just a slight lift. The deceleration puts weight on the front tires, and the nose tucks into the turn. Aim directly for your apex, then back on the gas as you unwind your steering wheel toward neutral. Done right, you will hit your apex and let the car track out back to the left. No drama, it’s a great place to practice this technique while looking ahead to stay smooth and consistent. Here’s some video – special thanks to my good friend, mentor, and national podium finisher Steve Stepanian for the in-car footage.

In March, one of my buddies showed up for his first HPDE in 3 years, and for the first time ever driving a Miata. After a couple of sessions that were fun but rather off the pace, he and a fellow racer went out together. The racer showed him the proper line and right foot technique in Turn 2, and my buddy came off the track with a newfound understanding of how to get the car to behave. He was blown away. So much so, that he brought it back up at dinner later that evening. Awesome.

Sweeper — Buttonwillow Raceway Park

Another great example of this is “Sweeper” at Buttonwillow Raceway Park. Often, we run Configuration 13 going clockwise, which gives us a mix of standard 90-degree turns, short straights, some cool S-turns, and some hilly terrain. In my car, Sweeper is a Third-gear right-hander with a very late apex that is handled much the same way as Turn 2 at WSIR.

The exit of Sweeper puts you into a series of esses that, if set up correctly, are a flat out affair, followed by a decent straight away. Maximizing your acceleration coming out of this turn has a dramatic effect on lowering lap times and vice versa. Screw it up and you lose a ton of time. In this scenario, you’re not only going to lift to get the nose to tuck in, but like some of the real hot-shoes, lift hard, upsetting the car enough to get the rear end to rotate to put the car in a straight line into the entry of the esses. Then it’s throttle down all the way to the left-hander known as Sunset. Go go go!

Turn 5A — Thunderhill Raceway Park

Ok, so now we’ve covered some basics about changing the attitude of the car mid-turn. Let’s move on to the next piece of the puzzle.

For this, I’m going to take you to Thunderhill Raceway Park in Northern California. Thunderhill is a very technical track with a great flow. When done right, it feels downright magical. It is also kind of frightening, with three cresting, off-camber, and blind turns that test your mettle and (as I came to find out at Nationals last year) just how much you understand weight transfer.

Turn 5A is one of those turns. You go flat out — STRAIGHT UPHILL, like climbing Kilimanjaro — at the last second, you lift off the throttle and turn the car into the apex of the turn which is placed after the crest of the hill, blind, somewhere to the right. What makes the turn rather technical, is that you have to rotate the car just before/as it gets unweighted, and the other side of the hill is steep.

No in-car camera can really show it, but if you’ve driven it you’ll agree. The first few times, it’s sheer terror – downhill and off-track isn’t far away. The amount you turn the car is important – too little, and you’re hauling ass down the hill to go off track. Too much, and you’re going into the dirt to the right, off the track. Just right, the car will be pointed down the track, and you will be off-camber, sliding a little bit sideways down that hill. Holy smokes, it took me a whole day to be convinced the car wasn’t going to just roll over.

My lap times (and confidence) were totally effected by that weird feeling of sliding sideways down this steep hill. I’d turn in, crest the hill, then wait for the car to finish sliding and really get settled before applying the throttle. All the while, I watched everyone in my class walk away from me. After the first day of frustration, I was determined to go faster.

The next day, a total lightbulb moment happened. I crested 5A, and in trying to go faster I said “eff it, I’m not waiting for the car to settle, I’m just pressing on the go-pedal to keep up with the guy in front of me.” What ended up happening is the early application of throttle transferred the weight of the car to the left-rear tire, and actually settled the car much sooner than before. The weight transfer essentially added downforce and traction. Lo and behold, the car no longer was sliding down the hill. Just gripping like a gorilla and shooting out of 5 towards 6. Hot damn and hallelujah, this whole weight transfer thing is real!

One other thing we should note, is “how much” throttle to add. Something that we often hear from instructors is to think of “squeeeeezing” the throttle, and not using it so much like an on/off switch. The application of throttle, especially in order to control weight transfer, requires a soft touch.

The first few times, it’s sheer terror – downhill and off-track isn’t far away. The amount you turn the car is important – too little, and you’re hauling ass down the hill to go off track. Too much, and you’re going into the dirt to the right, off the track. — Kasra Ajir

“Sunrise” — Buttonwillow Raceway Park

One of my favorite examples is “Sunrise” at Buttonwillow, running 13 clockwise. Sunrise is a rather quick left-hander at the end of the main straight. I have found the quickest line for me is to trailbrake towards the apex, then quickly transfer from braking to throttle to settle the back end of the car to get proper acceleration.

Too little throttle, and the back end is sliding from carrying more speed into the turn than the front of the car. Too much throttle, and the car will push towards a somewhat ill-placed flag tower. Too slow to go from brakes to throttle, and the whole thing turns into a kerfuffle ending up in a blender of arms and elbows. Do it correctly with the right amount of foot speed to get from brakes to throttle, and the right amount of touch to get perfect acceleration out of the turn makes it very rewarding and great for your lap times.

So the next time you’re at the track, consider there is more to the story with the loud pedal than pure acceleration. Controlling the car with your right foot is not just possible — it’s essential — to your success as a driver.

About the author

Kasra Ajir

Having competed, raced, or trained with SCORE, SCCA, NASA, BMW CCA, and more, Ajir is well seasoned in the various series that pollinate the grassroots and professional auto racing world.
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