I have a newb question related to driving on a racetrack. Keep in mind that I have never been to a track, but I hope to attend a trackday soon.

From the in car videos I've seen, it always appears that the steering input and throttle inputs are very jerky. For example, the steering wheel will have multiple minor (but quick) inputs in one direction instead of a smooth rotation. In addition throttle input is often quick stabs at the gas pedal through turns.

In my mind, I always thought smoother inputs would help with the balance of the car. And, these quick and abrupt inputs to the steering and throttle may upset the handling and weight distribution.

Can someone with real world track experience chime in on this?

Thanks.

 

in short, if you have a perfectly steady steering wheel and, in some cases smooth throttle and brake inputs, your not driving fast enough

at the limit the car essentially is sliding all four wheels, and the steering and pedal inputs keep the car from oversteering/understeering (in balance)

its explain in this video of the great, the phenominal, the legend...Michael Schumacher im a fan you could say.

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notice the steering inputs schumacher vs. herbert

hope this helps a little

 

http://youtube.com/watch?v=Uk2p2nRK-p4

 

I prefer smooth. Just my two cents.

 

If you are a perfect driver, you will be completely smooth. The quick corrections that you see are because we are not perfect (even Shumacher) when drivng a car near the limits of adhesion.

What is common is that inputs will look very smooth in an under-driven car. Over-driving results in the jerky inputs since corrections are required to keep the car on line.

 

I have to disagree somewhat with the comments so far. (Actually, I agree with CoralDoc's comments, but I'm going to explain them in a bit more detail.) Let's get down to theory, and then we can go back to practice.

Why is smooth good? What you are trying to do is find the absolute highest level of grip available. Let's take the example of being in a corner. If the car is being jerked around, it's going to load and unload the springs, turn in a bit more and then a bit less, etc. On an accelerometer you will see the Gs fluctuating. In order to keep the car from going outside the friction circle, the average level of Gs will have to be less so that the maximum Gs don't exceed the circle. If the driver is smooth, then the fluctuations of the circle will be much smaller and the average G-load can be moved out closer to the limit. This is why smooth is fast.

So what about that steering wheel sawing you often see really skilled drivers doing? Well to be really fast, you need to be on the limit of the tires' grip. The way you find the limit is to go over the limit. What those drivers are doing is feeling the limit. They turn a little more, feel the car lose traction; turn a little less, feel the car lose turning; turn the car a little more, feel the car lose traction; etc. They are actually exceeding the friction circle so they know just how big it is.

The key here is response time. If you can do that quickly enough and with enough feel for the limit, then to the car the turn is smooth. If you can't feel the limit well enough to just push past it a tiny bit and then correct a tiny bit, then that wheel sawing is going to crash your car (or at least cause the car to not be smooth, and thus have a lower level of average grip). But if you can be fast enough and sensitive enough to slip over that limit and back again without losing control, then it's going to help you stay right on the very limit.

As for the pedals, you always want those to be as smooth as possible. But you want to get to the pedal position you desire (say, a certain pressure on the brake pedal) as quickly as possible. So you have to learn how to be smooth and yet also get to the pedal position you want as quickly as possible. These are not quite opposing goals, but they are close to being so.

All this comes down to repitition and feel, which is why "seat time" is such a highly valuable commodity.

 

In addition to what's been stated, the track surface, the suspension setting (hard or soft) and even wind gusts can give the effect of "jerky" steering wheel input.

 

When the wheel appears jerky, that does not necessarily mean the car is being driven rough. It depends on the how quick the turns come at you or how fast the transition is. I mostly auto-x where your typical "smooth" drivers usually are way off pace. At a higher speed road course, you would be nuts to use those same steering inputs.

I have learned that my S2000 can be thrown around in all 2nd gear and some of third. Above that, you need to be smooth or you will loose traction by pushing or breaking the rear loose.

 

With the advent of YouTube, you can't assume that the drivers you see online are competent. In fact, you can safely assume the opposite -- hell, I post my videos these days.

As a rule of thumb, you want to avoid upsetting the car. Don't confuse "quick" with "jerky", though. As others have written above, when driving at the limit, you need to make constant quick, but small, adjustments to your inputs. It's the quick and large adjustments -- jerking the wheel, mashing or lifting the throttle -- which upset the car.

Note also that autocross' more frequent and abrupt turns force drivers to use more aggressive inputs than they'd use on a big track.

 

A little bit of steering goes a long way. A lot of steering goes the wrong way. Basically, you don't want to do too much and then have to make a huge correction and then make a huge correction to that correction, etc.