steering input question
 

While watching the recent Patrick Long movie that Chad Plavan posted I noticed that he has a lot of steering wheel movement even during a constant radius turn. I have noticed this on other videos with other drivers. My question is what does this accomplish (I really don't know just trying to learn here).
The car does not seem to be responding to the inputs (ie) the line stays straight even with large movements. This would make me think the car is pushing and he is trying to get it to hook back up by removing some steering input.
I have tried this myself (so many do it it must do something) in some pretty hard turns and find it doesn't really do much to help the turn. I usually try to keep the wheel inputs as steady and consistent as I can and purposefully try to avoid what I am seeing. (I am however slow)
The man didn't get where he is by accident so there must be a reason for this technic that I don't understand.

Early on, where he is really sawing at the wheel a lot, I believe that he is feeling out the limits of traction of the car. Pushing a little harder, going over the edge, recovering, etc.

Later on, I believe that he is dancing on the ragged edge of adhesion, and every time the steering wheel goes the "other way" he is catching a slide that is just starting to happen. We don't notice the slide from the inside because it is just barely starting.

I have noticed that quite a few top-level drivers do "saw at the wheel" fairly frequently.

--DD

I agree with Dave. If it was a question of understeer, he'd be trying to add in more steering input which wouldn't make any difference. If he were to be unloading the steering as you suggested dfink, he'd still be heading to the outside of the corner. 911's are essentially oversteering and so assuming the car was set-up right (which Long suggested it was), by modulating the steering and throttle he could balance the car around the corner. Basically using the 911's inate oversteer to rotate the car, offset by some extra throttle & counter-steering to keep it in check.

At the limits of speed/adhesion, the traction and potential turning radius are constantly changing and the wheel sawing is to catch the slides as the car unweights and to turn in as the car loads up. All happening VERY fast and right on the edge. If you're going fast enough, there is no other way to keep the car in control as it loads and unloads over various surface imperfections in the turn. It's not a matter of just implementing a "technique" of sawing the wheel. Without constant management, you'd lose control if just trying to keep the wheel smooth and consistent.

Watch some of Vintage911racer videos posted as well.

Thanks for the responses. It helps to understand what is possibly going on. The catch it, save it, go faster is probably where I just lose it.... :)

I've driven with Jack Olsen and Mike G (Ted) in their cars and observed the same thing with both of them. The speed at which you guys sense oversteer and understeer and then correct it is amazing to behold.

Sawing the wheel is an odd thing, because there are two different reasons that people do it. When they're first learning track driving, beginning drivers will saw the wheel because their inputs aren't precise enough, yet, and they're constantly correcting through a turn. What you want to do is to have a single steering input that stays as smooth and as steady as you can manage, and it's a lot harder to do than it sounds. So if I have a student who's sawing the wheel, it's something I will usually try to get them to correct.

Much further down the learning curve, drivers will use more input to change the deformation of the tire (and subsequent slip angle) when the tire is near its actual (as opposed to perceived) adhesion limits. I saw my wheel more when my tires are going away -- it's a way to win back little bites of traction.

Long is also doing it early on to put heat in his tires.

Glad to hear smooth is still good for the learning student.

I watched a special in SPEED channel a while ago that was comparing segment data for parts of F1 laps. They showed that there were much more steering inputs for the drivers that had a higher cornering speed and the explanation was that they were closer to the edge and constantly correcting for lose of traction, slipping, etc. The sawing wasn't haphazard, but responses to what the car was doing.

Also keep in mind that the 911 steering has a lot of feedback from the road. If you watch your hands as you go through a corner you'll see your hands sawing back and forth even if you don't do it on purpose. Having said that this effect is smaller than what you'll see from a top racer like Long.

-Andy

Smooth is important for everyone. When the student saws the wheel, the effect is to make the car less stable in turns. He's hunting, and you feel it. When Patrick Long does it, the car is still moving along a very smooth and precise line.

I've seen myself saw the wheel on tape, but while I'm actually driving, I don't even think about it. I think it's something that as you advance in skill and become more one with the car, your natural reactions to what you feel the car doing is what your hands are doing. If you have to think about it, you are WAY behind what the car is doing.

When my race car had two seats, and I took a student for a ride. I would do some slower paced laps to show lines, technique, etc. Then we we started some flyers, I always told them to just enjoy the ride and DO NOT try and duplicate what I was doing.

A lot has to do with your driving style. Alonso uses a lot of steering input, where as Michael was as smooth as it gets. But they are both VERY fast.