Hi Guys,

I was on the tail of cup car in a long right hand constant radius sweeper with a mild bank. I watched him wiggle the front steering and watched as the front tires turned out then turned in and corrected as he slid around the turn. The whole car would unsettle and wiggle like he was over doing it. It appeared more intentional than a corrective action and it had a very definate consistent tempo until the unwind after the turn. To me this is upsetting the car and the best line would be scribed by foot on the gas and a constant hold of the wheel, I.e. the more you turn the wheel the more speed you steal. So I though about this and then went out and tried his technique on the same turn. To my surprise I found another 5 mph through the turn! What in the heck am I doing? Why does this work? Will this work on all turns?

Rookie

 

NASCAR boys have been doing it since the 50's. Its called sawing the wheel.

I am sure some experts will chime in with data verified results to explain why it works. Personally, I dont think it makes the car faster. But I only race low budget SRFs with no data collection device, so I am probably wrong.

 

It allows You as the driver to know where the limit is. You know You are close, but are not quite sure where too much is....so You intentionally "test" and put the car at it or over it while You are near it to stay "nearer" to it. Sorry for the vagueness but it basically is allowing You to stay nearer the limit since You are constantly"testing" to make sure where the limit is. The other way is faster but You have to contend with much more of a "snap spin " when the car lets go with much less or no prior input to You as the driver. I know that Cervelli and Tim can give some data related input surrounding this but this is the best way I can describe what I believe You are experiencing as a driver.

 

It is a "feel" tool for me. When cornering rather than hold the wheel in a set position as you turn takes away from the "flexability" the wheels and suspension are going over, the faster you go the more the wheels and suspension are working and "sawing" the wheel allows the wheels to go back and forth as the you feel the tires grip the surface. Much like going fast over some decent bumps that when at hi speed will toss the vehicle around as it hits the bumps and "skip" over the tops reducing surface grip and get bumped into a different line or get the vehicle "cockeyed".

So in this practice you are feeling the grip while you "saw" the wheel as a form of compensation to speed and controlling a turn as the car is on edge as it turns. As said above you are feeling the edge through the wheel and sawing it to keep on line/settled.
The stiifer the suspension the more this practice factors in. Soft one and it is of little benefit due to loss of feedback from stock suspension.
This how I understand it to be.

 

If I am reading this correct, this procedure is similar to what people do while testing max g's on a skidpad. On a skidpad, you keep the car going on a set radius and then "dip" into the circle just a bit by turning in. You keep doing this at increasing speeds until control of the car is lost. You then calculate max g's from your speed (or now with data acq.) When you dip in you slightly increase your g's. So I guess you could kind of feel your way around the limit this way. However, it seems to me that at a highly skilled driving level this might be scrubbing off speed unecessarily because pros are better at staying right at the limit without doing this. Maybe some of the professionally experienced people can weigh in.

 

110
I believe one already did in post #3

 

When in a turn the tyre distorts to counteract the force of the turn, creating a slip angle for that tyre.If the force on the tyre is greater than the available grip the tyre (and car) begins to slide creating understeer typcaly in the first part of the turn. When the tyres slpi angle is exceeded the tyre "stalls" in that it has less grip than just prior to the loss of grip and hence the car has to corner slightly slower once understeer starts than right at the limit of grip. The best way to deal with understeer is to straighten the wheel until the grip comes back and then have another go.
As I understand it the tyre can develop its max slip angle during the act of turning in before the tyres elasticity causes the tyre to contract back somewhat meaning a slightly lower slip angle at constant steering input.
Perhaps sawing at the wheel makes use of this maximal slip angle turing the turn in part of the action. Counter steering would prevent the tyre from exceeding its slip angle and understeering when the tyres elasticity comes into play.

 

Could they be trying to induce a greater body slip angle (more oversteer) than achieved just by turn-in, without slowing the car by trailbraking? This steering input oscillation, depending on frequency, can be matched up with the suspension, causing the car to snap loose, even more predictably and with less decel than trail-braking (especially for an unbraked corner).

Of course, I would lean towards saying that the car's set up a little tight, and ought to be driven with more rear bar, if that's the case, but that's just me, and perhaps the drivers aren't comfortable with that suspension tune.

Don't even know if this is what they're after, but it was the first thing that popped into my head. If you want a real laugh, try it in an SUV...

 

I dont think one person here is describing sawing the wheel. Everyone is describing the natural motion of the wheels moving and turning (slightly) as they go through the turn. Obviuosly anyone with a modicum of race skills doesnt hold the wheel rock steady during a turn. Especially in the SRF as we are always sliding at one end or the other.

What everyone here (save for Glen) is describing is really tiny steering corrections that we all do as we go through a corner. Included in that is the natural tendacy of the wheels to turn slightly on their own as they go over bumps etc... But once again, none of these is sawing at the wheel.

For those of you doing this on purpose, I defy you to show me data that proves that you are faster through the corner by actually sawing and trying to find the actual (not theoretical) limit of the front and back tires. I bet you could go through the corner at the same speed or even faster by not sawing (compared to sawing to find the limit) if you knew the limit was approaching. The only way for this to happen is to get more experience in YOUR car. I know the limits of the SRF pretty well and race at them most of time. But then again, so do all the other fast SRF guys.

Now if we are talking about in the wet, forget it - all bets are off. We all need to find the grippy places on the track in the wet and this is the best way to do it.

 

EJ: This action definately appeared to be best described as sawing. Being an experienced "backmarker" I have watched many cars through this particular turn. Most people tend to take a set with the steering and the front wheels have little more than normal track variations and then driver corrections. This cup driver was sawing. Changes in steering angle were surprisingly large and abrupt. In my particular case if I do as you say and hit that sawing speed my car understeers and runs out of track. If I "saw" I can maintain the higher speed through the turn along the principle Tony Taylor postulates. I am very stiffly sprung as Dallas says and for my ability level in this turn it seems that I am faster.

Thanks for all the informative replys

 

Well, I can only imagine that the sawing action is actually scrubbing speed which allows you to FEEL like you are going faster (or maybe your entry is faster) but you scrub off to your old speed mid corner with the sawing.

 

I'm with E.J., I can imagine all kinds of things that this would do with bouncing around weight to make the car grab and let go and grab some more, but I can't imagine it being a really fast, consistent way through a corner.

Watch in car video of any of the Champ car leaders, or F1, ALMS, Rolex, whatever - they aren't sawing the wheel.

I know in my Cup car, the feedback from the front wheels causes me to be constantly making minute corrections, but on video it looks like a single set of the wheel. It's way easier to use the throttle to correct the arc, the car doesn't get anywhere near as squirrelly.

My free advice (worth what you're paying for it ): don't develop a bad habit this early on, it will be hell to get rid of later on.

Bruce

 

I'm a sawer, actually more of a wiggler. There i've said it, admittion is the first step to recovery.

While in a perfect world a perfect driver could go through a corner at the maximum g load and never exceed the limit of the car, I like to saw the wheel a little to feel out the grip that the car has throughout the corne (and modulate the throttle accordingly) . In my opinion, the ability to catch the car before the slip angle gets out of hand out weighs the speed lost through the corner when sawing the wheel back and forth. I tend to do it more in practice and races than in qualifying where i'm more focused.

 

I have "sawed" the wheel occasionally when driving my car. When driving a higher powered car, once you get past the turn-in, and any initial understeer, you are usually having to manage some power-oversteer, especially in the slower corners. As much as possible, I have the throttle floored as soon after turn-in as I can. This means that I have only one option if the rear "steps out" due to road irregularities, and that is to quickly turn out, to momentarily reduce the cornering load on the rear tires, and then to turn back to continue through the corner. This will allow the rear tires to hook back up again. If done in rapid succession, you would see this as "sawing". I find that this happens even more when I am sliding the car, as opposed to trying to drive it "stuck down". I feel that this method of controlling the rear of the car would be used even more if the car was very stiffly sprung, and more "twitchy". You are not really testing the limit of the front tires, because in this situation, the traction in the rear is the limiting factor.

 

Hey Larry, thats not sawing, thats driving at the limit. Big difference.

Neighbor - just moved to Villanova.