Quicky videos from this weekend at Putnam - spin in 2

[CL65 Captain]

I found out the fastest way through turn 7 is sideways and the fastest way through turn 2 is not.

Yes: Turn 7

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No: Turn 2

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I think I need drifting lessons.

I looked at the data log for this, and I was 6 mph faster entering this corner as I decided I didn't really need to tap the brakes. I was wrong. The data log showed 73.26 mph vs 67.1 mph. At the apex, I was only 1.5 mph faster but was pulling 1.30g vs 0.97g. The result.....

In order to get the car to rotate going into turn 2, I usually tap the brakes and let the back end slide just a bit and point the nose in towards the apex. I am then immediately back on the gas just enough to shift the weight rearward to stop the rotation with little or no steering correction. If you just try to power through turn 2, the car will understeer right out to track out.

On this lap, I was chasing the GT2 and decided that I didn't need to brake, shifted from 4-3 let the engine braking transfer the weight forward just for a second or two, turned to the apex and then was back on the gas to transfer the weight back to the rear. I held the gas just as the back started sliding and added left lock to stop the slide. I added too much correction as the car immediately reversed and I couldn't get the wheel back straight fast enough. Had I added a little less correction, the car would have continued to slide to the left, with a pause before it came back the other way giving me a chance to get the wheel back to neutral.

 

[SFDreamer]

Do you know what you did incorrectly?

Also, I hope they paid you for mowing that section of the lawn .

Glad you made it through, car and body unscathed!

 

[CL65 Captain]

Do you know what you did incorrectly?

Also, I hope they paid you for mowing that section of the lawn .

Glad you made it through, car and body unscathed!

Yep, the initial correction was too large and I didn't get it back straight quick enough causing it to swing the other way. Oh, and don't try and chase 911 GT2s on Hoosiers when you are running on street tires.

Had to pull both wheels and remove ALOT of grass because it had just been mowed. Washed it off and right back out.

 

[Brylek]

At least you experienced something new

 

[CL65 Captain]

At least you experienced something new

Unfortunately, spinning off the track at Putnam isn't anything new for me. But at least I am learning to spin in new spots. :tongue:


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Here I didn't just clip the curbing on the right of turn 6, I went over the top of it apexing it just a fraction too early. You can see the car bounce just a bit as this happens and it throws the car wide to the left, where I run out of room and the left tires run off into the grass. At this point it's a lost cause as the car is sliding left and had I even tapped the brakes it would have spun anyway. Moral of the story - driving over the curb, good. Jumping the curb - bad.

 

[Sir Stunna Lot]

this is quite entertaining... anymore? :tongue:

 

[Coz]

LOL...looks like you had fun...
Like the looks of that track...looks like it would be a blast...

Been there and done that, didn't work out for me either :redface:

Oh, and don't try and chase 911 GT2s on Hoosiers when you are running on street tires.

 

[ak]

Did u lift when you started to slide?

 

[CL65 Captain]

Did u lift when you started to slide?

nope.

 

[EdinKali]

Yeah, you can hear him stay on the throttle(nice work there resisting the urge to lift). At least you didn't hit anything CL.

Maybe you should turn the traction control back on. (Ed ducks)

 

[CL65 Captain]

this is quite entertaining... anymore? :tongue:

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This is turn 4. It is a left hander that is off camber as the track falls away to the right. The dry line is on the inside all the way around the turn to try and at least keep the inside tires on camber as the further to the outside you go the more off camber it is. The problem with this - when it rains, its slicker than snot as the pavement is pollished down from everyone running there over the years. Moral of the story - the wet line is where ever you can find grip, even if it's off camber, on the outside of the turns in the rubber shavings.

BTW: here's another person in turn 4 in the rain. Same spot, same line, same result.

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And my first spin at Putnam Park - off of turn 1. Spin is at the end of the video....

http://www.vimeo.com/1734154

 

[docjohn]

I'm amazed at the quality of your vids.The spins are good for folks to see.Of course your explanation as to why you spun would be good for the novice readers.Did the chief instructer have any words with you, being an instructer yourself?

 

[SFDreamer]

What was the error in your "first spin" video? I can't pick it out.

 

[CL65 Captain]

I'm amazed at the quality of your vids.The spins are good for folks to see.Of course your explanation as to why you spun would be good for the novice readers.Did the chief instructer have any words with you, being an instructer yourself?

Never had a chief lecture me (well except for the time I took Grandma's Camry and Nascar drafted a 911 GT3 RSR 3" off his bumper down the back straight at Mid Ohio in the novice group. He wouldn't give any one a point by, especially a Toyota Camry - so I decided to prove a point. Made a great photo though :biggrin. Chief Instructors know me and know I don't do foollish things, but I do spin once in a blue moon. It's part of the reason why are on the track - it's the E in DE.

OK - I will go back and edit the vids to try and state what went wrong for each.

 

[CL65 Captain]

What was the error in your "first spin" video? I can't pick it out.

If you are talking about the spin in the wet, it was a result of driving the dry line in the wet. See my edit above.

If you are talking about the link to Vimeo, with the spin at the end --- the front sway bar link snapped so I had no front bar and a Dali 1" track bar in the rear - OVERSTEER. My error was not making the correction fast enough, as by the time I started the correction the car was gone.

 

[nsx2tall]

If you are talking about the spin in the wet, it was a result of driving the dry line in the wet. See my edit above.

I've heard that turn 4 at Putnam sucks in the wet no matter where you are.

 

[CL65 Captain]

I've heard that turn 4 at Putnam sucks in the wet no matter where you are.

Yes, it does. There are those that have gone off there in the rain and those that haven't gone off there yet. :tongue:

 

[track-junkie]

Great crystal clear videos. I love learning from your videos, thank you.

The most common error made in skid control is not correcting quick enough. Catching the first slide requires a "Karate fast" or
instantaneous correction. The faster you correct the easier it is to save. The smaller the skid.

That's one reason why some drivers stay off the track when it rains for they correct to slowly. When they add their reaction time along with
tires that are less forgiving in the rain, slides become unmanageable.



Regarding the spin in turn 2 video. Other solutions:

1. Unwinding some steering at the apex before adding throttle.
2. Recovering the steering faster after the first correction.

 

[track-junkie]

A good explanation for why the slide was lost in turn 2 and 4.

Quoted from Paul Brand.
http://www.skipbarber.com/instructors/Paul-Brand

First, "overcorrection" is inaccurate. The "yaw" is generated by the rear tires sliding while the front tires are still gripping the pavement. The vehicle is effectively a pendulum pivoting around a vertical axis through the center of the front axle. There are only two key issues to saving a slide like this -- steer the same direction as the back end is sliding (just as you noted), and make the steering correction right now!
You're correct in noting "how little actual correction of the wheel is optimal," but only if the steering is corrected virtually instantly. The key to this is the eyes -- look where you need the car to go, not where it's going. Because the hands naturally follow the eyes, by looking in the direction the car is sliding, the hands tend to make the right correction.
Sadly, inattention, distraction, lack of understanding, inexperience and panic tend to delay the driver's recognition, processing and response to the slide. This allows the slide to increase in angle, meaning the front tires are no longer pointed where the car is headed, and once the correction is begun, more steering input is necessary.
Now, if the steering correction is properly dialed in, the pendulum effect begins to slow. If there's enough traction available from the pavement, the rear tires finally stop sliding, and the vehicle is at the limit of the yaw/slide and ready to snap back in the opposite direction. In performance driving vernacular, the energy built up in the rear springs unloads as the tires regain grip, initiating the "second reaction" hook slide. This occurs because the driver does not recognize the pause of the pendulum and the impending second reaction, and the back end snaps back in the opposite direction while the steering is still corrected in the direction of the initial slide. The instant the rear of the vehicle begins to swing back in the opposite direction, the front tires are no longer pointed where the vehicle needs to go -- thus the start of the back-and-forth "fishtailing," or, in the racing world, "death wiggle."
To prevent this, the three steps necessary to save a rear-end slide are correct, pause, recover -- or C-P-R in the motoring world. Steer into the slide just enough instantly, anticipate the pause as the back end rotation begins to slow, and continue to look where you need the vehicle to go. Prepare to steer back in the other direction at the same moment the back end begins to snap back. Timed correctly, C-P-R keeps the vehicle traveling in the same direction it originally was before the back-end sliding.
Thus, there's really no "overcorrecting." It's more of a delay in initial steering input, then a delay or lack of recovery -- turning the steering back toward the center/neutral position as the back end snaps back. It gives the appearance of overcorrecting because the front wheels, as the car snaps back, are still turned in the original direction of the skid. But it's because of the delay in recognizing and responding to the second reaction, not because the wheel was turned too much initially.
One final key point. In terms of how much steering correction to input, this is entirely dependent upon two things: How quickly the correction occurs (as you noted above), and how rapidly the pendulum or back end is rotating around. There are wimpy little slides on dry pavement that require only small corrections, but then there is the "mother of all slides" at higher speeds or on wet pavement that requires every bit of available steering wheel input/angle to keep the front wheels pointed where the vehicle is sliding. This is why the "shuffle steering" technique is so important. It doesn't matter how quickly the steering correction is done -- if the steering isn't turned far enough to keep the front wheels pointed where the vehicle is sliding, the back end is never going to pause, giving the driver a chance to recover.

http://www.startribune.com/cars/11354971.html

 

[SUNEDAZ]

^ wow he's good. Thanks for the lessons Captain and track-junkie

I can't wait for Summer. I'm taking mine to the track for the first time and I'm sure I'll have lots of video's to share. Hopefully some video of me not cutting the grass, but I'm sure I'll have to clean my wheels out a time or two.

Road Atlanta here I come!

 

[track-junkie]

SUNEDAZ

Keep a good following distance from the car in front of you on the track, even the best drivers may spin.

 

[CL65 Captain]

Regarding the spin in turn 2 video. Other solutions:

1. Unwinding some steering at the apex before adding throttle.
2. Recovering the steering faster after the first correction.

1. I was already on the gas prior to the apex to plant the rear. Lifting there is a no-no. Unwinding the wheel would have put me off the left curb into the grass. I thought I was going to make it, until I didn't. :biggrin: The slide started just past the apex. In hindsight, the Dunlops were at the end of their life in the rear and needed replacing when I got home.

2. I have watched the video 100x, plus numerous times in slow-motion frame by frame. I don't think I could have started my correction any sooner, the correction is being made just BEFORE you notice the slide and even hear any squealing. As well, I unwind the wheel immediately as soon as the correction is made. Contrary to your quote above - their IS such a thing as too much correction and this is the prime example. Too much correction makes it impossible to get the wheel back straight fast enough. Had I made a smaller initial correction, you would have seen the classic C-P-R. I didn't see a pause in there at all - thus the correction was too large.

I just watched it again in slow mo and the wheel starts unwinding towards neutral even before the slide to the left stops. Half way through unwinding the wheel (removing the correction) you can see the nose already yawing to the left as the car is now going the other way (tank slapping) and then I make a 3/4th wheel correction to the right and reverses back the other way again. And that point it was gone. The initial correction input WAS too large.

If you have quicktime, here is the raw clip trimmed down to just that corners. You can use the arrow key to advance frame by frame or hold it down for slow mo.

http://adsmidwest.com/working/Spin_turn2_slow.mov 11MB mov file

 

[fourringpilot]

Great vids and insight.

 

[latzke]

I added too much correction as the car immediately reversed and I couldn't get the wheel back straight fast enough. Had I added a little less correction, the car would have continued to slide to the left, with a pause before it came back the other way giving me a chance to get the wheel back to neutral.

[...on to later post...]

Had I made a smaller initial correction, you would have seen the classic C-P-R. I didn't see a pause in there at all - thus the correction was too large.

I was going to disagree...but after watching several times and I not only see the lack of pause but (specifically listening/watching for it) hear rear traction return just before you're completely unwound to neutral. Despite that, I think your recovery was fast enough to compensate for the initial (over) correction...but the degree of recovery was too harsh. In other words, given the same initial correction and speed of recovery you would have been fine had the recovery been to neutral (or just past, like 1-2 o-clock to prevent snap oversteer / wiggle) instead of 1/2 turn past (right) of neutral.

Regardless, excellent driving (I bow to your expertise).

It is for this kind of experience I'd love to have access to a skidpad or similar. The events they used to run at the retired Denver Stapleton airport would have been perfect for working on this. The "track" was defined by cones on the massive runways...so runoff, infield, etc were all still on the pavement. I catch myself drooling.

 

[tstruyk]

You think T4 at Putnam is slick on 4 wheels... try it on 2

Ive run a handful of trackdays there and at least for motorcycles its a treacherous corner especially early. For all the reasons you mention in the wet there is one in particular in the dry when temp is a little low.

Putnam is primarily a RH corner track its not surprising that at MC events most crashes are in T4 and dead bear. Both are off camber (T4 moreso but DB if you run it out past mid track) but the kicker for T4 is tire temp. Ive run there in the low 50's upper 40's and even though the right side stays nice and grippy on DOT rubber, the left side cools drastically from 8... AAAAAAALLLLLLLLL the way around to T4.

Regardless when I pick up my NSX (next month) this will be one of the first tracks I attend. At 3.5 hours from St. Louis its one of the closest tracks I can get to, and its a hoot. I'm not too keen on the walls at GIR. I race my MC there but I dont see me running my NSX for awhile. Bones heal on their own, it costs money replace parts :biggrin: after that I'd like to run HPT.