dnitake

As a rookie, I've been trying to learn from all the expert discussion here and going back to the video. Seems unanimous about how T10 should have been handled. No issues there. But it still seems hard to understand why the car stepped out so quickly. I can buy the issue w/ the transitioning from concrete to asphalt problem. Anyway, TD's video shows 5 laps. 1&2 have a big lift for T10 setup. 3 has traffic. 4 has a little lift prior to turn in. And 5 ( the bad boy if I'm counting right) is flat. Question: would a little half second lift similar to lap 4 also prevented this whole thing from happening, that is w/ regard to the rear coming around? If so, what might be the connection btwn said lift and the spin from a chassis setup point of view?

RedlineMan

Alright...

You caught me. I didn't even look at the data. I just assumed it was the usual squiggly gibberish. I don't find it that useful in any event. Pictures or videos either, as what I see you refute as not being the case. Too many variables.

"Meandering" is not meant to be derogatory toward you, of course. I guess anything but what I do there - a late, short, deliberate, decisive tug on the wheel - is "meandering." I was using it in the fashion of "not having nor displaying clear or urgent intent." Again, when I gradually dial my car into that turn, I feel that sick feeling in my stomach right away. The sick feeling you will have when you take that turn again. "Is this gonna work?"

When I do it my way, I know right away that I'm railed. If I don't have that confident feeling, I'm breathing the throttle or LFB-dabbing the brake (same effect). Nice thing is, I'm likely not even to the apex yet.

When I have my biff, you can interpret all my evidence wrong!

EDIT: Then again, maybe stuff like this is why I am perpetually about 2 seconds off the Club Race Pole Time. Not a big deal in the larger scheme of things, but I'd sure be proud to find that infernal 2 ticks.

RedlineMan

Interesting...

...As the way I saw it, it was VERY SLOW. Nothing visually arresting, just the creeping realization that the cornering arc was widening. Quick slips are usually handled with an equally quick whip of the wheel, the timing and efficacy of which are largely the result of the driver's intuition, instinct, and the level of tuning of his/her internal accelerometer. Done right, a novice passenger might wonder "what that was for, anyway?"

This turn should be simple, but at speed it is not. It is intimidating if you are trying to do it with brio. The lift you mention is quite common. The steering motion I describe is my way of accomplishing some of the same result without giving up any speed. The lift sets the nose down slightly, relative to the rear, and offers it increased grip for turn in. In reality, the lift is also more soothing to the driver's internal instinct.

My method of setting the car with the steering wheel loads the right side tires - specifically the rear - and also coincidentally sets the tail out just a tad, relative to the front. Having just a tad of rotation points you in toward your apex in no uncertain terms. Uncertainty in that turn is to be avoided!

TD in DC

Dan,

Typically, the rear of my car snaps out far faster than it did when I wrecked. Actually, the fact that the rear of my car has been known to snap out so quickly, but did NOT in this particular instance, is exactly why I was trying to be so gentle in the first place: I didn't want to make it snap around. Ironically, my decision about how to prevent the rear from snapping around (i.e., do nothing for a second while you wait for the car to hook back up again) is likely exactly the reason I wrecked.

I catch my car all the time now when the rear snaps out rapidly. I sometimes wonder whether I would have been fine in T10 if the car had snapped out as fast as it usually does, because then there would have been no hesitation in my mind about openinging the wheel big and fast . . .

You are absolutely right about the throttle at entry on various laps. That reflects a combination of me letting the car and tires get warmed up AND traffic through T10 on previous laps.

I am sure that the additional speed was a factor. However, keep in mind that the day before I had taken that turn flat out several times. I think my off during that particular lap was a combination of several factors.

TD

RSRRacer

Wow thats a ton of analysis. I am glad you are OK and the car is mostly OK.

Without even looking at the data, and only looking at the video once, I can tell you (like a few others here) that thsi would have been avoided with a clockwise steering input of about another 10-15 degrees for a duration of about 1/2 to 1 second just as the rear was starting to really slide.

Also if I am correct there is a dip in the track there..... and you must accomodate this by unwinding the wheel a few degrees when going over the dip.

Tony356993

The prof is dead on. Look at the video again. During TD's run, MANY cars did not hit the mark. As a virgin instructor, I spent most of my w/e @ the zone 1 Glen event riding with and watching white students. I think I need a neon sign........ "hit the apex" or "we missed that apex by a foot and a half"

I watched Larry's glen video again and I know the racing line is different, but many cars that had space (if even for a second) missed the apex.

I'm always learning on this forum and on the track. Larry, John, Colin, Prof etc - is the apex less important in racing?

I'm on my 2nd week w/o a track event and it's not pretty AND my driveway is blacktop - thank you!

TD in DC

No worries John. I have zero problems with admitting that I do a ton of things wrong. I think that most do, whether they are willing to admit it or not is another story. I do think it is important to not fall into the trap of thinking or accepting that you made one type of error when actually it was something else. I think that is very easy to do, particularly for people who do not run video or data. Video and data constantly make a liar out of you. Our ability to mis-perceive is really enormous. I believe that my studious review of video and data has helped me to advance rapidly over the past 1 1/2 years since I started this whole nonesense, not because I look at the data and then determine how I should drive, but rather because I can see whether I am actually doing what I wanted to do and what I intended to do.

John, funny you should mention that. Those 2 seconds, along with the confidence that comes with knowing what your car will do at any portion on the track at any time (i.e., not the DE line), is EXACTLY what I am focusing on right now. You have to admit, for my first time to the Glen in the 944 (and only my second or third time there ever), running 2:26s on nine-month old Toyos isn't horrible . . . but it is a few seconds off the pole position guys The problem is that, in racing, a few seconds is an eternity.

38D

Heck no. In fact you tend to see far better lines at a race than in even the instructor run groups.

Tony356993

So I should keep stressing to students to get the car TIGHT on the apex...

dnitake

Hi TD,
I think by quickly, I think I rather mean unexpectedly. I mean it seems you had a line committed, you had the set, for a brief instant at least everything looked predictable, and then the car starts overrotating for what seems to be no obvious reason visible in the video. As opposed to a quick rear stepout caused by a bump or lift throttle or some dynamic thing that a quick correction could resolve which didn't happen and wasn't what I meant.

Perhaps this is nothing more simple then you didn't give it a quick correction as the drift started and the rest was history. In my car, a 4 wheel drift is fine controlling it w/ the throttle. Sounds like it business as usual for you too. That you had your foot to the floor already and the rear comes around like that anyways, yikes. Is there a chassis issue here (pavement and tires aside)?

A video doesn't do justice, but putting myself in the drivers seat, I don't think I would've predicted that based on the previous laps. A lot of variables at play here, but I'm just looking for a sign. That it took you by surprise means I have to be extra damn vigilant :-). I'm coming away from this with "BEWARE OF CONCRETE". Don't have much of it out west (other than the walls of course). Laguna and Infineon have none. Thunderhill, don't recall, but maybe one or 2 spots. We'll see.

Can't tell you how much listenting to these discussions benefits me. Thanks for sharing the details of this incident.

Premier Motorsp

While the discussion of early vs. late apex or turn in on the crash lap is interesting and valid, I think it distracts from the real issue and cause of the crash:

Why didn't TD catch the spin?

THAT is what we ought to be discussing, if our goal is to prevent this kind of thing. Every driver makes numerous mistakes on every lap. Most of the time there is no crash because the driver can recognize the situation and adjust accordingly.

My guess from watching the video only (and this is not any kind of knock on TD's skill or experience level. There are two kinds of race drivers, those who have crashed and those who will crash....... I am firmly in the 1st category) is that the car oversteered at full throttle in a non-traction limited turn. Very unusual situation and one that demands a great deal of finesse to save. I can think of only one time this happened to me, and I spun.

The right thing to do (I am not sure it was possible to avoid an off) was to release the steering much more and come off the gas. This probably would have resulted in the car going off the outside of the track, which would not have been as big of a problem.

If TD is guilty of anything it is being slow on the steering. I gather that maybe he is not so used to oversteer. Compare TD's steering to that required by Keen's epic save in the bus stop. Leh was positive and aggressive with the wheel, and TD wasn't.

These are both examples of why I am such a proponent of P/S. It gives you the ability to make these saves.

Chris Cervelli
Premier Motorsports

RedlineMan

Oh sure...

Come in late and cherry pick so you can look ultra sage! Spot on analysis indeed. I agree completely in terms of what was needed to mitigate the loss of control, but I dissagree with the last portion. As I stated earlier, I see the corner setup, and what was or was not done to correct for the resultant difficulties, as two seperate issues. I'm also not willing to give one precedence over the other. I see them as equally important

Yeh... so we're beating it to death. I have been looking for technical talking points to back up my position, as no one else seems to support it. Oh... not forgetting the Dear Professor; my only ally. My reaction in watching the vid was exactly the same. I started yelling "WAAAAAY too early!" "But the data shows I did that before, and it worked" I might liken it to a game of Russian Roulette. "I pulled the trigger 5 times before I killed myself." That line may have worked before, on previous laps - and indeed for others - but it didn't work that time for sure. I still hold firmly that on that lap, the turn-in was perhaps incrementally, but DEFINITELY sooner, and with the parameters in play (speed, setup, grip, ad infinitum...), it was the turn-in that caused the problem.

Most of the turns we take are such that our cars can exceed the corners ability to hold them. Put another way, we cannot go as fast through the turn as the car will go. As we begin our driving pursuits, we learn to mitigate this largely through brakes & geometry. We learn how much we must brake in order to go through the corner safely while learning how to dissect the geometry of that turn. When we get the geometry right, we can brake less and carry more speed in a perfect linear fashion. Most of the problems that these drivers will experience occur at track out, as they are not aware of what they have done wrong until it smacks'em upside.

Many people's progression stops right there, at driving the corners to their geometric limit.

When we seek to go faster, we enter all manner of esoteric and continuously variable parameters into the mix. grip, slip angles, etc. The higher cornering speeds put the well-setup car into a slight drift as we accelerate past the apex. This is an exciting time for the intermediate driver, and a crucial one as well. Car control is learned here, for one cannot expect to always have a perfect situation. Most difficulties are encountered at the apex, as higher entry speeds force the driver to find new and different ways of managing the car's trajectory for success.

If one seeks to move yet further, into the realm of The Shoe, there is really only one place left to find significant time; corner entry. On turns where the car can exceed the geometry of the turn, this means an earlier turn-in in most cases, as the turn simply will not hold the type of entry speed you seek to carry if you use a late-turn-in DE line. This driver will be initiating the drift very much earlier, late apexing very much earlier as we have said. The car's vector is changing in each of these stages, from linear in the novice phase, to slight-to-moderate four-wheel-drift in the intermediate, to a very early and more pronounced tail-out attitude in the advanced state. The slip angle is gradually being approached, and in the advanced stage often exceeded to varying degrees, well before the apex. Most losses of control will therefore happen well before the apex in this stage as drivers push the limit of entry speed, and of their own ability to manage its consequences.

A 944 NA (or any car of similar potential) will not generate enough speed approaching Turn 10 to make any of that advanced corner entry technique necessary, or even adviseable. In turns where the slip angle cannot be exceeded - where the tail-out attitude is not created as a result of entry speed - the early turn in is simply not a wise thing to do in my opinion. I see no need for it, and I still maintain it is the cause of this problem we are flogging here.

My car is one of those slow pokes. I go in with throttle matted using a late turn-in DE approach. At some where South of 100mph, I certainly cannot create any significant rotation with entry speed alone. I don't want to lift even for a second, and I certainly am not going to be trail-braking. I don't have any power to start with, and there aint none left by the time I get into this turn for sure. As I have mentioned, I CREATE this tail-out attitude by pitching the tail out with a "smooth jerk" of the wheel. If I don't do this, the car never takes a set and floats all the way through. Man... I hate that feeling.

In fact, that is exactly the feeling Todd had there... or should have. As Chris said, it is a really sticky wicket to get through THOSE deals. Now that I've laid this all out, add what Chris said about how to clean up the mess that was made at turn in!

Most of you will probably be glad to hear that I can't think of anything else to say on this matter.

TD in DC

Hey Dan. OK, I understand what you meant now. Yes, all of that is true. Yes, I too think I could have avoided the whole thing if I had not made the erroneous decision to "wait just a second" to see if it would hook back up since the rear end was NOT coming around initially. I think what happened was that the combination of too much steering input (which took effect when I scrubbed off enough speed for the front to grip again), going from concrete to asphalt and going over that bump on the outside of the turn was enough to bring the rear around, slowly, but very deliberately. I opened the wheel immeidately once the rear end started to rotate, but it was too little, too late at that point.

I am glad you find the discussion helpful. I do too. Hopefully others can learn from my mistakes, and I can learn from the mistakes of others.

TD in DC

Chris, I agree completely. And yes, I was slow on the steering, no question. The ironic thing is that my slowness was not caused by me not being used to oversteer. Quite the contrary. I am used to snap oversteer, where the rear swings out very quickly. When that happens, I don't even think: I open the wheel up immediately and significantly to catch the rear, pause while I wait for the suspension to load up, and then "recover" my steering to the proper angle so that I do not go into a tank slapper. What really caught me off guard this time was the fact that the rear did not swing out when I went into the drift. I was really in an "understeer" drift for a few seconds. I didn't want to lift at that speed because I was afraid that the rear would swing around so quickly that I would not be able to catch it (which is my primary concern at that point since I experience snap oversteer rather frequently). I thought that I would scrub off enough speed that the car would hook up again on its own. THIS was my primary error. I am convinced now that this actually caused the rear to start coming around. When it did, I opened up, but it was too little, too late. Next time, the minute I go into the drift, i will breath the throttle a little (very subtley) and open the wheel. I honestly had zero concern about going off the right side of the track, so this had nothing to do with my decision making process.

With respect to the understeer/oversteer issue. I am convinced that John Luetjen has pegged what has been going on with my car. I think that my car has been significantly understeering. I didn't recognize the problem myself because the front tires typically do not break loose completely. Rather, the problem manifests itself in the form of very significant steering inputs. I actually thought that my car significantly oversteers, because it has a tendency to snap oversteer, which makes perfect sense. Turning the wheel so much has probably been scrubbing off a lot of speed through the turns. I was shocked when I first saw the data to see that I had scrubbed off nearly 10 mph from turn in to the drift point on the lap that I wrecked. What I now think has been happening is that when I scrub off that speed (despite the fact that I typically am on full throttle very shortly after turn in in most turns), the fronts really do hook up which causes the rear to snap around, typically violently, in light of the signficant steering input. When I first bought the car, I spun three times during the first two weekends. Until this incident, I had not spun the car again. I have quickly learned to drive around my car's handling tendency, and I had learned to expect and catch the snap oversteer.

I had never really focused on setting up the car because (1) I can always put it exactly where I want it on the track; and (2) I have been focusing on improving myself rather than blaming my equipment. I now think it is time to start dialing in the car. I can see how an understeering car could lead me to earlier turn ins and exascerbate the tendency to experience snap oversteer. I can't help but wonder how things would be with a car that is undoubtedly dialed in correctly.


Thanks for taking the time to contribute.

TD in DC

John,

I wouldn't disagree with you that this turn in was incrementally sooner. I had been experimenting a little with this all weekend. Compared to your description of the ideal turn-in, it may have been way early. As I think you now realize, it was not way earlier than I had been taking it, and making it fully hooked up, all weekend. THAT is why I did not view it as a "mistake," despite the fact that it may ultimately not be the best way to take the corner.

I also am not opposed at all to experimenting with the turn in approach you describe. Not at all. I am wed to nothing. I read tons, listen to what everyone has to say, then I methodically experiment with everything. I am definitely a "question authority" but "respect experience" type of guy. If I really ultimately want to be a good driver, I need to try a wide variety of different techniques to see what works best for me. That is what I am doing now. I mean, isn't that what DE is all about? Learning? My approach to this is not arbitrary, so I am not "dangerous" out there changing approach from lap to lap and trying to implement wildly different ideas from untested sources. Quite the contrary. I inch my way towards changes. I try and try until I find the limit of what works, or seems to work, for me. I think my accident was the result of inching my way towards the limit of early turn in, but more importantly my bad decision about how to handle this particular drift right at the apex.

I learned. Sure, it was the hard way, but it could have been worse. I could have met the tirewall and not learned a damned thing . . .