Second HPDE: Sonoma Raceway

kcbrown

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I'm sure many of you have already read my writeup on my first HPDE. In it and the ensuing discussion, we talk about the problems I had during that HPDE.

Now it's time for me to write up the second one. As before, there's good news and there's bad news. First, the good news...

The Good News

This event was MUCH better than before. I went into it determined to overcome whatever issues were holding me back the last time around. I went into this assuming that the problem was simply situational overload.

My preparation this time around included finding a PC game (SimRaceway, in this case) which had the track in it, and "driving" the car around the track. Interestingly enough, the game has multiple configurations of the track, so I had to determine which one was the "correct" one by driving each one and comparing it to my memory. The one I found to be correct was the "Sonoma Classic" track. I don't have my steering wheel and pedals hooked up to my PC, so they weren't of use for this. Instead, I used my mouse and keyboard to control the "car". Needless to say, that didn't work very well for things like driving the line accurately, but it wasn't uncontrollable either, and it was good enough that you could figure out which corners were likely to be more of an issue than the rest. But most importantly, it worked really well for ingraining the corner sequence of the track into my memory.

Armed with that, I headed off to the track.


The first day

The first session of the day was, as usual, driving around the track at 45 MPH to get (re)acquainted with it. This time around, though, rather than concentrate on the line, I directed my awareness out to the corner workers and tried to pay special attention to them. It wasn't as important to me to drive the line at that point as long as I could get around the track reasonably safely. Awareness of my surroundings was what I was aiming for here.

This paid off in spades. Between that, my existing familiarity with the track itself, and the determination to succeed, the next three sessions were massively improved over the last event. We wound up covering some of the finer points of the line while I simultaneously paid lots of attention to my surroundings (the corner workers, the traffic). I also tried to integrate my peripheral vision into the mix, particularly with respect to the upcoming apexes, and that worked better than I expected.

At lunchtime, we did "parade laps", where we were able to drive around the track at a leisurely 25 MPH. I took my wife with me on that and she enjoyed it much more than she expected, as well as gaining some understanding of what I was going up against. But the main benefit was, of course, gaining even greater familiarity with the track. I again paid special attention to the location of the corner workers on the track, acknowledging each of them every lap.

That helped with my afternoon sessions. With the greater familiarity with the line and the track, I was able to divert even more attention to the corner workers and the traffic. Most importantly with respect to the corner workers, I was able to start instantly checking their status as they came into view rather than hunting for them as I had been previously. That, of course, freed up a lot of bandwidth for looking at traffic and maintaining general situational awareness.

I think much of the success that day came from the sheer inner calmness I had during the experience. Rather than worry about how I might be doing, I simply decided to do what I could with determination and let the chips fall as they may. It worked brilliantly.

So brilliantly, in fact, that at the end of the day, my instructor signed me off for HPDE2! :clap:


The second day

The first day was magnificent. The second day, on the other hand, was near-perfection!

The first HPDE2 session was grouped with HPDE3. This proved to be one of the most enjoyable sessions of the day. It seems I'm not all that bad on the track after all. I started off near the front of the HPDE2 pack. HPDE3 went onto the track first, followed by HPDE2. It wasn't long before I passed one or two of the HPDE2 cars and kept up with the HPDE3 group. It was immensely enjoyable because I was able to attack the track at my own pace rather than be held up by traffic.

The remaining sessions were with HPDE1. The second and third of these were payback time for all the slow laps I did during the last event.
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I got caught up behind traffic multiple times. This wasn't the sort of traffic you could really safely pass when you're inexperienced, because we're talking strings of 15 cars or so. There's no way you're getting by all of them in one attempt, which means you would have to insert yourself into the middle of the line when everyone is braking and is going to head for the apex. I'm simply not going to do that when the people in question are probably in their first day on the track and probably don't have the awareness to make such a pass attempt successful. Attempts to escape via pitting briefly didn't work, in part because of all the exercises for the emergency crews they were performing (and, thus, the various cautions, emergency vehicle on track, etc., flags that were being thrown). We even had a full course stop (red flag) followed by full-course black flag (everyone into the pits!) during the third session. Did I let all that action upset me? Hell no! I used it as a good excuse to further familiarize myself with my surroundings, to further expand my awareness. I used the opportunity of driving in slower traffic to nail the line while increasing my awareness of the traffic (checking mirrors and such). All of this came in handy for the fourth and final session.

The last session was absolutely brilliant. I feel I did my best driving thus far in that session. I was able to pass up most of the cars that were slower than I was and otherwise comfortably drive the line and see my surroundings. Even though I don't feel like I was pushing the car quite as hard this time around, it feels like I was faster and more consistent around the track.

While I don't generally track my lap times, my wife did take some photos of me when I was going around the track, and a few of those were at the same location on successive laps. For that session (I can't remember which one, but it wasn't the last), my lap time around Sonoma was 2:16. There's certainly a lot left on the table, but I suspect that's not half bad. Not that I really care all that much -- I had a great time blasting around the track!


So in the end, this event was a resounding success. Brilliant. I can't say enough good things about it.


The car

The car performed admirably, even better than before. Whereas before I was maxing out at about 1.05G (according to the Track Apps accelerometer), this time around I maxed out at an astounding 1.20G. That to me is absolutely astonishing. I'm certain it's just the transient maximum, and that the continuous maximum is probably somewhere around 1.1G, but on Bridgestone S-04 Pole Position street tires?? I suppose the accelerometer might be lying, but I'd like to see some evidence of it if it is. Certainly, by the seat of my pants, it feels like I'm getting that kind of traction.

The car does indeed understeer some by default, but bringing the rear out is easy. It doesn't take a lot of additional throttle to do that, as I discovered upon exit from turn 11. Reining it back in was straightforward: just lift the throttle slightly, back to neutral, and the car will come right back into line. All of that tells me that while the car may not be neutral in its default handling, it's still reasonably well-balanced because you can easily control which regime of traction loss you want to be in.

The tires still still appear to be wearing evenly, and it certainly isn't for lack of use! I intend to modify this message to include a few pictures, a couple of which will show the tires so you can judge for yourself how much I was working them. Even after a couple of hundred miles since the event, there are still large ribbons of melted tire at the edges of the longitudinal tread. Pressures after coming back into the paddock from a cool down lap were around 40 PSI, with cold pressures at about 35 PSI. I doubt I'd be getting the kind of grip I'm obviously getting out of these if the contact patches were significantly compromised due to incorrect tire pressures or even incorrect camber up front.

There is some body lean in the corners, but it continues to feel well-controlled and not excessive. The suspension has never unbalanced the car when hitting the rumble strips or anything else thus far. The car has never felt unresponsive. If this is what a "poor" suspension is like, then I'll take it!

There is also, of course, some dive in braking. But at maximum braking (which I did once or twice just to see what it was like -- most of my braking was less than that because it's easier to precisely control more gradual braking), your face feels like it's going to come off of your head and for me, at least, my concentration is so much on where my braking targets are that I simply don't notice the brake dive. Maybe that'll change over time, but for now, it's not an issue.


All of this has me wondering if Ford did something to the 2014 Track Package cars to improve them. The overall experience with the stock suspension so far is that it remains very, very good. Enough so that my only complaint about it so far has nothing to do with driving on the track at all, and rather involves driving on the street: it feels harsher than it needs to on pavement that has mid-range surface height variability. Those of you who live in the SF Bay Area will probably be familiar with the section of 280 (particularly southbound) between 85 and De Anza. There aren't many suspensions that seem to cope truly nicely with that section. My suspicion is that Ford increased low speed compression damping to give the car sharper "reflexes", and that's why it feels as it does over that kind of pavement.



The Bad News

So after reading all of the above, you're wondering what the bad news could possibly be.

Psych! There is no bad news!

Well, okay, there is some bad news. The bad news is that I didn't get enough track time!
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Needless to say, the hook is deep in my mouth, and I can't dislodge it!

July is going to be a truly busy month for me. Not only do I have the Evolution driving school in Marina, I've also signed up for the Simraceway high performance driving school at Sonoma. The first day will get us some autocross and track time, the second day even more (2 hours of track time) and the third day even more than that (2.5 hours of track time). At $500 each, the expense isn't that much higher per hour of track time than I get at NASA events, and it's all with lots of instruction. I feel it's going to be money well spent.

And on top of that, I've signed up for a driving event at Laguna Seca! This is going to be perhaps the most interesting event of them all, because I get to see just how useful all those virtual laps around the track are. I've got many hundreds of laps around Laguna Seca in Gran Turismo, so it's really going to be a question of learning where the corner workers are and how the real car behaves in that environment. I'm stoked!



So, bottom line: it was indeed situational overload and maybe a bit of being overly-self-critical that was responsible for the problems I felt I had during the first event.

Thunderhill comes up in August. That's going to be a bit more interesting because there doesn't seem to be a game out there that has it in its list of tracks. But I've got an idea on how to familiarize myself with it: watch videos from inside a car while "driving" with my steering wheel setup, to sort of get a visceral sense of the track. Should be interesting to see how well that works. I'm going into HPDE1 for that track simply because I don't have any real-world familiarity with it, but have no reason to believe I won't be in HPDE2 by the second day.


Thanks, everyone, for being such a great help to me! It worked! :thumb:
 

Strengthrehab

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Great write up. Seems to be very satisfying.

I need to get back in track. Probably won't be until next season though. Sigh.

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SoundGuyDave

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I'll have to agree with your overall conclusions: situational overload, plus a bit of excessive self-criticism. Your descriptions from this event sound shockingly like a typical novice driver, which is absolutely wonderful to hear!

The only real "eyebrow raising" bit of data you threw out is the LatG number of 1.20. Personally, I would find this a bit suspicious. Generally speaking, street tires max out around 1.0-1.1, race rubber (Hoosier R6, Toyo RR, et al) will bump that up to 1.2-1.4, so I would be a tad distrustful of your device's accuracy/calibration. While in certain circumstances, it is entirely possible to peak a street tire into that range (momentary transient load, while in a STEEPLY banked section of track, like a Speedway circuit), to hit that on a flat track is simply suspect. My guess is that there was an acquisition error that polluted your data. Do you have a LonG max from your braking test that we could use to compare? IIRC, the stock ABS kicks in almost exactly at 1.0G decel, so if you're showing higher than that, something is off.

The metrics that really count, though, are the confidence, situational awareness (versus overload), and fun factor. Compared to your first outing, the important metrics seem to be through the roof! Nice job!
 

mitch

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Great write up!
I've been doing track days since the mid 90's and instructing for maybe 7 years.

I truly love giving back to the hobby. Hearing your (and other students) enthusiasm is priceless!! This is why I do it. You sound like you've been a great student, paying attention and really practicing what your instructors have preached to you.

Good luck, Keep up the good work!! It only gets better as you move up in groups.
 

kcbrown

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One thing I forgot to mention in the writeup: the last session of the first day was a solo session, with my instructor observing from afar. It was because I was able to handle myself during that session that I got signed off for HPDE2.

As for the accelerometer, it shows maximum braking at 1.11G. So I suppose it could be a bit "optimistic". It would be interesting to compare it against a calibrated accelerometer of some kind, to develop a calibration curve for it.

Assuming maximum braking actually happened at 1.0G, that would mean the 1.20G actually translates to 1.09G, which is still very, very good.

What I don't know is what effect tire size is going to have on this. I'm running 285/35-19 rubber here, which is 30mm wider than stock.
 

claudermilk

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Excellent writeup! I concur that it was likely situational overload & excessive self-criticism. I think we even floated that theory in your other thread. Sounds like you are making great progress.

I happen to be running the exact same tires. I started on the stock P Zero 255/40-19 autocrossing for about a year, then switched to the S-04's after chewing those up. The Bridgestones are far superior; grip is much better, and as you found the breakaway and ability to bring the rear end back is excellent. I think those tires help the stock S197's balance a ton. The funny thing is now that I have some suspension on the car, I've lost that easy breakaway. I need to play with my settings to allow a little of that back.
 

Rabee

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I like KcBrown threads, they are very honest and they stimulate a healthy dose of educational posts.
I am learning and I am loving it :bravo:
I like threads that focus on driving techniques and what goes inside our mind during the high adrenaline moments on the track!
 

barbaro

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KC. I am very familiar with the 85. It is a superb roadway. If the stock suspension bothers you on that highway don't change the suspension. The I-5 through LA would murder you. How do you like your tires? Do you have 285's all around and if you do; what size wheel do you have up front?
 

kcbrown

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KC. I am very familiar with the 85. It is a superb roadway.

85 isn't the problem. 280 (particularly southbound) between 85 and DeAnza is the problem (though much of the left lane for that is fine). I've not found a car that doesn't have some trouble with it, though the Mustang I got a chance to drive with KW v3 coilovers did better than the stock suspension despite the much higher spring rates. That, plus the general behavior of the suspension over bumps, is what leads me to believe that this is strictly a problem with the compression damping -- rebound damping does not seem excessive, and you can tell that it's the compression part of the damping that is at issue because when you go over a "shelf" (raised section of concrete relative to what you're on, without a smooth transition), the impact feels harsh despite the fact that the amount of available suspension motion is much greater than the distance it needs to travel in compression.


ETA:

It seems to me that ideally, the suspension would deal with all the motion in the road while the body doesn't move at all. That's because the purpose of the suspension is to keep the tires planted on the pavement No Matter What, and to do so in such a way that the amount of available grip is maximized throughout the motion. If the body is moving around as well (as it must be if you're feeling the motion underneath you), then it's likely to be somewhat out of phase with the motion of the suspension, and that would tend to vary the amount of grip available at the tires, thus making the cornering less consistent over less-than-perfectly-smooth surfaces. Except for the compression damping, the stock suspension doesn't seem to do a bad job at all, but my testing thus far has been limited to Sonoma Raceway, which may be an exceptionally smooth track (anyone here have comments about that? I'd love to hear opinions of how smooth that track is compared with others).

Hence, it seems to me that the best suspensions will, as a side effect, yield relatively little motion of the chassis -- the suspension does all the "work" -- and that makes for a smoother ride as well as better cornering characteristics. Note, however, that there's a big difference between the soft, squishy suspensions of luxury sedans and a proper performance suspension. The former is good until you start to corner, at which point it simply can't keep up, because half the suspension is in extreme compression while being asked to handle bumps, while the other half is in extreme extension while also being asked to handle bumps. The compression side is obviously much more important, as that's where most of the cornering load is. There are also responsiveness considerations.

This is why what you really want is a computer-controlled suspension with pavement height sensors placed such that they are always able to measure the surface height just before each tire. Such a suspension would be able to maintain an absolutely flat attitude around corners while soaking up all the bumps perfectly. Since such a thing would probably cost multiple times what our cars cost, I think we're going to have to settle for really good dampers and springs...


If the stock suspension bothers you on that highway don't change the suspension. The I-5 through LA would murder you. How do you like your tires? Do you have 285's all around and if you do; what size wheel do you have up front?
I love my tires (Bridgestone S-04 Pole Position). They're awesome. Super grippy on the track, and easily controlled all at the same time. Breakaway is gradual, just like you want it to be for maximum control. They're 285/35-19. I have 19x10 wheels on all four corners.
 
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Norm Peterson

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Sounds like your second event was a huge success.

I'm sure that your shock/strut compression damping curves are at least partly to blame for the poorish ride over expansion-jointed concrete. More specifically, too much damping in the high-speed range - high speed here refers to the piston speed inside the shock or strut - and Ford's OE dampers seem to consistently have too much of this. With high-end dampers, it is possible to adjust high speed compression damping (related to harshness) separately from low speed compression (which you want a fair amount of for control of chassis inertial motions).

Rear suspension details and side-view geometry are other contributors.

It is possible to get better results via computer-controlled damping - think magnetorheological damping as already exists on the ZL1 Camaros. Although then you need to address damping for ride comfort vs damping for transient cornering response and other matters of vehicle dynamics (and what gets priority when damping demands for more than one of these things is present), additional sensors/wiring/etc., and whether such a system even allows for end-user tweaking. Any OE computer-controlled damping is going to be biased in favor of understeer.


Norm
 
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kcbrown

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Sounds like your second event was a huge success.

I'm sure that your shock/strut compression damping curves are at least partly to blame for the poorish ride over expansion-jointed concrete. More specifically, too much damping in the high-speed range - high speed here refers to the piston speed inside the shock or strut - and Ford's OE dampers seem to consistently have too much of this.

I would have thought the low speed compression damping would have more to do with it, because the harshness is most apparent on small bumps and irregularities where there simply isn't enough height in the bump to move the suspension very much (and since speed is a function of acceleration and time, it follows that a larger bump with the same slope will yield faster suspension movements and, thus, if the high speed compression damping were too high, those bumps would feel overly harsh).

ETA: Of course, the damping curve is actually a continuous thing, so "high speed" and "low speed" are merely crude descriptions. It may be that the dampers in question are overdamped somewhere towards the middle of the range, but the harshness versus bump size curve is such that I'd have to place it more towards the low speed side than the high speed side.


It is possible to get better results via computer-controlled damping - think magnetorheological damping as already exists on the ZL1 Camaros. Although then you need to address damping for ride comfort vs damping for transient cornering response and other matters of vehicle dynamics (and what gets priority when damping demands for more than one of these things is present), additional sensors/wiring/etc., and whether such a system even allows for end-user tweaking. Any OE computer-controlled damping is going to be biased in favor of understeer.

Yeah, I was thinking that acceleration sensors would be useful for distinguishing between cornering transients and surface transients. Sensors that directly detect surface irregularities would theoretically make it possible to directly move the suspension over them. My thinking here involves eliminating damping altogether. Damping is required in conventional suspensions because of the use of springs for the purpose of controlling suspension motion, but the system I'm thinking of would control suspension motion directly, and thus springs wouldn't be involved at all.
 
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Norm Peterson

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A quarter inch bump taken at 60 mph probably produces a higher piston velocity than you suspect. Low speed is down in and below the 2 or 3 ips range. Relative to that, 10 ips is high.

Bose (the audio system people) was also working on an active suspension system 8, maybe 10 years ago. Don't know whatever became of that program, even a mechanical engineer acquaintance who worked in a different Bose business unit was never told very much.


Norm
 

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