[VIDEO] Why Did I Crash - Episode 2
01-11-2019, 01:06 AM
#21
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The car in the video is mine and I was driving. I had 305/660/18 front and 315/680/18 Pirelli Scrub Slicks. Cold Pressures were set at 26 psi and hot pressures after previous sessions were in the range of 32/33 psi across all 4 tires. The GM MR Calibration had been installed at the beginning of the year. The front alignment was set with -2.3 deg negative camber with +6.7 deg caster and about 1/32 of total toe in. Rear alignment was set at -1.7 deg camber with +0.7 deg of caster at each rear wheel with about 1/32 of total toe in and 0 deg thrust angle. The incident happened on the 10th lap after about 22 minutes of track time. My fastest lap was two laps before this where I turned a 2:07:90. The previous session I had turned a fastest lap of 2:06:90. I have turned laps as low as the high 2:03s over the last year.
Sean did the a great analysis and went into much more depth than he was able to when I first asked him to look at the data. he video shows I made a Rookie Mistake by applying too much throttle too soon. Whether or not I early apexed doesn't really matter as an experienced driver should be able to handle any corner entry since there are many things that can make them choose an off line entry. There are some things that a data recorder doesn't record. Tire Grip and Driver Focus are two of those things. T
From a Grip standpoint this event was the third event with these tires. They had 3 previous VIR track days and 2 Watkins Glen track days (or about 20 heat cycles) on them at the beginning of the day. I was at the end of my third 20+ minute session for the day when the incident happened. During the previous session I felt the rear tires starting to get greasy with the back end stepping out in several right hand turns.
From a Focus standpoint I was thinking about the run I wanted to make down the hill toward the Oak Tree corner (2 turns further).
That Focus led me to go full throttle too soon in the turn in an attempt to get that run down the hill and I didn't have the grip in the tires to do what I was trying to do.
All that defines a Rookie Mistake and that is what I told the Chief Instructor when he was filling out the insurance forms while I was being checked out in Medical. It turns out the mistake was a $7K lesson for me and hopefully others can learn from my error without spending that much money.
Bill
Sean did the a great analysis and went into much more depth than he was able to when I first asked him to look at the data. he video shows I made a Rookie Mistake by applying too much throttle too soon. Whether or not I early apexed doesn't really matter as an experienced driver should be able to handle any corner entry since there are many things that can make them choose an off line entry. There are some things that a data recorder doesn't record. Tire Grip and Driver Focus are two of those things. T
From a Grip standpoint this event was the third event with these tires. They had 3 previous VIR track days and 2 Watkins Glen track days (or about 20 heat cycles) on them at the beginning of the day. I was at the end of my third 20+ minute session for the day when the incident happened. During the previous session I felt the rear tires starting to get greasy with the back end stepping out in several right hand turns.
From a Focus standpoint I was thinking about the run I wanted to make down the hill toward the Oak Tree corner (2 turns further).
That Focus led me to go full throttle too soon in the turn in an attempt to get that run down the hill and I didn't have the grip in the tires to do what I was trying to do.
All that defines a Rookie Mistake and that is what I told the Chief Instructor when he was filling out the insurance forms while I was being checked out in Medical. It turns out the mistake was a $7K lesson for me and hopefully others can learn from my error without spending that much money.
Bill
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01-11-2019, 07:29 AM
#22
Track Rat
Thread Starter
Thanks Bill for chiming in. We all make mistakes no matter how seasoned and I've made far worse mistakes myself (wait until we get to that video!). We all greatly appreciate you elaborating on the situation and making this possible.
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01-11-2019, 08:39 AM
#23
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Do you think a setting like "Sport 1", pulling a little power on the corner exit would have saved it?
01-11-2019, 10:10 AM
#24
Melting Slicks
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I know most won't agree with the following and I've argued PTM can actually be dangerous with people going WOT out of a turn and letting PTM sort out the rest because it is "faster", but I question whether running full off might have resulted in this not happening (then again we can what-if any scenario until we are blue in the face). I'm not even referencing the particular turn from the video, you can crash a car in any mode, but with no PTM intervention a driver (again, not using Bill's specific example) can feel the car start to fall away as the tires loose grip. As Bill did mention, the tires were getting heat-cycled and this was toward the end of a longer session. In a non-traction control car, you start to "drive" the car much more when the tires fall away which could actually result in you slowing your laps and corners down as you become acutely aware of the reduction in grip. It is a backwards way of thinking but if PTM is doing its magic behind the scenes, the driver may not recognize how close to the edge the car is getting until it breaks traction and physics takes over.
Last edited by fleming23; 01-11-2019 at 10:10 AM.
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01-11-2019, 11:17 AM
#25
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I know most won't agree with the following and I've argued PTM can actually be dangerous with people going WOT out of a turn and letting PTM sort out the rest because it is "faster", but I question whether running full off might have resulted in this not happening (then again we can what-if any scenario until we are blue in the face). I'm not even referencing the particular turn from the video, you can crash a car in any mode, but with no PTM intervention a driver (again, not using Bill's specific example) can feel the car start to fall away as the tires loose grip. As Bill did mention, the tires were getting heat-cycled and this was toward the end of a longer session. In a non-traction control car, you start to "drive" the car much more when the tires fall away which could actually result in you slowing your laps and corners down as you become acutely aware of the reduction in grip. It is a backwards way of thinking but if PTM is doing its magic behind the scenes, the driver may not recognize how close to the edge the car is getting until it breaks traction and physics takes over.
01-11-2019, 01:26 PM
#26
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I know most won't agree with the following and I've argued PTM can actually be dangerous with people going WOT out of a turn and letting PTM sort out the rest because it is "faster", but I question whether running full off might have resulted in this not happening (then again we can what-if any scenario until we are blue in the face). I'm not even referencing the particular turn from the video, you can crash a car in any mode, but with no PTM intervention a driver (again, not using Bill's specific example) can feel the car start to fall away as the tires loose grip. As Bill did mention, the tires were getting heat-cycled and this was toward the end of a longer session. In a non-traction control car, you start to "drive" the car much more when the tires fall away which could actually result in you slowing your laps and corners down as you become acutely aware of the reduction in grip. It is a backwards way of thinking but if PTM is doing its magic behind the scenes, the driver may not recognize how close to the edge the car is getting until it breaks traction and physics takes over.
Bill
01-11-2019, 01:35 PM
#27
Drifting
The car in the video is mine and I was driving. I had 305/660/18 front and 315/680/18 Pirelli Scrub Slicks. Cold Pressures were set at 26 psi and hot pressures after previous sessions were in the range of 32/33 psi across all 4 tires. The GM MR Calibration had been installed at the beginning of the year. The front alignment was set with -2.3 deg negative camber with +6.7 deg caster and about 1/32 of total toe in. Rear alignment was set at -1.7 deg camber with +0.7 deg of caster at each rear wheel with about 1/32 of total toe in and 0 deg thrust angle. The incident happened on the 10th lap after about 22 minutes of track time. My fastest lap was two laps before this where I turned a 2:07:90. The previous session I had turned a fastest lap of 2:06:90. I have turned laps as low as the high 2:03s over the last year.
Sean did the a great analysis and went into much more depth than he was able to when I first asked him to look at the data. he video shows I made a Rookie Mistake by applying too much throttle too soon. Whether or not I early apexed doesn't really matter as an experienced driver should be able to handle any corner entry since there are many things that can make them choose an off line entry. There are some things that a data recorder doesn't record. Tire Grip and Driver Focus are two of those things. T
From a Grip standpoint this event was the third event with these tires. They had 3 previous VIR track days and 2 Watkins Glen track days (or about 20 heat cycles) on them at the beginning of the day. I was at the end of my third 20+ minute session for the day when the incident happened. During the previous session I felt the rear tires starting to get greasy with the back end stepping out in several right hand turns.
From a Focus standpoint I was thinking about the run I wanted to make down the hill toward the Oak Tree corner (2 turns further).
That Focus led me to go full throttle too soon in the turn in an attempt to get that run down the hill and I didn't have the grip in the tires to do what I was trying to do.
All that defines a Rookie Mistake and that is what I told the Chief Instructor when he was filling out the insurance forms while I was being checked out in Medical. It turns out the mistake was a $7K lesson for me and hopefully others can learn from my error without spending that much money.
Bill
Sean did the a great analysis and went into much more depth than he was able to when I first asked him to look at the data. he video shows I made a Rookie Mistake by applying too much throttle too soon. Whether or not I early apexed doesn't really matter as an experienced driver should be able to handle any corner entry since there are many things that can make them choose an off line entry. There are some things that a data recorder doesn't record. Tire Grip and Driver Focus are two of those things. T
From a Grip standpoint this event was the third event with these tires. They had 3 previous VIR track days and 2 Watkins Glen track days (or about 20 heat cycles) on them at the beginning of the day. I was at the end of my third 20+ minute session for the day when the incident happened. During the previous session I felt the rear tires starting to get greasy with the back end stepping out in several right hand turns.
From a Focus standpoint I was thinking about the run I wanted to make down the hill toward the Oak Tree corner (2 turns further).
That Focus led me to go full throttle too soon in the turn in an attempt to get that run down the hill and I didn't have the grip in the tires to do what I was trying to do.
All that defines a Rookie Mistake and that is what I told the Chief Instructor when he was filling out the insurance forms while I was being checked out in Medical. It turns out the mistake was a $7K lesson for me and hopefully others can learn from my error without spending that much money.
Bill
I just wanted to say thanks for sharing this with us. I can honestly say that if this had happened to me, I would have done the same thing, (meaning, sharing the PDR), If I can help someone not make the same mistake I did, I am all in. Although I have only been to VIR 3 times, turn 10 does scare me because of all the crash videos online IN turn 10. The last time I was there, I purposely tried to either apex it perfectly or late and made sure the car was straight before going full throttle. And yes I run a little slower than you and Sean, but until I get as good as you guys, I am staying slower. this is extremely helpful.
01-11-2019, 02:09 PM
#28
Melting Slicks
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The one thing that is interesting is Mero's test video shows he hadn't selected any PTM mode. The video doesn't show any mode selection so that means none of the Track Submodes had been selected. I know on my car the only Driving Modes that show up on the screen are when one of the 5 Track Submodes are selected. If I have the dial in Track Mode but haven't pushed the center button twice nothing shows on the screen. Same goes for Tour and Sport.
Bill
Bill
Anyway, live and learn I suppose. At least your car has been repaired and is ready for more!
Last edited by fleming23; 01-11-2019 at 02:51 PM.
01-11-2019, 02:42 PM
#29
Melting Slicks
Thanks for sharing, Bill. Just awesome that you can help us learn from this. 
01-14-2019, 01:31 AM
#30
Drifting
I know most won't agree with the following and I've argued PTM can actually be dangerous with people going WOT out of a turn and letting PTM sort out the rest because it is "faster", but I question whether running full off might have resulted in this not happening (then again we can what-if any scenario until we are blue in the face). I'm not even referencing the particular turn from the video, you can crash a car in any mode, but with no PTM intervention a driver (again, not using Bill's specific example) can feel the car start to fall away as the tires loose grip. As Bill did mention, the tires were getting heat-cycled and this was toward the end of a longer session. In a non-traction control car, you start to "drive" the car much more when the tires fall away which could actually result in you slowing your laps and corners down as you become acutely aware of the reduction in grip. It is a backwards way of thinking but if PTM is doing its magic behind the scenes, the driver may not recognize how close to the edge the car is getting until it breaks traction and physics takes over.
What is surprising to me is that PTM doesn't 'catch' more of these incidents. I'd be curious to see what percentage of 'saves' they engineer for. The mathematics must be daunting...
01-14-2019, 10:25 AM
#31
Burning Brakes
Great information. A easy way to break down the problem is using the percentages for the accelerator, brake, and steering angle. All 3 of those added together should add up to roughly 100%. Accelerator at 80%. Steering angle should be 20% or less with 0% brake. As its clearly outlined by the red, blue, and green laps. On the red lap accelerator was over 90% with 30% steering input. Over 120% and it got loose.
Look at it as if you have $1.00 to spend between steering, braking and accel on the track and the roadway. Spend $0.90 on accel, you have only $0.10 on steering. $0.50 on the brakes, $0.50 on steering. Anything over 1.00 and you're overdrawn.
Great thread, thanks for sharing the info and taking the time to help others.
Look at it as if you have $1.00 to spend between steering, braking and accel on the track and the roadway. Spend $0.90 on accel, you have only $0.10 on steering. $0.50 on the brakes, $0.50 on steering. Anything over 1.00 and you're overdrawn.
Great thread, thanks for sharing the info and taking the time to help others.
01-14-2019, 02:45 PM
#32
I wondered the same thing after my first off. It helped me to understand that PTM is predictive as opposed to reactive. The PTM mode (Wet, Dry, Sport, Race) tells the car to assume a minimum level of traction. PTM won't intervene unless you ask for more torque than the expected traction level will permit without wheel spin. You can safely demonstrate this by using Wet mode on a dry, warm track with warm tires. PTM will prematurely shut things down even though there is plenty of available traction. On the other end of the spectrum in Race mode, if the available traction is less than the expected traction level, you are effectively running with TC off since PTM won't intervene when needed. PTM works within a fairly narrow window where the actual available traction matches the PTM pre-programmed levels for each mode. The PTM mode names use surface conditions (Wet, Dry) as a proxy for available traction, but it's really important to understand that these are just proxies. PTM Wet probably makes sense on a very cold dry track with cold tires. If you want help from PTM, make sure the mode matches the actual conditions.
01-14-2019, 08:33 PM
#33
Drifting
Thanks Sean for doing these; they are really awesome.
Would you be interested in looking at my T10 off in my 2015 Z51?
I did the analysis which really helped me understand the mistakes I made and how the vehicle reacted, but I am a neophyte compared to you in this area.
I turned over my analysis & video to several clubs that now use it as part of their advanced classroom training.
If so, assuming you just need the PDR file trimmed to +/- 30 seconds of the event?
Would you be interested in looking at my T10 off in my 2015 Z51?
I did the analysis which really helped me understand the mistakes I made and how the vehicle reacted, but I am a neophyte compared to you in this area.
I turned over my analysis & video to several clubs that now use it as part of their advanced classroom training.
If so, assuming you just need the PDR file trimmed to +/- 30 seconds of the event?
01-14-2019, 09:16 PM
#34
Track Rat
Thread Starter
Thanks Sean for doing these; they are really awesome.
Would you be interested in looking at my T10 off in my 2015 Z51?
I did the analysis which really helped me understand the mistakes I made and how the vehicle reacted, but I am a neophyte compared to you in this area.
I turned over my analysis & video to several clubs that now use it as part of their advanced classroom training.
If so, assuming you just need the PDR file trimmed to +/- 30 seconds of the event?
Would you be interested in looking at my T10 off in my 2015 Z51?
I did the analysis which really helped me understand the mistakes I made and how the vehicle reacted, but I am a neophyte compared to you in this area.
I turned over my analysis & video to several clubs that now use it as part of their advanced classroom training.
If so, assuming you just need the PDR file trimmed to +/- 30 seconds of the event?
Thanks to Chuck Hawks who is not just an awesome driver coach but apparently is also an AV expert I've ordered some better audio equipment for the next episode. I've started crunching through the data and as always it's never as simple as it looks in the beginning...
01-14-2019, 09:22 PM
#35
Track Rat
Thread Starter
I remember reading the $1.00 analogy in Twist of the Wrist and having my track day epiphany. I was tracking motorcycles a lot back then and folks would always talk about traction as a seat of the pants thing you just had to feel. I agree with the fact that you do get in tune with the bike/car and track after a time, but the $1.00 analogy always reminds me to think of the inputs I'm making and how much change I have left. Break the bank and you end up in the run off area (hopefully), or worse.
01-14-2019, 11:06 PM
#36
Drifting
Sure thing. I need the full PDR file so PM me a dropbox/onedrive/google drive link or I can send you one. If you edit these files it removes the data stream which is where all the good stuff is.
Thanks to Chuck Hawks who is not just an awesome driver coach but apparently is also an AV expert I've ordered some better audio equipment for the next episode. I've started crunching through the data and as always it's never as simple as it looks in the beginning...
Thanks to Chuck Hawks who is not just an awesome driver coach but apparently is also an AV expert I've ordered some better audio equipment for the next episode. I've started crunching through the data and as always it's never as simple as it looks in the beginning...
I may instruct at some of his teen driving schools at VIR this summer; we shall see. Not sure if I have the patience though...
I'll see if I can turn up the unedited PDR file,
Any updates on the disposition of your ZR1?
My Z06 is going to the body shop for work this week. The mechanics got into it last week and said the damage doesn't appear to be that bad, and it's very doubtful the frame is bent. I may be back instructing by mid-late February if all goes well.
01-15-2019, 01:02 AM
#37
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Bill
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01-15-2019, 12:33 PM
#38
Bill:
Thanks for sharing your experience with us. If you don't mind, can you share with us the damage and which insurance company you used. And, how they handled the claim.
Thanks for sharing your experience with us. If you don't mind, can you share with us the damage and which insurance company you used. And, how they handled the claim.
01-15-2019, 03:40 PM
#39
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Very easy and simple. Other than the original phone call and sending a couple of emails back and forth there was nothing else I had to do. Relatively painless other than paying the $7000 deductible and kicking myself in the butt for damaging my favorite car.
I would also like to thank Mark at AMT Motorsports for his help. When I went to purchase a replacement Granatelli Toe link from Granatelli they told me they would gladly sell me just one but they didn't have any in stock because they were changing suppliers and that it might be several months before they would be able to provide one. They told me to check with their vendors and to specifically ask if they had any in stock. If they didn't they wouldn't be getting any either. I had dealt with Mark previously so called him. He had a set in stock but wouldn't be able to separate them. I agreed that he really couldn't sell me just one. What he did do was provide a nice discount for the two and got them out to me right away. Great Customer Service. If you need the types of parts and services he provides give him a call.
Bill
Last edited by Bill Dearborn; 01-15-2019 at 03:42 PM.
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01-15-2019, 04:09 PM
#40
^^ Thanks for the response, and sorry for your car. I hope to meet you sometime at VIR.