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[VIDEO] Why Did I Crash - Episode 2

Old 01-08-2019, 10:24 PM
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Poor-sha
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Default [VIDEO] Why Did I Crash - Episode 2

I started this video series last week and just posted the latest episode to my channel. This is designed to help all of us learn from the mistakes of others at the track and since the two I've done so far were both C7 Z06s I thought I'd post this one here. Big thanks to the driver for being willing to share their data and making this possible.

In case you missed the first episode it's here:
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Old 01-08-2019, 11:08 PM
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eddie-d
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Default Thanks for the insights....

This was super-helpful! ...and especially relevant for me as I anxiously await starting tracking my car this season. Thank you.
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Old 01-08-2019, 11:44 PM
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Great analysis. Lots to learn for a beginner like me, and this is very informative. Thanks to the guys who submitted your PDRs, so others could benefit.
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Old 01-08-2019, 11:50 PM
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Excellent thread, extremely informative. Keep ‘em coming!
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Old 01-09-2019, 12:24 AM
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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.
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Old 01-09-2019, 12:44 AM
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Originally Posted by Poor-sha View Post
I started this video series last week and just posted the latest episode to my channel. This is designed to help all of us learn from the mistakes of others at the track and since the two I've done so far were both C7 Z06s I thought I'd post this one here. Big thanks to the driver for being willing to share their data and making this possible.
https://youtu.be/vCbmPL9PLps

In case you missed the first episode it's here:
https://www.youtube.com/watch?v=F32E7QCijJU
Many thanks for taking the time to analyze and share the information/data, Poor-sha. That's very kind of you to do that and post. Just had 3 questions if you don't mind: 1) What specific tires and sizes were on each of the cars (episode 1 and 2) and what general conditions were they in (if you can comment of this)? 2) What was the resultant G loading when the back end came loose for each car? (3) Do you have any recommendations on how to train yourself not to lift as much off the throttle when you sense grip is lost in the back end? I have a bad habit of doing the same (over lifting), as I like 2nd gear too much and seem to fight the back end upon corner exit and beyond. So I'm in this situation more than I like. Thanks in advance for your time. Kind regards.
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Old 01-09-2019, 12:51 AM
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RegnaR
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Awesome! Some useful videos. Sucks that his car slid all the way into the wall.
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Old 01-09-2019, 07:40 AM
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Warp Factor
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Very nicely done, Poor-sha!
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Old 01-09-2019, 09:25 AM
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That was in the ZR1??
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Old 01-09-2019, 10:51 AM
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Originally Posted by Ice95z View Post
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.
That's way too conservative. When I was at Spring Mountain they taught me to ease into the throttle at or just past the apex. Here's a pic of me unwinding the wheel at 68 degrees and already at full throttle. I can do more screen shots to show you the progression. This was EXACTLY as they taught me.



Last edited by fatsport; 01-09-2019 at 01:28 PM.
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Old 01-09-2019, 01:59 PM
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PTM Race setting is a force to be reckoned with! I barely even go into Sport 2. For me, Sport 1 is where all the fun is at.
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Old 01-09-2019, 07:42 PM
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Thanks man, nicely done and helpful.
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Old 01-09-2019, 07:47 PM
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Bad_AX
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Thanks for another interesting and detailed analysis.

I would love to see the entire lap leading up to the crash. The question that comes to my mind is why was the driver putting in so much steering angle while going aggressive with the throttle? I think the driver probably apexed too early all the up through the esses including turn 10. In the approach to 10 he is not using the whole track, he apexes 10 very early and is digging out with a lot of throttle. The early apex means he has to steer the car more to complete the turn and application of throttle yields a predictable outcome. The steering input is like braking only the front wheels while dialing up over 600 lb/ft of torque to the rear wheels. The data explains the how, but the video gives us the why.

Last edited by Bad_AX; 01-09-2019 at 07:47 PM.
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Old 01-09-2019, 10:45 PM
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Tires? Suspension setup? Track temperature? To prevent crashes at HPDE where it isn't worth it, maybe drive 9.5 tenths, & don't early apex.
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Old 01-10-2019, 02:15 AM
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Thanks for the videos. Really liked the data traces. I donít push for early throttle at my HPDE and these crashes are a good reminder why I donít. Not going to try and set lap time records in my weekend cruiser just dialing it back 25í on braking or 10% throttle can make all the difference.
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Old 01-10-2019, 06:30 AM
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In the GM official video at VIR in a C7 Z06 with the magnetic ride calibration update, the driver almost loses it at the same spot, going over that crest, just past 1:03 into the video below. I'm also wondering just how unforgiving the Sport Cup 2's are (a case of "all or nothing grip"). I have the MPSS on my 2015 C7 Z06 3LZ M7, and noticed a big difference in acceleration when the tires are spinning and when the traction control kicks in, which is a straight line traction issue, and may not reflect the cornering characteristics of the tires.



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Old 01-10-2019, 09:14 AM
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Originally Posted by rcgldr View Post
In the GM official video at VIR in a C7 Z06 with the magnetic ride calibration update, the driver almost loses it at the same spot, going over that crest, just past 1:03 into the video below. I'm also wondering just how unforgiving the Sport Cup 2's are (a case of "all or nothing grip"). I have the MPSS on my 2015 C7 Z06 3LZ M7, and noticed a big difference in acceleration when the tires are spinning and when the traction control kicks in, which is a straight line traction issue, and may not reflect the cornering characteristics of the tires.

https://www.youtube.com/watch?v=Hq0cvWZkv5I
Interesting video. Full throttle while still cresting that hill, when downforce is reduced.
Also sounds like he is using the sound of the rev limiter to tell him when to upshift.
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Old 01-10-2019, 10:02 AM
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Hey I know that Z06, the driver, and have had intimate encounters with the T10 tirewall as well.

Thanks for taking the time to do this Sean!

Any update re your ZR1?
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Old 01-10-2019, 10:25 AM
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Originally Posted by Bad_AX View Post
Thanks for another interesting and detailed analysis.

I would love to see the entire lap leading up to the crash. The question that comes to my mind is why was the driver putting in so much steering angle while going aggressive with the throttle? I think the driver probably apexed too early all the up through the esses including turn 10. In the approach to 10 he is not using the whole track, he apexes 10 very early and is digging out with a lot of throttle. The early apex means he has to steer the car more to complete the turn and application of throttle yields a predictable outcome. The steering input is like braking only the front wheels while dialing up over 600 lb/ft of torque to the rear wheels. The data explains the how, but the video gives us the why.
I spoke to him afterward. He's an accomplished driver/instructor.

He pinched the turn & didn't unwind the wheel to track out. Everything was solid until after the apex.

T10 falls off camber so if the car isn't positioned correctly and you are heavy in the throttle, the rear will come around, even on Pirelli scrubs which he was running...
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Old 01-10-2019, 11:15 PM
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Other than tires (crash with Pirelli scrubs versus GM official run with Sport Cup 2's), were there any other differences, such as the magnetic ride calibration update? In the crash video, the Z06 is going about 90 mph, while in the GM video, the Z06 is going 100 mph and at full throttle by that point. What you can't see in the GM video is how quickly or by how much the driver (Jim Mero?) corrected to recover from the rear end stepping out a bit.

There is also a video of Randy Pobst at Laguna Seca with the 2015 Z06 before the calibration update, and he's having to make quick corrective actions to recover from the oversteer in a few of the turns. Randy comments on the entry oversteer a bit after 6:00 into the video below, and it can be seen and commented on from 6:00 to 7:20 or so into the video.


Last edited by rcgldr; 01-10-2019 at 11:17 PM.
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