ZR1 Pace Car at Detroit just crashed
06-06-2018, 05:54 PM
#341
I noticed the brake indicator in the PDR showed brake apply after you let off the throttle. Was that AH or you touching the brakes? I need to look at some of my own videos because I am not sure if it shows when AH applies brake, but I assume its just based on the brake pressure sensor.
I don't believe I touched the brakes but my 2015 did have a brake pedal position sensor that even at rest read about 4% pedal position. Looking at the steering data I suspect that the violent shake back and forth moved the pedal some or it's possible I touched the brakes as I was all arms and elbows inside the car. It doesn't look like AH intervention itself though will show up in the brake trace since that is from a pedal position sensor and not true brake application.
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djnice (06-07-2018)
06-06-2018, 07:07 PM
#343
I find it hard to be too critical of either the car or the driver -IMHO he was a victim of the hump and unlucky timing of power application. If you look at the video at 29 seconds, he applied counter-steer correction plenty early, but the car's balance is already upset. As the pavement continues to fall away on the backside of the hump (@ 30 seconds), the car is rolled to the right, the front wheels have insufficient pavement contact to be very effective in rotating the nose to the right (car needs to roll left to turn right by taking advantage of the dynamic camber), and the black marks from the rear tires appear to be coming only from the right side (passenger side) of the tires. It's a lot like a NASCAR car being tapped in the left rear (or losing aero downforce) at corner exit. If you unload the rear tires and apply power, you're probably along for the ride - nannies or not. Been there/done that - lightly tapped in the left rear as I applied full throttle off turn 4 at the Vegas Bull Ring in a Super Late Model - shot me head-on into the inside retaining wall - took about 2 seconds.
Pappy
Pappy
06-06-2018, 07:12 PM
#344
Le Mans Master
The car was in the wrong mode and there was an inappropriate response! ;)
I suspect that Mark was pretty excited to get out and pace the field and would have been on cold tires. He probably did get a little exuberant with the throttle in his excitement and maybe there was a bump that upset the car the rest was pretty much over from there. What I don't understand is that it sure looks like he had everything turned off when I see no reason he couldn't have run pace laps in Track - Sport 1 and left himself a safety margin. That seems like a poor judgement call but perhaps there is some other reason why they felt it needed to be off (course too bumpy?).
(IE Flying car available in touring?
) Goosing the throttle in touring!The appropriate response was cutting power and a right rear brake (the wheel that powered it into the wall - Thanks Pappy!)
Last edited by johnglenntwo; 06-06-2018 at 07:44 PM.
06-06-2018, 07:39 PM
#345
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See contributing cause #1 in Post #191 immediately above your post. Get your chassis setup with a proper alignment. Do some searching in the C7Z forum for several days worth of reading on how to address the issue you're experiencing. Operative words being REAR CASTER, REAR CASTER, REAR CASTER!!!
Rick
P.S. PLEASE note that few dealers and/or shops are unaware that the rear caster is adjustable on the C7. If they do know they don't have the tools/equipment to set it or they will lie to you and tell you they do.
Rick
P.S. PLEASE note that few dealers and/or shops are unaware that the rear caster is adjustable on the C7. If they do know they don't have the tools/equipment to set it or they will lie to you and tell you they do.
06-06-2018, 07:51 PM
#346
Racer
According to https://www.gmfleet.com/technology/stabilitrak.html, I think Stabilitrak should have applied the passenger-side front brake. Does anyone know if Stabilitrak also applies the brake lights? The brake lights were functional as you can see them on after he hits the wall.
I also wonder if cruise control had been set? That shouldn’t make a difference to Stabilitrak. But, it does make sense that a pace car driver would set it almost immediately.
It does not make any sense that a GM executive driving a pace car would disable any safety system, such as Stabilitrak.
This whole scenario just does not add up #headscratcher
I also wonder if cruise control had been set? That shouldn’t make a difference to Stabilitrak. But, it does make sense that a pace car driver would set it almost immediately.
It does not make any sense that a GM executive driving a pace car would disable any safety system, such as Stabilitrak.
This whole scenario just does not add up #headscratcher
06-06-2018, 08:14 PM
#348
So what’s a tank slapper and what does 2 feet in mean for us non track guys?
Also, why don’t you let off the throttle fully if you start to spin? So if you start a slide with all the nannies on should you let off the gas or not?
I did did the owners school but must have zoned out on the skid pad due to having too much fun. I kept letting off the gas when the spin started and tried to steer out and was unsuccessful each time with the nannies off.
But in wet mode, the computer shut the engine down when the spin started and I was easily able to recover. Out of habit, I kept letting off the throttle when the spin started and the engine sounded like it was cutting out. I can’t remember if the instructor was telling me to stay on the throttle or not. I think he was trying to say something about the computer resetting when I let off the gas.
Might as well learn something from this event.
Thanks!
Also, why don’t you let off the throttle fully if you start to spin? So if you start a slide with all the nannies on should you let off the gas or not?
I did did the owners school but must have zoned out on the skid pad due to having too much fun. I kept letting off the gas when the spin started and tried to steer out and was unsuccessful each time with the nannies off.
But in wet mode, the computer shut the engine down when the spin started and I was easily able to recover. Out of habit, I kept letting off the throttle when the spin started and the engine sounded like it was cutting out. I can’t remember if the instructor was telling me to stay on the throttle or not. I think he was trying to say something about the computer resetting when I let off the gas.
Might as well learn something from this event.
Thanks!
06-06-2018, 08:18 PM
#349
Le Mans Master
Good point on the front brake!
According to https://www.gmfleet.com/technology/stabilitrak.html, I think Stabilitrak should have applied the passenger-side front brake. Does anyone know if Stabilitrak also applies the brake lights? The brake lights were functional as you can see them on after he hits the wall.
I also wonder if cruise control had been set? That shouldn’t make a difference to Stabilitrak. But, it does make sense that a pace car driver would set it almost immediately.
It does not make any sense that a GM executive driving a pace car would disable any safety system, such as Stabilitrak.
This whole scenario just does not add up #headscratcher
I also wonder if cruise control had been set? That shouldn’t make a difference to Stabilitrak. But, it does make sense that a pace car driver would set it almost immediately.
It does not make any sense that a GM executive driving a pace car would disable any safety system, such as Stabilitrak.
This whole scenario just does not add up #headscratcher
06-06-2018, 08:25 PM
#350
Safety Car
Cold tires on a supercharged C7 is no joke. I had a similar experience twice in the C7 Z06, except I got lucky with lots of runoff to spin the car. If you turn off the TC and AH in track mode and have cold Cup 2 tires, anything can happen instantly in the C7. You can be Lewis Hamilton and still wreck it.
C7 is not the kind of car you can lean on on cold tires and nannies off. Simple.
I tracked the car for 3 years but in those two instances it was luck that saved me.
There are three choices here, different tires, nannies on, or a Camaro.
C7 is not the kind of car you can lean on on cold tires and nannies off. Simple.
I tracked the car for 3 years but in those two instances it was luck that saved me.
There are three choices here, different tires, nannies on, or a Camaro.
06-06-2018, 09:23 PM
#352
In a spin both feet in means to fully depress the clutch and the brake. Disengaging the clutch will stop any more power from going to the driven wheels and standing on the brakes should lock up all four wheels. It's not going to stop you from spinning but should stop the car in the minimum amount of travel distance.
As far as what to do in a slide with the nannies really depends on your relative skill level, what caused the slide, and what the car is doing. In power induced oversteer which I think we are presuming here the motor is spinning the wheels which causes them to lose traction. Ideally you want to breath off the accelerator enough to them to stop spinning but not so much that it drastically unweights the rear. Typically the AH can straighten the car out before you have time to do much because it can brake individual wheels which you cannot.
I did did the owners school but must have zoned out on the skid pad due to having too much fun. I kept letting off the gas when the spin started and tried to steer out and was unsuccessful each time with the nannies off.
But in wet mode, the computer shut the engine down when the spin started and I was easily able to recover. Out of habit, I kept letting off the throttle when the spin started and the engine sounded like it was cutting out. I can’t remember if the instructor was telling me to stay on the throttle or not. I think he was trying to say something about the computer resetting when I let off the gas.
Might as well learn something from this event.
But in wet mode, the computer shut the engine down when the spin started and I was easily able to recover. Out of habit, I kept letting off the throttle when the spin started and the engine sounded like it was cutting out. I can’t remember if the instructor was telling me to stay on the throttle or not. I think he was trying to say something about the computer resetting when I let off the gas.
Might as well learn something from this event.
06-07-2018, 05:03 AM
#353
Melting Slicks
You prompted me to go back and dig up the data. Here is a zoomed in trace of accel, brake, speed, steering angle, and when the AH was active for the less than 3 seconds that tank slapper occurred.
It doesn't look like AH intervention itself though will show up in the brake trace since that is from a pedal position sensor and not true brake application.
It doesn't look like AH intervention itself though will show up in the brake trace since that is from a pedal position sensor and not true brake application.
06-07-2018, 07:18 AM
#354
Le Mans Master
Hopefully it's not 755 HP, 3,600lbs, and FME, Plus bumps exceeds PTM! :0
Contrary to an Aerspace Masters Validation otherwise (SC C7)!?
I guess they are just going to have to prove it at that infamous bumpy European track after all!
(Watch that Popcorn it's radioactive!
)
I guess they are just going to have to prove it at that infamous bumpy European track after all!
(Watch that Popcorn it's radioactive!)
Last edited by johnglenntwo; 06-07-2018 at 09:40 PM.
06-07-2018, 07:33 AM
#355
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The simple answer is driver error, 1) too much throttle as soon as he saw the straight around the bend, 2) Traction Control off.
I do feel bad for Mark though.
I’m guessing that’s about a $10-15k repair. Possibly more.
I do feel bad for Mark though.
I’m guessing that’s about a $10-15k repair. Possibly more.
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Foosh (06-07-2018)
06-07-2018, 08:44 AM
#356
Le Mans Master
I believe the term tank slapper started in the motorcycle world where the bars wobbled side to side, thus "slapping the fuel tank".
Last edited by rbartick; 06-07-2018 at 12:39 PM.
06-07-2018, 09:03 AM
#357
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Not being a biker, I'm not criticizing but looking for education...
06-07-2018, 09:38 AM
#359
Le Mans Master
Objective C7R TC switch/pot? ;)
Why wouldn't it just stay on? Could it be just for those more limited traction times. IE Cold or worn tires, and weather
It sure would be nice to have everything and everyone working on the same page by CPU aumented always On Chassis Control, and idiot proofed. Fragmented
in between the lines - NOT. Can't connect the dots. Just sayin!
It sure would be nice to have everything and everyone working on the same page by CPU aumented always On Chassis Control, and idiot proofed. Fragmented
in between the lines - NOT. Can't connect the dots. Just sayin!
Last edited by johnglenntwo; 06-07-2018 at 10:22 AM.
Am I the only one having trouble following/understanding his posts?