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jvp asked:
There’s a lot of curiosity here and elsewhere as to what exactly happened with the yellow C7 Z06 at the N’Ring during your autumn visit. Do you have the data to know for sure, and can you share the details with us? I assume Mero's OK?
Tadge answered:
Since I wasn’t there and Jim was, I asked him to answer this week’s question. He goes beyond a narrow answer to the question, but some readers will be interested in more detail of what we do when we go to the Ring. Although fast laps get the headlines, the vast majority of our work there is related to tuning, testing and validation:
Jim Mero adds:
Although the day we hit the guard rail was almost 7 months ago it seems like it was yesterday.
As much as I’d like to have a super-cool story such as: the picture shown online was taken after we were airborne at 160 mph flipped 3 times and hit the Armco with a decel rate of 80g’s, when I started bleeding internally causing me to look much heavier than I actually am, unfortunately the actual story is quite simple and somewhat boring.
The incident happened on Monday September 29th which was the first day of Industrypool for the 2 week September session. It was also our first day on the track since September 2013. The track was open from 1 to 5pm conditions were dry (although it started raining shortly after the accident).
We were on the 5th and final session of the day tuning the dampers (our 10th lap). About 23 seconds into the lap, we entered the turn Hatzenbach exactly the same as we had during the previous 9 times. The car unexpectedly developed a vast amount of yaw acceleration rear to the left, I counter steered to the left, the rear of the car snapped back to the right and regained grip, immediately turning the car left head on into the Armco.
I wasn’t injured and we were recording data, and I thank god every day we were because immediately after the accident the only thing that perplexed me is “what happened”?
Upon examination of the data comparing the lap in question to the previous lap, up until the point the car lost grip, the speed, throttle, steering wheel angle, lateral acceleration etc., were pretty much identical.
I’ve put together a plot of Vehicle Speed, Throttle Position, Rear Wheel Speed, Steering Wheel Angle, Yaw Rate, and Yaw Rate Oversteer at the time of the incident. The Green Line is the previous lap, the Blue is the lap where the incident took place. As I stated, everything was line on line, then you can see a huge increase in yaw rate and yaw rate oversteer as well as the rear wheel speed at pretty much the same throttle position.
We sent the data files to Alex MacDonald our vehicle controls engineer and he stated that that only time he saw abrupt deviations in yaw rate in the oversteer coupled with a large decrease in lateral acceleration was when the car went from high coefficient of friction surfaces to very low coefficient friction surfaces. Not a dry surface to a wet surface, but a dry surface to ice or oil. So our theory is that another vehicle dropped a something slippery on the track and we hit it. Or, that’s my story and I’m sticking to it.
Some may also be wondering about data and video from out PDR system. The only thing I can say is the Nurburgring does not allow video recording during Industrypool time.
Being down 1 car was a major impediment to our goals for the remainder of the trip. We quickly moved to the blue automatic Z06, completing the Stage 1 and 2 aero package chassis tuning by the end of that week. One note is with the exception of heavy fog until about 10am, the weather the week of September 29th was outstanding.
Over the weekend of October 4th, 2014 our technicians converted the Blue automatic Z06 into a Z07. The changes included dampers, springs, complete brake assemblies, and an alignment including ride heights and cross weights and of course the correct rear caster.
Beginning October 6th, 2014, we completed a few days of tuning with the Z07. However, from sometime in the middle of the week of October 8th through November 15th the weather did a complete 180. During this time we never got an opportunity to run on a complete dry track. Between rain and fog, there were always sizeable wet sections prohibiting us from putting complete laps together. Also, in the 5 weeks between October 13th and November 15th, the track was open a total of 9 days, 4 of those were complete rain outs, the rest of them were with the track minimum ½ wet. We cherry picked our opportunities on a partially dry track to complete the tuning on the Z07 chassis package.
Friends and collogues always forward me forum inquiries about a fast laps. As we have always said, the fast lap is a secondary priority. The mission primary objective is to complete the tuning of the car for European roads and European driving habits. Having said that, I live for a fast lap opportunity.
Please note, when tuning the car we run at about 95%. The reason for this is twofold, first is consistency, you must be consistent to properly tune the car. The second is because when tuning the dampers or steering I always have a passenger monitoring and recording data for the shocks or steering algorithms and making the desired changes. I refuse to begin my quest to 100% with a passenger. When tuning is complete I will then drive alone exploring the limits of the car. Sometimes we don’t get these opportunities and just go for it after a day of tuning. This was the case in 2011 with the ZR1.
Also, the opportunities for exclusive track time have been diminishing over the past few years.
In 2008 we were able to rent the track for 50 minutes 2 times. Both times we were able to obtain a 7:26, both times on the second lap.
In 2011, we were given 3 “last lap of the day” opportunities. The first lap in the ZR1 was just over 7:20 which was not bad as I had to keep in mind that there was still work left to do the next day. We then completed our tuning right before the second attempt and I was able “go for it”. The second attempt produced the 7:19. After the second lap, Jeff Mosher and I looked at the data from the 2 laps. We could see improvements in the 7:19 lap and agreed a 7:17 was completely doable but we had only one attempt left. We chose to run the Z06 with the Z07 cup package as this car was magnificent to drive on the Nurburgring and the fast lap time for the Z06 was officially still at 7:43 without cup tires and from a standing start. Please note: Our data shows the standing start increases the lap time by about 1.5 second. This is because the start line is well inside the brake point (when making a flying start) and very close to first turn. With a single attempt we recorded a 7:22 second lap.
In 2013 with the C7 Z51, we had several last lap of the day opportunities. Rain prohibited every one of those attempts. One of these laps, I started about 3 to 4 minutes behind the Z28. This was the lap the Z28 recorded the 7:37 finishing in the rain. When I encountered the rain the track was more saturated than what Adam Dean (the Camaro driver) had encountered. I aborted the attempt after an 80 MPH drift as the track transitioned from dry to wet. Also, our objective for the Z51 was to obtain a lower time than the 7:37.9 of the Carrera S, and I knew completing the lap for a time in the wet would put the car at risk as we still had work left to do.
Now for the C7 Z06. As indicated above, after the about middle of the week October 6th, we never got a complete dry track. Also our tuning objectives had not been complete. I did had a few opportunities on the very last ½ day the Nurburgring was open for 2014 to run alone (in the car) on few the dry sections of the track for speed. We have data, we have segments, we have an idea what the car should be capable of. But we don’t post any time unless they are complete laps supported by video, so I have to just leave it at that. Sorry folks…
Last edited by jvp; 03-13-2015 at 12:56 PM.
Reason: Fixed punctuation.
Great explanation of the ring events. I started a thread on this that went on for weeks. There is so much interest in this and our forum has a large following of ring enthusiasts. I personally follow Bridge to Gantry and there was a lot of talk about the segment time analysis that Jim Mero refers to in the last paragraph. Evidently there were some crazy fast segments that they would be able to stitch together for a crazy fast time. Thankfully GM doesn't subscribe to segment time projections like our friends at Porsche have done in the past. Next year we'll get a time !!!
Two things from this for me: 1)I'm glad Mero wasn't hurt. I honestly wasn't as concerned about the car as GM can just make another one. Jim's irreplaceable. 2)That Jim took the time to write that epic book is fantastic for all of us. Tadge and I were both a little concerned it might lean a bit too far to the technical side at first, but ultimately I decided folks should just read and ask questions if they have them. To me it seems pretty straightforward; hopefully others understand and agree!
The more technical, the better !! The more educated the Corvette fan base becomes, the better Team Corvette responds. I went to LeMans last year and you cannot believe how many Euro Corvette fans were there asking questions about the car. On Friday the day before the race there were hordes of people around the Corvette pit, hungry for info and a look at the C7R.
Two things from this for me: 1)I'm glad Mero wasn't hurt. I honestly wasn't as concerned about the car as GM can just make another one. Jim's irreplaceable. 2)That Jim took the time to write that epic book is fantastic for all of us. Tadge and I were both a little concerned it might lean a bit too far to the technical side at first, but ultimately I decided folks should just read and ask questions if they have them. To me it seems pretty straightforward; hopefully others understand and agree!
Thanks again JVP, Tadge, and Jim. Funny thing I get from this is my famous spin at Rd Atlanta. Basically same situation. Speeds, braking, turn ins close. Car over steered at random car spun. I didn't attempt to catch it knowing the consequences. Its like the aero holding the car just let go in the turn. I was blaming the 40 psi rear tire pressures that I found on pit out. But just what if there is a period of just were the fabulous aero these cars just lets go? I know its way over some people's head they still will blame me.
That is a great response from Jim. That should put most speculation to rest regarding why it never got a time. I would be interested to find out for kicks sake what those segmented times equate to. Interesting as well that the ZR1 had a potential 7:17 and amazing what the Z07 pkg on the Z06 did to get 7:22. Damn!!!
Everything Jim said is perfectly logical and makes sense, and I much appreciate the thorough and technical answer.
But, a 'Ring time is a marketing tool. It is bragging rights. It is tres cool. So, Chevy needs to go to the 'Ring with a fully and finally tuned car and rip it for time. Let Johnny O or someone like that drive it if they need to so their test driver doesn't miss his next test. Rent the track, and get a time. Not because it is part of the turning process, or data gathering, etc., but for bragging rights, and because their competitors are all doing it.
Today, selling cars is about marketing, and fast 'Ring times sell fast cars....
Last edited by quick04Z06; 03-13-2015 at 04:34 PM.
As much as I’d like to have a super-cool story such as: the picture shown online was taken after we were airborne at 160 mph flipped 3 times and hit the Armco with a decel rate of 80g’s, when I started bleeding internally causing me to look much heavier than I actually am...
......
Originally Posted by Jim Mero
In 2013 with the C7 Z51, we had several last lap of the day opportunities. Rain prohibited every one of those attempts. One of these laps, I started about 3 to 4 minutes behind the Z28. This was the lap the Z28 recorded the 7:37 finishing in the rain. When I encountered the rain the track was more saturated than what Adam Dean (the Camaro driver) had encountered. I aborted the attempt after an 80 MPH drift as the track transitioned from dry to wet.
Here is an interesting article on Bridge to Gantry by Dale Lomas on the possibility of the ZO6 doing a sub 7 minute ring lap. Interesting rumor talk on the segment analysis over there in a German restaurant called Pistenklause. http://bridgetogantry.com/2/index.ph...eally-go-sub-7
Here is an interesting article on Bridge to Gantry by Dale Lomas on the possibility of the ZO6 doing a sub 7 minute ring lap. Interesting rumor talk on the segment analysis over there in a German restaurant called Pistenklause. http://bridgetogantry.com/2/index.ph...eally-go-sub-7
Sub 7 minute is too much i see something of 7:10 or below.
Excellent and detailed response from the man himself!
We have data, we have segments, we have an idea what the car should be capable of. But we don’t post any time unless they are complete laps supported by video, so I have to just leave it at that.
The Corvette team set the high-water mark in 2011 for video documentation of Nurburgring laps. It would be all too easy for them to basically make a lap time projection for the new Z06 as there is evidently enough data to do that. This is the Porsche standard as evidenced by their 7:20 projection for the new GT3 RS - oh, and don't hold your breath on that video as there isn't one. Nothing wrong with a projection especially when it is based on sufficient empirical as well as modeled data, but it's just not the Corvette standard.
It would be neat if Jim and/or Tadge could share when they expect to make another attempt. It may be later in the year and I suspect that it will be worth the wait.
I lived in Germany '82-'85, and have travelled back a couple times. I have driven the 'Ring, and was driving through the Eifel regularly. I know from personal experience how the 'Ring' has various microclimates from one segment to another. The Eifel is famous for that. It has to be wicked difficult to test there, and get a full flying lap in. Getting ahold of the track for testing is also difficult, and shipping all that testing gear is expensive. The "Lutzring" may be used more and more for calibration. It is a shame. Dueling 'ring runs between manufacturers makes for good fun and a baseline to compare cars in a general way.
Happy Jim Mero was OK. Thanks for the story.
Now get back out there and rip a 7 minute flat!
Two things from this for me: 1)I'm glad Mero wasn't hurt. I honestly wasn't as concerned about the car as GM can just make another one. Jim's irreplaceable. 2)That Jim took the time to write that epic book is fantastic for all of us. Tadge and I were both a little concerned it might lean a bit too far to the technical side at first, but ultimately I decided folks should just read and ask questions if they have them. To me it seems pretty straightforward; hopefully others understand and agree!
Today, selling cars is about marketing, and fast 'Ring times sell fast cars....
I do not agree. I don't think the general consensus of people seriously able to purchase the C7 ZO6 are going to hold off or buy the competition jus because GM was not able to get a official Ring lap time.
Does anyone else find it REMARKABLE that we have Jim Mero answering the question AND providing data????
And kudos to jvp for making this happen. It's just amazing that these guys take time out of their day to do this.
And to Jim Mero....THE CAMERA ADDS 10 POUNDS, you look lean and mean in person!
Jimmy
PS. I learned a lot from Jim about how things work at the Nurburgring. Many on this Forum have implied (or said) that there was some big conspiracy as to why no time was posted. Hopefully, they read this and now understand.
I believe we are spoiled on here with Tadge answering and now Jim. Great answers and thank you for taking the time to post Jim Mero. You do have a skill with the written word and I am dying for more. This is the type of article us gearheads love.
Can we please have more updates from Jim on a regular basis? Maybe some track tips, updates on testing, or just some good old stories about life behind the scenes.
03-13-2015, 12:34 PM
[ANSWERED] Nurburgring and the C7 Z06
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