Mu$cle

Another great job. Thanks for expending your time to help educate us.

NSFW

Very educational, thanks!

_zebra

yeah, the couple times i was there, that turn was a conservative one because of how tight it is - especially relative to coming off that 1st straight.
my flub was passing a guy into turn 1 & going in 20mph too hot on the left, whereby i ran out of pavement while braking & had to start turning right as the suspension unloaded - sending my back end around just enough for me to kiss the inside wall & bounce back across to the left grass.

truth.b

Poor-sha,

Thanks again for the putting in the time to bring this content to the community. Do you think the same/similar analysis can be done on a C6 with and Aim SoloDL? I know we don't have a brake channel but for the most part I think everything else is there. Lastly, how does the vertical (g) channel work ? Meaning if 1.0g is when the car is perfectly flat at equilibrium, than is 0.90g when the car is unweighted (i.e suspension under rebound) and 1.10g weighted (i.e. suspension under compression)?

harrydirty

I think the vertical channels are for acceleration and braking...........

Poor-sha

Sure you could do a lot of the same things with an Aim. It just depends on what channels are there and what you can reconstruct from other sources or a math channel. For instance, you can use longitudinal G to infer braking. On the vertical Gs, 1.0 is flat, 0.9 means the car is unweighted so in effect it weights 10% less like going over a rise, 1.1G would mean it is being compressed so it in effect weighs 10% more like the compression in hogpen.

That would be the longitudinal G.

harrydirty

Ah, so the channels are programmable for vertical acceleration as well, did not know that.......it would be interesting to watch data for Laguna's Corkscrew.

Poor-sha

Episode 3 is live, this week it's T17 at VIR and a C7 GS. Thanks as always to the driver that provided the data.

fleming23

It doesn't take much to upset a car when you are pushing the limit of traction.... Forgot I had this close call. I can hear myself playing with the throttle, trying to maximize corner grip by getting the car to the limit. It sounds like I may have just barely lifted a little at corner exit which was enough to upset the car. Fortunately(?) I was able to get it into a tank slapper instead of looping around into the wall. Pretty sure I forgot to put the SD card back in before the trip, so no data.

GoatHead

In episode No.3. The main reason for loosing the rear end was lack of grip and sudden throttle left, right?

What is the best course of action in situation like this (loosing the rear end due to lack for grip in a corner)?

1- Breath the throttle and hope additional grip is gained?
2- Straighten the wheel, go off road, brake and clutch in?
???

Please discuss.

Thanks,

Poor-sha

I believe the cause was that he dropped one or both wheels off track. The best thing to do is straighten the wheel and breath off the throttle. Ride it out off road and slowly release throttle. Do not snap the throttle shut.

TKOGTO

This may be semantics but IMO the main reason for losing the rear end happens well before the throttle lift. Had the driver entered Hog Pen @ a speed that allowed him to put enough steering in to keep him from going wide, the lift would not had been necessary. Inability to put enough steering in, likely from a bit too much speed caused the crash. Sean mentions this in the vid.

Hopefully the driver takes comfort in the fact that this error occurs all too often. I have been guilty of this quite often @ the downhill @ LRP as I try push the envelope on entry speed. I did the same 3 or 4 times @ Hog Pen in my 1st visit to VIR last Oct. I carry too much speed on entry (either not enough brake in the brake zone or a bit too much throttle after turn in). This prevents enough steering input to make it anywhere near the apex. If I did apply the necessary steering, I wouldn't need to wait for an excessive throttle lift near track out to crash as I would have spun out before mid-corner. What has saved my bacon in these cases is early recognition. As soon as I see I have no shot @ the apex, I back off on the gas to ~ 15% throttle, hold the wheel steady until I pass the apex then slowly straighten the wheel while maintaining the lowest level of maintenance throttle as possible. Essentially, I give up the corner. If I need to countersteer near track out, it is usually not much. The reduced speed and lower g's allows me to countersteer and/or go 2 off without snap hooking it to the inside.

The lesson here is early recognition. If you're going to miss the apex by a fair amount, give up immediately. Survive the mistake with your car intact and correct the mistake the next time around. I look at it as a competition vs. the track. When I mess up, the track wins. The next lap, it's payback time. Of course, if you don't recognize early, never snap off with the suspension loaded. A slightish lift is crisis management. Necessary to know and execute but focus on the underlying (initial) cause and hopefully avoid it altogether.

NSFW

What do you all think of putting the clutch in, rather than easing off the throttle? Probably slower that way, but I'm guessing it would be a little easier to recover from a slide/spin that way, and I'm more concerned with staying off the walls than with winning.

Your thoughts?

GoatHead

Thanks for your perspective. It make sense to me. Hopefully, there is enough room to go off track.

truth.b

For the class,

I have a general question for those that have experience with driving the C7 platform near or slightly over the limit. In various videos I've seen including those listed; it seems that when a C7 lets go it is very sudden/quick, violent, and usually with the back-end coming around. In general, what do you guys think? Is this anecdotal? Are these types of wrecks a by-product of the C7's platform much higher performance envelope and the type of driving situations? To me it seems like if the driver gets in over his/her head and comes off the throttle too much the back-end "will" come around very 911 like. Do you guys think it was the same on C6's? If not, why?

Racingswh

In this last crash example, from my armchair Quarterback position, I am just thinking what I might have done. Don't know if it's correct or not. Being so far off the apex on the right I would have tried to recognize the "definitely going to be wide left" car placement for the corner as early as possible. If I was able I would have immediately opened my hands left to straighten the car and gone to the brakes really hard making that last bit of track a brake zone before I went into the grass as straight as possible. Once the car was slowed down a little more I would have come off the brakes and let the car roll out into the grass on the left and then back to maintenance throttle and slowly "guide" the car back on the track keeping the steering wheel as straight as possible.

As far as C7's are concerned I found the Grand Sport to be a fun and pretty easy car to drive on the track in the dry. Way easier than a stock or stockish C6Z which we had as well IMO. That said the C7GS is the only car that has really caught me out since 2001 at Laguna Seca when I destroyed a Barber Dodge open wheel car. It happened on a cold, damp day and man did it come around quick when it did.

Stock other than pads with nannies set to Track/Race

Spin that caught me out NJMP Tbolt track:


Same event but NJMP Lightning track in the cold but dry and the car seemed fine:

ErnieN85

TKOGTO

A good question Truth.

Although I have not driven a C7 Z06 in anger on track, my first impression when seeing Sean's vids were exactly what you've observed / are questioning, i.e., "a C7 lets go it is very sudden/quick, violent, and usually with the back-end coming around." I have not seen this with base or GS C7 models, just the Z06. To me, the most informative part of Sean's vids are the torque charts. Having the motor produce ~650 lb/ft @ 85-90mph on entry to T10 @ VIR is staggering and clear evidence it is quite easy to lose the rear with the C7 Z06. You may recall magazine reviews of the C6 noting one of the negatives being snap oversteer. In the GS, that's @ 435 lb/ft. Throw in another 215 and it's no wonder even very good drivers loop them from time to time.

I do think snap oversteer is an issue with the C6, just @ a much reduced level.

The HACK

ANY front engined, rear wheel driven platform will behave just like this, not just the C7. You can drive in a lowly Miata and when you lift off throttle when in trouble, it will spin around exactly like a C7 (insert model here). The only difference is the limit of adhesion is so much higher in a Corvette and the terminal speed so much quicker that in a car like a Miata it'll give you ample time to correct, pause, and recover.

As for the back-end coming around "911" like? No. The 911 has so much of its mass concentrated on or behind the rear wheels that when it goes into a pendulum pivoting on the front tire, it snaps around much more quickly and violently. The C7 actually drives and moves much like a high horsepower BMW M car than a Porsche.

village idiot

Kind of. C7 has 50-50 weight but it's at the far polar extremes