Forum Question: Accident
 

Three days ago while driving in las Vegas, I was passing some slower traffic and accelerating at about half throttle in third gear (about 50/60 mph) when the car abruptly made a 90 degree right hand turn with zero contol (competitive driving mode on). No amount of correction seemed to work as the brakes afforded no help either. The car spun a 720, hit another SUV (lightly) and proceeded to curb facing the opposite way before going airborne three feet and coming to rest in the dirt enbankment/ditch between two light poles. It was clear, no oil or other contaminants on the road surface visible and absolutely no warning. The off-duty officer behind me said it looked like a blow-out of the left rear but it acted like a catastrophic parts failure (like CV or half shaft), locking a wheel? Anyone heard of anything like this anywhere else? Damage estimates are near the $24,000 mark. Was ticketed for a "unsafe" lane change. Strange as I was going straight when it happened and wasn't even shifting or changing lanes. Guess I didn't signal when I was out of control???

Dunno! It would sound like a missed shift from 3rd to 2nd instead to fourth. But you said you weren't shifting. :willy:

Sorry to read of your misfortune.

Couple questions.

Night or daytime?

What was the air temp?

How far had the car been driven?

A characteristic behavior of the C6Z tires is poor traction at cold temps, meaning a combination of road surface temp and tire temp.

If you were to add to that
(1) a steering wheel not center, eg turned to render a lane change AND
(2) application of throttle, even 3d at 50-60

Then you have a combination that will unsettle the car.

Most owners have experienced that combination, but were fortunate to have different results than you did.

Ranger

I find it hard to believe that the cops would ticket you when one of there own said it was due to the rear tire blowing. That sucks...unless the tires were balled and they claimed it was due to not maintaining your car. You would have no control over a tire blowing. Anyway, I would have the rearend investigated to see if anything failed and caused the problem. The computer will log the events leading up to the accident if you want that pulled. Anyway, that totally sucks and feel bad for your situation. Good luck.

trapp

I can't help but think the "competitive driving mode button" should be relabeled "suicide button". Sorry for your loss.

If you were cruising around in 3rd at that speed, i wouldn't think you would have anywhere near the torque for the car to suddenly go haywire like that. I have raced from a stop in 30 degree weather and didn't have any real problems of losing control of the car. Most be some foul plague involved here

Did a message or has a message appeared lately saying service active handling? Many have had that message and a few have had the active handling go haywire.

It has been said that if it goes haywire, you could lose control of the car.

ICU812, Sorry to hear of your misfortune. If you live in a cold climate this could have very well been the cause. It doesn't take much to get the rear end to swing out at speeds even as low as 50-60. You claim you where on a clear road, but public roads have plenty of dust and fluids on them. You didn't mention you heard or felt anything at the time of incident. When you spun, do you remember what you did and if you had both feet in? (on the brake and clutch?) Once the car showed oversteer, if you applied the brake that would just catapult it further. :bigears



Mike :cheers:

Yep, there is no good reason to use that in normal street driving, especially for the driver with average skills or below. However, there really is no way to diagnose what happened except that I doubt it was breakage, under the circumstances described.

"Half-throttle" as described in the report could easily have been much more. Given it was Las Vegas, dust on the road surface, cold tires, too much power in Comp Mode, and a late correction are the likely culprits.

Sorry about the accident.

Sorry to hear about your situation. I had a similar incident and thought about Gremlins, etc., even took my car back to the dealer to check the system. Was also passing in third gear and outside temp was 50. The car fishtailed hard to the left ("90 degree right turn") and I fought to get it back, over corrected and went the other way. Straightened it out and bumped the car in front of me (both doing about 60 mph). No where near your damage, but scuffed the paint and had to repaint the fascia ($475). I was in normal driving mode when this happened. I imagine it’s much worse in competition. I joined CF mainly due to this event (to see what happened) and have learned much (Thanks CF members!) about the tires and the TC system. My previous '03C5 Stage2 acted COMPLETELY different under similar conditions. Frankly, it was difficult to get in trouble with my C5 and the exact opposite in the C6Z. Bottom line is you really need to “get on it” slower (slower than stomping your foot to the floor – like I do!) in the lower gears, the tires can be very squirrelly in lower temps (55 or less) and the traction control has been set in such a way as to allow owners of these beasts to enjoy them (not overly controlled by the computers). Again, sorry to hear about your mishap. I am sure we are not the only members of this particular club. (Got to admit, it was quite the ride – and I got off pretty easy.)

Ranger-Answer
 

It was daytime, about 70 degrees. Was going absolutely straight and was not changing lanes. Had been going straight for about 5 seconds when it happened. Have had numerous race and drag cars and have never had anything like this happen even in rain or snow. Wierdest thing with zero warning and car felt like it was on ice when trying to steer into slide with virtually no brake control. Tires are good, only 990 miles on car. Like I said, an off duty officer behind me said it looked as if the car was "yanked" 90 degrees off center instantly (like a blown tire). Just wonder if a half shalf failure or CV joint could have caused this. Suspension is history so don't know if they will be able to tell.

Thanks for the elaboration.

I suspect that the rear got loose from the rear tires spinning, perhaps aggravated by dust/sand on the road surface. Unless the throttle is progressively squeezed, the driver can break the rear loose easily at 50-60 in 3d. I've done it. So have most owners.

Driving in Competitive Driving mode invokes the "permissive" form of Active Handling. Therein the computer allows move movement before intervention than it does in normal mode or Traction System Off.

Chevy has a lot of experience examining broken CV joints and the breakage occurs in a predictable form. So An inspection of the rear drive components and tires should reveal if a catastrophic failure were involved.

From your description I suspect, though, too much throttle for the available traction was the root cause, aggravated by the absense of aggressive Active Handling due to running in Comp mode. But even full AH can't overcome the laws of physics.

With less than 200 miles on the OD on warm tires at 60 mph, I downshifted to 3d and applied too much throttle. Rear got loose, very loose. AH intervened as I struggle to keep the car within the two lanes of my side of the interstate. Fortunately no other car were within 400 meters. Happy ending. But taught me (1)respect for the power of the car (2) the need to make smooth moves with the throttle and (3) the favorable outcome of staying off the brakes when the rear got loose.

Not trying to lecture here. Sorry for the bad situation you had. Just trying to share experiences that may shed light on what happened.

Ranger Answers
 

I was about 6 miles from home and the throttle was contant at the time the "incident" occured. I had just gone (about 5-6 seconds earlier) from the center lane of a 6 lane (sligtly downhill) road to the fast lane to pass slower traffic and had already accelerated to a constant speed and was maintaining that speed (50-60) getting ready to move back over to the center but had not as of yet started any steering movement. If caught me totally off-guard as the car went suddenly 90 degrees to the left. When I tried to correct, it felt like it was on ice with zero control and proceed to do between a 360 and 720 in the curb before coming to a rest. I am nearly 60 and have been drag and road racing cars all my life (this is my third ZO6) and also had 2 ZR-1s, plus other Vette's etc. This was all new to me. Love new experiences but not this kind.:willy: Thanks for the help. Just wanted opinions as to whether it could have been parts failure or I need to go back to driver's school.

To me, and I'm nobody, I'd say the active handling system freaked out on you. I've heard of this happening a couple times way back in the day with C5's. If you weren't on it I don't see how the rear could have just broke on you. It's possible of course...hell you never know when your roof could just fly off. Again I think the computer did it. Can't they check out what was going on with the electronics? Look into it. Computer's do make mistakes. It's a proven fact and a scary one at that.

Have a Dealer record the codes--If there are any--Start a work order ticket.KEEP a copy of any and all codes and work order ticket.

if its under 60 degrees, I'd say 6 miles isn't near enough to warm up the tires. I can't believe how long it takes (oil temp, too). The car can be downright scary when cold and on a cold road surface. those rear tires can resemble skim boards :willy:

In my opinion...
 

It sounds like a "parts" failure or an ABS/active handling system hiccup to me.

That's the only thing it could be if it instantly turned you 90 degrees and you weren't getting on it!

Did the airbags deploy in the impact? If so, the Blackbox has the last 15-20 seconds of the main PCM info. If you do suspect a mechanical issue, you can ask the insurance company to pull the data for analysis. But of course that cuts both ways.

Ranger

I see three possibilities:
1. Active handling computer went crazy
2. Mechanical failure somewhere in the drive train
3. Driver error, most likely a distant maybe
Must get to the bottom of this and see what the cause was, if it's a computer glitch/mechanical failure then GM have got son esplaynin to do.
As to the car, as sad as it is, it's replacable as you know, main thing you were OK.
Please post updates.

Thanks for the post...being a new Z06 owner I will take the advise to heart...maybe this thread will save me some future accident or grief. I will avoid putting car in competitive mode and learn to respect the car better. Sorry for the loss.

trapp