Rainier- all that matters is that both of you are fine. Car will get back in shape in no time ...and repair cost, well again, you both are ok...that's what matters!!

 

No, definitely not.
This was a "slow speed" event. Very slow speed. Like 20 mph or so. The fronts had perfect traction all the time, no doubt about it. The rears where doing the spinning so fast that they where not in contact with the tarmac (hence no "rubber" trail left on the road). Loss of traction was likely caused by a very slippery mixture of fine white sand and water. Once the rears where spinning like that the correct reaction would have been to simply reduce throttle (either via PSM or by the driver) to allow regaining of traction.
The exact events as I remember where thus:
Drive off at sharp right turn to get into road - it's a fast road so you need a bit of go as there is a constant stream of traffic. At this time it was fairly quiet with a good traffic gap so no need to push hard. I had my wife in the car so would not push too hard anyway (she would not take kindly to wild driving).

Anyway, perhaps 10 feet into the turn and the rears go mad, RPM instantly very high and the car oversteers to the left (back goes out to the left). No problem so far, I counter steer and get back on track however now there is a very rapid oversteer in the other direction - almost a whiplash kind of moment as if something is braking the left front tire. That's where I froze - unexpected, no time to think and I'm in the ditch wonding what just happened.

OK, condense that last chapter in say 1 to 2 seconds and you get the picture.

Rainier

 

How much of tread is left on the rears? Perhaps it's the freakin pzeros...never liked these tires anyways!

 

Around 70% thread is left, tyres about half life.
But you may have a point. Yes, these tires do not like wet.

Rainier

 

Not necessarily true the World over (in spite of having a major impact in the US market).

 

Actually exactly that is what first crossed my mind too when I read rainiers post. And made me question my choice for a c2 instead of a c4 ! Rainier states fronts kept traction at all times. C4 could have saved the day ! Relaying power to front wheels, allowing those to pull you straight ?!
Pure speculation off course, we'll never know for sure !

 

PDK?

In Auto and, if so, in Sport or Sport+?

 

Glad you are OK.

Exact questions I was wondering about.

So it was wet. Ambient temperature? PSM off?

 

Sorry to hear about the accident. I know the feeling of not wanting to push the car anymore or being "tainted" by an incident like this, but don't let that affect your enjoyment of the 911 (or any other car, for that matter). This could have happened in a $5,000 Miata or a $300,000 Ferrari. You'll be back in business soon!

 

No, PSM was on (I never touch that button except for once during a Porsche driving school task).
It was in Sport and auto stop/start (which I hate) was off.
The car has PDK and it is a C2S S-PASM, no performance or suspension mods, original tyres. Just on 12.000 Km on the clock. 11 months of age.
Temps around 20 degrees Celcius - not cold.
It was only wet over a small patch perhaps 20 sqft in size - moisture mixed in with fine sand. Pretty much grease...
It is here the wheels spun - the rest of the road was perfectly dry and in good condition.
The wetness was caused by cracks in the road surface and water (and fine sand) seeping to the surface after recent rains. I did not notice this patch when I drove off.

Something here made the traction control decide all is well. I'm not blaming it - don't get me wrong. It likely did exactly what it was designed to do given the sensor inputs at the time. It does not have eyes - that's its biggest problem. It probably satbilised the car simply in the wrong direction (something the Porsche driving instructors warned about).

The problem is the driver. Me. I have conditioned myself to drive a vehicle with a near perfect traction control. My natural reactions related to power input have been wiped out. My foot no longer controls power modulation - the traction control reacts way faster than my foot can do so my foot has unlearned reflexes it would apply in the past without my brain involved.
Traction control has become a natural part of driving the car - likely many times you don't even realize it is working for you.
That works until the day things don't go to plan. This is why I think my foot remained on the power (rather than backing off when the wheels spun). In the past, the car would retard the throttle so fast my foot would simply not be able to beat that - so it just stays where it is and the traction control fixes the problem to perfection. That is wrong. I can see that now.
In this case the traction control did not do the right thing so my foot should have done it. My foot no longer knew what to do. Makes sense ?

The only question remaining to me is why did the throttle not retard ? The Porsche manual does not give enough information I think. I am somewhat worried that in a similar cirumstance the same thing may happen and again I'll end up in a ditch.

Rainier

 

Yes you are right, while my baby is being fixed I'm driving my MX-5 (Miata in your World). And I'm enjoying it as much as ever. It's actually a brilliant, perhaps underrated little car. Like a happy puppy: eager and fun. A real joy to drive and thrash around in. No electric steering assist, heck - not even hydraulic steering assist - just simple direct. Sometimes that is nice. Pure perhaps.

Rainier

 

From what I recall, Sport mode allows a more permissive loss of traction and yaw angle before it kicks in.

 

OK, you have PDK and you were in Sport (which automatically turns Auto Stop off). PSM was ON.

But were you in Automatic mode or in Manual mode (using paddles or buttons to shift)?


The reason I ask is that I have noticed one PDK condition in my C2S that I don't like, but it is in Automatic mode with Sport Plus:

Sometimes when driving moderately aggressively, when approaching an intersection in second gear and making a 90 degree right turn, as I begin to round the corner the gearbox will suddenly drop down into first gear, resulting in a spike in my RPMs into the 5500 range. It's unexpected, loud and can be pretty jerky.

I would imagine that if the road was slick due to sand, gravel, slime or anything else greasy, it might result in some pretty aggressive wheel spin when this happens, especially if I was just coincidentally stepping back onto the gas at the same time the unexpected kickdown happened.


Anything above adaptable to what happened to you?


An additional thought: My PDK software was recently updated in response to the recent recall campaign. I have not tried to replicate this condition since then.

 

Happy to hear you and your wife are okay. The car will be as good as new.

 

Well, I was in auto which is pretty much my normal way of driving. I use manual seldom. Can't beat the box. Yes, I have the PDK update and yes, it is MUCH more aggressive than before when you get going. That of course must have contributed and I have had several cases of unexpected wheelspin after the update (so far on a straight line - usualy caused by road markings etc which tend to be a bit slippery sometimes).
I can't recall any shift taking place so I think all of this happened in first gear (but I may be mistaken, I'm just not sure).

You do raise a good point. Thinking about this - I don't think this would have happened before the update - the power uptake had much more lag to it from a standstil. After the update it's effectively instant. Nice but obviously has to be taken with care or else, like me, you could run out of talent...

Rainier