mastiffdog

Shouldn't the PTM have done its's job? Porsche Traction Management, this is the system that supposedly detects wheel slipage on less than ideal road conditions and is able to transfer power to the axle in need in less that 0.1 of a second.

docjackson1

dog-you are right, but that is assuming that you have traction. if he is sliding, and his hard summer tires can't get any adhesion or traction, you can transfer all the power you want to any wheel-if there is no traction, it will continue to slide. i know that you live out west, but if you try to drive your turbo in the snow, for example, unless you have winter tires on it, that baby is going to slip and slide uncontrollably-with winter tires, it drives like a jeep.

photonscience

When temp went below 40, I could "feel"my 996tt's tires become rock hard through the suspension - the ride became even more jarring. In the 997tt, I can't feel any ride quality change whether the tires are warm or cold - I think PASM soaks up the rough ride and may not be transmitting as much information about what the tires are "seeing" to the driver.

W211

According to the original post, the car spun out when accelerated which is strange, as I thought Porsche Traction would have kicked in cutting the power.

99firehawk

trust me I have had plenty of customers loose it with psm while showing me how "great" of drivers they are

eclou

No matter how much driving experience you have, the most dangerous time you will have is when switching to a new car or new setup. Each newer generation of max performance tires come closer and closer to the characteristics of racing tires, which also means that their cold weather capabilities will be worse and worse. In 30 deg weather tires like the PS2's will need some major warm-up time before they come into their own. The Skippy schools are great, but until you do some HPDE's in a broad array of temps, it is hard to grasp how important temps are to traction. Not saying that your car did not experience a failure of some sorts, just saying that temps and tires were undoubtedly a contributing factor.

Whoopsy

On damp road and with temperature at around 30, below freezing, he could have hit a patch of black ice without knowing, unlike a wide open road track, there won't be much room to save the car on an onramp even with all the electronics working. That patch of ice could have melted away before he and the towtruck driver walk back to check the road.

Black ice normally occurs just around the freezing temperature, any colder they turn to white ice which one can see and any warmer it will just melt away.

It could also be that the boost just kicked in at the moment he hit the patch of ice, and the combination send the car so out of control even god himself can't save it. This was his first turbo-ed 911, he may very well not used to the 'kick' yet.

I had been 'practicing' in the snow and ice with the PS2 last week. We had a major snow storm late last month and everywhere is covered in the white stuff. The car does wiggle quite a bit before the electronics kicks in, it gives you more 'slack' than the 996 version but those slacks had me spun a few 180+ in the parking lot. No harm done and very fun but not the safest way to drive in the winter without winter tires.

1AS

Seems odd. I don't have a 997tt, but have driven my 996ttX50 on summer rubber in snow (now switched to winter snows). The intrusion of traction control/skid control is unmistakable. I'd be very surprised if one couldn't easily feel the intrusion. But, I don't think the car will function normally without it. Even with the skid controls off, the car is hard to throw into oversteer at lower speeds.
My 996tt on summer tires can be forced into oversteer on slippery roads when accelerating, but it isn't at all like the old 911's. You have to first feel front grip, then accelerate very aggressively in a lower gear (second is ideal) to make the rear come around.
Is the 997tt set up so differently?
When you get your car back, I agree that some experimentaton on a big parking lot or track is essential. While I felt comfortable sliding an 80 targa and a 1990C2 on dry or wet pavement in the summer, my 90 on summer tires was unmanageable in the cold/snow. My 996tt is a very tricky car to slide, and basically doesn't without aggressive throttle use. How aggressive were you? AS

Frino

It's been at or below 32 degrees in the mornings all week here in DC. Have driven my C2S on PS2's with no drama. While I will park the car when there is the slightest chance of precip, I have come to the conclusion that you can, with care and in the dry, drive on summer tires in the winter without an inordinate amount of risk.

Been thinking about mytt's incident and it just doesn't add up in terms of psm and ptm not kicking in.

99firehawk

also fwiw the psm/ptm/pasm systems are really not going to not have an error and not light the dash like a christmas tree. We replace lots of turbo rims and suspesnion when the driver runs out of skill befroe the car runs out of ability

eclou

Depending on temps and driving styles, it is also possible that at 400 miles not all the release mold is gone from the tires.

Kevin

firehawk, just like AS mentioned shouldn't the PSM have lit up the dash? Similar to the 996TT?

99firehawk

if your spining off the road, are you looking at the road or the dash ?

1AS

It would be really hard not to feel it. Just the sudden loss of power is very obvious, aside from all the brake applications. Unless th 997tt is a vastly different animal, it is a bit difficult to understand. From my last track experience, I also thought you could hear the brakes comin on and off. AS

99firehawk

something that comes with seat time in the car, 400 mile car probaly has only a few hours of seat time and most of it just cruising, the limits and abilitys of the car not learned