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    Jan 18, 2007 11:16:23 PM

    Flash
    Junior
    Flash
    Loc: Aberdeen
    Posts: 51, Gallery
    Registered on: Oct 8, 2006

    997C4SX51 meets Black Ice

    Was heading home on Tuesday night. It had been a really mild day, and I didn't notice the cold as I crossed the 25 feet between dojo and 997. Once inside I neglected to notice the dash thermometer was reading -2C.

    The journey proceeded with my usual enthusiasm, and by the time I reached the big roundabout the car was fully warmed up. I was turning right, so this entailed navigating 270 degrees around the roundabout. Still I failed to notice the dash thermom was reading less then zero...

    I attacked the roundabout at a fair old pelt, keen to feel those big tyres gripping. If the police had seen me enter a roundabout at that speed they'd have banged me up and thrown away the key.

    Unbeknown to me the road surface was completely covered in a sheet of black ice. What do you think happened next?

    Well the first thing I knew was that the roundabout seemed to be moving towards the right away from me. At first it was barely perceptable, and then I thought I must be having a fuckin fit or something. Then it struck me that the car was in some sort of neutral drift. I backed off and the car returned to it's intended road position. I planted the throttle again and the car drifted sweetly to the left again. The more I planted the throttle the further it drifted. This was lovely and controllable. Neither the front nor surprisingly the rear stepped out. The drift was 100% neutral.

    Then my exit arrived and we were back on the straight. This was when i glanced at the dash thermometer. Holy [beep]!

    So in case anyone is interested, 4WD 997s work incredibly well on sheet ice. Even when blasting 270 degrees around roundabouts.

    Hope it freezes again tonight!

    That is all

    Jan 18, 2007 11:23:43 PM

    Kevin034
    Pilot
    Kevin034
    Loc: WA
    Posts: 393, Gallery
    Registered on: Oct 7, 2005
    Reply to: Flash

    Re: 997C4SX51 meets Black Ice

    My C2S is better.

    Jan 18, 2007 11:28:48 PM

    rhino
    Rennteam Pro
    rhino
    Loc: Island , Saint Lucia
    Posts: 2866, Gallery
    Registered on: Jan 26, 2006
    Reply to: Flash

    Re: 997C4SX51 meets Black Ice

    Sounds fun, but very dangerous! Be careful

    Jan 19, 2007 12:20:53 AM

    Le Chef
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    Le Chef
    Loc: Chicago , United States
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    Reply to: Flash

    Thank God you weren't in Milton Keynes

    That might well have been one roundabout too many. Once you get close to zero your summer tires are just crap. You're very lucky!

    Here in the MidWest we don't f*ck about with tires and just put the winter set on at the end of November to be sure what happened to you doesn't happen.

    Enjoy the drive!

    Jan 19, 2007 7:31:01 AM

    Queram Offline
    Pilot
    Queram
    Loc: Istanbul , Turkey
    Posts: 330, Gallery
    Registered on: Jun 27, 2006
    Reply to: Le Chef

    Re: Thank God you weren't in Milton Keynes

    Bridgstones seem to hold quite well in low temperatures. At least that is my experience. Although it is very easy to fool C4S:) What flash experienced I believe is mild icy road surface. As fas as I know once you are on black ice there is no control whether its 2 or 4 wheel drive.

    Jan 19, 2007 7:53:28 AM

    wtsnet
    Rennteam Pro
    wtsnet
    Loc: Bath, UK
    Posts: 2430, Gallery
    Registered on: Nov 19, 2004
    Reply to: Queram

    Re: Thank God you weren't in Milton Keynes

    Sounds like fun, but it sounds like the road wasn't iced, though I wasn't there I admit. If it had been ice, you would probably have had no control at all.

    I've had a similar 4 wheel drift in winter, and it's more scary when you're taking an inside line to overtake a car on the outside of the bend I can tell you!

    I think there's two things that come in to play at this time of year:
    1) Summer tyres aren't so grippy in cold temperatures, particularly bad just after you start.
    2) The roads are more slippery, mainly due to the grit that is applied, ironically to improve the grip. I think it's worse with wider tyres.

    Jan 19, 2007 7:59:53 AM

    BlackSparrow
    Pilot
    BlackSparrow
    Loc: Bahamas , Bahamas
    Posts: 424, Gallery
    Registered on: Oct 28, 2006
    Reply to: wtsnet

    Re: Thank God you weren't in Milton Keynes

    I just drove targa 4s with summer tires on ice and snow... never again. these tires are too "summer"...

    Jan 19, 2007 12:23:46 PM

    Silver Bullet
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    Silver Bullet
    Loc: Canada
    Posts: 1126, Gallery
    Registered on: Nov 24, 2004
    Reply to: BlackSparrow

    Re: Thank God you weren't in Milton Keynes

    Quote:
    wtsnet said:
    Sounds like fun, but it sounds like the road wasn't iced, though I wasn't there I admit. If it had been ice, you would probably have had no control at all.



    I agree and have no doubt that if a roundabout was entered at a speed high enough to be locked up by the cops, on stock tires, if that really was black ice, you'd have gone right into the ditch.

    Black ice is black because it's clear - no bubbles in it, very smooth (if not polished from other cars sailing right over it), and probably wet at just around zero. You can't even walk on that stuff.

    There's no way it was black ice. Either that's wrong, or the whole story is BS.

    Jan 19, 2007 2:26:12 PM

    Trundle_GT3
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    Trundle_GT3
    Loc: CA, USA
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    Reply to: Flash

    Re: 997C4SX51 meets Black Ice

    PSM would have been going nuts

    If you had PSM off, your nuts

    Jan 19, 2007 6:06:40 PM

    Flash
    Junior
    Flash
    Loc: Aberdeen
    Posts: 51, Gallery
    Registered on: Oct 8, 2006
    Reply to: Trundle_GT3

    Re: 997C4SX51 meets Black Ice

    I think we have different localised definitions of what constitues black ice. Although it's cold here we never see sheet ice on the road unless some [beep] has washed their car in sub zero temps.

    We do get snow, but it's rarely so deep you can't drive through it. The slipperiest thing we encounter is probably compacted snow.

    The road was slippy with frost, but this was not visible on the surface. It was not akin to an ice rink, but there's a good chance that someone would have slid on their ass if they were careless walking on it.

    It was as slippery as anything I have experienced in my 20 years of motoring in NE Scotland where the road surface is visible and not buried under compacted snow.

    The post was not intended to start a pissing contest on who has encountered the worst black ice. I'm sure that in Greenland there is sheet ice which tyres could not grip even if they were equipped with 9" diamond tipped stainless steel heated spikes!

    The post was intended to highlight how marvelous these cars are at coping with slippery conditions. My expectation would be that regardless of 4WD and traction control, the car would probably have spun, or at least attempted to do so. Failing that I would have expected to sense some sort of gargantuan struggle between PSM and the laws of physics. The way the car coped was incredible. The drift was totally neutral. The car was stable, it did not wigggle, to all intents and purposes it held kept it's intended attitude to the road, albeit drifting wide.

    I am seriously impressed.

    Jan 19, 2007 6:11:20 PM

    Flash
    Junior
    Flash
    Loc: Aberdeen
    Posts: 51, Gallery
    Registered on: Oct 8, 2006
    Reply to: Flash

    Re: 997C4SX51 meets Black Ice

    EDIT: I should add that this was a medium sized two lane roundabout, and the car drifted about 8 feet to the left, going from the right hand lane, through the left hand lane, and close to the outside curb. This was not just a little skip to the side.

    Would be very intersting to play on a skid pan with varying levels of slippiness and see just what it can take when pushed.

    BTW winter tyres are possibly a less commonly employed thing here, as we rarely see the temp much below zero. Our coldest ever night that I can recall was in late December 1995 when it reached -25C, but that was anomolous. Usually we would consider anything below -5C to be very cold.

    Jan 19, 2007 7:12:21 PM

    easy_rider911
    Rennteam VIP
    easy_rider911
    Loc: London , United Kingdom
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    Reply to: Flash

    Re: 997C4SX51 meets Black Ice

    I understand that winter tyres should be used from 7C and below (not zero C and below)...

    Jan 19, 2007 8:02:46 PM

    roadtrip
    Veteran
    roadtrip
    Loc: new mexico, usa
    Posts: 1172, Gallery
    Registered on: May 31, 2006
    Reply to: easy_rider911

    Re: 997C4SX51 meets Black Ice

    i suppose theres nothing quite like experiencing first hand what your cars response is to a definitely pcm moment...i would think your confidence level in whats possible would increase greatly....wonder how many p-car owners have had this experience intentionally or otherwise

    Jan 19, 2007 8:40:32 PM

    stork
    Junior
    stork
    Loc: OH and NC
    Posts: 145, Gallery
    Registered on: Dec 3, 2005
    Reply to: Flash

    Re: 997C4SX51 meets Black Ice

    I have 997C4S with 19 inch rims and winter tires. I used them part of last winter. We have only had a few days of snow and ice so far this year. Today there was about only an inch of snow, but around the stop signs it get a bit icey. This is no test. However, I have had NO problems. My wifes Lexus SC430 (rear wheel drive) with all season tires was a bit slipperly, but we put some weight in the trunk and things are ok now. I had a Cayenne when they first came out with summer tires and it drove like a formula one car in an ice rink...it just did not go. Summer tires cannot over come the laws of physics. When you need a screw driver, then do not use a fork. Pick the correct tire for each application.

    Jan 19, 2007 9:15:56 PM

    9ILD
    Newbie
    9ILD
    Loc: Hereford
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    Reply to: stork

    Re: 997C4SX51 meets Black Ice

    Flash, i liked your post anyway!

    Jan 20, 2007 8:24:21 AM

    Dan L
    Expert
    Dan L
    Loc: Santa Barbara, CA , United States
    Posts: 1957, Gallery
    Registered on: Jan 2, 2006
    Reply to: 9ILD

    Re: 997C4SX51 meets Black Ice

    I, too, have found the Bridgestones not as affected by the cold as I expected.

    Jan 20, 2007 1:54:28 PM

    donkeyman
    Junior
    donkeyman
    Loc: Hong Kong
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    Registered on: Jun 16, 2005
    Reply to: Dan L

    Re: 997C4SX51 meets Black Ice

    Great Post Flash

    Jan 22, 2007 10:58:34 AM

    Flash
    Junior
    Flash
    Loc: Aberdeen
    Posts: 51, Gallery
    Registered on: Oct 8, 2006
    Reply to: easy_rider911

    Re: 997C4SX51 meets Black Ice

    Quote:
    easy_rider911 said:
    I understand that winter tyres should be used from 7C and below (not zero C and below)...



    7C is almost like summer in Aberdeen LOL.

    Jan 22, 2007 12:38:14 PM

    WAY
    Rennteam Master
    WAY
    Loc: Melbourne, Australia
    Posts: 3342, Gallery
    Registered on: May 11, 2004
    Reply to: Flash

    Re: 997C4SX51 meets Black Ice

    Your description of the little incident sounds exactly like how I drift my C2 on a skid pan...:)

    Jan 22, 2007 1:21:15 PM

    Silver Bullet
    Veteran
    Silver Bullet
    Loc: Canada
    Posts: 1126, Gallery
    Registered on: Nov 24, 2004
    Reply to: Flash

    Re: 997C4SX51 meets Black Ice

    Quote:
    Flash said:I was turning right, so this entailed navigating 270 degrees around the roundabout . . . I attacked the roundabout at a fair old pelt, keen to feel those big tyres gripping. If the police had seen me enter a roundabout at that speed they'd have banged me up and thrown away the key . . . Well the first thing I knew was that the roundabout seemed to be moving towards the right away from me. At first it was barely perceptable, and then I thought I must be having a fuckin fit or something. Then it struck me that the car was in some sort of neutral drift. I backed off and the car returned to it's intended road position. I planted the throttle again and the car drifted sweetly to the left again. The more I planted the throttle the further it drifted. This was lovely and controllable. Neither the front nor surprisingly the rear stepped out. The drift was 100% neutral . . . So in case anyone is interested, 4WD 997s work incredibly well on sheet ice. Even when blasting 270 degrees around roundabouts.



    If the roundabout seemed to be moving to the right, which is the direction you were wanting to go in, then you were experiencing understeer, which is typical of AWD cars and also of slippery conditions at initial turn in. For throttle to have corrected the problem, then the rear tires must have lost grip (power oversteer, also typical of slippery conditions). If the rear tires hadn't lost grip, the understeer would have just gotten worse as you'd get more torque steer on the front wheels and also transfer weight off of the already slipping front wheels to the rear wheels, causing the front wheels to lose more grip. Thus, all 4 wheels must have lost traction, hence, your term 'neutral drift' meaning, I suppose, all 4 wheels were involved. (Neutral drift otherwise refers to the eventual spread throughout an entire population of a neutral gene!)

    However, at first, when the car was understeering, PSM would have sensed that the car was not travelling in the direction the front wheels were pointing at and intervened. Also, later when the rear tires started to spin (which must have happened to correct the turn), again, PSM would have been going berserk.

    Was PSM off? Or is it smart enought to know NOT to intervene when the driver is doing all the work already?
     
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