Dec 7, 2005 1:05:11 AM
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JJBlade said:
A 997C2S v a 996C4S on snow is so similar it comes down to who is the better driver. Absolutely no advantage for the 4wd despite what you may think.
Proof = My trips to the Alps in March this year where I could comfortably drive over the same icy/snowy roads as my mate.
Quote:
JJBlade said:
A 997C2S v a 996C4S on snow is so similar it comes down to who is the better driver. Absolutely no advantage for the 4wd despite what you may think.
Proof = My trips to the Alps in March this year where I could comfortably drive over the same icy/snowy roads as my mate.
Dec 7, 2005 4:46:56 PM
Dec 7, 2005 6:40:06 PM
Dec 7, 2005 10:56:03 PM
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KiwiCanuck said:
But on the roads I came to work on this am, clear of snow, minus 20C, well used, but with a few ice crystals in the air, C2 or C4 would have been in equal trouble, as adhesion was very low. I tickled the throttle on the FWD 280bhp Acura TL, and the TC light immediately came on. Subtle--but actually low adhesion ice driving. These are the conditions that see 4WD SUV and Audis in the ditch, as thier owners think that they have superior adhesion. Of course Carrera drivers are too smart to do that! This a.m. I drive the FWD car, and have no wisch to be in the Carrera ---- the arrow head wins!
KiwiCanuck
Dec 8, 2005 12:03:52 AM
Dec 8, 2005 2:06:08 AM
Quote:
KiwiCanuck said:
Given excellent winter tires and some grip, the sophisticated 4WD is obviously best (Audi, Porsche or the new Acura RL that can put 100% drive into the best tire of the 4), and a sophisticated mid/rear engine RWD (Porsche, NSX) or FWD (like my Acura TL) are both excellent, AS LONG as the transition into very low adhesion DOES NOT occur.
KiwiCanuck
Dec 9, 2005 4:49:31 PM
Quote:
JJBlade said:
A 997C2S v a 996C4S on snow is so similar it comes down to who is the better driver. Absolutely no advantage for the 4wd despite what you may think.
Proof = My trips to the Alps in March this year where I could comfortably drive over the same icy/snowy roads as my mate.
Dec 10, 2005 12:24:15 PM
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temm said:
[I always find these "2wd is as good as 4wd on snow" posts interesting, and they always seem to come from countries with little or no snow in winter
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schmuy said:
Well said Temm, Exactly what i wanted to say when i responded to this thread but it didn't come out right. This "special" driving technique you speak of seems like common sense to me, however its amazing how many people continue to brake late in low grip situations and end up sliding through an intersection or into a ditch. they seem to typically be 4x4s who think they can stop faster too which, as stated, is not the case.
While we are on the 4wd topic may i ask if Porsche's 4wd system is truely 4wd. I remember one christmas pushing a "4x4" which got stuck on our road. only the back right and front left wheels were drive wheels on this "4x4". however on my dad's truck its limited slip front and rear.
Quote:
temm said:
The 4wd system in the 911 is not a true 4wd system, it only has a viscous coupling centre diff and open diffs front and back (except on those equipped with the -20 mm sport suspension which has a limited slip diff on the rear axle)
Temm,
Please explain in laymans terms- if possible. Thanks!
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SVNSVN said:
Temm,
Please explain in laymans terms- if possible. Thanks!
Quote:
The all-wheel drive system featured in the new 911 Carrera 4 models includes a viscous-coupled centre differential. This ingenious device provides automatic torque distribution to the front and rear axles in precisely the proportions required. It also compensates for any externally induced difference in the speed of rotation at each axle. The coupling itself consists of an outer casing and a central shaft, both of which are fitted with a series of interleaved plates. The space between these plates is filled with a high-viscosity silicone fluid.
If the front and rear axles are rotating at different speeds, the frictional properties of the silicone fluid cause torque to be directed away from the plates that are rotating more quickly and towards those rotating more slowly. At least 5 % of drive torque is always applied to the front wheels. In normal driving conditions, the proportion is approximately 35%, rising as high as 40 % in extreme situations (e.g., loss of traction on wet or uneven surfaces, or following sudden throttle lift-off while cornering).
The system is augmented by a new evolution of Porsche Stability Management (PSM) developed for the 911 Carrera 4 models. In addition to the benefits of the rear-drive version, this revised PSM offers two new functions which help to minimise braking distances. If the driver suddenly releases the throttle, PSM automatically readies the braking system. The pressure in the brake lines is marginally increased, bringing each of the pads into light contact with the corresponding disc.
If the driver goes on to apply the brakes, the response from each caliper is that much more immediate and braking distances are reduced. In an emergency stop - i.e., when the pressure on the brake pedal exceeds a predefined threshold - the brake assist function uses the PSM hydraulics to apply maximum braking force at all four wheels. Working in conjunction with the variable differential, this new evolution of PSM offers better dynamics, greater agility and exceptional vehicle stability.
In short: all of the things that make your car a Porsche.
Dec 12, 2005 8:54:20 AM
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LowPolarMoment said:
Well, let me combine this with the thread I started on the Turbo board about understeer. Why would the 4wd car understeer less in the snow but more in the dry?