Dennis C

The 996 AWD system uses a mechanical, viscous coupling to apply up to 40% of the power to the front wheels. The viscous coupling is only activated when there is a speed differential between the front and rear wheels. In this situation, the dilatant fluid in the front differential heats up rapidly and thinkens to the point that the front clutch pack engages and drives the front wheels. This scenario occurs in spirited driving through corners, or on the track. Typically the traction control system isn't activated in this scenario.

In winter conditions, the rear wheels often slip due to loss of traction on snow or ice. When the rear wheels slip, the traction control system is activated and it brakes the rear wheels before the VC can apply power to the front wheels. I experienced this situation in my C4S multiple times trying to drive up my snowy driveway. I had to turn PCM off, or back up the driveway to successfully get to my garage.

In winter conditions in the 996 series cars, a C2 with winter tires will perform as well as a C4 with winter tires.

The VC system is also very sensitive to tire sizes. This is the reason that it's so important to keep the size differential between front and rear within recommended specifications on AWD cars. If you don't, then the VC activates because of the rotational speed differential between the front and rear, and it quickly wears the front clutch pack.

a.wilder

It's maddening, imo. I've been looking for a C2 + aerokit in anything other than black and silver. I've found a few but not many that are also: Clean title, reasonable mileage, in good shape, not highly overvalued. I'm in no rush to buy and am willing to travel for the right car so i am just waiting patiently. Maybe i will even increase my budget to TT territory if i wait long enough.

docmirror

I have what y'all want. But - it's not free. PM me for info if you like.

Southern Man

I looked for 6 months when I was looking for my car, which I've now had 5 years. Any color but black or red, only because I've owned several black cars, which are hard to keep clean, and I thought red was too "common". I really wanted silver, or seal gray, with black interior. Getting the right car mechanically outweighed any color concerns.

But alas the right car ended up being black with gray interior, and I couldn't be happier. I thought this might be my starter P car, but it's ended up a keeper. Keep looking and you'll find your car.

911Syncro

Besides the PSM, what "traction control systems" are you referring to?

No, the AWD is always active, front wheels get traction when the rear wheels start to slip -- even just a bit. Like someone else wrote, there is no decision made, the torque transfer profile is simply a characteristic of the fluid in the VC.

The PSM is designed to prevent the car from spinning and the driver loosing control -- at the limit -- at the end -- not 'before' anything else except the crash. Has nothing to do with powering out of corners. In a left curve, if the car exhibits understeer, the PSM applies the left rear brake, which makes the car act like a pivot and brings the front end into the turn. In a left curve, if the car has oversteer, the PSM applies the right front brake, to bring the nose out of the turn.

Think of it this way: the AWD helps prevent a wheel from spinning and PSM helps prevent the car from spinning. (AWD also adds some nice balance to the handling, )

On C4S, factory tests at Nurburgring showed it is faster than all other 996 variants (except of course the GT3, Turbo, GT2). Can read about it here:
https://rennlist.com/forums/996-foru...l#post14125769

Mine is silver, but given equal condition and features, I'd trade for an Arena Red or Forrest Green any day.

And, perhaps some of us would vote this quote is the most important consideration of all:

FRUNKenstein

I would highly recommend buying a car from a private seller rather than a dealer.

Dennis C

Yes, you are correct; the AWD system is always active. It is rear wheel biased - it typically sends 5% of the power to the front wheels, but it can send up to 40% of the power to the front wheels.

The dilatant fluid in the VC reacts very quickly, no doubt about that. You're correct that there is "no decision made"; it's a mechanical system that reacts to the wheel speed and friction in the front differential. That is one of the reasons that the C4S is faster around the Nurburgring that the C2; the AWD allows it to power our of corners as I mentioned above. I think the suspension, wider rear tires, and brakes play a role too, because the C4S is quite a bit heavier than the C2.

The traction control functionality is part of the PSM system. This system will brake individual wheels as necessary to correct oversteer, among other things. You are also correct that PSM has nothing to do with powering out of corners. The traction control functionality comes into play on slippery surfaces, such as winter driving as I mentioned above. If you try to start a 996 on ice with the PSM active, and the rear wheels begin to slip or lose traction, the car will apply the rear brakes to slow the rear wheel and allow for traction. It will eventually cut engine power if brakes are not enough. This is the traction control functionality that I mentioned, and I found it to be quite intrusive in my C4S. In this scenario, the car will not send enough power to the front wheels to move the car forward; it will cut power to the rear wheels. I've experienced this behavior many, many times in winter conditions. As I mentioned, I was able to get my car to drive up my snowy driveway by deactivating PSM, which in turn deactivated the traction control functionality. This allowed the AWD system to help pull the car up the driveway. That being said, not many people want to drive in winter conditions with PSM deactivated (including me).

I'm with you on green; one of our local PCA members has a 2004 C4S cabriolet in green and it's gorgeous.

docmirror

Uh - I think it has an extra 50HP? Might account for the time diff.

Dennis C

Nope. Same engine.

MSGGrunt

I have noticed that if I increase my budget and search parameters to $25,000 I find more cars in the brighter colors, a coupe of the C4S models and more with the aero package.

Sorry for an obvious question... Is it only the C4 that gets the wider turbo look with upgraded components or is the "regular" C4 wider as well?

And why so few Targas? I always though the targas of the 80's were a great look other than the seals being problematic when they started to leak. Not that the 996 targa replicates that look. Just seems to be an overly large panoramic sunroof.

I only ask as let's assume at some point the 996 values will increase, even if slightly and if my budget could buy me a C4S or Targa or a car with the aero options would this be a more desirable car over the standard C2?

Volkert

C4 and C4S were sold in parallel where the C4S has the wider "turbo" body and the C4 the regular body, like a C2. Smart marketing on the part of Porsche that still works today.

Targas only sold in low numbers.

Yes, over time 996 values will start to appreciate BUT this car sold in huge numbers AND in the meantime 997 values are still dropping. So I for now don't see much upward potential. For sure any car which is more desirable now will be more desirable later but for now the best thing to do is to pick the one car that YOU find desirable. Best to go for a car you really like with the options you want and then find one with a good history, reasonable mileage that gives you confidence you made a good buy. Then make sure you have some money in the bank just in case something drastic happens.
There are good cars out there. Just be careful you don't run into one on which the previous owner found some issue and decided to dump it or car sales people that like to flip cars. I would for instance be very careful with a car that had a recent IMS/RMS swap etc. Why sell now if you just went through that expense? I would echo what KCattorney just mentioned, see if you can buy it from somebody you can trust.

Atrox

Watch this, good way to sum up the line.
(plug this when I can it's great)

Mike Murphy

The coupes are usually and will probably will always be the most desirable model compared to cabs and targas

dporto

Wrong... The suspensions are indeed the same...

Palting

LOL. Okay, the C4S has a wider rear stance than the C4 but they have the same suspension, or is it that the turbo has 100 more HP and at least 100lbs more weight but has the same suspension as the C4S? Or is it that the C4, C4S and the turbo all have the same suspension?