garrett376

No, no... the 964 AWD system is not any more problematic than the rest of the systems - it was too expensive to manufacture at a time when Porsche was not doing well. It works extremely well, is extremely reliable, and doesn't require any further repairs over the cheaper viscous systems. It had the capability of sending 0-100% of the power to the front wheels almost instantaneously without a delay from a viscous clutch - the 964 version multi-clutch plate system is what the 997 turbos have gone back to using with a couple changes thanks to technology advances.

Not that this matters for this discussion, but no need for further 964 rumors to spread!

granracing

Thanks for all of the information - this has been helpful.

smackboy1

The nature of the viscous slip AWD means that there is a slight delay before power is transferred to the front. So it handles more or less like a RWD. It does not handle like the other AWD systems that sends even power to all 4 wheels at once. In the snow/ice the AWD helps, but the front can be a little more squirmy compared to FWD, especially changing lanes.

The steering on the AWD feels a little heavier because the front tires are being driven. The AWD feels a little more stable under power coming out of corners when conditions are slippery. A C4S is about 275 lbs. heavier than the C2.

For the Top Gear comparo:

http://coochas.com/porsche/Resources...Gear121105.mp4

jyoteen

the weight differential is not only due to the AWD system, but wider tires and heavier wheels, WB vs NB, and brake system being larger among other things. I would suspect the turbo bumper is heavier as well.

CosmosC4S

Wow, 275lbs is a lot of weight! I know most people would love to be able to shed that weight off for an instant hp-gain mod!

uberskier

My thought process a year ago was that I'm not going to take the car on the track that much and I live in the northeast. Even when I take it on the track, is it really "that" much slower than a C2? Most of the time it should be driving like a RWD with a bit of pull from the front (5%-95%). I really never get to the point where the viscous coupling will have transferred 30% to the front, which is supposedly at about 155 mph. The only time it exceeds 30% and gos up to almost 40% is when the rear weals are spinning.

So I couldn't go wrong with a C4S, plus I absolutely love the looks of a C4S!

Ray S

I think you are misunderstanding how the coupling operates. It is not speed dependent, rather it is slip dependent. The more slip the rears experience the more power the coupling transfers to the front wheels.

Some info here

http://www.awd.ee/viscous.html

996 vs 997 system

http://www.porsche.com/microsite/tec...PMT911TurboAll

uberskier

Ray,
Thanks for the info. I was under the impression from the "Essential Companion" that it had a combination of both, slip would take it up to 40% and normal driving would take it up to 30% (at 155mph/250kph).
Thanks,
Eric

Ray S

I had not heard that. You could be correct.

jumper5836

The C2 is faster at the top end but at the Ring the 4S was faster.

Edgy01

Why is it that a significant number of 964 (4) owners inquire about converting their 4s back to 2s then?

garrett376

Because the grass is always greener...

While not an absolute, in the 6 years of being active on the Rennlist 964 forum, I know of just 3 owners that have done the conversion for various reasons, not due to problems. Joel Reiser's article in Panorama seemed to scare a lot of people... just like the internet does with 996 engine failures.

redridge

+1.... though he promotes that the 996 doesnt have any oil starvation issues.

ArneeA

At the track, the C2 "would" be faster with the correct driver. With the average driver, the C4S will instill confidence much more than the C2 that the C4S will "seem" faster.

Also, we're not racing for medals on DE's. So it doesn't matter in the end. What matters is how much fun and education the owner experiences.

It's similar to people always saying PS2 is much better than, say, Conti SportContact 2 simply because it's stickier when it's the same people who can't even reach the PS2's limits, especially on the street.

SH || NC

Ray, the EC book states speed related criteria.