RCD

Does the 2000-2004 C4 use the same all wheel drive system as the 2002-2004 C4S? If not, is there a significant advantage to the C4S system?

Thanks,

Robert

Dharn55

Same system in all 996 C4's. I don't think they changed it until the 997.2 which just came out.

Ahmet

How's the current version different, if you know?

RCD

Thanks for the quick response.

jumper5836

The new awd system is a computer sensor controlled system. Ours and the first gen 997 is mechanical controlled viscous coupling system.
I believe the new system can send 100% power to any wheel, while the older system can only deliver 5% - 40% tp the front diff. It uses the braking system to cut power from one side to the other side.

rs10

I understood C4S differed in the electronics (software, and maybe hardware) - perhaps in how it uses the brakes, perhaps in PSM, maybe both. Though I've wondered if they didn't upgrade the C4 after introducing the C4S.

wwest

Prior to the 997.2 the Porsche AWD system was/is virtually useless, a true no-op.

Dennis C

The 996 AWD system (whether C4 or C4S) is entirely mechanical. PSM is a different system, which is a standard feature on the AWD cars.

The AWD system on the 996 wasn't designed for use in snow/ice/slippery conditions, which is the reason it is "useless" in these situations as wwest mentions above. It is useful in spirited driving and on the track to help the car accelerate more quickly out of corners, which is exactly why it was designed.

gnat

I've never found our AWD system to be useless in any reasonable situation and the unreasonable situations (wrong tires, snow higher than the front lip, etc..) weren't a fault of the system.

DaveCarrera4

From what I've read, The AWD system used in the 996 was first introduced in the 993 series, before that starting in 1989 with the 964 C4 it was an electronically controlled clutch pack system fore and aft, same as the 959. The 996 C4S has the turbo brakes and suspension, which all other flavors of C2 and C4 lack. IMHO based on owning both cars, the 996 AWD is mellowed and subdued, yet omni present when needed, versus the electro mechanical system of the 964. Incidentally, no manufacturer could make the silicone filled viscous clutch system available until sophisticated machine tooling was invented that could economically produce the required parts.

5CHN3LL

Mine's useless, but that's probably due to it sitting in pieces in my garage.

Seeeu911

Snow ? what's that ? The C4S with turbo underpinnings is as sure footed as a mountain goat on a slate mountain.
Rain, slippery roads, curves, lateral sideways moves in traffic all handled with incredible stability. the only thing comparable is a sport bike motorcycle. The fastest driver of its era street Porsche on or off track.

Seeeu911

Although the PSM is too abrupt and intrusive. I turn PSM off for fun runs and consistently am amazed at what the C4S can do.

Dennis C

With PSM deactivated, the AWD system comes into play much more often.

I agree with you - I'm quite amazed by the capabilities of this vehicle. I think the issue that some people have is that they believe that AWD = good snow traction. The AWD system in the 996 wasn't designed for snow, so this isn't necessarily the case.

rs10

I didn't necessarily mean to suggest any of the electronics are part of the awd system per se, rather that they might be the kind of significant difference the OP was asking about.

As per Jumper5836's post, I understand the car sends power to the left side when a right wheel spins by braking the right, thus acting as an e-diff. Some would say any diff, whether e or not, is part of the system. I guess it depends on where one draws the line between the electronics and the mechanical system. (Is this function disabled when PSM is switched off? I can imagine not - it might continue to send power to a wheel with more grip regardless how much the car is understeering/oversteering/spinning. Or not.)