Somewhere there's a write-up (it may be in a thread on here, but I don't have the time to hunt it down tonight) that says the 'AWD' system in the 997.1 non-turbo (and the 996's) is really there as a cornering/handling assist, and not really a slippery surface solution. Given how the coupling works, I tend to agree with that perspective.

Anyone have a line on the old 4/4S Porsche marketing materials from 2006/2007? It'd be interesting to see how they couch the 4 wheel power.

 

Again. It should do something. Not spin the rear tires freely.

 

OK, let's check the obvious first. Go to https://vinanalytics.com/ and enter your vin to see if your car is in fact a "4". Maybe the previous owner just like that number after "Carrera".

 

I have checked a car for driveshafts before. Turns out the clutch or whatever was shot

 

yeah, it checks out. I have seen the build sheet too and it says C4.

 

You all have me paranoid now. Wondering if a PO took out the driveshaft.

 

Over the years I've seen a lot of AWD cars get stuck, spinning just the one tire with the least grip. Yes, even Jeeps. With a viscous coupling (in all 997.1 cars ... this wasn't changed until the 997.2) it is even more likely. 997.1 AWD was for handling rather than traction. Occum's Razor would point to ...

1. Normal behavior
2. Worn clutches

But other concerns would also include ...

1. When was the last time the oil in the front drive components (plural) changed?
2. Are the front tires frozen to the ground giving yet more resistance against the clutches in the viscous coupling?
3. Unlikely, but the driveshafts could be missing, but this requires a special kit that few in their right mind would use.

 

Update? Were you finally able to get the car to move?

 

Having owned a C4S for a number of years, this doesn't seem right.

 

What a sh*t show mess ... drag that car back n the garage where it belongs this time of year . Geeez you guys are maniacs..

 

A few others have mentioned the 997.1 has a viscous clutch AWD system. As I understand it, all viscous clutches will eventually need replacement. As they age the silicone based oil breaks down or dries out. They degrade gradually and there is no indication of failure. It is passive and engagement depends on a difference in rotational speeds between the rear and front wheels. 5% is normally sent to the front but when there is a speed difference the oil heats up, changes it's viscosity, and sends more power to the front. A tired VC system will need more of a speed difference to engage the fronts (hence the recommendation to really spin the rears). A dead VC system is dead. The options are replacement or conversion to RWD only.

This is the same AWD system first used in the 993. The 964 had an active AWD system but it was a headache to maintain. The Viscous Clutch system is much cheaper, lighter, and simpler but is not the best system for getting one unstuck. The 997.1 Turbo returned to an active AWD system but with more robust and versatile electro-mechanical clutches. The C4 didn't inherit this system until the 997.2.

 

I'm guessing the service/maintenance on this particular Front Differential has been lacking.
I've owned 4 996 C4S, 3 997 C4S and 2 997 C4 examples. Never any issues and never any issues on my current 2006 C4 I've owned for 3 years. (A personal record for me)
Have to make sure Front Differential has been maintained/serviced properly at correct intervals using correct OEM Porsche Fluid, which I have noticed over the years some owners don't use.

......But if Front Differential does crap out, they are easily replaced with warrantied used unit from many Porsche used parts suppliers for $1100-$1200 shipping included.

 

There are no clutches in the viscous coupling, it works using the fluid as resistance. Not sure about the 997.1, but removing the driveshaft is all that is needed on the 996, no special tools.

If the front differential is bad there would be lots of noise and other problems. Changing the oil is a great idea, as everything from the axles to the ring and pinion as well as the driveshaft rotate when the car is moving. Changing the oil won’t change the outcome of front wheels not spinning.
There is no other oil to change, the front driveshaft comes out of the transmission directly to the front diff. In a tiptronic car there is differential oil , but again if that were bad ther would be other bigger issues.

The only option you have is to replace the coupler, as testing it is a complex procedure that requires brake rollers.



That’s the procedure to test, from Porsche. I would suggest replacing the coupler if you would like to make sure it is fully functional. I believe it’s about $2000 from sunset Porsche. A used one would be a gamble, as they are sealed units that require machining to get open.

 

Hello! I have a 2010 Carrera 4S, no errors, but my front wheels are not pulling the car. I have changed the oil in the PDK, differentials, and AWD clutch. I have the car for half a year. Do you have any procedure to test the AWD system?