delhi

being both 911 models will hardly see snow, i doubt the differences will be huge. i wouldn't lose sleep over the mechanical 964 awd vs the VC 993 awd. if porsche saw it fit to have 5f/95r distribution for the 993, i'm sure they know why. otherwise it wouldn've been the same split as the 964.
so is the 964 a torsen equipped unit or no? it seems to be using sensors for brakes, lateral movements etc to modulate the awd system. If so, it reminisce subaru's awd system found in their automatic cars.
tb993tt, the v/c reacts very quickly. just not as quick as a mechanical (is it bevel geared driven?) units or Torsen units. in return, you get a simple lighter weight awd system.

Adrian

The 964 AWD is not a Torsen system.
I like the statement both 911s will hardly see snow. Come visit me sometime we have a 964, 993 and 996 C4 in my village. You will only see C4s out in the snow in Europe and in the heavy snow only the 964s. I had great fun overtaking a big V8 4X4 Jeep going uphill earlier this week in the snow.
I also think that comparing Subarus with their front engines, primary front end drive and tad more sophisticated systems to a rear engine rear wheel biased 993 is also a mistake.
I guess you would have to ask Porsche why they went to 5/95 viscous couplings but I suspect it had more to do with manufacturing costs more than anything else. The 993 system is much cheaper to produce. Viscous couplings cannot provide normal 31/69 anyway simply because of the design and how it works. The 5% front drive is like a residual drive. However as you have said you have never driven one so it would be better to drive one first under all conditions and then drive a 964C4 in the same conditions and then come back and tell us your findings.
Ciao,
Adrian
964C4

Speedraser

Adrian,

By "better traction system" I guess you were referring to fairly extreme conditions. I can't recall the exact figures, but VCs react extremely quickly, in a small fraction of a second. That said, I don't doubt that the more complex 964 system reacts even more quicky. In any event, it seems to me that the 964's advantage in the snow comes more from the 31/69 front/rear torque split than the difference in differential types.

As I recall, Porsche changed to the 5/95 torque split for the 993 because they wanted the C4 to handle more like the C2 in response to criticism that the 964 C4 understeered too much. They said they were less interested in extreme-weather performance than with everyday driving situations with the 993 C4. With only 5% of the torque going to the front wheels under normal conditions, the 993 C4 feels more like the 993 C2, whereas the 964 C4's 31% torque to the nose makes it feel quite different from the 964 C2. If I remember correctly, the 993 C4 system will only send a maximum of 35% of the torque to the front wheels. I don't recall the range of the 964's torque split, but I know it will send a lot more torque to the front wheels than the 993's setup. So, in stock form, the 993 C4 is supposed to handle better than the 964 C4 in most situations, but the 964 C4 is definitely the better car for serious snow or other very low traction situations.

A 964 C4 might be just what I need for the coming winter...

Adrian

Dear Todd,
What you call extreme is normal for myself and the millions more that live in the Alpine regions of the world. The 993C4 performs better in the dry than the 964C4. They are failry equal in the wet and the 964C4 out performs the 993C4 in the snow and ice. This is purely down to the AWD and the traction control systems used.
I purchased a 964C4 simply because in winter it is the most superior AWD Porsche 911 that was available and in the 911 range remains so.
Ciao,
Adrian
964C4

delhi

adrian,
i guess it's an euro thing. i have never seen a 911 out in the snow ever in canada.
i don't understand why you mention that v/c cannot have split at 31/69. Surely it can't be a Porsche engineering design limit as again, drawing from my limited experience with subaru's their v/c distribution is at 50/50 all the time.
IMHO, the best bet is to have all three differential. front, mid and rear. therefore aportioning power to each wheel instead of just front and rear. But that would add more weight. IIRC, the 964 only has a limited slip diff for front to back power distribution. No rear nor front (open diff). Imagine having all three, now that would be an awesome awd machine! However from the consumer demographic, Porsche in their infinite wisdom knows that kind of soft-road prowess will see very limited use. If anything, the awd system in C4s are really there to quell the tail happiness of it's rear engined design.

the 964 KID

I drive my C4 out in the snow every winter - i love it. I'll see a few more 911s out in the snow also - only C4s of course, and mostly 964s, but an occassional 993 or 996 too. My 911 was the first AWD car I've owned, and continues to be the best one I've had in the snow period ( I was a fan of the swedish cars for years).

gjvander

I was real proud of my C4 and insisted on driving it to work the first snow storm we had. Did I mention I had some high performance tires fitted?

It was an absolute nightmare. With the heavy tail the engine kept trying to pass me every time I lift off the throttle.

What snow tires works well on the C4? I love being able to play with the car in marginal traction conditions. Will probably end up in a ditch one of these days.... AWD is awesome, and when you add a little horsepower, well, it becomes addictive.

Regards,

Geo

Adrian

Dear Geo,
It is a good idea to use winter tyres in winter. I use Michelin pilot Alpin winter tyres, 205/55R16 front and 225/50R16 rear. Anything wider and you have snow shoes. These tyres will take you through the worst storms unless the snow is higher than the front.
DO NOT USE SUMMER TYRES IN WINTER.
Dear Delhi,
The 964 C4 has differential locking of centre power transfer unit and the rear differential. Porsche actually call it a LSD. On the 964 you can lock rear wheel to rear wheel and rear wheels to front wheels providing torque transfer from left to right or right to left at the rear and from back to front or front to back.
The same rear differential locking assembly was available for the 928 from 1990 to 1995. It was called PSD.
I do not know what the maximum drive to the front of a 993 is however it is normally 5% and can only increase with a loss of traction on the rear wheels. This drive transfer is only temporary and normally only lasts a second or less.
Ciao,
Adrian
964C4

DangerousDan

Adrian, if you were building an offroad/safari project which AWD system would you use?

carlskisWP

I think Adrian probably moved on from 964s several years ago. ; )

I wonder what he drives now?

Foxman

John McM

911Jetta

It think we're going to see a bunch more of these projects now.... (given the excitement over the Keen project)

My question, is the 964 (as awesome as it is) the best candidate for this? Or is a G-body better? Curious

https://rennlist.com/forums/964-foru...ion-2-0-a.html


https://rennlist.com/forums/964-foru...964-build.html

sideways-964-tarmac-rally-video.html

crowds-around-a-964-carrera-4-lwt.html
964-rally-agostino-rizzardi.html

Goughary

The C4 can't handle race or off-road race situations with the stock system. The only way to go if one is to do this, is to get rid of the computer controlled hydraulics and install a manual system like the C4 lightweight and the Porsche rally cars had.

The system can't maintain enough pressure to continuously work the diff locks along with the brakes and clutch.

Further- the stresses on the stock components , clutch packs, planetary gear, etc, will mean for a very expensive ownership as those come due quickly for maintenance and replacement.

Would be a fun car...but if it were me, I'd use an SC like keen does, and keep it light and fun. Add some hp and torque and have a blast.

911Jetta

Thanks for the response. That's what I was thinking.