997.one

EDIT! This is in reference to the .1 but open to hearing solutions for both .1 and .2 if compatible.

With a complete overhaul of the suspension about to happen, I figured this would be the time to revisit this topic. It seems there are a lot of people interested in this but and then abandon the idea after a few speedbumps.

I would like to open up a free discussion of ideas if possible.

It seems that there are a few kits available for the 996/997 and the general consensus is that the real problem lies with the AWD Electrical Control Unit? There is talk of the silly-priced PFF box, which I think is actually discontinued if I remember correctly, and didn't work that well? - but what would need to take place with OEM parts to make the car think/act as if it's a C2S when it comes to the AWD system? Would replacing the ABS system with say the Bosch system have any effect on this?

@997.One on IG for more details on the project

andino

I did a bunch of research on this recently and it seems that for 996 c4/s/turbo and 997.1 C4/s, removing the torque tube, front diff, and front axles (to replace with axle stubs) is possible because they use a mechanical AWD setup with a viscous coupler. With 997.1 turbos and 997.2 cars, there is an electronic AWD control which means you'd need to deal with the electronics involved there. I don't know too much about defeating this use case as I didn't research primarily around the 7.1 c4 platform since that's what I have.

arscottp

I'm not an expert, but will tackle this at some point.
As I understand it, once you sort out the front diff electronics issues (tbd), you still need front stub axles for wheel speed / ABS purposes. Not sure if you can remove the stub axles from the front driveshafts easily. The GT2 and C2S stub axles are the same part number.

andino

This isn't the case for 997.1 non-turbo cars. There are no electronics and the awd is purely mechanical. Creating an axle stub from the front halfshaft is fairly straight forward, albeit destructive as it requires you break the front outer CV to make it happen. Once that CV is broken, you can clean up the stub and that'll have the necessary hardware to maintain PASM and ABS.

I also don't think you can fit the rwd axle stubs into an awd carrier for any model 997. I didn't take a look at 997.2 PET though to verify that but I'm making a bit of an assumption that's the case because the c4 uprights are different from c2 across the entire 997 generation.

Fwiw, I'll probably be doing the conversion this year so I'll be able to have some first hand input on this for 997.1 c4 folks. Everything seems to the same as the 996 c4/turbo conversion so I'm confident it should all work.

groovzilla

May I ask why you are removing all All Wheel Drive components? Is it not working properly?

997.one

Interesting! I didn't realize the .1 didn't have the AWD Electrical Control Unit. This is fantastic.

All is well! It was always the hope to make this a more affordable, widebody, RWD option.

groovzilla

I asked because if it is functioning well why remove it. Probably more cost to remove then to leave in place and use it like intended.
Having all wheel drive is a bonus.
As long as the front differential is properly serviced there shouldn't be any additional costs having it operational.
Hardly ever hear of any issues with the Front Differential and on rare occasion when I've seen issues come up and from what I recently discussed with my 50 year Porsche Indy, it is due to poor service history/not changing fluid.
But for some reason IF the 997.1 front differential did need replacement, there are many used 997.1 front differential units for sale on Ebay and used parts shops.
Not the case with the 997.2. They are harder to locate and expensive new.

ADias

AWD is an option and offers far different driving dynamics. I've owned both and prefer RWD - personal choice.

But I agree, I would not mutilate a AWD 911.

groovzilla

I've had both also. For me it's a toss up but notice a little better performance cornering w/C4 & C4S

bheit1

I second the idea of leaving it. These "mutilations" seldom work out well and the value of the car suffers severely, if that matters. If it isn't what you need, sell it and buy what you want.

andino

It really depends what you're after tbh. There wasn't an option for RWD and widebody for 997.1 cars. Driving dynamics of RWD and AWD are very different even if the c4 is rwd biased. Folks that are considering this probably aren't concerned about values and all of it is reversible anyways.

As far as costs, it really isn't much to do a rwd conversion on the 7.1 platform. Since it's all mechanical, just removing the awd components and then either buy or make your own halfshafts. Hell if you wanted to just get a taste, just remove the torque tube shaft and you'll get yourself 85% of the way there.

Butzi 997

Hey skaper, tried to look you up on IG to see how far along you are on the project, but no luck. I was just curious if you investigated the price delta on just selling your C4 and buying a .1 C2 over modification? Perhaps you just want a project?

I get wanting to go RWD over AWD tho. During my 8 mo. search for my car, a buddy bought a perfect 997.2 C4S and flipped me the keys. It was beautiful, but driving dynamics felt a bit sluggish compared to RWD. I could really feel the weight in the front end. But of course, no shame in loving a C4. Solid cars too.

Petza914

Not necessarily. Depends on the use case for the car and the driver.

The rwd cars have much better steering feel, feel lighter and more alive, don't understeer through the turns as much, and it removes things that need to be serviced from the equation.

Unless driving in heavy rain frequently or snow, with the rear weight bias due to the engine over the driving wheels, the 997 really doesn't need the AWD and is more fun without it. Just my opinion of course.

Jack667

I had a 964 C4 (see avatar) and got the understeer dialed out with adjustable sway bars. This was about 20 years ago so memory fades, but I think we adjusted steering feel with toe.
I'm in the camp to leave it AWD and use simpler methods to address the perceived downside issues as best as you can within reason. If it's that bad, swap out the car to a C2. But - I'm also a believer in - to each his own - so have at it if that's what you really want to do.
One last thought is to complete the mentioned suspension work and get it tuned optimally to your tastes, and see if that gets you close enough to where you want to be.

PCarFan16

I just recently completed removal of the FWD drive components on my 997 C4. It’s easy to do and fully reversible. Remove front drive shaft, front differential and axles. Replace axles with Gt3 stub axles which fit into the C4/C4S wheel carrier. Some people also disassemble the front CV joint to reuse the stubs, but they are hard to reassemble if you want to reverse the mod. This is a fully mechanical system (on .1 cars) so does not affect PSM or ABS.

why? Well, C2/C2S widebodies are kinda unique, but it’s really about the driving experience. The steering feel is significantly better without the front drivetrain to mute and numb response and feedback. Steering is now lighter and more communicative. I was disappointed with the steering feel on my C4 but now it’s what I expected a 997 to be. For a fair weather street driven car, AWD is unnecessary, creates understeer, and doesn’t add much traction advantage with all the weight over the rear wheels. The only downside for cars without an LSD is that high speed corners with wheel lift may cause the outer wheel to spin. This is more of an issue for cars that are tracked. An LSD can be added.

as far as value, who cares? This can be fully reversed in about 3 hours with no long term impact to value. The car is much much more enjoyable this way!

just my 2 cents!