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I am looking to undertake this project and turn my C4S into a "C2S". Not having a garage or access to air tools, is there anybody in the Denver area that would be interested in lending a hand or space for the conversion?
Hello, I’ve got a question, please: I’m looking into buying a Carrera, preferably a C2, but all the cool colours and the nice options come with a front diff.
So I found this thread!
Would the C4 be very different from a C2 after removing the front transmission? And PSM would just operate on the back, correct?
Captain Obvious, did you solve the front end problems after a new wheel alignment, please?
The C4 has less front trunk space than a C2. PSM operates through the brakes - independent of the drive components - so removing the front diff shouldn't have any impact.
The C4 has less front trunk space than a C2. PSM operates through the brakes - independent of the drive components - so removing the front diff shouldn't have any impact.
I find that PSM is much less intrusive now that the front wheels are completely undriven. Still works fine - but less frequently.
I find that PSM is much less intrusive now that the front wheels are completely undriven. Still works fine - but less frequently.
Interesting. I guess that removing drive to the front wheels changes the dynamics of each wheels speed when traction to the rear is lost. My rudimentary understanding of PSM is that it essentially works by monitoring each wheels speed and applying braking independently to each wheel. One thing I'd be curious about is whether it takes into account the impact of braking one front wheel to force drive to the other. If thats the case I could see that removing the front diff would have some impact on its effectiveness. I honestly can't remember if PSM was available on C2 models - and if so I wonder if the software is different or the same.
Interesting. I guess that removing drive to the front wheels changes the dynamics of each wheels speed when traction to the rear is lost. My rudimentary understanding of PSM is that it essentially works by monitoring each wheels speed and applying braking independently to each wheel. One thing I'd be curious about is whether it takes into account the impact of braking one front wheel to force drive to the other. If thats the case I could see that removing the front diff would have some impact on its effectiveness. I honestly can't remember if PSM was available on C2 models - and if so I wonder if the software is different or the same.
PSM is available on C2. Can't confirm whether the program parameters are the same, but I'd expect they are. It's just using the brakes and reducing engine power to reconcile wheel speeds to driver inputs.
Interesting. I guess that removing drive to the front wheels changes the dynamics of each wheels speed when traction to the rear is lost. My rudimentary understanding of PSM is that it essentially works by monitoring each wheels speed and applying braking independently to each wheel. One thing I'd be curious about is whether it takes into account the impact of braking one front wheel to force drive to the other. If thats the case I could see that removing the front diff would have some impact on its effectiveness. I honestly can't remember if PSM was available on C2 models - and if so I wonder if the software is different or the same.
In addition to differential braking, PSM also retards engine timing for some slip situations. However, I do not believe that PSM is "on" long enough to direct power to the other wheel (like active brake differential in other cars).
Well I took the plunge yesterday and pulled the front differential, cardan shaft, and axles. With the use of an air impact wrench, the axle nuts came off in about 20 seconds and HIGHLY recommend anybody doing this conversion to find a shop with air tools.
At this point, the big hangup is removing the c-clip on the outer end of the stub axle. No matter what I do with pliers or screwdrivers, I cannot get it to lift off the groove and release the axle. Everybody is tired after a long day - back at it today.
How about getting two new CV joints and leaving the half shafts complete?
How much would they cost, non OEM? See if it’s worth to spend some money and save some frustration, me thinks.
Also because, smacking or heating them up you’ll probably damage them anyway.
That is an option, but it's an expensive route to take when taking apart the factory CVs is free and you are unlikely to damage anything if you do it correctly.
Well I'm genuinely impressed with those of you who were able to expand the c-clip and just tap the race to remove it from the axle shaft. I spent 4 hours playing with it on Saturday, and another 3 on Sunday. No luck! Screwdrivers of all sizes, pliers, snap ring pliers - no matter what I did the clip wouldn't move inboard or stay expanded long enough for me to disassemble. I finally gave in to brute force, placing the axle in a vice, expanding one side of the clip and beating the living daylights out of the race with a hammer. With that kind of persuasion, the race started to move back and finally broke free. Elegant? Not in the least bit. Effective. It sure was.
With the race out, the stub axles were easy to clean up and reassemble. As others have said, it's amazing how compact the AWD system really is and it's an amazing piece of engineering. I ended up reinstalling all the braces underneath the car, and taking the additional step of removing the front differential mounting bolts and hardware associated with the system.
I cannot give an accurate review of the car in RWD, as I haven't really gotten on it yet. First impressions (just driving around town and on highway) are:
I can feel the weight gone from the front. Steering still feels tight, but the car feels like it's floating more at highway speeds and through corners
I feel the transmission more. Not sure if I need to re-tighten the transmission bolts, if the trans needs to settle now that it's not connected to anything upfront, or I'm just overly sensitive, but I'm much more aware of my shifts. Shifts feel slightly clunkier...hard to explain and I'm keeping an eye on it
The car still grips like hell. Porsches are just amazing (and overengineered) machines. The car still feels so planted at moderate speeds and it's not unruly by any means (you C2 owners can attest to this). I intentionally lifted the throttle on an empty onramp and the rear end felt planted. Where the AWD car wouldn't change feel at all doing that, the RWD car has a slight "sway" to it. Not dangerous or unnerving, but you can feel the weight shift of the back end more. Running 295s in back, I think it's going to take a lot to really break the back end loose.
I'll report back after I drive the car for a month and can push it more. Happy so far as I'm looking for a more visceral feeling and to really connect with the car by stripping out as many driving aids as possible. With the conversion done, I'm one step closer to that goal!
A reminder that removing the AWD may result in a slower car. The C4S was faster than any C2 in factory testing on the Nurburgring. See here on the bottom of page 81. https://rennlist.com/forums/996-foru...l#post14125769
With the 80 lbs removed, it should accelerate faster at slower speeds, and it may be faster in lower speed racing. The stability provided by the AWD, and I suppose extra drive traction, are probably what makes it faster at higher speeds. Or maybe it is the fatter tires or better brakes, who knows. Does anybody think they put AWD on every 996 Turbo for some reason other than to make it a faster / better car?
A reminder that removing the AWD may result in a slower car. The C4S was faster than any C2 in factory testing on the Nurburgring. See here on the bottom of page 81. https://rennlist.com/forums/996-foru...l#post14125769
With the 80 lbs removed, it should accelerate faster at slower speeds, and it may be faster in lower speed racing. The stability provided by the AWD, and I suppose extra drive traction, are probably what makes it faster at higher speeds. Or maybe it is the fatter tires or better brakes, who knows. Does anybody think they put AWD on every 996 Turbo for some reason other than to make it a faster / better car?
The GT2 must be quite an experience, I don't think I could handle it. And the C4S is such an excellent car, and plenty for me.... after 1.5 years still loving it. I also should add that the AE is undoubtedly faster than the C4S.
I was out driving and thinking about this subject, and I also like the safety that the AWD adds. The viscous coupler (VC) is first class technology, when a wheel spins it transfers the power to the other wheels. So this car is safer whenever you are driving, and especially useful in poor road conditions (rain, snow, loose surface, etc). I think Porsches have always been made "rough and ready" and to me the AWD adds another dimension of utility and safety. Oddly I don't think I've ever heard of VC failure, or the failure rate is very low.
10-17-2017, 04:27 PM
