Considering Converting to RWD....Has anyone successfully done this????
 

I have been having issues with my front inner CV boots boiling over and exploding within 100-150 miles after installation. First was with a re-built CV boot and after failing we then installed completely new OEM axles, once again, failed within 150 highway miles.

We are now thinking something has failed with the front differential, potentially a bearing or race, thus causing excessive heat. We have been keeping an eye on the diff fluid....levels are good, but we are seeing fluid seeping out of the breather/overflow vent at the top of the diff.

Unfortunately the front diff is not re-buildable nor can we order bearings or races to trouble shoot. The cost for a new front diff is stupid crazy....$6,500ish! I do not see the value in replacing it. Therefore, we are considering removing it altogether.

Has anyone ever perform such surgery on a 997.1? In doing so, is their anything we need to be aware of? Is this really just a simple process of removing the diff and transfer case, etc...as sighted in many 996TT AWD to RWD conversion threads, or is there way more involved with doing so with a 997.1? i.e. electronic sensors dictating the amount of drive to the front wheels, left or right, Traction Control, ABS, etc...

The vehicle is primarily used on road courses. ie: its a "Track RAT" with plates.

Concerns from the shop that might be performing the surgery:
"There is some concern here that the tranny may also have to be changed, once the front driveshaft is removed. If there is no load on the front driveshaft (it would be gone), then we believe the transfer case may be set up to transfer all load to the unload front or rear, which now would be the front, and there would be no power to the rear...."

Thanks in advance for any insight on this matter.
VID997

Subscribed.


How about sensors also?

Its easy to do on a turbo but according to my guy everyone goes back and puts the AWD back.

Hey squat, do you happen to know why this is the case? Also, do you. Know what is involved with this conversion?

You disconnect the front driveshaft, you need the part from the gt2 to hold the pieces in the front. The handling changes too much is why

^^^ FYI: My vehicle is a heavily modified track machine and is not very usable as a street car. It has one purpose....that being... going around in kinky circles, (hilarious) which requires one to turn the steering wheel left and right while controlling the throttle....not just left, or holding it straight while keeping the pedal flat.

Squat, alignment and suspension wise...everything has been replace with CUP car bits and in 2013 it spent an entire season fine tuning the suspension and alignments with everything based on Ohlins TTX 46 & 36's.

We have already began bench marking set-up with a GT-2RS and feel we are at a very good starting point (if we eliminate the front wheel drive system).

Then buy the piece in the front front a GT2 and take out the driveshaft. I forget what its clled

Hence, my subscription. I am in the same boat with the cup car parts and monoball bushings.

Great thread! Looking for some answers.

My guess is most people don't like the 997TT RWD conversion because in order to do it correctly and see a benefit you need to do more than just rip out the front diff. Ideally you'll want to correct the front geometry by installing GT2/3 uprights which turns into a costly exercise. At the very least, you will need different spring rates with a smaller front to rear split which will necessitate new shocks. This is a perfect excuse for a good set of motorsport coil overs. Finally, a quality Motorsport type LSD like a Guard or a CUP 40/60 LSD is virtually a must because you need an effective way to put the power to the ground now that the front drive is gone. Adjustable front and rear sways are a given but you already have all those goodies. I'm not sure what type of LSD the 997TT comes with but even the LSD that Porsche puts on stock GT2/3s (their track car) is very weak and wears out in a few track days. Most guys rebuild the stock LSDs with Guard guts. I would imagine the stock 997TT LSD will be even weaker as the car is designed as a GT cruiser and not a track car. The biggest obstacle I see is defeating the electronics on the 7TT. I'm not sure if the car would go haywire if the front drive is removed. Maybe not, only one way to find out, right? On the 996TT it's easy. You pull one plug and all you have is ABS. If someone could figure out how to fully defeat the PSM on the 7TT, this would be a killer conversion. About $10K worth of stuff (Suspension and LSD) would get you close to a GT2 for a fraction of the price. I'd love to see it...

you can do it easily, and I don't think you need to modify your transmission.
its more fun than AWD specially once the turbo kicks off, but YOU HAVE to consider the LSD


I Had a problem with my front differential earlier this year, and unfortunately I replaced it with a new one and the cost was around $7500 including labor


All the best

^^PowderHound,

The car currently has a Guard GT2 PRO 40/60 LSD, AASCO Lightweight Aluminum Fly Wheel, SACHS RACE Clutch, CUP Cables, Numeric Shifter, GMG Semi Solid Tranny Mounts, RSS Semi Solid Engine Mounts, Ohlins TTX Fully Adjustable Coilovers, RSS Adjustable Control Arms (Front), GT3 CUP Adjustable Control Arms (Rear), RSS Adjustable Front Toe/Bump Steer Kit, RSS Adjustable Rear Links, RSS Adjustable Rear Toe Steer Kit, TRG Adjustable Drop Links (Front), Champion Adjustable Sway bars (Front and Rear), Turbo Kraft Monoball Camber Plates (Front & Rear), and I am sure I am forgetting to mention some other bits...

We are more concerned about electronics and what to do with the output drive on the transmission which powers the transfer case for the front wheels.

Thanks,
VID

I was more referring to someone trying to do a RWD mod a stock 997TT. You are 90% there. As I said, the hurdle is the electronics. Or is it a hurdle at all? Maybe it will work just fine. I'm not sure if anyone really knows but it seems like it should be easy enough to try. Someone has to know the electronic feedback from the front diff to the ECU. On the 996TT, the front diff is purely mechanical so it's a no brainer. As far as the output drive on the gearbox, there is nothing do do. You just unbolt the cardan shaft, and remover the whole front drive including the axles. You will have to disassemble the front axles to use the stub axles in the uprights.

you can disconnect the front drive and go RWD, but you wont be able to get into sport mode.

the right way to do RWD is by changing the front up rights to gt3/gt2 spec. the handling will be night and day.

as far as transmission issues, you wont have any.

if/when my front diff dies i will go rwd as well.

you do nothing to the tranny output just leave it there and let it spin. that in no way will impact anything. take the front drive out, cut the axels and make stub axels out of them. for the electronics you can get a proffessional version of duramtric and code out the AWD and make the car think its a gt2. simple. just need the Pro cable, enthusiast cable will not do it.

Also, you will need to adequately modify the front suspension and add negative camber. Ripping the AWD alone makes the car severally understeer.

^^SteveK: Sport Mode as in NO OVER BOOST....OR...The ability to stiffen the suspension? Sport suspension mode has already been eliminated when the Ohlins TTX's were installed.

^Prodigymb: RE: "code out AWD" Thanks! I'll pass the info along. The car is getting dropped off tomorrow night so they can begin working on it first thing Monday morning.

If you can believe it, when the first CV exploded it rubbed through the fuel tank shield and burned through part of the gas tank...not all the way....but dangerously close. Thus, a new tank is getting installed.

When you take into consideration the price of the conversation + the depreciation on the car, it wouldn't cost that much more to sale the turbo and buy a GT2? Especially since the GT2 will end up appreciating whereas a modified turbo will depreciate.

I Think the part that replaced the diff, is about 1200$. Its not expensive and you really ripping things apart. Call Todd and trophy performance in Las vegas. He can give you the run down.

^Squat: New OEM front Diff, $1,200??? Dealer quoted me $6500....

^^997.2TTS: The vehicle already has everything done, installed and proven....the issue is that the front diff has failed and a new one is $6500 plus labor to install....verses two hours to just remove it altogether. Removing it opens up a new set of tire and wheel options for me....9.5" x 18's with Michelin Slicks up front... 12.0 X 18 rears. The car spends the majority of its time on track...not the street.

VID, sport mode as in overboost.
rwd is easy for the 997. u already have an LSD, all you need is upper mounts in the front to get that "on rails" feeling that a gt3 gives ya.


btw, Squat is right. ive seen 997 front diffs (taken off a totaled car i assume) for $1200 (exactly) on ebay.

Vid, one more thing. as far as tire sizes... remember, gt2s and gt3s have a similar tire set up (taller rear than front). rear always need to be taller than the front.
with that being said, i can only imagine your car on a 265/345 set up !!! :)


one last thing, if the tank is getting replaced, you can put a 25 gallon gt2 tank !! it will fit once your front diff is removed.

I am not sure if the software checks for a front diff before going into overboost. I had mine out and never lost the overboost.

Squat: So you have had your 997.1 TT (Model Year 07-09) converted to RWD?

Steve K: 25 gallon tank would be nice. Unfortunately the tank was ordered two weeks ago. I just found out earlier today it would not make it state side for another three weeks. Therefore, the car did not get dropped off this evening. I found a place in SoCal that might be able to re-build/service the diff. Bill Rader recently serviced my rear tranny....I will check with him regarding a re-build/service of the front diff if it is even possible. I also was able to locate three used units today for $2500 with a 90 day guarantee. The units between $700-$1200 were for 996TT's...completely different unit than the 997.1.

UPDATE:

Well, the new fuel cell arrived earlier today as did the GT2RS Axle Stubs!

Out with the driveshaft, left & right front axles, and then the differential!

Hopefully all will go smoothly. The vehicle should be ready for pickup Monday evening!

Cheers,
VID

https://cimg6.ibsrv.net/gimg/www.6sp...f47ebabfbc.jpg

https://cimg9.ibsrv.net/gimg/www.6sp...b8a770b74a.jpg

https://cimg0.ibsrv.net/gimg/www.6sp...bffb7a162f.jpg

Nice! Look forward to hearing your outcome.

Had this bad boy installed back in October while we were trying to trouble shoot diff issues.

Champion GT2 Pro 40/60 Spec Guards Rear LSD.

https://cimg6.ibsrv.net/gimg/www.6sp...33ba96e288.jpg

subscribed......good luck!

Are you changing out your front uprights also to the proper GT2/3 units? The reason I ask is that the GT2/3 tension bolts (aka axle stubs) are NOT compatible with the AWD front uprights. At least on a 996 they are not but I don't know about the 997. It's a bit of a moot point as you really wanna change the uprights to correct the front geometry and you're probably doing that anyway. Just curious.

This is a great thread. Subscribed and good luck.

the 997 will fit

Everything is out and I test drove the car last night, all felt good. However, we do have some code issues.

We currently have a PTM error code. Sport Mode/Over Boost is not functioning either because of the PTM code. Also, If I try and disable PSM it will not allow it to be turned off because of the PTM error code.

We were considering re-flashing the car to making it believe it's a GT2RS. However, in doing so that would zap out my custom GIAC Champion mapping.

The shop may have a solution to trick the electronic pickup sensors from the front diff which are no longer in place. Currently we are doing a little bit of homework to see if this is a viable solution.

Still forging ahead with this mission....:cool::confused::cool:

Subscribed.

It should be possible to turn the code off in the program, it takes some detective work to find the right adress. The GT2rs program won´t work in the turbo, they are completely diffrent.

Interesting test day at Sonoma on Sunday.

Primary purpose for testing was for suspension set-up. We started off by adjusting the sway bars to full soft up front and full stiff in the rear, while leaving all my shock settings were we typically have them for Sonoma. We were getting some oversteer as well as some nervousness with the rear when exiting the higher speed turns. After the first session we opted to adjust/soften the Compression dampening. This did help to minimize some of the oversteer, however the rear end was still nervous and unsettled under hard acceleration coming out of the exit of T10. Before heading out for S3 we adjusted the rear sway bar to the middle position. This really helped smooth things out. Next up S4, Sunday's race...did okay in finished the best I could considering the circumstances. After the race and downloading feed back to my Suspension support. The car actually felt really good and now only suffering from mild turn-in under steer at T7 and T11. We feel we can dial that out by softening the compression dampening on the front shocks, which we will try on our next outing.

Now for the BIGGER ISSUES.....the electronics were not happy at all!!! Stability and Traction control were going crazy and constantly trying to control the vehicle to the point were it would cut off power to the engine (meaning, it was chopping the throttle as I was accelerating through and out of the turns)....VERY FRUSTRATING!!!

This was a test session to see how the car would behave with the removal of the differential. This info will now be passed on to the software gurus. Hopefully they can come up with a solution, or already have one.

I am not done yet with this experiment....


SPEEDFREAK:

Do you have any insight why a 2010 GT2RS program will not work?
Thanks,
VID

Addresses in the gt2 and rs file are all mixed up compared to the turbo, I have personally looked at the two files and they have moved every thing around.

Any update Vid? Did the electronic issue get resolved? I might want to do this to my 997 c4.

Slow for now. Ran into some tranny/throw-out bearing issues when we last tested at Sonoma. Actually had to get a tow back to the pits. Currently we are waiting for the rain to stop here (San Jose, NorCal) to get the undercarriage steam cleaned (its covered in differential fluid, and it stinks!!!!). Once we get it cleaned up we will then drop the tranny and see what's going on with the throw out bearing, shaft, or release arm??? Most likely with the up coming holidays, I won't get to this until mid January.

Plan currently is to sort out the throw out bearing and then reprogram the car to a GT2/GT2RS. My GIAC tune will get zapped in the process, so I will need my ECU to be re-flashed as well. I have custom maps with GIAC, so that is a pretty simple and painless process, other than having to send it out for re-flashing.

I'll keep the thread updated as I take the next steps.

Thanks for checking in.
Cheers,
VID

Did you try calling Todd at trophy performance? I know he has done this for some guys. I know most didnt like it after but he might have some ideas. He is the most qualified Porsche guy in the LV area and that is including the techs at the local incompetent dealer.
I think he is still the only guy in that area qualified to work on the Carrera GT based of the gold status.
Anyways he might have some ideas on how do get around the PTM issue.

Make your first loss your best .Sell your car and go find a GT2 .You will save in the long run and have a more valuable car that will hold value.