Hi all. I've been lurking for a long time, at first just gawking at all the beautiful rides on the site. and more recently trying to inform myself on the 996. I'm not a P-car owner at the moment, and will not be for a reasonable amount of time, but from what i've been seeing in the 996 Turbo market, I believe it's reasonable to think it will be a reality a one point in my future. Alright, enough with the intro, now let me get into my question.


So what exactly are the differences between the Turbo and GT2 suspension? I've read of people converting their Turbos to RWD and being unsatisfied with the handling, and it always comes down to something like "the suspension on the GT2 is different/better."

So what exactly are the differences? The spring/shock/strut setup must obviously be different, given the different ride heights, but wouldn't that difference be nullified with a aftermarket set of coilovers?

So i'm guessing the differences go deeper than that. So is it merely a difference of other components (suspension arms, links, uprights) that give the GT2 different/better geometry for a RWD layout? Is it possible to swap parts over? Is there a list of components? How much would that set someone back?

Are the unibody suspension mounting points different? Is the GT2's unibody reinforced differently (seam welding, extra bracing, etc.) from the Turbo? I've heard it has less sound deadening material, thus saving some weight.

Thanks for your help.

 

The GT2 has adjustable coilover suspension. The front wheel carrier is different. The lower control arms are different. The GT2 suspension WILL NOT fit on a 996TT. The part that the top part of the front struts attach to is different. As far as I know the rear suspension is the same. The GT2 rear C/O's will fit in the back, but I can't confirm that.

I called Aaron at Suncoast Porsche and spent about an hour talking with him about doing this. He says he's heard of a couple people doing it. The parts associated with doing the switch totalled close to $2000. I purchased a used set of GT2 C/O here. Luckily the seller was a great guy and refunded my money. Good luck.

TXGold

 

My understanding is the GT2 upright has control arm pickup points that are 10mm higher (the car can sit 10mm lower while retaining good control arm geometry).

IMO honing your driving skills will result in a better outcome than changing to GT2 suspension bits.

Personally, I don't want to drive a car that has no stability management. Obviously Porsche agrees because the 997 GT2 comes with it standard. I like the fact that the 996 Turbo has a stability control defeat switch that comes on under braking. I have yet to be given a scenario where that is a real detriment, and can tell you that as an amateur, PSM under braking probably kept from at least one spin at the track.

I'm strongly considering installing a good LSD (guard?) when I'm in need of a clutch upgrade. I'm hoping it will be as fun as teh fantastic ///M differential.

Maybe one these tuners will make available a PSM for the GT2?

 

After talking with several guys who track their GT2s, I found that all the complaints we make about soft suspensions and changing camber and toe at track like conditions are STILL the same issues observed on a stock GT2 suspension.

What I know needs to be improved on the 996TT:

upper strut to uni-body mounts:
The OEM 996TT mounts are rubber and have a lot of vibration damping built in. That means they also move around a fair amount under braking/cornering/acceleration.

Camber Adjustment:
Max camber you can get on a 996TT in the front is about 1.5 degrees negative... That is insufficient for anything above intermediate levels of HPDE. You'll KILL tires on the outside edges... I've got corded MPSCs that looked new on the inside 1/2 of the tire... Rear camber maxes out at 2 degrees negative. Same scenario... You'll wast THOUSANDS in tires as I have this year. The Turbo has no adjustable control arms, and rely on the upper tower slots up front and the eccentrics in the rear. You're very limited.

Motor Mounts:
Ever go to downshift from 4th to 3rd at the track and not be able to find 3rd? You'd be amazed at how much the drivetrain in the car is moving around... Enough to over time pull turbo hoses loose... THIS one area can improve a number of "feel" related actions on track...

Thrust Rod Bushings:
These rods (the tuning fork sound emits when you bump the forked end) have bushings at one end that bolt to the unibody of the car. Those bushings are so "plyable" that when you unbolt the forked end from the control arm, it'll drop and hang almost to 60 degrees... Only to be stopped by the unibody. They're filled with fluid and have a tremendous amount of movement/vibration damping.

Toe links:
The OEM toe links have a lot of rubber in them and allow camber and toe changes at the track under hard braking/cornering/acceleration.

Other related bushings:
Control arm bushings are not as soft as the thrust rod bushings, but certainly could be replaced. They're designed to soak up vibrations so the 996TT can truly deliver that "civility" it has been knowd for, since it was produced.

Shocks:
The OEM shocks on these cars are designed and valved to help with that civility. They're also designed to work with a more compliant coil spring. Again, not a "performance" shock match.

Sway bars/drop links:
The OEM sway bars are also designed to work with the OEM suspension and therefore not very stiff... The droplinks are horridly tiny and will snap at the track...

I'm sure I've missed a few other items... I believe it's probably time for a Suspension DIY, much like the Brake DIY I did previously...

Also, There are some here who will say "just keep it all porsche and do the X73 suspension"... If you're gonna pay the labor, and you're shooting for a track suspension you can live with on the street, and grow into on the track, I'd look elsewhere... The X73 gives you a 20MM drop in suspension, and a "total package" designed to work well together. But it has its limits, and for enything above intermediate HPDE, you'll out grow it.

Mike

 

THIS HAS TO BE ONE OF THE BEST WRITE UPS I HAVE READ ON 6 SPEED. GOOD JOB!
ROBERT

 

Robert, Thanks, but honestly the compliments should go to the guys who answer my endless questions about "Why is the car doing this under this condition" or "What do I need to replace in order to make the car do XYZ better"...

Guys like Kevin at UMW, and Robert at Lufteknic and Kenny at Flyin' Lizard. There are a lot of smart guys out there who can help if you understand how to communicate what it is you're feeling and trying to fix.

More important than anything else, we need answers. These cars, with the right upgrades and modifications can run down Cup Cars. We need to know the combinations to do so... And if that isn't the goal, what is? What is the right combination of parts to make the car civil enough to drive daily, but fast enough to keep those pesky GT3s, Z06s, and GTRs in our mirrors and not in front of us...

Mike

 

Not sure what you are looking for but for 99% of people the twin turbo stock form is a great car. one modded correctly more than anyone I know needs.

get a good deal on a 996TT and buy a good set of coilovers and dont sweat the small stuff cause the cost to benefit ratio is NOT in your favor.

the remaining suspension changes give tenths of seconds on a 2 mile lap circuit. seconds that really no one other than guys racing need to be concerned about.

my 2 cents

 

Tom, I hope to prove you wrong in two weeks... I expect to gain SECONDS, not 10ths, from my recent suspension alignment/camber/control arm changes.

This car has been transformed, but still has issues with handling, especially with the vague "set" of the suspension, once it takes a "set" and starts to track in to a corner. I believe that swapping to solid upper shock mounts, the solid (WEVO or RSR) motor mounts, as well as adjustable toe links should be among the "first" mods to the suspension... Adjustable sway bars/drop links and the appropriate coil over would also be on that list.

Mike

 

Great info Mike! Your earlier post was impressive as well. I can't wait to see the outcome of your experiment! Good luck!

 

from what info I have gathered it is possible to use the GT2 coil overs with out changing the carriers. you can machine a bushing to insert the carrier that will accept the GT2 coil over. the rears should be just be a simple swap. you can just change out the lower control arms to the two piece and add some toe arms and some adjustable sways and a pair of good drop links and you should be comperable with a GT2.

 

Oak,
Do you have any more info on machining the bushing for the carrier to accept the GT2 C/O's? I am not sure I understand. My local wrench(a bit of an understatement ) also has a machine shop in-house, so any info you can give me would be great.
Ryan

 

After reading your post, I am on my way to Shalala's Pro Technik to have the C/O's installed and get a proper corner balance. Thanks for the push,Oak!

 

Here's the other thing to contemplate:

Labor cost to do a suspension is going to be "the cost". You can't get away from the re-alignment/ cornerweigh. You also can't get away from having to pay multiple times of suspension components being replaced piece-mill...

If you're planning to do coil overs/pillow mounts, and you think you're going to want more camber adjustment, or other "stuff" directly connected to the strut/upright assembly, get it all done at the same time and save the money... the thrust bushings in the TC rods and toe links are about the only thing, maybe the motor mounts as well, that could be done without impacting the alignment, so long as the installer is careful during the instal and takes the proper measurements before hand.

Mike

 

Another great post/response...subscribed! I'm starting to run into some of the issues described...

 

OK, what are the best motor mounts to run in our Turbos?