Ahmet

Porsche has said that this was the reason. If I remember correctly, the 2004-5 GT3 has a modified C4S chassis which was mated to the C2's rear (narrow) section. Further modifications were made to the rear for mounting that engine as well as additional stiffening. Hard to say how much weight that all adds up to, but appears to be substantially more than a C2.

sprintamx

The GT3 vs C2 hp/weight ratio should be a hefty consolation for the 100+ lbs difference. On the other hand, I'm certainly not ready for a more tail happy car in the real tight twisties. Someday . . .

jrgordonsenior

It's all about setup. It doesn't have to be tail happy if someone who knows their stuff sets it up....

sprintamx

The trick for me has been to know that I found "someone who knows their stuff."

I'm working hard to be an educated consumer so that I really understand what is going on with the chassis and suspension, how all the pieces work and need to come together, what elements I need or don't, etc. It's also been tough to understand what "results" I want to achieve and why. And, its been tough to understand whether I received good value and advice for the money.

As an example, when I picked up the C2--moving from an '88 Carrera with some "work"--I immediately went to adjustable coilovers, adjustable sways, adjustable camber plates, drop links, etc. Leaving aside whether that was too much, too quickly, I had great difficulty with controlling the rear-end. Well, everything was set-up pretty darn stiff. But I did not really know or understand what that meant or what results would be likely at my skill level. Add poor throttle control--lifting--and I quickly became the spin doctor. I've since loosened up the suspension a bit, which helps as I develop better throttle control and feel.

So, I'm learning what to look for and why. I'm also learning to understand how to difficult it is to find good value and advice for those hard earned dollars. The process continues . . .

KobaltBlau

Ahmet, I have also read that is the reason they used the C4 chassis, but when you say "I thoroughly enjoyed tracking my 99 C2s, but they didn't drive much like a GT3 even w/similar suspension set ups" what differences did you notice?

Aaron, I do think too many variables were changed at once on your car and you need a good chassis guy to sort your car out. This will not be cheap but it will be worth it. I think this forum should be able to give you good recommendations for a chassis guy in your area, but that's probably another thread...

Ahmet

The GT3 has crisper turn-in and is a bit trickier to drive in part because it's throttle response is a lot more touchy, the rear end moves around a little bit more under load and breaks away more suddenly. The C2 feels more stable, and doesn't require as much minute input near the limit. For example I had to open the wheel in the GT3 at the uphill S' (@the middle bump) at VIR at 115mph indicated on street tires. At 110mph the GT3 feels a lot bouncier and more abrupt than at 115-117mph. Same thing at the kink at CMP, near the exit a GT3 is a bit more tail-happy. At these spots the C2 doesn't seem to be as lively, even on the same coil overs.

All in all I'd say the GT3 takes more precision to rotate under trail braking at lower speeds, that's probably the biggest difference to me. Also as I alluded to above, the GT3 likes to be loaded and behaves very differently at 85-90% than it does at 95%. The C2 is progressive in comparison.

quickxotica

I've got a low-optioned 2003 C2 aero. It's got factory PSE exhaust, but no PSM. With no driver, no gas, no spare, no toolkit, no wiper fluid, no floormats, no stereo at all, empty trunk & glovebox, CCW wheels, 2 gt3 seats, odyssey 925 battery, and all else stock: it's dead-on 3,000lbs.

If money/smog were no object, delete the mufflers, cats, sunroof, soundproofing, install LWFW and TRG carbon hood...you'd be at <2900 easy-peasy with no gas. And this is for a streetable mk2 with full A/C.

sprintamx

Definitely don't want to hi-jack the thread away from the topic of car & weight comparison.

If anyone wants to PM me with their thoughts/recommendations for a good chassis/suspension outfit in the Philly area, please do.

jrgordonsenior

IMHO it's all about the LSD that the car does or doesn't have. Some C2's came with a 2 plate diff that was a very good LSD, but most are open diffs. And we all know by now that the GT3 diff is usually toast by 15k mile or less. I can't stress enough how important a good/functioning LSD is to a performance orientated Porsche. It's more relevant than shocks, springs, or even a mildy crappy setup.....

KobaltBlau

Thanks Ahmet, that's very helpful. One further question: in the C2s were you running rubber stock suspension arms and strut tops or monoball stuff?

John, thanks. That's a very useful data point.

Aaron, no worries - I didn't feel like the thread was hi-jacked, but I do think you would get some value in posting a thread looking for a suspension specialist, perhaps in the East US forum?

Interesting feedback on the LSD, JR. Makes sense, a functioning LSD is a beautiful thing on the track.

SparkyRacer

FWIW, I haven't found that a limited-slip diff makes much of a difference in a C2. There's quite a bit of weight over the rear tires and the car doesn't really make enough power to spin the inside wheel. The GT3 would likely be a different story. I think it probably does make enough power to overwhelm an open diff in tight corners. Actually, I have witnessed multiple people carry on about how much they like the limited-slip differential in their C2 / Turbo when, in fact, those particular cars had open diffs.

Also, at 46k miles the diff in my GT3 is still just fine. For that matter, my partner's '99, 114k mile C2's intermediate shaft hasn't exploded either, so go figure.

Ahmet

I've actually driven a large number of C2s, including several of my own at different states of modification including rubber suspension mounts as well as monoball/spherical rod ends/solid metal "bushings". I've also instructed/ridden in quite a few different examples, same goes for the GT3s at many tracks. In my feedback I tried to concentrate on the things that I feel carried across all C2s vs. GT3s.

Of course as the LSD debate shows, many people disagree on car set up. Another example is suspension stiffness, I think the GT3's factory set up is bordering on too stiff (for street tires or a lower grip R-comp) at CMP whereas at VIR a stiffer suspension seems a bit more beneficial. -Though without enough tire wouldn't suit certain sections well such as the upper S'.

Speaking of LSDs;
I've driven a "higher" mile GT3 that sees the track several times a year which doesn't have any symptoms of a bad diff.

LSD makes the car a bit more easy to control during oversteer and causes a small amount of understeer on power during lower speed turns, but that's about it. The Caymans and turbos (and 944 turbos and such) will spin an inside wheel on power but for a C2 I don't think it's really necessary. I suppose with a stiff enough set up it could be more of an issue.

altonj

Nice sized shop Jasper! You know me, I will likely sell car once we have it fully sorted...

Lost of interseting insights into the LSD.... I like them for what they do under braking but YMMV....

Cheers

jrgordonsenior

Exactly. Carrying a 450 lb. weight behind the rear wheels while breaking into a turn at speed can be a touch tricky. For me, the benefit of a good diff isn't just controlling wheel spin under accelleration, it's the ability to go faster and deeper into a corner without the car trying to swap ends or jump into the stands. Once you've learned how to take advantage of a diff with a high decel lockup ratio like Guards 50/80 you'll wonder how you lived without one....

mglobe

+1000

I was not a believer in the need for an LSD until I put one in my race car. It's much more stable under braking, and the back end is a lot more planted on exit... provided you keep your foot in it.