usctrojanGT3

+981 My car felt a bit lite going 125-130mph in a long straight with a slight right at Spring Mountain. Definitely doing these aero adjustments.

jphughan

I'm not sure. But having read up on sway bars more, it's clearly much more complicated than that. It depends on your springs and whether you're lifting the inside tire (in which case soften the bar) or rolling onto the outside tire's sidewall (in which case stiffen the bar), but too soft and too stiff both exist and can be bad. A softer bar also provides more gradual weight transfer, whereas a stiffer bar can make for snappier handling, not necessarily in a good way, and can also magnify the effects of running one wheel over a surface such as stepped curbing, since the stiffer bar will transfer more of that force to the opposite wheel.

So it seems the answer is that it depends on what the car is doing under your driving style and any other setup changes you've made. The sweet spot is at some happy medium whose location depends on many other variables, but reducing understeer and increasing front grip are not always the same thing.

bhgt2

Didn't lift the car, very easy to do without. I used a star hex key to remove 2 screws at the bottom of the plastic pieces

usctrojanGT3

What are the sway bars set at from the factory?

bhgt2

Medium front and back

BRNGT4

I will be doing this and joining BHGT2 on the track this Friday. We should have lots more to report in the quest for better handling.

Ochocoronas

Can anybody produce any data on down force, drag or any kind of wind tunnel testing? Not that I need this for scientific purpose. I would just like to see them.

IrishAndy

I'm pretty sure somebody posted a link to Auto Motor und Sport with CD and downforce figures from testing, but I can't remember which thread. Anybody?

matttheboatman

Exactly what JPhugan posted. AP said it was a regulatory issue having to see brake lights at certain angles. He also said that otherwise it would be no problem to have car at full aero because at highway speeds aero has little effect.

IrishAndy

Found it. This was originally posted by ShakeNBake:

Ochocoronas

^^^^^ 85 LBs at 126 MPH Great...Thanks

ShakeNBake

Which is more than the GT3!

https://rennlist.com/forums/997-gt2-...r-997-1-a.html

Sport-Auto tests basic lift/drag in the Mercedes wind tunnel at 200km/h.

991TurboS Front 20Kg, Rear 40Kg
991GT3 Front 18Kg, Rear 29Kg, 0.33Cd
991S Virtually none, Cd 0.29
GT3RS4.0 Front 14Kg, Rear: 58Kg on highest setting, 0.35Cd
GT3RS.2 Front: 11Kg, Rear: 49Kg on lowest setting, 0.33Cd (On high setting it's same as 4.0)
GT3.2 Front: 15Kg, Rear: 19Kg on lowest setting, 0.32Cd
GT2RS Front 14Kg, Rear 35Kg
GT2.1 Front 9Kg, Rear 29Kg
GT3RS.1 Front: -2Kg, Rear 10Kg, 0.3Cd
GT3.1 Front ~0, Rear ~0 (they said it was virtually non existent, but not buoyant.), 0.29Cd
996GT3RS Front -19Kg, Rear 25Kg

BMW M3GTS Front 7Kg, Rear 30Kg, 0.32Cd

Petevb

Those Sport Auto downforce numbers are for a PCCB equipped car. In the text they note that iron rotor cars make significantly more front downforce: 5 kg more with the inserts, 7 kg more without. So a standard brake car in high downforce config is probably running 19 kg front, 38 kg rear, 57 kg/ 125 lbs downforce total at 125 mph.

BRNGT4

I can confirm that on the GT4 without the front inserts removed and without the rear wing adjusted to the higher level the car felt light and loose on the high speed sweeper at Bahrain International Circuit. I will be trying the aero adjustments next friday

C.J. Ichiban

you might be better off running a taller gurney flap insert on the top/trailing edge of the rear wing as opposed to just increasing the rake. might want to try that as a single layer CF gurney flap would be pretty cheap.