Hi all. I'm trying to find the right alignment spec for my street driven 997.1 GT3. The car might see a track day, but I'd like to set it up mostly for spirited street driving. My goal is to dial out the excessive understeer I was experiencing before (Before Measurements) and arrive at a much more neutral setup while still being a bit forgiving.

After a bunch of time researching here and discussing with other folks, I landed on the following specs:

Camber (stock suspension)
Front: maxed at -1.9 degrees
Rear: maxed at -2.2 degrees

Caster
Leave as-is
LF 8.2
RF 7.9

Toe
Front: 1mm total OUT
Rear: 4-5mm total IN

Ride Height
Stock -5mm F and R, Stock rake
103mm front
128mm rear

Swaybars
Front: middle hole
Rear: one from full stiff

Wheels + Tires
Front: 19x9+50, 245/35/19
Rear: 19x12+62.5, 305/30/19

Driving on some faster curves, steering felt very vague above 55mph and the rear was stepping out a lot more than I'd like. At 60mph, I could move the steering wheel about 1" left and right of center without really steering the car. The rear would step out just on hard accel in a straight line. So I revisited the alignment sheet and noticed the shop didn't quite get there on rear toe.

I know this topic has been covered quite a bit here, and there are many opinions, but I'd really appreciate any feedback on this setup above, what's actually on the car, and if adding rear toe will solve the issue. Thanks!

 

This is a personal choice but toe out in front is going make the car darty on the highway.. it may give you a false sense of an more oversteer but that's just an illusion. I would suggest you keep all stock alignment (with 0 front toe) with exception of front camber.. add a half a degree or so using the control arm spacers. Keep the rear sway at full stiff assuming you don't have monoball dogleg upper arms because those can make the rear too twitchy with full stiff sways almost to a dangerous level.

 

Makes sense. Thank you for the quick reply. When you say stock, looks like you're referring to something closer to the "Race circuit" settings in the manual, yeah?

 

i wouldn't say "darty". it just turns in quicker. if anybody is confusing turn in with oversteer, they probably should just pay a shop to set their car up for them.

disagree with rsb on full stiff. i prefer a softer rear

 

Any other specific feedback on here? Trying to land on a total setup, but also understand the reasons why.

 

I suggest go with the factory alignment setting for a street car. Ie oem was a well sorted setup.

 

I tried an aggressive alignment (toe out front) similar to yours on my 2007 RS. It was indeed 'darty' as described elsewhere here. As I have updated much of the suspension to 997.2RS (and better) suspension components, I went back to a completely stock 997.2 alignment (including rake) setup. The car feels a hundred times better. The darty feeling is gone, and it now seems to take better advantage of the larger tire widths, sway bars, and Tractive/DSC/Swift shocks. I feels more 'planted' and far less 'lively'. I don't track mine, so your needs are different. How in the world did you get 305s on the 9" front wheels, let alone under the fenders? If this is not a misprint (I see the f/r sizes are reversed), then first thing I would be checking is that monster tire on that width rim. Porsche runs a 245 tire on their 9" wide front RS rims. I cannot imagine how any legitimate tire installer would not catch this.

 

Ah, good catch. That was a typo – meant to write 245

 

for mostly street use fronts should be straight or slight toe in. I prefer straight. toe out turns in harder but then you lose steering angle at mid corner, so I prefer no toe out.
your alignment needs to consider ride height and rake F/R. Rake can make a big difference on braking, trail, and turn in feel.