I thought I would share my experience on alignment specifications after lowering my 997 C4S that might be useful to others in the future. This is not only for the C4S, but all 997’s. Since I live in Idaho, there are not a lot of tuners to choose from; ok, more to the point, none. The supposed “best alignment shop in the valley” didn’t have proper specs for the 997 (I dreaded going to the dealer for an alignment). I was fortunate enough to have the dealer fax me the specs for the C4S, GT3 and the GT2.

I knew that after installing the HRE springs, I would have to let them “settle” for a few hundred miles, then get the alignment. I called the shop, explained that the car had been lowered, and that I needed an alignment. He asked me over the phone which option I wanted; aggressive, factory or the “what’s best for tire wear”. Oblivious to anything else, I told him factory; but not before asking what “aggressive” meant to him. I was told, “Aggressive is working within factory spec’s, but using the outer limits”. I still didn’t know what that meant; so go with the factory specs, right?

They did align the car back to MY08 factory specs just fine; and the price wasn’t bad at all, $180. They did give me the before and after sheet for my records. Upon driving the car home, I noticed it didn’t feel at all like it did before… wasn’t happy; but they did do what I asked them to, “align to factory specs”.

After getting the car home, I went over the sheet, studying the specs to see what it could be. The car felt very twitchy, or more so than I had experienced before; it wanted to follow any “rut” in the asphalt, and wanted to chase any bump.
The specs after alignment (front) were:

Camber: -0.40
Caster: +8.00
Toe: 0.00

These numbers were all “centered” within the specs for the 997, but I was disappointed in the lack of “heavy” steering that I had enjoyed for the past couple of years. There is no track here, just a lot of highway. I like the car to go straight down the road, feel planted while driving, etc… on the twisty mountain roads it is a bit heavy on turn ins, but this is just my personal preference. This was now gone.

I checked the tire pressure after filling up the tank. 33psi front, and 39 in back; this is what the owners manual calls for with full fuel, one passenger, and no luggage. My girlfriend and I took it out last Wednesday night, nice fresh roads. I had to constantly hold the steering wheel, especially on hard acceleration. It was a little scary at 80mph, even though we were on a “runway esque” type of road. I will note that before, doing 120mph down the freeway, you could figuratively let go of the steering wheel for five minutes; the car was very planted.

I found a stretch of road off the beaten path, to see what it felt like from a standstill to full acceleration to third gear. The best I can describe it is this, the faster the car went, the more I had to hang on to the wheel… not good.

I concluded that if the car was now relatively low as a GT3 RS, with the same body dimensions, that I should have a look at those. Online, I was able to find GT3 RS specs for the 997.

Camber -1.20
Caster: +8.00
Toe: +6.00 [total] (+3.00 per wheel)

The toe spec made sense; if the car is +3.00 per wheel, the wheels would want to follow an inside line for straight line driving; as opposed to 0.00 or even a -2.00 per wheel (I found a lot of people prefer this feel). Not being certain how accurate these numbers might be, I called the dealer Thursday morning, and they faxed me the numbers. They were the same that I had found online earlier (the back of the car was the same as the 4S, no need to mess with that). I called the alignment shop back and they said they could take the car anytime.

I typed out what I wanted for specs, and made them a copy of what the dealer had faxed to me. They said, “No problem”. After getting the car back, oh my hell what a difference (and they only charged me $89 to do this again). The car now felt as it did before. The positive toe had given the car back that oh so sexy “planted” feel. And the -1.20 camber, was there for the corners. It felt like the toe was set perfectly for highway use; planted, firm and user friendly; and the negative caster was for balance in the corners.

So if your like me, and you like the way your car feels before lowering, these specs will give you back that same feel IMO. I did find online, that most people prefer to have negative toe out; this makes the car feel a bit like a go-cart, very twitchy on the straights, but very responsive in the corners. If this makes any sense, one tire of a negative toe out is always competing with the other tire to turn “out”; whereas, positive to in is always competing with the other tire to turn “in”, giving it that nice, centered, planted feel.

 

So if I'm aligning our 997 S after putting on springs, I should go for the for the regular GT3 specs? Cool.

 

Just because I do it, does not necessarily mean that you should as well. If you read the post, I stated that the handling and feel of this setup was more to my liking than what others have done; most prefer toe out for better cornering, whereas I prefer some toe in for straight line stability and that oh so nice planted feel.

So back to your question, my answer would have to be, "you should go for whatever you like".

 

Great informative thread on 997 alignment.

 

This is great info! I ordered Eibach springs this morning, so this will come in handy.

Thanks. Rep for you!

 

Wow, this is a great information thread!

Eibach springs for what? In my experience they were way too low for my mercedes.

 

Eibach springs for my 997 C2S. H&R springs drop the car too much. Eibach makes the springs for Techart, so I'm confident they'll work out great.