Dalema

Base C2 no PASM on 20s. What is the factory alignment (camber)?

Should I be adjusting that for autocross / more aggressive driving and what is the max you can go to?

Seem to be wearing the outside of the tires more - wondering if more camber may help. It's probably just a function of my bad driving, but a couple of the AX guys recommended I max out the camber.

What would be the downside as I use the car as my DD?

chuck911

Camber, like everything else, is a trade-off. Increasing camber will improve cornering. Depending on the amount of time the car is being driven hard it may even result in more even tire wear. In most cases however, and especially when the car is a daily driver, then it can reach a point where the insides wear faster. There also can be a risk where even though cornering is improved, tire temps are not even across the tire which again can result in uneven wear, and even worse handling.

Another challenge is that whenever camber is changed at one end then the other must be done as well, and carefully, else the f/r balance be altered. Which you may want. Or not.

Vast majority of the time people launch into things like this without first taking time to really understand what they are doing. In my experience, if there are 100 auto crossers at an event, maybe three of four of them really get it. So you want to seek out those few people and pick their brains. At this point however you are well advised to heed my prior warning that racers are happy to feign ignorance or even lie right in your face! Imagine: you spent years and countless thousands earning hard won experience, now some newbie wants to know how to set up his car to beat you- you gonna lay it all out for him? Dream on!

These are just a few of the many great reasons to be patient and learn to drive what you got. Next time, how about looking around for the guy running killer times who is bone stock. Guaranteed there will be one there somewhere. Get to know that guy. See if he'll let you ride along, or ride with you. If not then find an instructor. Either approach is bound to improve your times far more than anything you can change on your car.

Dalema

Thanks. Still learning and coming to terms with the many variables - question was coming from two separate perspectives - the tire wear I'm seeing on the outside (seems opposite to what others are reporting) and the unsolicited advice at AX. That advice was actually from two different instructors - I've been trying to gain as much instruction as possible at each event.

Olcha911

With the stock, (non- pasm) suspension- you can only get a maximum of about 1.1 degrees of negative camber. You will also want a very small amount of toe-out in the front also. Doing that will improve the turn-in and handling of the car and take maybe 10-15% off the tire life of the front tires- which still wear less than the rears anyway.

That will still not be enough negative camber to run a decent DE line with the car and not wear the outside of the front tires prematurely, but it will slow it down. You need about 1.5-2 degrees of negative camber for optimum track handling. More than that and without a track suspension on the car, you won't see any benefit except inside tire wear. For the daily driver that sees track duty, I would say maxing the stock suspension or installing H&R lowering springs and running 1.4 degrees of negative camber (max with those springs) and a set of track wheels and tires would give you a big bang for the buck. You'll get a benefit in braking from the track tires, as the tire grip will now match up to the caliper's grip and you won't activate ABS so much. The problem really is when you decide to buy track brake pads- switching them out or using them on the street (they often squeal) becomes the dilemma.

I have experimented with this on my 991 3.4, as well as my 2007 Cayman S. The race cars have about 3 degrees negative camber both front and rear but they have track suspensions and are lighter so they support the theory.

-Keith.

008

For stock pirellis on a street car get as close to -2.2 front and rear as you can and run a total of 1/4 toe out in the front, 0 to slight toe in at the rear. You can shim the lower control arm in the front with oem parts from the cup car and the rear should have that range of adjustment without touching anything if you have SPASM. Otherwise you can get lowers from Tarret, RSS or Elephant and get you there no problem. It's a very good compromise for a street car that also sees some track or AX. At the above I'm getting very even wear and with vigilant monitoring of pressures I get proper heat load across the contact patch. The car is much more stable in transitions but will also rotate more willingly at turn in and apex. It's a lot more fun not to be under-steering well below the car's potential. Find a local shop that is familiar with Porsches that are run on the track and have a tech who understands the dynamics and has the patience to work to get to where you want to be. In the Bay area I suspect you will have plenty of options but also check out the 997 GT3 and GT2 sections of this forum and ask some of the local folks there for a shop recommendation.

chuck911

Good. Keep getting lots of ride-alongs. You'll get better faster with more feedback. Try and keep them focused on driving skills- looking ahead, which lines they recommend, tips on using throttle to control balance. Because of the known rear-weight bias Porsche does do things to make the car more user-friendly for the average driver- front brake bias, tire inflation recommendations, suspension alignments- which once you become more skilled actually kind of get in the way. Hence all these guys recommending changes. The thing you want to keep in mind is, don't put the kart before the horse. Get the skills, then make changes.

One great skill for autocross is learning to read the course. Beginners drive around cones. Experienced drivers create a course that clears the cones. The first way you're driving close to every cone. The second often times creates more sweeping turns that may or may not come close to certain cones. Ask around if this is hard to understand, it can take a while.

Right now, if you want something to change or experiment with, it should be tire pressures. Huge cost/benefit ratio, immense improvement in understanding car balance, just really hard to beat.

Olcha911

Just a quick clarification point, if you go somewhere to have work done, or start doing it yourself- The OP has a 3.4 with no PASM, correct? The front lower control arms on that stock car have no shims. You need to have the front cup car or other manufacturer's front lower control arms installed and then shimmed to get additional negative camber.

Dalema

Great - thanks for the advice! Do you know what camber they run factory?

Dalema

Thanks for the tips.

Dalema

Agree with all your points. I did adjust tire pressures to see the impact. At the end of my last AX the pressures were getting high and I noted the loss of control. I went into this AX with lower tire pressure initially which had a dramatic impact. I need to invest in a tire pump to maintain a constant pressure.

On balance - that was my greatest learning from the last AX with an instructor helping me with throttle feather in and lift off (or lack there of) in helping turn the car.

I understand what you mean on figuring out the course - it is hard with lack of experience.

008

Honestly I'm not versed in the differences between the 3.4 non pasm and the SPASM. From what I was told You can shim the stock suspension in some cases. If you buy lower control arms from any of the AM companies mentioned you don't need shims, they're eccentric and easily adjusted in the ranges we're talking about. Here's the link that illustrates it:
http://www.elephantracing.com/suspen...ngs.htm#prod_1

I would give those folks a call if you need more adjustability, they're active here on the forum, and by all accounts produce quality stuff. They also write cool technical articles and videos.

Stock I could only get -1.7 and -1.9 on spasm. I couldn't stay for my last alignment but he does a lot of the local cup cars and he was able to me to -2.2 up front by shimming with Porsche parts. I saw the printout but didn't have time to discuss with him. My rear is at -2 but I need to go a little more before the next track event. Hope it helps.

Key Left

In think, if I am correct: more negative camber means less available braking tire surface. AX is all about braking...no?

008

I don't AX and have haven't measured how compression affects camber on the 991 chassis but for the track any contact patch loss that might occur during braking is far out weighed by the patch gained in cornering.