986s autocross alignment
 

Hey all, long time reader, first time poster. I know this has been covered time and time again in one form or another, but I'm still having trouble deciding on an alignment set up for my car. Here's the short of my setup...

2003 boxster s (74k miles) with stock suspension, stock 17" wheels and (currently) stock size Sumitomo HTR Z III tires, but I plan to upgrade the front to 225's before next season, I also have 17" wheels, 1/2" wider than stock, but still 255 / 205 setup with p-zero's I run on the street. I am awaiting delivery of one more part before I re-allign, but I'll have new(er) junk yard bilstein struts in the rear, and Pedro's Techno brace. Can anyone give any insight on alignment settings to help with the inherent understeer?

Right now I'm looking at as much negative camber in the front as the stock suspension will allow ( not much, I know), 0 toe front (maybe slight positive) to maintain some streetability, but in the rear I'm totally lost as to optimal settings for a starting point. I've got a mechanical background, and I understand the physics and geometry behind what changes affect the handling how, but I still need assistance in figuring it out. The more neutral the handling, the better, maybe leaning more towards overseer for a more "tossable" feel on the course. I know it might not be very possible with the stock set-up, as Porsche made the car to be "idiot proof", but I have future plans for changes as money allows (camber plates, coilovers, wider, stickier tires, etc.)

So, what it boils down to is...what's a good starting point for me to tell the shop to set my alignment to? The car is a weekend "play toy", car meet go-er, and autocrosser with plans to take in some DE events in the future...NOT an every day driver. That's what the Subaru is for haha.

i have been auto-crossing since 2003. I am also an autocross instructor for the SPACE COAST PCA region. I have a 2.7 2002 Boxster and I am constantly top 5 in the region. The 2 best mods after improving your skills through tons and tons of auto crosses and auto crossing schools are tires # 1 and Alignment # 2.

Bridgestone 71R's can't be match unless you have a race compound.

Aligment. Max out negative at the front and i would add 1/16 or 1/32 of toe out per side
Rear: if you can afford too.. (Tires are expensive) go for negative 1.7 to 1.8 of camber per side.
Toe IN: 1/16 to 1/8 per side

For starters. The Sumi HTR ZIII while a pretty good street tire, not a great AX or track tire.

Get RE-71's for your play wheels and keep the sumi's for street DD use. Another tire to consider for AX id the Dunlop Direzza Star Spec. Not as much performance as the RE-71, but competitive and will last longer.

As far as Alignment

Max out camber front and back
no toe in front and a smidge of toe in the back

Do a search and you will find a few threads on this

Ditto on the other posts. Max negative camber all around, toe out in front, toe in on rear... But EQUAL side to side. Find a shop (chat with local PCA, SCCA, Cars & Coffee for recommendations) that knows both the Boxster and race alignment. The tech doing the job will make or break your alignment. To really be spot on, get bags of sand, dog food, whatever and put your weight in the driver's seat/ side.

Thanks for the input, guys. You're all pretty much pointing towards the set-up I was considering, but I just needed some re-afirmation. One question that I have though, considering how much camber the rear can adjust to compared to the front, couldn't maxing out the rear still result in understeer? I know the toe angle has allot to do with it as well (along with pretty much everything else). I'm looking at the print-out from my last alignment now... I had -.1 front, and -1.5 left and -2.2 right (bent, leaking strut, hence the new struts) and 0 toe front, .15 total positive rear. Thanks for the tire recommendations as well...that's on my list for next season, and I'm always open to suggestions for better rubber

Jeffrey, you're always fast at my PCA autocrosses, so your opinion is one I value. Any suggestions for a good shop to give me guidance? Do you still do alignments in your garage? I'll finally be starting my job at BMW in the next week, and one of my mentors used to be a mechanic for the Synergy Porsche team, so I'll be picking his brain as well...

Couldn't agree more... Use a performance shop that has been in service for years. Make sure they use a reputable alignment machine like hunter's and ask when it was calibrated. Less than 1 year is a max. If you go to a Dyno shop they will charge you 200 plus if you go to a shady mechanic it will be 59.99. The guys I go to charge me 80.00 plus tip for a one hour alignment with me sitting on the drivers seat.

For track alignment I have always gone with
Front: -2.8 camber and toe Out
Rear: -2.3 camber and toe Out

Any reason why you guys run toe Out in the front and toe In at the rear?

I thought the toe out in the rear would help with turn in.

Nice settings, but those won't happen with a stock suspension
Around .9 front and 1.8 max rear is all you get

Yes, zero toe in the front and a smidge of toe out in the back

Toe out in the front helps with turn in. Toe in in the rear keeps the car more stable at speed.

I'm running

Front- Total toe out 1/4"
Camber -3.4

Rear- Zero toe
Camber -3.0

Running on a square set of 275 DOT legal slicks, K sport coilovers and no rear bar.

Its interesting to see what everyone else is running.