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My wife and I just started Autocross racing together.  It's addicting a really fun to do together.  Turns out she's really good at it and hence really into it.  

 

I'd like to know proven ways to get the most out of the car.  I think the driver is the key - we still have a ways to go.  We keep getting beat by these 1999 Boxsters, that the local PCA put into our same class, by about 2 seconds in a ~ 45s course.  We'll get to be better drivers, but I'd really hate loosing.  For the pride of the 968 community (and mine), I'm asking for good advice.  

 

My car:  93 coupe, M030 sway bars,  KLA top brace,  (Note I have the DR1. I'm stuck because I want to put the firewall brace on and I have to figure out where to drill a hole in the plate - separate subject),  Lower DR1 steering brace,  K&N air filter, airbox mod, 6-speed manual, option 220 LSD.  I think I have a good car.   Shocks are stock Sachs (from ~ 2006) - about 15K miles on them.  I've been using 17" rims with Bridgestone Potenza RE11A's.    

 

My tire pressures were too low last time (in the pic).   I came in about 30PSI.  The chalk was instantly gone.  The last race course was slower and my pressure was higher.   I'll come in with 38/38 next time as a start.    

 

At the last race, a friend took 1000 pics of cars on the course.  He noted that ours rolls the most.  The 968 does roll a lot.  I'm not sure if this is really a problem or not.  The problem shows up the most in wide higher speed 180-degree + corners (almost skid-pads).  

 

I welcome advice.  I'm trying to load a few example pics of the car's amount of roll.  Note the tire pressure was way too low.  

 

Love the car and autocross racing.  Getting my wife to do this with me is a blast.  We ride with each other and help look head at the course.  At the end of each race we give each other feedback.  Goal = beat boxsters.  Makes it easier to pour money into the car to keep it up to snuff too.  Thanks.  

Pic attached - I hope.  

[attachment=13173]Another pic.  

[attachment=13174]

Hi Peter give me a call as PCA runs a school in Washington or at least they used to on Auto crossing. I did it and it was a blast and learned a lot. William Moss

503-590-7978

What is the recommended tire pressure? How much if at all did they heat up?

Thanks William.  I took the class.  It was a blast.  My wife let an instructor drive our car (just once). She managed to get her last times down to with-in 0.5 seconds of the instructor.  I got to with-in 0.7.  We felt pretty good.  I saw that the BMW club has a longer "car control clinic".  This might be better.  

 

Rap:  Last time we started at 30psi.  I didn't see how hot.  The prior time I ran 33PSI and they got up to 35.  I put them back down to 32 and this wasn't enough.  There was a big difference is courses.  The last course was slower and much more technical.  This one had a few straights with big sweeping curves - much faster.  From this forum, folks are tending to run closer to 38 to 35psi and often putting lower pressure in the back.  

they have 3 classes

Finding the proper tire pressure for the course, track temp and outside temp is always a bit of a trial and error.

Generally with auto cross you start higher on tire pressure than with DE or long track. You aren't driving for as long so the tire temp, thus pressure, doesn't increase that much. Sounds like you are using chalk marking on the tires which is the best way to test pressure. Have a really good Guage that shows enough detail to see less than one lbs of pressure and keep a log book of tire pressures and track times. Experiment with the race lines, don't follow the line of any rear-end heavy cars (you know what those are). Sounds like you have a nice set up on your 968. You could move to koni adjustable shocks, or similar, and get a little tighter ride.

There are several ways to tighten up suspension and reduce body roll. $$$$

Yep, the rule is how fast do you want to spend?

"How fast do you want to spend?".  Good quote.  Maybe $$, not $$$$.  I'm getting my yearly free inspection from the Porsche dealer next week - I don't know if they can really tell if shocks are shot.  I tried to bounce the car and I've got to push pretty hard to get it moving.  Frankly I'm afraid I'm going to dent it.  I'm thinking my shocks are fine and amount of roll I've got is normal for a mostly stock car.  Is the consensus that the 968 rolls a lot when compared to a Boxster or a Cayman?  

 

What is the next move on the suspension?  What I don't want to do is experiment.  I'm a R&D engineering in computer chip process development - I know how expensive experiments can be.  

 

Thanks for the advice on the tires - yes I'm using chalk.  I'll start at 38.  I may need a better pressue gauge.  Here's a loaded question, do I adjust every tire independently based on the chalk mark?  I'm trying to hit the middle of the little triangle right? 

yes, you may need to adjust each based on track and driver weight.
I just mark several stripes on each tire from the tread around to the start of the sidewall. Then see what is scrubbed off each tire.
Don't roll above the tread on the side of the tire, maybe half way up. Others, your thoughts?

Get a good pressure gauge so you can be accurate. There is a good tread on tire gauges here.
I have an analog Meiser Accu-gage, I don't like digital gauges. They gave a real life time warranty on it.
They replaced the hose after 25+ yrs of use.

968 do roll more than newer cars, but there are some pics on the site of other cars and yours seems to have more roll.
A bounce test wont really tell you much, esp. about the other rubber bits. Good dealer inspection would show that,
but don't replace with stock if you want to tighten up the car. There are others here that can make more specific recommendations,
they track their cars, I don't.

Fastest and cheapest way to go faster is to keep practicing.

I had your problem then went to bilstein coilovers. Major difference. Costs $$. Well worth it. There are no doubt other options. Will you continue to autocross or will this be a short term thing? My car was not as much fun to drive on the street after the change. In fact I made it a straight track car and started trailering it.

Do not know if this would help you in any way but my car which was an M030 with LSD and konis from the factory.  Also what about the brakes? most of the time in autocross it is more gas more gas. But my car has over sized brakes on it? If you wanted to look at it come on over

Too bad Leda went out of business. Really affordable adjustable shocks. A big step up from Koni but not near as expensive as the big boys. 

Trying to have a street and track or Autocross combo is difficult. 

I would give some suggestions off line about setups I have worked with. Some good and some bad. 

Thanks for the advice.   If the shocks are shot or need to come off, I'll give you call Pete and try to get advice.  I definitely don't want to make the car un-drive-able on the road.  I like how the 968 is a practical sports car.  I can use it every day.  I can put a bike in the back, loaded up 10 cases of wine bottles, put the dog in the back (GSP- not a small dog) and so on.  

What's a GSP, and how come I don't get to ride in the 968?[attachment=13175]

Mine is very drivable on the road with the yellow Koni's, M030 bars, RS improvements, etc. Larger brakes also.