Autocross

How about a quick refresher on braking, turning in, accellerating out of the turn, cone clipping, attitude management (of the car), tire pressure and anything that you feel like expanding upon? I need to get my creative juices flowing. The wife won't be there next weekend so I get a free practice session. Almost forgot, I need to preregister.

Things I need to practice this year.

Brake harder

Accellerate earlier

Turn less aggressively and make more minor corrections

Piss myself off before the run. (I drive better)

I'm sure there are a few more.

You could just follow your wife around the course a few times and do like she does...................................and that would also piss you off......................

May well have to do a car swap and see what happens.

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Good start.
I'll write something in the morning at 6 a.m. before I wake up (that's when I do my best).

Tire press? Which car? Do you have a temp gun? Do you have a REAL pressure gauge?

I'll be back.

83 911 widebody. Stock performance pressures 34 rear 28 front. Running street performance W rated Falken Ziex tires. Digital pressure guage (describe real) No heat gun.
I drive up, run and drive home. Just interested in any tips/suggestions you may have to offer. I'm more of a doing it for fun type autocrosser. I don't suck but I'll never be a champion kind of driver. I drive amoung a group of serious multiyear experienced competion driven operators. To tell the truth our instructors are all first rate, experienced, national competition level event winners. There is no lack of on course learning oportunities. These guys and girls are there to help. All you have to do is ask.

Here's my baby.

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For those of you that wonder. I also have run my 90 and 91 Corvettes. I just like the course handling characteristics of the 911 over the C4 at these events. Probably gonna bring my 90 Z51 up for a run later in the season. The 91 is better suited for drags. It is a PCA event but we run an X-class for non Porsche vehicles. 50 to 75 car average.

Here's the wife and her steed.

87 911 wide body

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Have I forgot to mention, we run in different classes.

I have a 3.0 litre, single exhaust 189 bhp car, P03 class

She runs a 3.2 litre, dual exhaust, 219 bhp car, P04L

Here's a couple of the 90 and 91 in action.

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That's the one and only autocross pic of the 91.

Here's a link to the PCA Gold Coast orginization to check out club opportunities in our region. I don't know of a Florida Corvette group similar to this Porsche group although there are several large South Florida Corvette clubs that offer car shows, drag racing challenges, cruise ins, etc.

http://goldcoastregion.org/

If you look closely at the autocross results link there is a video of a 911 running the course on the top right. You can clearly see me at the start waving cars up and giving them the go. There is even an excellent shot of my forearm.

Typical raceday scores


Thomas C 1983 911 SC Coupe Black 68.667 66.665 67.275 67.189 64.84 64.689 > 64.265 65.304 64.265



Susan C 1987 911 Carrera Cabriolet White 66.986 64.608 64.11 > 63.867 66.003+1 65.135 64.726 64.124 63.867

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Purddy car. Tire press are slightly tough to get right. Even if you ask someone who has a var close to yours, their driving style may make initial setting incorrect for you. But they can be a decent starting point. Start with the stock pressure. I really don't like the digital gauges (even the good ones). A good gauge isn't that much money, they are more accurate and let you bleed down the tire press, you can make a change that is as little as a half pound. The thing with tire pressures is tire temps. The big thing with pressure is the hot pressure (as soon as your run is done). The bigger thing is tire temps. Tire temps tell you if the pressure is correct (along with what the car is doing on track).

I constantly get asked "What press do I run?",

I ask "What did you run the last time?" - "I'm not sure."

         "What was the track temp, was it cold or hot?" - "I don't know"

So, these guys are starting over every time they get on the track.

What you can do is start at 28/34 and feel what the car is doing, is it pushing, is there oversteer that is not throrttle induced? AND you have to keep notes,you can't keep this shit in your head, there's way too much to think about at the track. Doing it this way. you're only choice is experimentation, drop or raise press by 2-3 lbs (1/2 lb drops come after you get this figured out) and you may want to drop/raise just the front or just the rear depending on what the car's doing.

The correct way - get a tire pyrometer (not as good, but better than nothing, an Infrared Thermometer with Laser Targeting, HF-$40).

As soon as you shut the car off after a run, take temp readings in 3 places on every tire, then take the pressures, write them down. Then drink your water and bs with the other drivers.

What you look for is even temps across the tire (though camber plays into this, i can explain that later). If the center of the tire is cooler, the press is too low, if the center is hotter, the press is too high.

On the first run group of the day, the track temp will come into play for your initial settings, you may have to bump up a bit.

Pressures in a run group after your first run may be too high (tires too hot). Our fast guys water the tires down with a garden sprayer to cool then down rather than droppinp pressure.

Easy peasy, huh---no, it's about homework just like driving faster is about seat time.

Let me know if you have any questions.

Here's my good gauge (s).

And my tire temp/pressure sheet. One of these sheets gets filled out every time I go to the track.

 

 

 

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Good info Bill and one of the things I can actually do to improve track performance.

I have on a couple of occasions done back to back runs. Once I did three in a row with no break. Out of the finish into the start. One thing I noticed is the hotter my tires the less grip I seemed to have. My thinking was that hot tires would have more bite but in application the opposite appeared to be true. The cooler tires seemed to give me more bite. I may well have been pushing harder into the turns because I thought I'd have more grip. As you mentioned though. It's a matter of adjusting and finding the right combo for tire and track conditions. We'll see how motivated I get this season and how hard I push. If I want improvement bad enough I'll heed your well spoken advice.

Due to medical issues, jobs and the move we ended up skipping last years events. We're getting back in the game this year. Looks like I've lost my job as starter and be back on the track as a cone head or flagman. I'll have to work my way back to the front. I like working the line. You don't have as far to walk.

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Yea, this is a seat time thing. To brake harder, you need to brake later. First, do you have specific brake points in your head? 10 feet before a certain cone? If not, it's much harder to be consistent and really hard to push that point ahead.
Walk the track, then walk it again (without any one with you) walk it every chance you get. If your lucky, the event will have course maps. You can also draw a map, make notes.
What this does is put this stuff in your subconscious.

Threshold braking braking harder at the limits of the tire contact patch). Do you "jump on the brakes"?
Hold your left hand up and open then smack it with your fist. Now, put your fist against your open hand and push it logarithmically with agression so that the force starts low and pushes up to a peak like a martial arts punch. This should happen in a couple tenths of a second.
Don't laugh, I use this to teach my students.
What this does - it settles the front end down smoothly rather than slamming it down. This combined with a smooth turn in will use the contact patches to the max.
This is a very agressive application of the brakes.
You should try it off track at lower speeds, like 40. Increase your agressiveness until you start to feel the brakes lock up.

If you get practice runs, try moving your braking points in by 5 feet at a time, see if you can agressively brake without locking up the tires and still get thru thr corner.
Remember, if your fronts are locked, you won't be able to steer the car and you'll need to lighten your pedal effort to bring the steering back.

Threshold braking at precisely the correct point so that you reach the desired turn in speed is hard to do consistantly - seat time, seat time, practice, practice,

If this isn't working (pushing your braking points ahead) try lifting off the throttle a bit earlier, then agressively brake. You don't want to be so focused on braking harder that you loose your position on the track (ie. driving past your turn in point because you don't feel that you've slowed the car down enough). Track position (to the left, right, center of the track) is way more important than early braking, you want to take the largest arc possible thru each turn, thia lets you get on the gas earlier.
Acceleration out of a turn earler will reduce lap times much more than braking later.

And most drivers over use the brakes (especially Corvette drivers for some silly reason).

AND - no coasting, there's no place on any track or course where you should be coasting, it's either on the throttle or on the brakes. Always, even if its only on the throttle for 2 tenths of a second.

Last but not least - how you release the brakes is extremely important, you need to ease off the brakes. This is the opposite of slamming the brakes on, think - what is the chassis doing? When you ease off the brakes, the front end doesn't come up as fast, you maintain the tire contact patch that you need to steer the car with.

Smooth is fast.

God my head hurts.

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Yea, I'd recognize that forearm anywhere.

Here's a good PCA read:
http://www.pca.org/Activities/Autocross/AutocrossDefined.aspx

I may post some other points tomorrow.

I've read that and other SCCA/autocross material before. Funny thing is every time I reread it I think to myself ... Oh ya! I remember reading that before. I started as a coaster and gradually improved my ingress and egress to the curves but I was such a bad coaster it still likes to take control every now and then. I have to push those impulses aside. That's when driving agitated helps. I can get mad at myself for driving like a wimp. It sharpens my movements throughout the run as I have given myself a little edge. If it worked out I can smile again when I see the timeclock.

I wonder if that's how Central Coaster got his screen name?



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Still coasting once in a while is just seat time. This shit ain't supposed to be easy. If it was, everybody would be running 61 flat.

Yes, driving agitated helps. So, does laughing.
Try screaming in your helmit when you leave the line.

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Driving agitated is OK when it's about your driving, not good when it's about the car. Doing the tire management/pressures thing is one small step, after the first few times, it bscomes really easy to do and is a natural thing that you do on eash run.
What it will do is put that particular concern out of your head and you can fill up that empty space with concentration on a particular corner. That will make your smile even bigger.
It's all about extreme, intense concentration for 60 seconds.
It's the little things like not thinking about tires that make you faster. And a lot of them are easy to do.

Heck be glad you don't have to fill out this:

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Looks like work. LOL

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Want to improve your braking and corner entry?
Teach yourself to heel & toe. It takes a little time but is fairly easy to learn.
And it should be done on the street, not at the track.
It makes a big difference in lap times.

AND, everyone who drives a 6 speed should be at least blipping the throttle on every downshift, every time.

With my size 11 1/2s it's more like mid foot and toe.On top of that my joints have little to no movement options. Some people are flexible. I'm tight and stiff naturally. Every action takes extra effort. Sucks bigtime. Heel and toe is the way to go though Bill.

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Believe it or not T, Heel & toe is done mostly with your knee.