Autocrossing my Probe GT has been a lot of fun, but I went a step further last Saturday and attended a day long SCCA Autocross School at 3COM Park. What a blast!
You don't get much seat time racing autocross- the courses are short, and you don't get much time to think about what you are doing; it is extremely fast paced. I would think about my line, braking points, etc before racing while on the course walk, but when it came time to race, I was pretty much just trying to stay on the course and floor it when I could. The autocross school promised a lot of practice time.
Here is my instructor, Darren
My fellow student and his R1-shod bimmer
They had a great lunch included with the school, yum!
The first half of the day was devoted to running several different shaped exercises and course walking.
I ran only three of the five exercises, The House, The Figure 8, and the Slalom.
We ran the "house" both clockwise and counterclockwise. It felt very different in the different directions. We got basically as many runs of 4 and 6 laps each as we could stand.
Darren drove my car for one of the runs and I got to observe his technique. The first thing I noticed was that he slowed down more for the corners and got very close to the cone. He also approached the right angle turns differently, starting his turn in sooner and getting on the throttle as we passed the cone.
Right Angle Turns: This was a pretty difficult figure; right angle turns are deceptively difficult. One reason is that it is hard to "look ahead" when the new direction is 90 deg from the direction you are traveling. In a hairpin you can get the suspension set, then look ahead to the exit, and on compound slalom style turns the exit is often more or less ahead of you where you can see it.
This was a very large figure, and I was able to get to redline in 2nd gear (about 70mph) on the straight between the sweepers at the ends of the "8". It was good practice for waiting as long as possible before braking to the maximum speed you could handle through the sweeper portion.
The main lesson was how to control the car when it was at the limit of cornering adhesion (about 40-45mph here). In my PGT I really could not get on the throttle much at all during the corner. If I did, the front end would start to wash out, my turning radius would increase, I would dial in more steering angle and the car would scrub and slow down. Safe, but SLOW!!!
Then Darren taught me something that changed the way I treat any and all corners. He told me to saw the wheel toward the outside of the turn. This turned the wheels in the direction the car was going, but just for an instant, to try to regain full traction. You could feel the car hook up and then you could turn at a faster speed! The figure 8 was great because I could try different speeds and try stabbing the thottle, easing the thottle, sawing the wheel, turning it back and forth, etc to see how the car reacts. I learned a lot.
My car never threatened to rotate, but the Miatas sure did. Exceed the cornering limit and SPIN! One guy I talked to burned up a set of R1's just during the school.
I discovered that I could floor it getting into the slalom, then steer quickly and hang on. the big tires just grabbed and the intake wailed. The back end stayed planted, and observers said it was understeering a lot. An instructor came by and drove a Mustang on this exercise. Wow, when you can balance steering and throttle inputs exactly it looks really fast- the natural understeer was perfectly compensated with throttle oversteer. Not going to happen in my car.
I had studied before how to visualize a line through the course, but the school went a step farther and encouraged us to devise a plan for whole course. Then after driving to evaluate the plan and see if you managed to execute it.
If you are completely new to autocrossing this won't help much because you won't have a good idea of where the car can go in different situations.
If you didn't execute your plan, then maybe you goofed when driving, such as not braking soon enough for a sharp turn. If you did execute your plan but you aren't fast enough, then maybe your plan is faulty- for example if you need to be more in the middle of the course for a certain turn rather than the inside. There are good books written about this so I will go on the driving.
I had asked Darren about my confusion over some advice I've heard alot. "Turn in sooner" is something many people will tell you. What has happened to me in the past is that I turn in sooner and early apex the corner. I went off the track at 85mph in Turn 10 at Sear's Point trying this. (read about it on James' Second NASA School). So Darren explained it like this, you take the same shape curve, and just move it back:
The shape of the curve is exactly the same, we are just moving it to start a little early. Since you are starting your braking sooner, you also need to do less of it. This really helped me, especially on right angle corners.
Note, the curve above may look a little different in the two pictures, but believe me, it isn't. I drew one curve, then copied it onto the two turns.
I got only 5 runs, plus one with my instructor driving. I was experimenting with what I had learned, so wasn't terribly fast. The PGT is hard to drive really badly, and small mistakes don't result in spins or dramatic corrections, the car just goes slower, so it takes a bit of finesse to get the last 20% of speed from the car.
There was a fun feature in the course we called "The Box". It looked like this
For my work shift I decided to position myself near The Box. Several cars decided that it was too much trouble and just drove straight through. I watched carefully how the fastest cars went through. Almost as soon as the car had entered the box, I could see the suspension leaning the other way and the car accelerating. The slower drivers would enter the much more deeply before counter steering and then would have to stay off the gas as they hoped to miss outside cone.
When I got the chance to run, I knew the PGT is very good at quick sideways transitions like the box. I'd enter pretty fast, then counter steer while just entering and floor it! Gripping the steering wheel and that outside cone is coming up fast but the car just hangs on and squirts through what looked like an impossibly narrow opening.
After The Box was a pretty long straight across the dreaded 3COM ridge (a long speedbump-like crease in the pavement). I just kept my right foot planted and hung on around a bend down to the slalom. My instructor said later that he was white knuckled and I was scaring him with the throttle. In fact, I think I hurt my leg a little I was pressing the throttle down so hard :). Being chicken with the throttle is not one of my problems, one I get it down I am very reluctant to let it up!! But one thing I learned from road racing school was to trust the car to stick and it did.
The slalom in the course was down hill and so I had to be mostly off the throttle and lost full power steering boost. This is the first time I had noticed it in autocross. I've taken to blipping the throttle with the clutch in to get boost while driving on the street.
I could have hung around and had more runs at the end of the day, but I was pretty tired about by 4:30.
The next day, however, there was a real autocross, and I had gained quite a bit in speed, finishing 2nd out of 23 in my class and 61st out of 189 overall, even on street tires. But best of all I felt a lot better about my driving, and could see lots of place for improvement yet. Since then I have bought some rims with huge (245ZR45/16) sticky, sticky tires. Look out!!
Copyright 1998 James This original material may not copied or reproduced without permission of the author.