Alignment

Standard street alignment of wheels is designed for safety, which means maximum straight line stability at the expense of quick turning responsiveness. (See also Camber and Toe)

Apex

The point at which you come the closest to the inside of the turn.* (See also Early Apexing, Geometric Apex, and Late Apexing)

Back-Side (of a cone)

The back side of a cone is the side facing the far end of that section of the course. As you steer through a slalom, keep your car as close as possible to the back side of the cone you're at, to be in position for the next cone (sometimes referred to as late apexing a cone). If you're driving by the front side of that next cone, then you're “just making it" and getting “late" in the slalom, which is slow.

Camber

The tilt angle of your wheels / tires relative to vertical. If the bottoms of your tires are closer together than the tops, you have positive camber, whereas if the tops are closer together than the bottoms, you have negative camber. Finding and setting a car’s camber angles for maximum turning capability is one of the black arts of suspension tuning. More (negative) camber increases tire temperatures and positions the tire for a better contact patch on the ground when the car leans into it. Positive camber is useless in autocrossing.

Chicago Box

A short and tight slalom set inside an irrelevant and visually confusing box of cones: a bad joke with an interesting history.

Clamshell

A clamshell is a course element where you drive a path between a pointer cone and a series of 3 to 5 cones set in an arc, actually shaped more like a scallop than a clam shell.

Class

Drivers compete against one another in groups (classes) according to certain characteristics of their cars, such as engine size, tires, modifications, etc. The SCCA website has the Solo rules and some quick reference sheets for classing your car. You can also visit the Solo forums on this site to ask for help.

Co-Driver

Two drivers who use the same car; each one is scored as an individual competitor and has his/her registration, runs and times recorded under a different number.

Crossover Steering

When your hands remain in place while steering through a turn by crossing your arms. Useful in slaloms but not preferable when so much steering input is required that hand-over-hand must be resorted to from a crossed arm position. [Hand-over-hand Steering: when only one hand is gripping the wheel while the other is lifted to crossover to a new position. In Solo, it's generally not good to steer like this unless you can do it without having to cross your arms.] (See also Shuffle Steering and Pre-position Steering)

Decreasing Radius Turn

The radius of a decreasing radius turn gets tighter as you go through it, requiring a gradual increase of steering input and/or decrease in speed to exit appropriately. (See also Late Apexing and Increasing Radius Turn)

DNF

Did Not Finish, often because of getting lost on the course. While hitting a cone costs a time penalty of 2 seconds, missing a cone or gate entirely results in an off-course call, or DNF. If your run is terminated due to a red flag caused by another car, you'll get a re-run. (See also Red Flag)

DNS

Did Not Start usually is a rare condition of a participant leaving before running for one reason or another.

Drift

A partial loss of traction when tires are sliding instead of rolling: usually not a good thing in autocross because it leads to slower times. An experienced driver who knows his car [especially with high power, rear-wheel drive] can sometimes drift to get a faster time through a curve if s/he can control it and go forward more than sideways. Excessive drifting (like burnouts and donuts) is heavily frowned upon and could result in being ejected from the site. (See also Slip Angle)

Early Apexing

Any apex that occurs (or could occur) before the geometric apex.* Turn-in starts too early, braking keeps happening at the apex, acceleration happens late, and the exit line may be too wide. Friends don't let friends early apex. (See also Geometric Apex and Late Apexing)

Even Apex

(see Geometric Apex)

Gate

Two cones, arranged so that you must drive between them to stay on course. One will be to your left and the other to your right.

Geometric Apex

This is the point at which an arc of constant radius (the largest one that will fit) will touch the inside of the turn.* This is also referred to even apexing, when a driver meets this point in a turn.

Grid

The area where cars line up in a row, ready to run, either in a pre-assigned order or at the direction of grid workers.

Heat

Cars in several classes are assigned to run in heats; how many heats depends on the number of participants. Only the cars currently running and running in the next heat are in the grid area; all other cars are parked in the paddock area while their drivers are working on the course. Ideally, the same number of cars run in each heat, so driver time working the course is equal. (See also Run Order)

Increasing Radius Turn

An increasing radius turn opens up, and you can accelerate through it with little steering adjustment. (See also Late Apexing and Decreasing Radius Turn)

Kenny Cone

A cone that’s often hit because it’s set so that it forces a driver to change his/her line. So named for the often-ill-fated South Park character of the same name.

Late Apexing

This is any apex that occurs (or could occur) after the geometric apex.* Turn-in starts late, braking stops before the apex, acceleration begins much sooner -- usually the fastest way through a curve. (See also Geometric Apex and Early Apexing)

Line

The path your car takes: a good line is fast, usually because it involves the least amount of steering adjustment.

Novice

A competitor during his/her first season of events; novices usually run in the same heat as experienced drivers in the same class, but they are competing against each other, according to PAX times. Instructors are available to ride with novices (and anyone, for that matter) -- request this from a grid worker when you grid for your run.

Offsets

Series of cones -- similary to a Slalom, but not set in a straight line -- that you must weave through. The spacing between cones may vary. (See also Slalom)

Overcooking

When you enter a turn (curve or slalom) too fast (or too hot), and the car’s forward, straight-line momentum interferes with you ability to negotiate the turn.

Oversteer

Oversteer is the condition when the car is rotating more than the steering input you're using would suggest. This is when the rear-end of a car is all too happy to slide -- often induced by sudden changes in throttle or brake application and a common characteristic of rear-wheel drive vehicles.

PAX index

A handicap, equalizer formula developed for comparing the times of drivers of cars in different classes. Technically, PAX is the deprecated term in favor of the newer term, RTP or Racer Theoretical Performance. PAX is still the commonly-used term though. The numbers are calculated yearly based on the relative performance of the different classes and updated here: http://www.scca-chicago.com/solo/indexes/

Paddock

The area where cars and trailers park for the day -- a driver claims a spot and returns his/her competition car there at the end of each heat (before heading out to his/her work assignment).

Pivot (Hairpin)

A sharp, greater than 90 degree, turn -- indicated by one or a series of 3 cones.

Plowing

(See Understeer)

Pointer Cone (Marker Cone)

The tip of a cone placed lying down [next to a standing cone] is a pointer to indicate which side of the standing cone you should drive by. Pointer cones do not count for 2-second penalties.

Pre-position Steering

When the driver moves his/her hands to the top and bottom of the steering wheel before entering a turn, so that there’s no need for hand movement during the turn. (See also Shuffle Steering and Crossover Steering)

ProSolo

The SCCA ProSolo National Series are two-day events that combine Solo driving with drag-race competition. Two parallel courses are simultaneously run by two competitors. Each driver gets runs on both courses and his/her best time from each are combined. Due to the difficulty finding sites which can accommodate two mirror-image Solo courses, some ProSolos are run on one course, with scoring just like a true ProSolo.

Pushing

(See Understeer)

R-Compounds

Racing tires, with minimal tread pattern and maximum grip -- not intended for street use: in SCCA events, legal in all classes except STS, STU and STX.

Red Flag

Literally, a red flag waved by a course worker to indicate you should come to a full stop as quickly as is safely possible because something on the course has created a potentially dangerous situation. If the fault is not yours, you will be given a re-run. After being told to proceed through the finish, please proceed at a reasonably quick pace below competition speed, so that other drivers behind you won't also need to be flagged.

RTP

Racer Theoretical Performance. (See PAX)

Run Order

Which classes run in each heat varies from event to event, so the same group of competitors don’t always have to drive first or last.

Season Points

Championship points accumulated for the season: awarded only to SCCA members who participate in more than half the season events in the same class. Novices are scored against other novices for Novice Championships. See Rules and Regulations for more details.

Shuffle Steering

When a driver’s hands move in small increments by sliding one while the other keeps a firm grip. Neither hand is ever entirely off the steering wheel; your left and right hands remain on their own side of the steering wheel, for full control of steering input without crossed arms. (See also Pre-position Steering and Crossover Steering)

Slalom

This is a course feature where the car must weave back and forth between pylons that have been set up in a straight line. The cones may be equidistant from each other, or not. Sometimes a pointer cone indicates which side you must start the slalom on, and sometime it’s up to the driver to make the better choice. (See also Offsets)

Slip Angle

The slip angle is the difference between the direction your tires are pointing in and the direction they are travelling. Stickier tires will have less slip angle. (See also Drift)

Solo

The SCCA name for Autocross, sometimes abbreviated, autox. Until 2007, this was called Solo2.

Staging

Staging is pulling up to the start line at the prompting of a grid worker and lining up at the start line to make your run.

Stock

Classes for cars with no structural modifications from OEM (Original Equipment of the Manufacturer). Stock classes may only change consumable items, like struts, tires, brake components, etc.

Stop Box

A series of cones which is a gate that marks where the timing device records the end of your run; a stop box is longer than a normal gate to allow for deceleration. You should be stopped before exiting a stop box at a non-competitive and controlled speed. NER events do not [usually] utilize a stop box, but a finish box where only a slow-down is necessary.

Surface Camber

Camber relative to the road surface rather than camber relative to the car’s chassis, or the slant of the road surface. Positive surface camber of curves means increased traction and speed because the road surface will be banked in your favor.

Sweepers

Sweepers are long, wide corners that can be traversed with a pretty good deal of speed.

Threshold Braking

Braking up to but not quite reaching the point at which the brakes lock [or, at which your ABS takes over].

Toe

One of the two aspects of alignment often adjusted for autocrossing. As with your feet, if your left-and-right foot toes and heels are equidistant from each other, your feet are parallel, and there’s no toe, or neutral toe. If you’re standing pigeon -toed, your toes are pointed in -- that’s negative toe, or toe-in. If your toes -- or wheels / tires -- are pointed out that’s positive toe, or toe-out. Neutral toe provides the greatest straight line stability, but some toe-out often helps with the initiation of a turn [steering responsiveness]. Too much toe causes excessive tire wear. Toe-in is useless in autocrossing.

Trail Braking

Continuing to apply some pressure on the brake pedal as you enter a turn, so that weight isn’t transferred as much to the rear wheels and the rear end can more readily rotate. Other footwork techniques used to improve times in autox are left-foot braking and heel-and-toe.

Trailing Throttle

Oversteer is initiated by backing off the accelerator pedal in a corner.

Two Feet In

What an instructor will shout at you when you spin out: a reminder that your clutch should be depressed (as well as your brake) to prevent damage to your car’s engine.

Understeer

Understeer is the condition when the car is not steering as much as the steering input suggests. This is also called "pushing" or "plowing" and is usually a bad thing. When a car resists turning further, it may be because the driver is heavy on the gas and spinning tires while trying to turn more. It can be corrected by braking sooner, backing off steering input and accelerating. [Characteristic of front wheel drive, diminished by alignment or tires/tire pressure change and suspension modification] (See also Oversteer)

Unsprung Weight

Unsprung weight is all the weight of a car that isn't supported by the suspension. When it comes to vehicle dynamics, all weight is bad and less weight is just about always better. Weight that is supported by the suspension though is at least controllable.

Walking the Course

Literally what it says: you walk the course to familiarize yourself with its sequence of slaloms, offsets, hairpins, etc. Instructors usually recommend you walk (as if you were behind the wheel) the line you think you should take during your runs.

Weekend Membership

Facilitates participation by non SCCA members. See our registration page for details.

* These definitions are borrowed from Henry A. Watts book, Secrets of Solo Racing. I couldn't put them in better wording, but if anyone has any wording for me, I'll adjust it.