Driver experience and proficiency, as well as the quality of the work performed on a model slot car, are of prime importance in AFX racing.
To go beyond these factors in creating further improvements, the forces that act on the model car must be understood.
These are the same forces that act on real cars, and their results are identical.
The laws of gravity and motion dictate how fast you can go, corner, and stop in any size car.
Geometry-- How round, how square, at what angle, and how precisely everything works together -- determines how effectively you can reduce friction and take advantage of these laws. Acceleration and speed are depended on torque and horsepower at the driven wheels; deceleration(braking) depends on the weight of the car and the resistance of the motor.
For slot car racing, the lower the center of gravity the better (this means that the greatest part of the car's weight should be down close to the track).
A low center of gravity improves cornering; it also reduces weight transfer during acceleration and braking.
The lower the chassis, the better, to minimize drag caused by air getting under it.
Remember, too, that a lower body profile reduces frontal area and decreases air resistance so higher speeds can be obtained.
Lowering the chassis is rather easy; Just reduce the tire diameter.
Lowering the center of gravity requires the use of a brass pan, lead weights, or similar devices.
Some of these are articulated to cancel shock and vibration.
Replacing the stock body with a light-weight, vacuum-formed one also lowers the center of gravity.
These changes will improve cornering which, in turn, will improve your speeds on the straights since you'll be cornering faster with more speed in hand when you start down the 'chute.
To further improve cornering speeds, chassis balance must be understood.
Proper balance between "oversteer" and "understeer" is essential to fast cornering and the bonus it gives-- faster speed on the straightaways.
These two terms, "oversteer" and "understeer", are much used in real racing to describe car handling into, around, and out of corners. In real racing,engine and fuel replacement; tire pressures, widths, and compounds; sway-bar settings; spring rates; and aerodynamic devices; are all used to balance oversteer and understeer to optimize car handling.
Understeer is unwillingness of a car to turn into and follow through a corner. Although, in theory, the guide pin should lead the AFX car's front end around the turn, chassis understeer may be so great as to cause deslotting; The car simply won't go around the corner at the desired speed. Several things may cause this disturbing situation. When you accelerate the motor, it develops a torque reaction that causes the chassis to lift in front--sometimes enough to lift the pin right out of the slot. It also happens when you go into a corner much too fast. Or, it may be caused by putting wider or stickier rear tires on the car to get a better "bite", thus increasing torque lift of the chassis. In stock car terms, understeer is known as "pushing" or "plowing".
The solution to excess understeer or deslotting is to add weight at the front of the chassis to keep the guide pin in the slot. Remember, tho' that adding weight reduces the acceleration as the motor must do more work to push the car along the track.
For faster racing, the idea is to get your front end to stick well so you can corner faster and--as we've said above-- exit from the turn with more speed available for the straightaway run, thus covering more distance per second than your competition.
Oversteer refers to the behavior of the car's rear end.
If a slot car habitually slides toward the outside of a turn, it is oversteering.
If this tendency can be overcome, the car will lap the track
More rapidly since so much of the motor's performance is wasted by spinning the tires. Also, exiting from a turn with the car sideways isn't the fastest way out of the 'chute'. Ask any drag racer or racing driver. It looks "hairy", but it's not the winning way. While there are a number of tricks you can use for correcting understeer, such as reshaping guide pins and pickup shoes, only two things will reduce oversteer. The first is addding weight, the second is using a wider or stickier tire. If these are overdone, your front end will start plowing again and deslotting, so a delicate balance must be achieved for the greatest success.
Increasing power will change the situation as more weight can be added front and rear to control balance without cutting acceleration drastically. Heavier cars will stop more quickly, although that may seem to be a paradox.
More power and heavier cars require larger powerpacks and controllers, which generally create more heat and require more expensive components -- and a higher cost of racing. In model car racing, just as in real car racing, the objective is to select a class that you want to race in because it's the one you can afford or like best. Improve your car until it's running with the fastest in the field. Balance it, because that makes it easier to drive. In a way, your car then becomes like a finely tuned musical instrument.
The Race Mechanic's Tool Kit - 2
AFX racing is just like real racing in many ways, and one of these is the need for tools to work on your cars. Exactly what tools you'll require depends on whether you wish to keep your stock AFX cars in perfect tune, or undertake more ambitious projects like rebuilding cars or designing your own. In either case, take care of your tools, and they'll take care of you!
The PIT KIT is the ideal tool box for keeping your cars, controllers, tools, and spare parts all together in one place. Find a spot for each item and learn to keep it there. When you need it quickly in a race, you'll know just where to reach!
Here's a list of tools and materials you'll find useful:
FOR CAR TUNING REPAIR: PIT KIT No.1469 or RACE CASE No.1489, screwdrivers, tweezers, wrench for 0-80 axle nuts, AFX track cleaning eraser, diagonal cutting pliers, jewelers' file, stiff brush, oil, 600-grit wet-or-dry sandpaper, clean cloth, detergent soap, scissors,X-acto No. 1 knife with N0.11 blades, jewelers' loup (magnifying glass)
ADDED TOOLS FOR BUILDING CARS AND MAKING PANS: vise, jewelers' saw with extra blades,razor saw, soldering iron and rosin-core solder, noncorrosive soldering flux, assorted files, scale steel rule, scriber, epoxy cement, small hammer, putty, 0.016-inch brass sheet, 0.025-inch brass sheet, phosphorus bronze strip, 1/16-inch brass tubing, hand drill and/or pin vise, drills, 1/16 thru' 5/32 inch
Fine Tuning Your Stock AFX Cars For Performance - 3
INCHES CAN ADD UP TO MILES -- Your stock AFX cars can run better -- faster -- and your competitors may not even know why!
This is the story of AFX fine tuning:
A brand new AFX car, straight from the box, is just like an automobile fresh from a Detroit assembly line. It will run well, but performance improves as it becomes "broken-in" and can be made even better by fine-tuning. In this chapter, we'll take a look at some "fine-tuning" steps that are easy to do, yet makes a big difference when the car is on the track.
Speaking of track, consistent good performance begins with a clean track, properly wired to minimize power losses. This is the first step in fine tuning, so see the Chapter on track before you start work on your car. Note especially that the slot must be clean as well, to permit smooth running without deslotting.
The new AFX high performance track has deep slots so super speeds may be attained. All AFX cars manufactured after 1971 are fitted with reversible guide pins that snap into place. Use the deep slot blade for highest speeds on the new track, or reverse the guide and use the pin end when racing on tracks made prior to 1972. Make sure the guide runs freely in the slot and has no burrs to slow you down.
One of the easiest and yet most significant improvements you can make on your stock AFX cars is to 'run-sand' the rear tires. These are cut from sponge rubber and have high spots that cause wheel hopping and poor handling. 'Runsanding' is the only way to remove these high spots and make sure the tires are perfectly round.
The first step is to remove the body by holding the rear end with one hand and pulling the side of the body with the other. Lay the body aside, then remove the rear tires and spread a thin coat of contact cement inside both of them. Next, scrape the chrome off the rear wheel hubs and apply contact cement to the rims. replace the tires and let the cement dry for at least 30 minutes. The cement bonds the tires to the hubs so that once you true them up, they will stay.
Cement a sheet of fine sandpaper to a piece of thin wood or cardboard (such as a tablet-back). Place your car on the track (or hook it directly to the power supply), turn up the controller to 'fullbore', and touch the rear tires to the sandpaper. True up the tread surfaces, rounding the inner and outer edges a little to prevent flipping, but DON'T SAND TOO FAR or you'll reduce tire diameter to the point where the chassis drags on the track rails.
Important: Run-sand the tires first because you'll have tire dust all over the chassis and, in fine tuning, cleanliness is the watchword!
After the rear tires are trued up, check the front ones for out-of-roundness and replace them of necessary. The stock Aurora front tires are adequate as they are neither so hard that they amplify vibration nor so soft that they 'scrub' and slow you down.
In model car racing, as in any type of racing, you must get to know your machine inside and out. Practice taking it apart often enough so that you can put it together in the dark; when thew time comes that you may have to so this in a race, you'll win.
With the body removed, spin the rear tires and note that three gears revolve. Look under the rear gear and you'll see two additional ones underneath that drive the rear wheels. This is a lot of gearing for a small race car, and means plenty of drag. While the gears are made of Nylatron, a self-lubricating plastic, a tiny drop of oil in a few spots (as indicated on the chart) will reduce drag. Don't use more than a tiny drop, however, as oil spreads readily and has the bad habit of collecting dust, dirt, and fuzz. All those will only slow you down! The applicator on the Aurora oiler is too big: Use a needle or pin instead.
Before you remove the gear clamp, note carefully which color magnet goes where so you'll get them right in assembly, and remember that underneath the armature are two small, cylindrical motor brushes that will fall out. Keeping this in mind, remove the clamp and gear plate noting that the front end of the latter hooks into the chassis.
Flip the gear plate over carefully and look at the armature commutator. If you see any oil or lubricant on its surface, clean it off with tissue and hot soapy water. Polish it with very fine (600-grit) sandpaper or eraser, taking care not to damage the armature windings. Spin the armature while checking the gears and making sure they're not warped, that there's no flash or dirt on them, and that they aren't binding. Examine the motor brushes and clean these as well. Brushes and commutator must make the best possible electrical contact for maximum performance. Any dirt, fuzz, or oil between them results in poor operation.
