C
Calling Traffic -- Some tracks have a policy of telling racers that are getting
lapped that the leader of the race is coming up behind them. The backmarker is expected
to move over and not interfere with the leader and any battles for position. However,
not all tracks have this policy.
Camber-- Seen from the front and rear of the car,
the angle of the tires in relation to the ground; tires that are perfectly perpendicular
to the ground (90 degrees) are said to be at 'zero camber'. If the tops of the tires
lean towards each other, the tires have negative camber, and if they lean out, the
tires have positive camber. As a general rule, never have positive camber, and make
sure the camber of, say, your front right wheel equals the camber of your front left
wheel (make the camber angles on each axle match). If we were talking about oval
racing, the rules would be different, but we're not. Sedan racing, with it's straights,
turns and chicanes requires that, among other things, camber angles match. Usually
one degree of negative camber on the fronts is good, because you want a good contact
patch throughout a turn, and one or two degrees of negative camber on the rear wheels
is fine. From there, experiment, one degree at a time.
Camber Link--Normally made
up of a turnbuckle or threaded rod with a ball cup at each end, this allows the suspension
arm and upright to flex a little more than an upper arm would.
Carburetor--Called
carb for short. The mechanism on an engine that controls the ratio of fuel and air
that enters the engine. There are different types of carburetors:
Barrel Carburetor:
the standard model engine carburetor, carried over from airplane engines when they
were adapted for car use. For most hobbyists and racers this type of carburetor is
fine, because it is simple to install and adjust. The throttle servo turns a barrel
which has a hole through it, and this controls the amount of air going into the engine.
A needle valve on the carburetor controls the amount of fuel going into the engine.
A
Slide Carburetor: a highly modified, car-specific type of carb that has the barrel
of the carb slide along its axis, instead of turning. This provides a quicker response
at the expense of a complicated set-up procedure. This type of carb has almost become
the industry standard for the RC Hobby. Two or three needle valves control the fuel
intake at different RPM ranges.
Car Stand -- Simply, this is something a R/C car will
be on while work is being done to it. It can be as simple as a block of wood, or
as complicated as a padded rotating stand with parts bins. Another main function
of a car stand is to keep the wheels off the ground during breakin and while work
is being done.
Caster -- Almost every car has some caster built-in. Caster is the
angle that the car's front wheels pivot on when turning. Most on-road Touring Car
type kits use between 5 and 10 degrees of caster. Off-road kits like buggies and
trucks have about 25 to 30 degrees of 'kick-up' on the front axles. More caster generally
gives more steering going into a turn, but less coming out. The opposite is also
true: less caster give less steering going into a turn (initial steering), but more
steering as you exit. Caster also gives more stability on straightaways, but this
effect is more pronounced in 2WD vehicles.
Cell -- Another term for batteries, but
in a singular reference (such as, look at this cell), this generally refers to the
nickel-cadmium or nickel-metal hydride batteries used in Rc cars.
Center of Gravity
-- can be shortened to CG or cg. A point in space that represents the central point
of a car's mass. If you don't race or are just starting, the only thing you need
to know about center of gravity is that if you have a high CG the car or truck will
be easier to tip over in tight turns, especially at high speed. As you get more experienced
in racing, you will learn to keep everything on the car or truck as low as possible
to enhance handling.
Chassis --The foundation of an Rc car or truck, this is the main
portion of the car that everything attaches to. It can be made from woven graphite,
molded plastic composites or aluminum. Normally it is flat with lightening holes
cut into it but if molded from plastics it can have bent-up sides and other features.
Class
--In radio controlled car racing, the class refers to the type of car you have, and
what class it would race in. In general, there are Touring Car, Mini, 2WD buggies,
2WD trucks, 4WD buggies, Rally, Super-Size, Oval Pan Car, 1/10th scale Pan Car, 1/12th
scale Pan Car and a couple of other classes. These classes are further divided by
the mode of power, either Electric or Nitro. The some of the popular classes are
electric and Nitro Touring Car, electric 2WD buggy, nitro 4WD buggy, Monster Truck,
Truggy and Stadium Trucks. To just name a few. When deciding what type of kit you
want to get for your first R/C kit, try to decide what type of kit and what type
of power source you will get, this will narrow your selections down considerably!
Closed
Cell Foam -- A type of foam that is molded, normally used in Rc for molded inner
foams. More expensive than open cell foam, it holds its shape better and if molded
it does not move back and forth on a wheel.
Clutch Bell-- The equivalent of a pinion
gear on a nitro engine, the clutch bell is on the end of the crank shaft and connects
with the car's spur gear(s). In a cutaway view, the clutch bell looks like a bell,
which is where it gets the name. Inside the hollow part of the clutch bell are the
clutch shoes, which will expand with engine RPMs to come in contact with the clutch
bell, making it spin. This makes the spur gear turn, and the car moves forward!
Clutch
Shoes -- Clutch shoes are attached to the engine flywheel and expand under increasing
RPM to contact the clutch bell. The clutch bell spinning makes the spur gear turn,
and the car moves forward!
Compound-- When talking about tires, the firmer (harder)
the compound, the longer life it will have, but it won't have as much grip as a softer
tire would. Most racers use a firm compound tire as the racing surface heats up during
the day. A softer compound tire is best used when the track is cool, such as in the
morning or late evening. Examples of these compounds include 20R tires (softest),
23R, 27R (medium), 33R and 35R (firmest).
Contact Patch-- The footprintof the car's
tire, or the area of the tire that comes in contact with the ground at any given
moment. Affected by camber, turning and acceleration. A wider contact patch (from
wider wheels) does NOT mean you will automatically get more traction.
Coupe -- In
general terms, this refers to a 2-door car. Some Rc touring car body manufacturers
offer bodies that represent full-size cars.
Crank Shaft-- A part of a Nitro engine
that is rotated by the piston, providing circular motion to the outer part of the
crank shaft, which is attached to the flywheel and clutch shoes.
Crystal-- The part
of a radio system that tells the transmitter to emit a particular frequency, and
also tells the receiver to look for a particular frequency. Crystals normally are
packaged in pairs, because the receiver requires a different crystal than the transmitter.
You must use the same frequency crystals in the transmitter and receiver to make
the car respond correctly to your commands.
CVD-- An abbreviation for Constant Velocity
Drive. CVD is a trademark of MIP (Moore's Ideal Products, Inc.). MIP offers their
CVD universal dogbones for many Rc Trucks and Cars. The main features of the MIP
CVD's are their improved efficiency over standard universal dogbones, ability to
be rebuilt if an axle or bone is bent or damaged and ease of finding replacement
parts. The MIP website is www.miponline.com.
D
Damping -- Damping is a highly variable part of car tuning. It's affected by the
strength of the shock spring (length and thickness of the wire, plus the number of
coils), the size and number of holes in the shock piston, and the viscosity, or weight,
of the oil in the shocks. The spring controls how hard the shock compresses, and
both the piston and the oil control how quickly the spring pushes the shock to its
full length (which can be limited by shock spacers), and so affect the quickness
of the shock's return. Stiffer springs need heavier oil and/or smaller-hole pistons
to control the speed of the rebound, and bumpy tracks need lighter oil so the shocks,
or dampers, can compress and rebound quickly. Softer damping gives more 'stick' on
a particular wheel, but makes the car less responsive because the chassis takes longer
to reset after a turn, and is also more forgiving to drive. Softer damping also reduces
weight transfer at that wheel. Stiffer damping makes handling more responsive, but
reduces traction to a particular wheel which can make the car slippery as the chassis
snaps back into place after a turn. Stiffer damping also increases weight transfer
at that wheel.
Differential-- A system that transfers power equally from a shaft input
to shaft outputs. A differential (or diff) allows the outside wheel of a car going
through a corner to travel farther than the inside wheel, preserving corner speed
and efficiency. There are two main types used in radio control cars:
Ball Differentials
or Gear Differentials. Ball differentials should be initially set to the kit specifications:
the diff should be set so that the pulley is not be able to be turned with two flat
head screwdrivers or Allen wrenches slid through the outdrive. A different type of
differential is the One-Way Diff, which uses expensive one-way bearings to control
wheelspin.
Ball Differential(Ball Diff) -- A differential that uses a series of steel
or carbide-steel ball bearings in a circle, pressed between two metal rings, to provide
the differential action, allowing one wheel to rotate more than another in a turn.
Ball diffs are easier to adjust than gear diffs but are harder to maintain, as they
need checking every day of running and are not recommended for Nitro racers. Normally
a screw on one side controls the tension between the metal rings, which controls
how much the outside wheel in a corner can turn. The looser (to a point) a diff is,
the more traction there is at that end of the car. To start tuning your car, set
the ball diffs to the same tension at each end, and use the diffs only to fine-tune
the car. Do not change the settings of your diffs first.
Gear Differential (Gear Diff)
-- A differential that uses a series of gears to provide the differential action,
allowing one wheel to rotate more than another in a turn. Gear diffs are harder to
adjust than gear diffs but are much easier to maintain, because they must be sealed
to keep the grease inside from coming off the gears. Tuning a gear diff can only
be accomplished by changing the weight (viscosity) of the grease inside the gear
diff case. The looser (to a point) a diff is, the more traction there is at that
end of the car. To start tuning your car, set the ball diffs to the same tension
at each end, and use the diffs only to fine-tune the car. Do not change the settings
of your diffs first.
Dogbone -- A part of the drivetrain that connects the outdrive
to the axle. This allows the differential to get its power to the axle and tires
of the car.
Double Wishbone -- A type of suspension design that uses two wishbone
arms (parallel to the ground and each other - one for the main suspension arm and
one for the upper arm) to help maintain a constant tire camber as the suspension
is compressed. Most Rc cars have this type of suspension design, because, although
it is expensive to have on a full-size car because of cost and space issues, on a
miniature car where there is no concern over the space needed for a driver, it is
much easier to make. Older Rc cars used different suspension technologies that are
no longer in use today (at least in Rc) including swing-arm and trailing arm suspensions.
Downforce
-- The effect of air contacting the car body's sloped surfaces. Downforce is created
by the air dam, hood, windshield, roof, spoiler(s) and wing(s) of the car. More downforce
increases drag and slows the car, but raises the tire temperature, making the car
easier to drive. Less downforce raises the top speed by reducing drag. The car should
be set up so that it can drive with minimal downforce.
Drag -- In car design, drag
is the force of air that slows down the car. The lower the drag of the car (in other
words, the more aerodynamically efficient it is), the faster the car can go while
using the same amount of power.
Drag Link-- Another term for Ackerman link
Draft --
In racing terms, draft is the area directly behind a car where the air is disturbed
and there is very little wind. A real-world example would be putting your hand outside
the window of your car, and moving it behind the side mirror, then out from behind
the mirror. Behind the mirror is the draft.
Drafting -- In racing terms, this is the
act of following the car in front of you close enough that your car does not have
to fight drag. This lessens the load on your engine or motor, and on a long straight
section of the track your car and the car in front of you can go faster than another
car on its own. In R/C racing, this is very rarely able to be used because of the
size of the cars and the maneuverability of the cars, even on an oval track.
Droop
-- The measure of shock droop is the amount of uptravel the chassis will have if
you weigh the car with its full running gear (servo, batteries, motor, etc.), settle
the chassis (press down and release on the chassis), then lift each end until the
tires lift off the ground. The total upward movement of the chassis at each end is
measured as droop.
Dyno -- An expensive piece of computerized equipment that measures
the efficiency of a motor. Can be used to select the right gearing, but the dyno
in this function is normally only used by pan car or oval racers.
E
E-Clip --A small device that holds cylindrical parts like hinge pins in place on
the car.
Electric-- This general term usually refers to the power source of the car,
meaning it uses a battery pack
Electronic Speed Controller --An electronic device
that takes the power from the battery pack and the signal from the receiver and measures
a certain amount of power to the car's motor. Only used in electric R/C cars, boats
and planes.
Engine -- In Rc terms, this is a fuel-powered engine that provides the
power for forward motion.
ESC -- an abbreviation for Electronic Speed Controller
