S
Scale-- For Rc hobbyists, this refers to the general size of the car. Many companies
offer radio control cars in several different sizes: 1/18, 1/12, 1/10, 1/8, 1/5 and
1/4 scale. The smaller the number after the 1, the larger the actual scale car is.
For example, a 1/18 scale car is about 9 inches (23cm) long, while a 1/5 scale car
can be up to 36 inches (91cm) long! Most cars are of the 1/10 or 1/8 scale size (because
the cost of manufacture and ownership is balanced to the controllability of the car),
but there are many types of kits that fall under this size label: Buggy, Truck, Monster
Truck, Truggy, Touring Car and more.
Sedan -- In general terms, this refers to a 4-door
car that has a separate trunk. In Rc terms, this refers to a car that is generally
1/10 scale in size, and is one of the more popular form of on-road Rc racing in the
world right now. These kits started out modeling the cars that formed the DTM racing
league in Germany in the early 1990's, but (because of interchangeable bodies) now
can represent anything from the latest LeMans racer, to street trucks, to the newest
cruiser on the road.
Servo -- A small box full of motorized gears that turns the steering
and/or throttle linkage in an R/C car. Available in a range of strengths and speeds,
with the faster/more powerful servos more expensive than slower/weaker servos. Stock
servos usually cost about $15-30 (US dollars) and are the standard servos that are
included with most radio sets. These servos are fine to get a kit running, but in
the future you may want to upgrade to stronger servos, especially for racing or for
the steering of a large-tire off-road vehicle.
Shell -- Another term for a car body.
Side
Plates -- The sides of a wing, they help direct air over the wing and help in stability.
Larger side plates help in stability on a long straight section but can affect the
turning ability. Smaller side plates aid in turning but don't provide as much straight-line
stability.
Side Skirt -- The part of the body panel that is under the door. This term
usually refers to an extension of this panel that lowers the effective 'body ride
height'. Helps keep air from getting underneath the car, and helps channel air underneath
the car from the front to the rear, increasing downforce.
Shock Oil -- A petroleum-
or silicon-based oil that is available in different degrees of thickness, used to
fine-tune the damping of a shock absorber. As the shock shaft travels up and down,
the piston moves up and down also, so the oil must flow through the holes in the
piston. The smaller the holes are in the piston, the slower the piston is able to
move, and with larger holes the piston is able to move faster. When you are starting
out racing and you want to try adjusting your shock settings, you should try changing
your springs first, then your piston/shock oil combination.
Shock -- See Damping
Shock
Absorber -- The complete assembly of a shock damper that includes the shock body,
cap, spring, shaft and connectors.
Shock Angle -- Move the upper end of the shocks up, and you should get more bite,
or grip, at that end. Lay the shocks further down, and you will loosen that end of
the car.
Shock Bladder -- Many shocks use a shock bladder to assist in bleeding the
shocks properly, and to make sure they maintain the correct pressure.
Shock Body --
The wide cylindrical part of a shock absorber that contains the shock oil, shock
piston and o-rings, topped by the shock cap and sometimes a shock bladder.
Shock Cap
-- Usually a threaded top (or bottom, on some shocks) that closes the shock body
and keeps the shock oil inside. Usually sealed with an o-ring, some shocks use a
shock bladder to help keep the oil pressure inside at a constant level.
Shock Shaft
-- The long metal rod that sticks out of the shock body, usually with a pivot piece
on the end that mounts to a suspension arm. The other end (inside the shock body)
has a shock piston on it.
Shock Spring-- The coil spring that usually surrounds the
shock body of an oil-filled shock. Some shocks consist of just the spring (like a
pan car front shock).
Shock Travel -- This does not refer to shock spacers that clip
to the shock body, compressing the spring. There are two ways to limit shock travel:
Spacers inside the shock, under the piston on the shock shaft or an o-ring or two
on the outside of the shock body, on the shock shaft above the spring retainer. The
inside spacers limit how far down the shock can extend, and the more you have, the
shorter the shock gets at its full length, but you may have to change your ride height.
The outside spacers (be sure to use old o-rings!) remove shock travel without compromising
the shock length or ride height, so the shock can still deal with dips in the track,
but stroke is lessened.
Silicone -- A type of synthetic rubber that is heat-resistant
and more durable than standard or natural rubber.
Sleeve -- Refers to an internal
part of a nitro engine, which the engine's piston slides up and down in. If the engine's
sleeve is replaced, the piston must also be replaced and the engine broken in. Sleeves
in 2-stroke R/C car engines are either nickel-plated or chrome-plated. Nickel plating
offers cheaper parts but it can wear out faster. Chrome plating is more expensive
but worth it for racing.
Slipper -- A short term for the slipper clutch.
Slipper Clutch
-- A traction control device that uses metal plates and a fiber pad that controls
how much power is transmitter from the drive gears of an Rc car to the rest of the
drive train. Used mainly on off-road vehicles.
Speed Controller -- Another name for
electronic speed controller.
Speedo -- Another name for electronic speed controller.
Spoiler
-- An angle on the rear of a car that is built into the body lines of the car, or
bolted on. No space exists between the spoiler and the bodywork. A front spoiler
is technically an air dam. The angle that the spoiler contacts the air is the angle
of attack.
Spring Rate -- This basically refers to the stiffness of a set of springs.
If you want more traction at one end, put on a softer set of springs. If you want
less traction, harder springs. If you are bottoming out or the track is really bumpy
and the soft springs can't extend fast enough to make the tires contact the surface,
put on stiffer springs. If you change the spring rate by a large margin, you'll probably
have to switch out the oil or pistons too.
Spur Gear -- The large (usually plastic)
gear that a pinion gear or clutchbell turns to provide power to a car or truck drivetrain.
Available in different pitches. Many newcomers to the Rc hobby will ask about metal
spur gears to prevent gear stripping, however it is usually gear mesh that determines
if the gear strips out or not.
Standard Narrow-- see width, wheel.
Starting Grid --
The order the cars are lined up at the start of a race. Most races are started with
Le Mans Starts, meaning the cars start from a dead stop.
Straightaway-- Normally refers
to the longest, straightest part of a race track. If there is any place to go full
throttle, this is it!
Steel -- Not used very often throughout a modern Rc kit, steel
is a strong yet heavy metal that is still used in some critical parts of today's
Rc kit. Typical places you can find steel on an Rc car: pinion gears, turnbuckles
or threaded rods, axles, dogbones, ball ends, screws and lock nuts.
Steering Arm --
Parts of a bellcrank steering system that are connected with a central Ackerman link
and connect to the steering knuckles with turnbuckles or fixed links.
Steering Block
-- see steering knuckle.
Steering Knuckle -- Generally, this refers to the of the
car's front suspension that steers the wheels. The steering turnbuckles connect the
steering arms and steering knuckles. The front axle will be connected to or pass
through the knuckle. If the car is four-wheel drive, the steering knuckle will have
two bearings or bushings that support the front axle. Sometimes the steering knuckle
can be referred to as front uprights, front hub carriers, or steering blocks.
Steering
Link -- The turnbuckle or fixed link that connects the steering arms in a bellcrank
steering system to the steering knuckle.
Steering Servo -- The servo that controls
the direction of the front wheels of a car.
Straight Axle -- Another name for pan
cars, so called because of the axle that goes all the way across the rear end of
the car.
Stroke -- How far the shock absorber can compress. Can be limited by clips
or o-rings on the shock shaft.
Super Narrow -- see width, wheel.
Super-Size -- A class
of cars that feature larger bodies, tires, chassis and suspension arms to have a
larger car overall. Easier to drive because of their larger size, the Super-Size
class is really taking off!
Super Touring -- Another name for sedan racing or touring
car racing.
Suspension Arm - A part of the car to which the uprights, hub carriers,
shocks and/or steering knuckles are attached. It will swing up and down as it is
absorbing bumps or lowering into dips. It is usually in the shape of a capital "A",
which is where the name "A Arm" comes from.
Sway Bar -- Bars that attach to the suspension
arms at either or both the front or rear end to limit wheel travel and take away
some traction. Normally used only for fine-tuning the car. Not recommended for bumpy
tracks. Use a thin bar at first to experiment, then try thicker bars.
T
Threaded Rod --A type of connecting rod that has threads facing the same direction.
As opposed to a turnbuckle, a threaded rod is harder to adjust because one or both
ends must be detached to make an adjustment. Also, the threaded rod forces large
adjustments to be made because of the nature of the threads. A turnbuckle can be
adjusted in small or large amounts.
Throttle -- Usually refers to the act of accelerating.
Throttle
Servo -- A servo that controls the linkage that connects to the engine carburetor
of a Nitro car. This same servo also connects to the brake.
Titanium -- An extremely
strong metal, titanium is a rare metal that is stronger than steel yet can be as
light as aluminum. Various alloy mixtures of titanium exist, with the strongest alloys
featuring the same weight as aircraft aluminum but a much higher rigidity.
Toe Angle
-- Refers to the direction the tires face when steering is straight ahead and the
car is seen from above. Applies to both the front and rear. Usually, most drivers
use one or two degrees of toe-in on their car's front wheels (fully adjustable by
turnbuckles on race kits). Most kits come with two or three degrees of toe-in standard
on the rear wheels (adjustable by the lower suspension mount or hub carriers on some
cars). Slight toe-in (one or two degrees) at either end helps to stabilize the car,
but too much (three or more degrees) scrubs off speed, offsetting the benefit of
stability. Toe-out on the front end will give increased steering, useful for quick
turn-ins, but sacrificing cornering speed and straight-line stability. Toe-out at
the rear gives twitchy handling, and it's definitely not recommended. Nearly all
Rc kits have rear toe-in.
Top Qualifier -- After each round of racing, the person
with the fastest time in each class is said to be the top qualifier, meaning they
sit on the pole position for the start of the main event. Usually good only for bragging
rights, because once the race starts all bets are off, as anything can happen in
the main event. Note that top qualifier refers only to the fastest qualifier in the
class, the person starting in first place for the B Main is NOT the top qualifier,
just the 11th fastest driver.
Touring Car -- In Rc racing, a Touring Car is a 1/10
scale version of a normal street car that has been converted to a race car. Most
Rc Touring Cars are four-wheel drive (4WD), meaning all four wheels drive the car.
This makes the car easier to drive for most people.
TQ -- see Top Qualifier
Track Width
-- The width of the car, measured from the center of the front axis wheels and the
rear axis wheels. A wider stance is more stable and gives better cornering, but with
a wider frontal area the car experiences more drag, slowing it down on long straights.
See wheel offset for an additional explanation of different offset wheels, and how
to use them to get a wide stance with a narrow setup and body.
Transmitter-- The part
of the radio system that sends signals to the receiver in the car. Separated into
two general categories: stick, which uses two sticks to control movement; and wheel
or pistol grip, which has one hand hold the radio with the index finger to control
throttle and brake and the other hand control a small steering wheel. Transmitters
are also divided into categories by complexity: AM radios are usually cheaper because
the parts are cheaper to make, while FM radios are available in simple dial- and
potentiometer-controlled versions or digital versions, or digital/computer radios.
Transponder
-- A small radio transmitter that fits in the car to help race directors count laps
during races. Many permanent tracks use transponders at their facilities. Most tracks
that are starting out cannot afford the high cost of a transponder setup, so they
will use a computer keyboard and fast finger-punching to record lap times.
Tuned Pipe
-- A highly modified muffler that substantially increases the power from a Nitro
car's engine.
Turnbuckle -- Similar to a threaded rod, except that the screw threads
face opposite directions so adjustments can be made without removing the rod.
Turn
Marshal -- At Rc racing events, drivers must turn marshal after their race, meaning
they must turn over cars that have flipped, and return cars to the racing surface
if they have crashed.
Tweak -- A condition at the front or rear of the car where one
tire has more load on it than the other. For example, if the right rear tire has
more weight on it than the left rear tire, the car is said to be tweaked. This can
make the car behave unpredictably, including spinning out in turns, turning more
in one direction than the other, upsetting the steering trim, and many other problems.
To
check tweak (you should check between each race):
A) Hobby Knife Method: Set the car
on a flat, level surface. Using a hobby knife, lift one end of the car at the center
point. Watch closely which tire lifts off the surface first. If both tires lift off
at the same time, that end of the car is not tweaked. If one tire lifts off before
the other, adjust the tweak (see below), turn the car around and check the other
end. Adjusting the tweak using the "hobby knife method" must be done by adjusting
shock length.
B) Tweak Device Method: Devices like this set one end of the car level,
and puts the other end of the car on a pivoting surface. This lets the device show
the tweak at either end of the car, without being affected by the opposite end. If
the bubble is level, the car is not tweaked at that end. If the bubble is not level,
that end of the car is tweaked. Adjust the tweak (see below), turn the car around
and check the other end. Adjusting the tweak using this type of device requires adjusting
the shock preload using threaded shock bodies or ride height clips. NOTE: before
using a tweak device, use the adjustable legs to make sure the device is completely
level, and set the shock preloads to the same amounts left and right at each end
of your car.
To adjust tweak:
a) Using the Hobby Knife Method above, if a tire lifts
off the ground first, you must lengthen the shock shaft that attaches to that tire's
suspension arm. This requires removing the whole shock from the car, taking off the
spring perch and spring, holding the shaft with a pair of needle nose pliers, and
turning the shock shaft end so it makes the shaft longer.
b) Using a tweak device,
if the bubble is to one side of the level, add more preload to the same side (by
adding ride height clips or turning the threaded shock collar towards the bottom
of the shock) until the bubble is level.
Two Speed -- A clutch and gear system that
can be installed on most Nitro cars that increases top speed substantially. In general
terms, when the first gear ratio has the engine reach a certain RPM range, the second
gear is engaged and the car is then accelerated using the second gear ratio.
U
Underbody -- On a real car, a smooth underbody makes the drag of the car much lower
at high speeds. In Rc racing you don't need to worry about this, because a totally
smooth underbody means that no cooling air gets to the electronics or engine.
Understeer
-- (also called push) When your car just doesn't seem to be turning as sharp as it
should, or it can't stay in the low groove and keeps drifting to the outside of sweeper
turns, your car is experiencing push, or understeer. The front wheels of a car that
is understeering don't have enough grip, so when you try to steer, the car may continue
to go straight ahead, or just seem to not turn as much as it should. Easy solutions
include slowing down or adding downforce, but more severe problems may need tire,
shock or weight adjustments.
Universal Dogbone -- A driveshaft that combines the conventional
dogbone and axle into one unit, providing more efficiency and power transfer.
Unloading
-- At some points on a race track, the inside wheels can lift up because of high
cornering forces. This causes a normal ball diff or gear diff to transfer all the
available power to the wheel that is in the air. (For an example of this, pull the
throttle gently on your car while holding one tire - all the power at that end of
the car will go to the opposite, free, wheel.) This is because the differential will
put any power at the wheel that is the easiest to turn. This is called diff unloading.
To counter this, racers sometimes use one-way diffs, which allow the tires connected
to the one-way diff to continue providing power the wheel on the ground, even if
a wheel on the same axle is in the air.
Upper Arm -- Similar to a camber link, except
that instead of a turnbuckle with ball ends at each end, the upper arm features a
wider hinge area on the inner link, using a hinge pin to pivot on. The outer link
usually uses a single attachment point, normally a rod end or pivot ball.
Upright
-- Another term for hub carriers.
V
Velineon -- The name for the Traxxas Rc brushles system.
W
Wheel -- Tires are mounted on wheels for stability and precision. Wheels come in
several different widths to fit tires of different widths.
Wheelbase -- The distance
between the front and rear axles of a car. A longer wheelbase gives a bit more stability,
but a shorter wheelbase gives quicker turning and better acceleration, because the
weight of the car is closer to the wheels (in relation to the long axis).
Wheel Offset
-- This is in relation to track width, but refers specifically to the wheels of the
car. The more offset a pair of wheels has, the wider the track and overall width
of the car will be. Most wheels are 0mm offset, meaning the edge of the wheel hub
that comes in contact with the axle hex adapter is exactly in the middle of the wheel.
Some of our sedan wheels feature an offset of 3mm, which widens the car a total of
6mm. While some off-road wheels are 1/2" off set which widens the vehicle a total
of 1 inch.
Wheel Spin -- Occurs when a tire loses grip, either during acceleration
(normally because of too much applied throttle), or through a turn (normally because
of a high side load on the tires.
Wide -- see width, wheel or width, chassis.
Width,
Chassis -- when referring to bodies or chassis designs, we often hear about width.
This is measured from the outside edges of the wheels, front and rear. Most hobbyists
will at some point worry about fitting a narrow body on a wide car, or a wide body
on a narrow car. At this time, most electric sedans are 180mm to 190mm wide, and
most Nitro sedans are 195mm to 200mm wide. Because of the extreme popularity of Nitro
sedans, many newcomers to Rc want to know if they can fit narrow bodies on their
car, bodies that aren't yet available in wide sizes. Sometimes there isn't a problem
with fitting, but this will vary from body to body. Most narrow bodies on wide cars
will have some wheel rubbing.
Width, Wheel -- another area where the term width; is
used. Many tires and wheels are 26mm wide, this is considered standard narrow or
narrow width. Early in the history of touring cars, some companies offered 31mm tires
and wheels, called wide since they are the widest ever offered for touring cars.
A few years ago, some companies offered 22mm super narrow tires and wheels for less
rotating mass. These were never legalized for sanctioned racing, and worldwide rules
organizations kept the tires between 24mm and 26mm, so the most recent development
in tires has been the 24mm mid-narrow tire and wheel, which is a great compromise
between the light weight of the super narrow wheels and the contact patch of the
narrow tires.
Wing -- As opposed to a spoiler, which has no space between the car body and spoiler
itself, the wing is raised off the mounting surface using posts of some sort. Most
wings have upright 'rudder' supports, or side plates, which help stabilize the car
in the straights.
To help tune your car:
A track with many turns and short straights
will need small side plates, which won't interfere with turning too much but still
give you stability in the straight.
A track with many straightaways or two or more
long straights could use larger side plates for more straight-line stability. See
angle of attack for an explanation of how to use a wing.
Wishbone -- An older name
for a suspension arm. Suspension arms used to be shaped like wishbone from a chicken
or other bird. Cars using a pivot-ball suspension still use wishbone-shaped suspension
arms because of the design requirements. Also used to refer to a double wishbone
suspension.
X
Y
Z
Zip Tie -- The common name for a nylon tie wrap, named zip tie because of the sound
it makes as you tighten the strap.
