| Spark
knock |
Same
as Preignition. See Preignition. |
|
|
| Spark
plug |
An
electrical device which protrudes inside the combustion chamber
and creates the "spark" which ignites the air/fuel mixture.
A spark plug wire hooks to the top of a spark plug and sends current
to an electrode inside the plug. The electrode runs the length of
the spark plug and protrudes out it's bottom end (inside the combustion
chamber). At the bottom of the spark plug is another electrode which
is connected to the spark plug body (ground). The energy from the
inner electrode seeks ground and leaps across from one electrode
to the other producing a spark in the meantime. The spark ignites
air/fuel mix in the combustion chamber. |
|
|
| Spark
plug wires |
The
large wires which carry current from the distributor cap to each
of the engine's spark plugs. Also referred to as Secondary ignition
wires, Ignition wires, Plug wires, Wires, and High tension leads.
Also see, High tension leads. |
|
|
| Speaker |
An
electromechanical device used with the radio which converts electrical
signals into sound. Low voltage current is sent to a coil which
is surrounded by a magnet. The coil is attached to a paper cone.
Current creates a magnetic field around the coil which causes the
coil to be quickly pushed away from the magnet. The precise control
of the current causes speaker movement which creates sound waves. |
|
|
| Speaker
3-way |
A
speaker assembly which contains three speakers, usually a primary
large cone, for deep bass, a smaller speaker for midrange tones,
and a tweeter for high frequencies. Three-way speakers generally
provide better sound throughout a wider range. |
|
|
| Speed |
The
rate of motion which an object is traveling. In an automobile it
is measured in mph and km/h (metric) |
|
|
| Speed
control |
See
Cruise control. |
|
|
| Speedometer |
An
instrument that measures and indicates a car's speed. Older vehicles
used a cable and gear system, however, modern speedometers are electrically
operated. |
|
|
| Speed
rating |
A
rating system printed on the sidewall of U.S. performance tires
to specify the maximum speed it can sustain for a short period
of time. Can be a letter ahead of the tire's construction type
(e.g.. P195/70 HR14 or P195/70 ZR 15), or a letter
following the tire load index (eg. 195/75 R14 85T).
Speed
ratings are S=112 mph, T=118 mph, H=130 mph, V=149 mph, Z=149+
mph. In the U.S. only high-performance tires carry speed ratings,
however, all tires must be capable of 85 mph speeds. In addition
to measuring a tire's speed, a speed rated tire is generally a
higher quality tire that dissipates heat better and usually has
a stiffer sidewall resulting in more nimble handling.
All
European tires include speed rating ranging from A5 (15mph max)
to Z (above 195 mph).
|
|
|
| Speed-sensitive
power steering |
A
power steering system that uses valves and speed sensors to vary
the amount of steering assist according to engine or vehicle speed.
At slow speeds more steering assist is delivered and steering the
wheels is easier; necessary for parking, etc.. At higher speeds,
steering assist is reduced and more steering effort is required
to steer the car, giving the driver greater feel of the road. |
|
|
| Speed
shift |
A
shifting technique used by drag racers. During acceleration, the
driver keeps his/her foot to the floor while upshifting a manual
transmission. When done properly, it reduces shifting time and results
in faster run times. The down side is that it is very hard on the
transmission and substantially reduces transmission life. |
|
|
| Spherical
rod end |
See
Heim joint. |
|
|
| Spider |
An
open, two-seat body style applied to sports cars. Originates from
a lightweight, spindly, horse-drawn carriage and later applied to
early lightweight automobiles. After WWII it was revived by Italians
to designate open two-seat sports cars. Also spelled Spyder. |
|
|
| Spider
gear |
Small
side gears in a differential that mesh with larger gears and allow
each wheel to rotate at it's own speed. Necessary for turning corners. |
|
|
| Spindle |
The
short shaft which the wheel and tire mount to and spins on. The
wheel's bearings ride on the spindle. |
|
|
| Spinner
hubcaps |
Wheel
covers found on many 1960's muscle cars which have a raised center
section that contain small protruding arms (usually 3). Designed
to mimic expensive quick-change "knock-off" racing wheels
which can be quickly removed by removing one center bolt/spinner
combination. On knock-off racing wheels, the protruding fingers
on the spinner act as a place where a special lead hammer can be
used to tighten/loosen the retaining bolt. Spinner hubcaps are also
so-called because they accentuate the rotating motion as the wheel
turns. |
|
|
| Spline |
Grooves
cut lengthwise onto the outside of a shaft or on the inside of a
gear or metal tube. When a gear with internal splines is slid over
a splined shaft, the gear turns with the shaft but can slide lengthwise
on the shaft. Splines are commonly used at one end of a driveshaft
to allow the driveshaft length to be increased/decreased yet transmit
power. Also see Slip joint. |
|
|
| Spoiler |
A
rubber or fiberglass device attached to the front of a car below
it's bumper or high on it's tail to reduce aerodynamic drag or create
downforce to improve handling. Dubbed a spoiler because it "spoils"
normal airflow under or over the rear of the car. |
|
|
| Sport's
car |
A
label applied to open-top or two-seater car, or cars with high-performance
motors or suspension systems, but can be applied to nearly any vehicle
with some bend of sporty performance in mind. Typically fun-to-drive
cars. |
|
|
| Sport
Utility Vehicle (SUV) |
A
newly popularized vehicle type that is a cross between a van,
station wagon and pickup truck. Early sport utility vehicles were
built on truck chassis and used full frames; in fact, many were
trucks with modified cabs which extended to the rear of the frame.
Most still share engine and suspension virtues with their truck
brethren utilizing four-wheel-drive drivetrains, real leaf-spring
suspension and full frames. However, many new sport utility vehicles
are based on automotive platforms and use unitized construction
which results in a lighter, more rigid body structure. Owners
appreciate their go-anywhere readiness and roomy interiors. Their
downside is poor fuel economy.
|
|
|
| Spotlight |
A
high-intensity light which can be controlled with a handle from
the inside of the vehicle. Used in squad cars and by farmers to
locate cattle. |
|
|
| Spray-on
bed liner |
See
Bed liner. |
|
|
| Spring |
Elastic
metal or fiberglass devices used throughout vehicles to absorb road
bumps, close engine valves and in many other applications. Springs
are typically made of special spring steel which has high elasticity
properties. Under pressure a spring absorbs energy and yields to
the pressure. When released, it return the energy and returns to
it's original position. There are many different type of springs
such as coil springs, leaf springs, torsion bar, and air springs
(air bags used in air suspension systems). |
|
|
| Spring
rate |
A
spring's resistance to compression during a given length of travel.
Spring rates can be constant or variable over the coarse of compression.
For example, if a spring compresses an inch for each 100 lb of
weight added it's constant is 100 lb/in. A variable rate spring
may compress 1 inch after 100 lb of weight, but may require 200
lb to compress another inch.
Variable
rate springs are used widely in automotive suspension systems
to produce a comfortable ride while carrying a wide number of
passengers and still provide good handling.
|
|
|
| Spring
shackle |
See
Shackle. |
|
|
| Sprocket |
A
wheel with teeth or projections on it's outer edge that mesh with
a drive chain or belt. |
|
|
| Sprung
weight |
The
portion of a vehicle that is supported by the springs weight. Includes
the body, frame, engine and transmission. Also see Unsprung weight. |
|
|
| Spur
gear |
A
gear that has teeth that are straight to its centerline. Not often
used because it is a noisier and slightly weaker design than a helical
gear design. |
|
|
| Spyder |
Another
spelling of Spider often used by Italian automakers. See Spider. |
|
|
| Squareback |
Another
term for station wagon. |
|
|
| Squat |
The
lowering of a car's rear end during hard acceleration. Caused by
the transfer of some vehicle weight toward the rear end and twisting
forces in the differential. |
|
|
| Squeegee |
A
flat rubber or plastic device with a straight edge which can be
used to wipe water away. Also used by autobody technicians to apply
plastic body filler and adhesives. |
|
|
| Squish
area |
An
area in some engine's combustion chambers that aids mixing the air/fuel
charge. At the end of the compression stroke, as the piston approaches
TDC, the mixture is squeezed or "squished". As it is pushed
out of the squish area, turbulence is created and further mixing
of the air/fuel charge occurs. |
|
|
| SRS |
See
Supplemental Restraint System. |
|
|
| Stability |
Handling
characteristics which are predictable, stable and linear during
normal driving and when undertaking sudden maneuvers. Vehicle is
not affected by wind or uneven road surfaces. Factors such as suspension
design and geometry, weight distribution and tires all contribute
to vehicle stability. |
|
|
| Stabilizer
bar |
Another
term for Anti-roll bar. See Anti-roll bar. |
|
|
| Stabilizer
jacks |
[campers/trailers] |
|
|
| Stacks |
See
Exhaust stacks. |
|
|
| Stagger |
Using
different sized tires on one side of a race car to improve cornering
in one direction. Also helps compensate for uneven ride height on
oval tracks. |
|
|
| Stainless
steel |
An
alloy of steel and nickel which is very hard, resists rusting and
can be polished to a mirror-like finish. Used widely for trim on
classic cars but has been steadily phased out and replaced with
anodized aluminum and painted parts on modern vehicles. Stainless
steel is often used to make new vehicle exhaust systems. Such systems
can last the lifetime of an automobile. |
|
|
| Stainless
steel simulated wheel inserts |
Polished
metal pieces, usually made of stainless steel, which can be inserted
to a standard steel wheel and made to look like a more expensive
aluminum wheel. A common aftermarket customizing job often applied
to larger pickup trucks. Dresses up wheels for a fraction of the
cost of new wheels. |
|
|
| Stall |
Unplanned
stopping of an engine. Stalling can be caused by ignition, fuel
or other electrical problems. If a driver released the clutch too
quickly in a manual transmission-equipped vehicle stalling can also
occur. |
|
|
| Stall
speed |
The
speed at which a torque converter's stator begins to rotate in the
same direction as the impeller and turbine. Maximum torque multiplication
occurs at a torque converter's stall speed. |
|
|
| Stamping |
A
process of cutting and forming parts, like brackets and body panels
by stamping sheet metal with large heavy dies. |
|
|
| Starter |
A
small electric motor with a one-way gear on it's end that engages
the flywheel and turns the motor over until can run by itself. |
|
|
| Starter
motor |
Same
as Starter (above). |
|
|
| Starter
solenoid |
A
remotely controlled switch usually near the battery or on the starter
that when engaged completes the circuit and allows current to flow
to the starter, and thus begin to start the vehicle. |
|
|
| Static
balance |
A
method of balancing a tire using a bubble balancer. The tire is
placed horizontally on the balancer and wheel weights are placed
around the perimeter of the rim to correct for slight out-of-roundness
and uneven weight. Reduces tire-hop and wheel vibration. Since the
tire is not moving is said to be "static". Newer methods
of spin balancing tires using a dynamic method are more precise.
|
|
|
| Static
loaded radius |
The
distance from the center of a wheel to the contact surface (where
tire meets pavement) when the tire is properly inflated and loaded
with vehicle weight. |
|
|
| Station
wagon |
A
car where the passenger compartment and roof extend all the way
to the rear of the vehicle. Provides extra capacity for storing
and moving larger items than can normally be carried in a regular
sedan. In addition, most station wagons feature a single fold-down
rear door for easy access.
Station
wagons originate from wagon-like vehicles in the early 1920's
which were used to ferry passengers to hotels from railway stations
and deliver goods to customers. Early "wagons" had all-wood
bodies which were replaced by all-steel bodies in 1949. However,
the motif is still carried over to modern station wagons in the
form of simulated wood grain on side panels.
Station
wagons have declined in popularity in modern times being replaced
by sport utility vehicles.
|
|
|
| Stator |
In
an alternator, the stator is the windings inside which help produce
current. Three windings are found in most alternators which produce
overlapping AC current pulses.
In
a torque converter, the stator is a vaned wheel inside the converter
which is sandwiched between an impeller and turbine. The stator
redirects oil flow which helps the impeller multiply torque.
|
|
|
| Steam
engine |
An
external combustion engine preceding gasoline engines where steam
(expanding air) rather than an air/fuel explosion inside a cylinder
is used to move a piston. Steam engines are considered external
combustion engines because water is converted to steam in a boiler
outside of the cylinder. When it enters the cylinder, the expanding
air moves a piston and produces power. During expansion in the
cylinder, the steam cools and condenses, water droplets and excess
steam are forced out during the return stroke into a condenser
where remaining steam is recondensed into water and returned to
the boiler for reuse.
Some
main drawbacks of steam engines include, required warm-up period,
water freezing in cold temperatures, high maintenance. Some advantages
of steam power are very good potential fuel economy and power,
and the way steam is admitted allows an engine to start from stop
without needing to rev an engine, therefore no clutch is needed.
A transmission with different gear ratios may also be omitted
because steams produce high torque at low rpms.
|
|
|
| Steel |
An
alloy that is used throughout an automobile to make the chassis,
body pannels and engine components. Consists of iron, carbon, nickel,
manganese and chromium. By varying the amounts of compounds in the
iron, steels with different hardness, strengths and other properties
can be produced. |
|
|
| Steering |
See
Steering system. |
|
|
| Steering
arm |
A
connecting arm which connects to and moves a steering knuckle and/or
other steering linkage and turns the wheels. Usually the pitman
arm which comes off the steering box is the steering arm. On older
four-wheel-drive trucks the steering arm attached between the pitman
arm and steering knuckle. A long rod ran the width of the vehicle
and connected one steering knuckle to the other. When one steering
knuckle was steered, the other would also move. |
|
|
| Steering
axis |
An
imaginary line drawn through the ball-joints in a front suspension.
|
|
|
| Steering
axis inclination |
The
angle of the steering axis (see above) to the tire's vertical centerline.
Steering axis angle is a compromise between steering effort, steering
wheel returnability and wheel pull while braking. |
|
|
| Steering
box |
A
critical component of a recirculating ball steering system. Consists
of a heavy gearbox located at the bottom end of the steering column
that contains gears which converts rotary motion from the steering
wheel into lateral, straight-line motion to steer the wheels.
A pitman arm (steering linkage) is attached to the bottom end
of the steering box which connects to other steering linkages.
Manual steering boxes are filled with thick gear lube; power-assist
steering boxes use pressurized hydraulic fluid to reduce steering
effort. An adjuster screw/nut is typically located at the top
or side of a steering box to compensate for steering gear wear.
Another
popular steering system, Rack-and-pinion steering is completely
different. See Rack-and-pinion steering.
|
|
|
| Steering
column |
A
tube-shaped housing assembly directly behind the steering wheel
where the steering shaft, steering wheel lock assembly, gear selector,
blinker levers and ignition switch are located. A long steering
shaft runs through the center of the steering column and connects
the steering wheel to the steering box. A steering column may have
a tilt feature which allows shorter drivers to lower the position
of the steering wheel for better visibility. All steering columns
are designed to collapse in the event of a collision to reduce injury
to the driver. The steering shaft inside also collapses. |
|
|
| Steering
effort |
The
amount of driver effort needed to steer a vehicle. Sports cars often
have stiffer steering which provides drivers with a better "feel"
for the road. Luxury cars often utilize variable assist power steering
which reduces the amount of steering effort required at slow speeds
(good for parking), but reduces the amount of steering assist at
higher speeds for better feel of the road. Steering effort is largely
determines by a vehicle's steering geometry and amount of steering
assist. |
|
|
| Steering
geometry |
The
location, design and positioning of a vehicle's wheels and suspension
components in relation to it's chassis. Caster, camber, toe and
steering axis inclination are important components of steering geometry
that affect handling. |
|
|
| Steering
knuckle |
A
steering component near the front wheels, connects to the ball joints,
steering linkages and allows the wheels to swivel sideways while
steering. The steering knuckle is a heavy-duty cast iron part which
essentially supports the vehicle's weight and allows steering of
the wheels. The wheel hub, brake rotor, and brake calipers also
bolt to the steering knuckle. |
|
|
| Steering
lock |
A
system of locking the steering wheel when the key is removed from
the ignition or the vehicle is turned off. A theft deterrent; prevents
steering the vehicle when the key is removed. Usually achieved by
a perforated plate and a pin inside the steering column. When the
ignition is turned to remove the key, a metal rod is inserted into
a hole on the plate (which is connected to the steering shaft).
|
|
|
| Steering
linkage |
Rods
and arms which transfer steering movement from the steering box
(or rack-and-pinion) to the wheels. Typical steering linkages
include inner tie rods, outer tie-rods, center link, pitman arm,
idler arm and drag link. Steering linkages typically have integral
ball-joints on their ends which allow vertical motion during suspension
flex.
On
most modern vehicles, the steering linkages are greased at the
factory and cannot be greased as a part of routine maintenance.
A slight amount of wear can lead to steering irregularities such
as wandering, pulling and accelerated tire wear.
|
|
|
| Steering
lock |
The
amount the front wheels can turn from straight ahead to far left
or far right. Measured in degrees. The more steering lock, the shorter
turning radius a vehicle has. Too much steering lock may allow the
tires to rub against the frame. |
|
|
| Steering
offset |
The
distance between where the steering axis (imaginary line drawn
between the ball joints) meets the pavement and the center of
the tire's contact patch. The steering offset is like a lever
which acts on steering linkages and the steering mechanism. The
more offset, the longer the lever. If wider rims with a positive
offset are installed (essentially pushing the tire's tread further
outward) the steering offset will be greater and any forces which
act on the tire will be amplified and transmitted through the
steering system. For example, encountering a harsh bump or a tire
low on air will increase the tendency of the steering wheel to
pull
Positive
offset is where the steering axis line is inside the center of
the tire's contact area on the ground. Installing wider rims generally
increases offset because it moves the tire's footprint further
away from the steering axis. Also see Negative offset and Positive
offset.
|
|
|
| Steering
overall ratio |
The
amount that the steering wheel must turn in order to turn the wheels
one degree when positioned straight ahead. Measured in degrees. |
|
|
| Steering
ratio |
The
ration of gears in a steering box or rack-and-pinion system. In
a rack-and-pinion system, it's the ratio of the rack gear to the
pinion gear. In a recirculating ball system, it's the ratio of the
worm gear to the teeth on the ball-and-nut assembly. The higher
the numerical ratio the slower the steering will be, meaning wheels
turn less for a given turn of the steering wheel. Sports cars, race
cars and most police cars have low (numerically) ratios which provide
quick steering. |
|
|
| Steering
response |
How
well a car steers. Affected by steering effort, steering ratio and
steering geometry. |
|
|
| Steering
shaft |
The
long metal shaft which connects the steering wheel to the steering
box. Runs through the center of the steering column. Designed to
collapse in the event of a serious collision. |
|
|
| Steering
spindle |
A
short shaft on a steering knuckle which the hub and wheel mount
to. The hub's bearings (wheel bearings) ride on the spindle. Found
on all rear-wheel driven vehicles and some front-wheel-drive.
|
|
|
| Steering
system |
All
parts of an automobile which allow a driver to steer it. Includes
steering knuckles, linkages, steering gear, steering column and
steering wheel. |
|
|
| Steering
wheel |
A
circular device which a driver grips to control a vehicle's steering.
Mounted to the top of the steering column and bolted to the steering
shaft which is connected to the steering box. Moving the steering
wheel moves the gears in the steering box. |
|
|
| Steering
wheel cover |
A
cloth, vinyl or leather piece of material which can be inserted
over a steering wheel for purposes of appearance or comfort. Leather
and vinyl covers can provide a sportier look and provide a more
comfortable, less fatiguing grip, while cloth covers can protect
a driver's hands from a very hot or cold steering wheel. |
|
|
| Step
bumper |
A
bumper found on many pickup trucks and some sport utility vehicles
which has a horizontal surface on it's outer ends which can be
used to step onto when climb into or out of the truck box. The
center section of most step bumpers usually contains a sturdy
recessed area where ball hitches and trailer tongues can be hitched
to.
A
drop step bumper is similar to a step bumper but has a lowered
center section (dropped) that allows taller trucks to maintain
a parallel tongue angle.
|
|
|
| Step
rails |
See
Nerf bars. |
|
|
| Stick
shift |
A
name for a manual transmission, usually with a floor-mounted shifter.
Some older manual transmission-equipped vehicles had a manual shifter
mounted on the steering column (three-on-the-tree). |
|
|
| Stiction |
Friction
that occurs when initially moving an object. Combination of sticking
and friction. |
|
|
| Stirling
engine |
An
external combustion engine where a gas in a cylinder is heated and
cooled successively from a heat source outside the cylinder. The
expanding and contracting moves a piston also inside the cylinder.
It makes for a low noise, long life, efficient engine but the design
suffers from high costs and control control problems. |
|
|
| Stoichiometric
ratio |
An
"ideal" air/fuel ratio of 14.7:1. A stiochiometric ratio
is a compromise between a rich air/fuel ratio which yields best
power, and a lean air/fuel ratio which provides good fuel economy.
|
|
|
| Stop
Control System (SCS) |
An
inexpensive, mechanical antilock braking system designed by the
Lucas-Girlin Co. Can be used on front-wheel-drive vehicles. Mounted
near each wheel is a hydromechanical modulator which is driven by
a belt that runs off the constant velocity joint. A flywheel on
the modulator acts as the speed sensor. When wheel lockup occurs,
a ball-and-ramp drive inside the modulator opens a valve which reduces
hydraulic brake pressure to the brake at that wheel. |
|
|
| Stopping
distance |
See
Braking distance. |
|
|
| Storage
battery |
A
device used in automobiles which converts chemical energy into electrical
energy. Provides power to start the vehicle and operate accessories.
Nearly all automotive batteries are of the lead-acid type. Once
an engine is started current needed for the engine to run and power
for accessories is supplied by the alternator. The battery is also
charged up. |
|
|
| Straight-cut
gear |
A
gear where the teeth are cut directly across the edge of the gear
at a right angle to the gear's centerline. Also called Spur gear.
Most gears used in automobile transmissions are cut diagonally (helical
cut). Helical cut gears have a longer gear tooth which increases
strength and reduces noise. |
|
|
| Straight
eight |
An
eight cylinder engine where all eight cylinders are aligned in a
single row. Also known as an inline engine. See Inline engine. |
|
|
| Straight-line
stability |
See
Directional stability. |
|
|
| Straight-line
tracking |
How
well a car runs in a straight line without steering correction;
resists veering left or right due to road irregularities. Generally
a result of suspension geometry and tires. |
|
|
| Stratified
charge |
A
type of combustion where the air/fuel mix near the spark plug is
richer than the surrounding mixture. The rich mixture ignites easier
and combustion spreads to the leaner mixture which otherwise might
be prone to misfire. The result is increased fuel economy, low combustion
temperatures and therefore low emissions. A popular example of an
engine that used such a system was the Honda CVCC dual-combustion
engine. Combustion was initiated in a small chamber aside from the
main combustion chamber. |
|
|
| Stressed
body |
An
automobile where the body panels carry part of the vehicle load
(stress) rather than it being transmitted solely to the frame. The
jaguar E-type is a good example. Also see Monocoque. |
|
|
| Striker |
A
sturdy post or U-shaped assembly usually mounted to the body of
a vehicle that the door latch secures to. For doors it is usually
found in the door jam near seat backs and at the bottom side of
the opening for a hatchback or liftgate Often is secured by bolts
which may or may not be adjustable. Adjustment can be made to the
striker correct door alignment problems after a collision or eliminate
air or water leaks at the door seals. Also see Door latch and Door
jams. |
|
|
| Stroke |
Movement
of a piston in it's cylinder from bottom dead center (BDC) to top
dead center (TDC) or vise versa. All automobile engines requires
four strokes to complete one combustion cycle: intake, compression,
power, exhaust. Also see Four-stroke engine. |
|
|
| Stroked |
An
engine whose stroke has been lengthened, usually by installing a
crankshaft with longer throws. The result is increased displacement.
|
|
|
| Strut |
A
suspension component used on most front wheel drive cars which
combines a long shock absorber and coil spring into one unit.
A single strut and lower A arm is all that is needed to locate
the wheel. Therefore the number of wear components and weight
are reduced. The most popular type of strut used is the MacPherson
strut, named after it's inventor Earle MacPherson, who worked
for Ford Motor Company (England).
Another
type of strut is the Chapman strut which is essentially a modified
MacPherson strut. See Chapman strut.
Also:
A small gas-pressurized strut is used in place of hood springs
on many vehicles to hold the hood open. They are also used to
hold open hatchbacks, SUV liftgates and trunk lids on many vehicles.
They wear out after many years and often require replacing. Also
called Hood struts or Lift struts.
|
|
|
| Stub
axle |
Another
name for spindle. See Spindle. |
|
|
| Stud |
A
fastener used on engines and other places on an automobile. Resembles
a headless bolt. It is threaded on both ends so when inserted
in a hole, threads protrude which can be used to fasten other
parts.
Also,
small metal protrusions inserted into snow tires to increase traction
on ice and snow. Very effective but can cause road damage, therefore
they are banned in most states.
|
|
|
| Stumble |
A
driveability problem similar to hesitation but more severe. Can
be caused by a clogged or poorly adjusted carburetor or ignition
problems. |
|
|
| Subwoofer |
A
speaker which produces sound in low audible range. Usually a large
speaker often controlled by a special separate amplifier. |
|
|
| Subframe |
A
frame structure used in the front of some unitized vehicles that
supports the engine, transmission and suspension components. Only
extend to about the center of the floorpans. The advantage of such
a system is added strength and durability to the suspension and
better road noise isolation. Used on a number of General Motors
vehicles in the 70's and 80's. Street rodders and racers appreciated
the design because of the ease to which a frame could be updated,
simply weld a subframe onto a vintage frame or race chassis to achieve
correct modern steering geometry, disc brakes and engine mounts. |
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Sump |
Another
name for oil pan. The reservoir at the bottom of an engine where
the oil drains back to. |
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| Sun
gear |
The
large center gear of a planetary gear system. See Planetary gears. |
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| Sunroof |
An
opening in a vehicle's metal roof where a cover can be slid back
or removed to let in sunlight or assist in ventilation. Few vehicles
have full sun roofs, most have the opening above the front seats
and can be covered with a metal panel or glass which can be slid
back into the rear portion of the roof, or tilted upward at it's
rear edge either electrically or manually. Windows with tinted glass
are often referred to as moonroofs. |
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| Sun
shields |
Louvered
assembly used on the rear of many early hatchbacks to reduce sunlight
and glare on the rear window. Also a popular accessory added to
hatchback vehicles. |
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| Sun
visor |
1.
A small interior panel mounted at the top of the windshield which
can be flipped down or moved to the side to shield sun from the
passenger's or driver's eyes.
2. A fiberglass aftermarket panel which can be mounted on a vehicle's
roof above the windshield to block overhead sunlight from entering.
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| Supercharger |
A
pump that delivers pressurized air (boost) to an engine which results
in increased horsepower. The air/fuel mix is compressed and therefore
more dense which results in more powerful explosions in the combustion
chamber. Superchargers are typically driven by a cogged belt which
runs off the engine's crankshaft. The advantage of a supercharger
over a turbocharger is that the supercharger is always running and
there is no lag. But it does consume some engine power. Commonly
found on drag cars and street rods. |
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| Supplemental
Restraint System (SRS) |
Passenger
restraining devices, in addition to seat belts, designed to reduce
injury in an accident. The airbags, side air curtains and padded
kneed bolsters are a few examples. Also referred to as a Supplemental
Inflatable Restraint (SIR) system. Also see Airbag. |
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| Suppressor
spark plug |
A
spark plug designed to reduce (suppress) radio frequency interference
(RFI). Most spark plugs do this by building resistance into the
electrode core. Nearly all automotive spark plugs are resistor plugs.
Otherwise, the result would be severe radio interference to the
car's radio and other radios nearby. |
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| Surge |
An
undesirable condition in which the engine speed increases and decreases.
The car is unable to run at a steady speed. Usually caused by very
lean air/fuel mixtures and/or retarded timing. A problem more associated
with carbureted vehicles that fuel injected cars. |
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| Surge
tank |
Another
term for Expansion tank -- the tank near the radiator where excess
coolant is stored. For more info, see Expansion tank. |
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| Suspension |
Springs,
shocks, suspension arms which suspend a vehicle's body, frame, engine
and drivetrain from it's wheels. Allows automobiles to absorb road
bumps for a more comfortable ride. |
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| Suspension
geometry |
The
design and fit of a vehicle's front and rear suspension components
relative to each other and the body of the automobile. |
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| Suspension
travel |
The
maximum amount of vertical movement of a vehicle's wheels. Allows
a vehicle to smoothly traverse road bumps and rough surfaces for
passenger comfort. When a wheel encounters a bump (suspension is
compressed) is known as jounce. The return from the compression
is, rebound. Generally, vehicles with greater suspension traverse
larger bumps more smoothly. |
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| Suppressor |
See
Noise suppressor. |
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| SUV |
See
Sport utility vehicle. |
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| Sway
bar |
See
Anti-roll bar. |
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| Sway
bar bushings |
Rubber
bushings which support the anti-sway bar. Sway bar bushings wear
over time because the anti-sway bar (also referred to as a sway
bar) moves each time a bump is encountered. Worn bushings lead to
unresponsive handling characteristics. For increased performance,
racers, street rodders and off-roaders often install new bushings
made of urethane rubber which are harder and 'give' less during
hard cornering resulting in more crisp handling. |
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| Sway
bar [quick] disconnects |
Custom
aftermarket anti-sway bar end links used by off-roaders which
essentially allow the anti-sway bar to be quickly disconnected
from the vehicle's suspension in order to increase wheel travel
and provide greater off-road comfort, yet allow good on-road handling
when connected.
Sway
bars control body roll by limiting the independent movement of
suspension components. While desirable on the highway, off-roaders
desire as much suspension movement as possible to traverse rough
trails and obstacles. Sway bar disconnects allow off-roaders to
enjoy good onroad manners as well as good off-road suspension
travel. Also see Sway bar end links (below).
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| Sway
bar end links |
A
short linkage that connects the ends of a sway bar to the vehicle's
suspension in order to prevent body roll. Bushings at the end of
the end links often wear out and require replacement to maintain
good handling. Racers, street rodders and off-roaders often install
harder urethane bushings for increased cornering responsiveness. |
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| Swept
volume |
Also
called engine displacement. The total volume displaced by an engine's
cylinder as it moves downward in it's cylinder, multiplied by the
number of cylinders in an engine. The primary method of measuring
engine size because it represents the theoretical amount of air/fuel
mix that can be drawn into a cylinder during the intake stroke. |
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| Swing
away mirrors |
Large
mirrors usually found on pickup trucks and sport utility vehicles
which can fold forward or backward when pushed to avoid becoming
damaged. A particularly nice feature with electric and heated mirrors
whose replacement costs can be high. |
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| Swing
axle |
A
seldom-used independent rear suspension design where each wheel's
rear axle contain one universal joint near the differential. During
cornering and suspension flex, the axle and wheel swing in an arc
resulting in large camber changes. During hard cornering positive
camber at the outside rear wheel can cause sudden and significant
oversteer. |
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| Swirl
intake ports |
An
intake port design which causes the air/fuel mixture to swirl in
the combustion chamber which results in more even distribution and
better ignition. |
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| Switch |
An
electrical device that opens and closes an electrical circuit. |
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| SWR
meter |
A
meter used to fine tune CB antennas for greater transmission distance.
Also see CB. |
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| Synchro |
Short
for Synchronizer. |
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| Synchromesh
transmission |
A
transmission that uses synchronizers which reduces gear-clash, increases
transmission life and improves shifting smoothness. Older transmissions
often did not used synchronizers for first gear. Also see Synchronizer. |
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| Synchronizer |
A
cone-shaped ring, usually made of brass, that slides on the transmission
shaft and slows or speeds up the gear being shifted into so it turns
the same speed as the shaft (and other gears) and prevents gear
teeth from clashing. While driving, gears which are not in use may
turn at different speeds to the main shaft inside the transmission.
To facilitate shifting into a gear and prevent broken teeth gears
speed need to be matched. While shifting, the cone area of the brass
synchronizer ring pressed up to a cone on the gear and changes it's
speed to match that of the shaft. |
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| Synthetic
oil |
Lubricants
which are created in a laboratory and produced from materials
other than organic petroleum. Most synthetic lubricants are produced
from synthetic (man-made) base fluids (usually polyalphaolefins
- PAO's). The idea of synthetic lubricants came about out of W.W.II
oil shortage needs and were later developed in order to find a
lubricant which could hold up to the demanding conditions of jet
aircraft engine use. With synthetic lubricants, engineers can
produce a lubricant with particle sizes smaller and more uniform
than those produced from base oils. The result is a lubricant
that is slipperier and reduces friction better than regular oils.
Synthetic motor oils can withstand harsher engine conditions longer
and don't break down as quickly as regular motor oil. They can
also help extend the life of important oil seals and eliminate
sludge buildup.
Synthetic
lubricants are race proven. Race car engines run with synthetic
oil show significantly less wear upon teardown than those used
with regular motor oil. The down side is that synthetic lubricants
are they are more expensive. And because synthetic oil and gear
lube has a smaller molecule size than regular oil, they tend to
find potential leaks faster if used in vehicles with high miles
or slightly worn seals. Many manufacturers recommend begin using
synthetics in vehicles in the under 50,000 mile range. But they
can be used in vehicles with many more miles as well.
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