Dictionary of Automotive Terms Abbreviations

DICTIONARY OF AUTOMOTIVE TERMS - "Sp"

Space: See
Dead space
Parking space
Unmanned machinery spaces

Space frame: A type of Frame construction which has high rigidity for its low weight. It is used with some racing and low production cars. It is made up of several lengths of tubing welded into a strong, light web-like structure to which the engine, Suspension, and other Components are attached.

Spacer

A Component which moves two items further apart. Sometimes it is just a washer and at others it is a metal or plastic cylinder or a block of rubber or plastic.
A band on demountable rims which fits between two rims in dual mounting to provide clearance between the duals.
A circular metal plate having a bolt hole circle and center bore and fitting between the faces of disc wheels to provide additional dual clearance.
Pieces designed to prevent crushing of sandwich-type and other lightweight structural materials at fastening points. Sometimes called inserts.

Also See
Between wheel spacer
Phenolic Spacer
Threaded Spacer
Wheel spacer

Spacer entry EGR system: Exhaust gases are routed directly from the exhaust manifold through a stainless steel tube to the carburetor base

Spacer plate: See
Valve body separator plate

Spacer ring: See
Expander spacer

Spacer washer: A sheet of metal or other material placed between two surfaces to reduce clearance or to provide a better surface for a fastener

Space saver spare: A spare wheel and tire which is much smaller than the regular tires and can be used to replace a flat tire. However, the spare is limited in speed as well as performance. The British call it a tempa spare wheel. Also called Collapsible spare tire.
Also see
Full-size spare

Space-saving spare wheel: See
Space saver spare

Space saver wheel: See
Space saver spare

Space saving tire: A Spare tire which is smaller than normal and has limited use only when a flat tire occurs.

Space wagon: A vehicle category introduced in the USA in 1983 with the Chrysler Voyager, and in Europe at the end of the 1980s with the Renault Espace; a multi-purpose vehicle for everyday and recreational use that combines the handling and luxury of a sedan with the space and headroom of a van; usually with three rows of seats for at least six people and with a sliding door on the side

Spacing: See
Dual spacing
Hub Spacing
Quire Spacing

Spade Screws: A threaded, round body with a finger tightening projection. (Regular Offset or Bent). Primarily used in places needed for frequent adjustments or for knock-down assemblies.

Spade terminal: A terminal used to connect a wire to a screw or stud terminal. The spade the has two forked ends, either straight or with upturned tips. They are more convenient to install than ring term, but slight less secure for rugged applications. Comes in soldered and unsoldered versions

Spalling: A flaking of the surface of a bearing

Spangles: Crystal structure on hot-dip galvanized metals

Spanner: Although a British term for a wrench, it is also used for many Bicycle tools in the U.S.A. and Canada.
Also See
Adjustable spanner
Box spanner
Brake adjusting spanner
C-spanner
Chainring nut spanner
Combination spanner
Double-ended spanner
Drain plug spanner
Electrical spanner
Flare nut spanner
Girder spanner
Pin spanner
Ring spanner
Socket spanner

Spanner Screws: Special unslotted screws surface, in Round undrilled, Flat drilled and others, that require a special wrench.

Spanner Wrenches: Tools used to turn and tighten spanner screws.

Spare: See
Full-size spare
Instant spare
Space saver spare
Spare part
Tempa spare

Spare part: A replacement part, either available from a dealer or carried with the vehicle (like bulbs, fuses, plugs, etc.)

Spares car: See
Donor car

Spare tire: An extra wheel and tire assembly which is stored in the vehicle in the event of a flat tire.

Also See
Space saving tire
Collapsible spare tire

Spare tire carrier: The horizontal rack near the rear axles, below the loading area of light commercial vehicles where the spare wheel is usually mounted

Spare wheel: See
Conventional spare tire
Spare tire
Tempa spare wheel

Spare wheel well: An indentation in a flat trunk floor that houses the spare wheel in a horizontal position

Spark: The bridging or jumping of a gap between two Electrodes by a Current of electricity. One of the essential factors in a Combustion engine (Fuel, Air, Proper proportion of mixture, Compression, Timing, Spark).
Also See
Electronic spark advance
Electronic spark control
Electronic spark timing
Follow-up spark
High energy ignition system with electronic spark timing
Hot spark plug
Jump spark
Negative spark
Platinum spark plug
Projected spark position
Recessed spark position
Resistor spark plug
RFI suppressed spark plugs
Transmission controlled spark

Spark advance: A device which causes the Spark plug to fire earlier by altering the position of the Distributor's Breaker points in relation to the Distributor shaft.
Also See
Advance
Electronic spark advance
Ignition advance

Spark Advance Control: See
Orifice Spark Advance Control

Spark air gap: The gap between the electrodes of a spark plug.
Also see
Surface gap

Spark angle: See
Ignition angle

Spark-angle map: See
Ignition map

Spark arrester: A device which hinders flames from exiting the Exhaust pipe.

Spark breakaway: The end of spark duration

Spark control: See
Electronic spark control

Spark control computer: (SCC) electronic control unit with electronic spark timing

Spark current: Current that flows across the electrodes of a spark gap at a particular point in time

Spark delay valve: (SDV) a valve in the vacuum advance hose that delays the vacuum to the vacuum advance unit during rapid acceleration from idle or from speeds below 15 mph, and cuts off spark advance immediately on deceleration. Has an internal sintered orifice to slow air in one direction, a check valve for free air flow in the opposite direction and a filter

Spark discharge voltage: See
Ignition voltage

Spark duration

The burning time of the arc following the initial flashover between the spark plug electrodes until the residual energy decays
The length of time measured in milliseconds that the spark is established across the spark plug gap

Spark gap: The space between the center and side Electrode tips on a Spark plug.
Also see
Gap.

Spark gap coil tester: A tester providing a spark gap or neon tube to provide a comparison for the coil being tested. The coil to be tested is connected to the spark gap of the tester, and the length of the spark it produces is measured; a good coil is used as a standard of performance

Spark head: Displayed as a firing spike on an oscilloscope pattern

Spark ignition: An ignition initiated by an electric spark in a spark ignition engine.

Also See
Self-ignition

Spark ignition angle: See
Ignition angle

Spark ignition engine: (SI engine) In contrast with a diesel engine (which does not use a spark plug), a spark ignition engine uses a spark plug to ignite the fuel/air mixture.

Spark knock: See
Preignition
Engine knock

Spark map: See
Ignition map

Spark method: See
Waste spark method

Spark plug: Spark plug

A device containing two Electrodes across which electricity jumps to produce a Spark to fire the fuel charge. The center Electrode is insulated from the spark plug shell by means of a molded Insulator resembling Porcelain. The side Electrode protrudes from the bottom edge of the spark plug shell and is so positioned that there is a gap between it and the center electrode.
Also See
Cold plug
Hot plug
Platinum spark plug
Resistor spark plug
RFI suppressed spark plugs
Split electrode spark plug
Surface gap spark plug
TC spark plug
Thermocouple spark plug

Sparkplug: See
Spark plug.

Spark plug body: See
Spark plug shell

Spark plug boot: A molded rubber or plastic insulator at the end of the spark plug wire and which fits over a spark plug terminal

Spark plug boot puller: A special automotive tool for the safe removal and installation of spark plug boots

Spark plug brush: A hard, compact brush for removing carbon from spark plug electrodes

Spark plug cable: British term for Spark plug wire

Spark plug cable cover strip: The connecting system that integrates the spark plug connectors, spark plug leads, distributor cap, distributor connector, high-voltage cable, and ignition coil connector

Spark plug cable loom: Typically, a T-shaped and sometimes chrome-plated steel holder with cable guide holes and plastic inserts; keeps cables neatly in place and eliminates ignition leakage

Spark plug cable separator: Typically, a T-shaped and sometimes chrome-plated steel holder with cable guide holes and plastic inserts; keeps cables neatly in place and eliminates ignition leakage

Spark plug cable marker: A numbered snap-on C-clip which identifies the firing order

Spark plug cap: The device on the end of the high tension wire coming from the coil and mounted on the spark plug. Also called Plug cap

Spark plug condition: A visual appearance of the spark plug electrodes and insulator

Spark plug electrode: The two electrodes in a spark plug are the center electrode and the side (or ground) electrode

Spark plug gap: The space between the center and side Electrodes of a Spark plug across which the Spark must jump to ignite the Air-fuel mixture in the Combustion chamber.

Spark plug gauge: A tool used for checking spark plug gaps; usually with metal feeler blades or calibrated wire feelers (the wire-type is preferred over the blade type). It often includes an electrode adjusting tool for altering the gap between the electrodes

Spark plug heat range: The ability of the spark plug to dissipate heat.

Spark plug insert tap: A tool used to enlarge and tap new threads in damaged spark plug holes in order to accept spark plug inserts

Spark plug insulator: A highly stressed part of the spark plug, usually made of alumina ceramic, which serves to insulate the center electrode and the terminal stud from the shell; its material must have high dielectric, mechanical and thermal strength as well as good thermal conductivity

Spark plug lead: See
Spark plug wire

Spark plug pliers: A pliers-like tool with specially shaped jaws to securely grip spark plug boots for removal and installation, and insulated handles for a shock-proof grip

Spark plug shell: The metal body of the spark plug which encloses the lower part of the insulator

Spark plug socket: A tool used to remove or install Spark plugs. It is a metal cylinder with a rubber lining that fits over the exposed end of the spark plug to make it easy to remove the plug without damaging its porcelain surface.
Also See
Universal spark plug socket

Spark plug spanner: See
Spark plug wrench

Spark plug tester

A screwdriver with a bulb inside the handle, which lights up if a spark is present when the blade is touched against the outside insulation of the spark plug wire.
A large instrument into which a spark plug is screwed and a high tension wire is secured to the top of the plug to duplicate an ignition system. By looking into the sight glass, you can see how well the spark plug is firing.

Spark plug whiskering: See
Gap bridging

Spark plug wire: A high-voltage wire (either copper core or carbon core) with thick insulation. It comes from the distributor to the spark plug. Also called Ignition cable

Spark plug wire cover strip: The connecting system that integrates the spark plug connectors, spark plug leads, distributor cap, distributor connector, high-voltage wire, and ignition coil connector

Spark plug wire loom: Typically, a T-shaped and sometimes chrome-plated steel holder with wire guide holes and plastic inserts; keeps wires neatly in place and eliminates ignition leakage

Spark plug wire separator: Typically, a T-shaped and sometimes chrome-plated steel holder with wire guide holes and plastic inserts; keeps wires neatly in place and eliminates ignition leakage

Spark plug wire marker: A numbered snap-on C-clip which identifies the firing order

Spark plug wrench: A tool for removing and installing spark plugs. It comes in a variety of shapes, e.g., with swivel or T-handle, and many have rubber inserts to prevent damage to the fragile insulating porcelain

Spark position: The position of the spark gap in the combustion chamber.
Also see
Projected spark position
Recessed spark position

Spark rate: The spark rate per minute in a spark ignition engine is the number of cylinders multiplied by half the engine speed

Spark retard: The action of changing the Ignition timing so that the Spark occurs after what is specified by the manufacturer.

Also See
Retard
Ignition retard

Spark timing: See
Electronic spark timing
High energy ignition system with electronic spark timing
Ignition timing

Spark timing system: See
Electronic Spark Timing System

Spark voltage

The voltage required to maintain the spark after reduction of the firing voltage.
The voltage measured at the electrodes of a spark gap at a particular point in time.

Also see
Ignition voltage

Sparring: See
Cargo battens

Spar-type frame: See
Twin spar-type frame

Spat: See
Rear wheel spat

Spatter: Sparks produced during the welding process; more pronounced if the welding parameters are not correctly set or if impurities are present on the welded area

Spd: Abbreviation for Speed, as in 4-spd. transmission.

SPD compatible: A Shimano developed bolt pattern drilled into the sole of cycling shoes resembles two parallel, identically sized slots into which an SPD pedal cleat is attached.

SPD-R compatible: A newer style of Shimano's pedal bolt pattern. SPD-R compatible shoes are drilled differently from the original SPD system. The drilling for an SPD-R cleat has a long slot on the right side of the sole with three bolt holes. Next to this long slot is a shorter slot to the left with one bolt hole.

Speaker: A sound device which contains a magnet and a relatively large vibrating diaphragm which translates electrical impulses into sound vibrations.
Also See
Door speaker
Flush mounted speaker
Surface-mounted speaker

Speaker grille: A covering over the speaker which protects the sensitive diaphragm and yet permits the maximum output of sound.

Speaker enclosure: The housing for the speaker (i.e., its box) which may enhance the output of sound.

Spear: See
Battery Spear

Spec: Abbreviation for special, as in spec. paint colors or for Specification

Special body: A body not supplied by the car manufacturer or by an approved body supplier in the case of manufacturers that do not build their own bodies, but rather by an independent coachbuilder who produces a body different from the standard body. A One-off body refers specifically to a body of which only one example is made, whereas in general, special or coachbuilt bodies may be produced in small-scale series

Special collector: An evacuated tube collector or a concentrating (focusing) collector. Special collectors operate in the temperature range from just above ambient temperature (low concentration for pool heating) to several hundred degrees Fahrenheit (high concentration for air conditioning and specialized industrial processes).

Speciale: See
Alfa Romeo.

Special Import Measures Act: (SIMA) Helps to protect Canadian producers from harm or injury caused by the dumping of goods into Canada by foreign exporters or the subsidizing of goods by foreign governments.

Special ledge: (SL) A safety bead seat contour mainly used on American passenger cars

Special mileage tire: A tire manufactured with an extra layer of rubber between the cord body and the original tread design. This extra layer is designed for the purpose of recutting and regrooving, and is specifically labeled as a special mileage commercial tire. Also called regrooveable tire.

Special naphthas: All finished products within the Naphtha boiling range that are used as paint thinners, cleaners, or solvents. These products are refined to a specified flash point. Special naphthas include all commercial hexane and cleaning solvents conforming to ASTM Specification D1836 and D484, respectively. Naphthas to be blended or marketed as motor gasoline or aviation gasoline, or that are to be used as petrochemical and synthetic natural gas (SNG) feedstocks are excluded.

Special services: A category that describes plants which add value to automotive parts manufactured by others by using process such as painting, plating, heat treatment, etc.

Specialty repair shop: Retail outlet which offers specialized vehicle products and service.

Specific activity: The conversion rate of a given catalytic converter per unit volume; it is desirable to have a high specific activity, i.e., a small but efficient converter

Specification: See
Specifications.

Specifications

A list of the measurements of each Component of a vehicle and the requirements for proper installation. The size, description, or part numbers for various items needed to maintain or repair a vehicle.
The properties of a product within certain parameters such as quantity, temperature, pressure, humidity, specific gravity, purity, pour point, viscosity, and shape. For instance if you contracted to buy a full bucket of water, and I gave you a full bucket of ice cubes, when they melted, you would not have a full bucket of liquid. Thus the need for correct specifications. This applies to crude oil and petroleum products including gasoline and motor oil.

Also see
British Standard Specification

Specific fuel consumption: (SFC) The amount of fuel consumed by an engine for each unit of energy produced; measured in kilograms-per-megajoule or kilograms-per-kilowatt-hour or pounds-per-bhp-hour
Also see
Brake Specific Fuel Consumption

Specific gravity

(Sp.Gr.)

Weight of a liquid compared to water at 15°C, which is assigned the value of 1.0.
The relative weight of liquid (Battery Electrolyte) as compared to the weight of an equal Volume of water.
Gasoline has a specific gravity of 0.720 which means that it weighs 0.72 times as much as water, or it is 72 percent of the weight of water. Most gasolines weigh about 6.2 pounds per US gallon (0.72 kg per liter).
A more appropriate term is Relative density

Specific heat

In physics, the number of calories required to raise the temperature of 1 gram of a substance 1°C or the number of BTUs per pound per degree F. In air conditioners, the quantity of heat required to change the temperature of one pound of a substance by 1°F.
Ratio of quantity of heat required to raise temperature of a body 1 degree to that required to raise temperature of equal mass of water 1 degree.

Specific heat capacity: (SHC) The quantity of heat which unit of mass of a substance requires to raise its temperature by one degree.

Specific power: (kW/kg). A measure of the energy generating or storage potential of a system per unit of weight.

Specific speed: An index which provides information on the general profile or shape of the impeller of a pump. The specific speed is the speed in revolutions per minute at which an impeller would run if reduced in size to deliver one gallon per minute against a total head of one foot; impellers for high heads usually have low specific speeds and impellers for low heads usually have high specific speeds

Specific volume: Volume per unit mass of a substance.

Specs: Abbreviation for Specifications.

Spec series: A general describing several of the racing series where the rules for the series specify a certain chassis, or engine that the racers are required to use. Thus, the reference to spec. Examples of a spec series is the Formula Atlantic series, where all the cars must use the Toyota engine.

Spec. Sheet: Specification Sheet. Detailed information of a product including, tests, color, odor, specific gravity, bacterial strains, size, shape, texture, other major ingredients, etc.

Spectacle frame: A large casting extending outboard from the main hull for supporting for the ends of the propeller shafts in a multi-screw ship

Spectrometer: See
Beta-ray Spectrometer

Spectrum: See
Band Spectrum
Solar Spectrum

Specular finish: A mirror-like finish of high reflectivity

Specular gloss: A mirror-like finish of high reflectivity

Specular reflectors: Specular reflectors have mirrorlike characteristics. The most common materials used for ballasts, the devices that turn on and operate Fluorescent tubes, are aluminum and silver. Silver has the highest reflectivity; aluminum has the lowest cost. The materials and shape of the reflector are designed to reduce absorption of light within the fixture while delivering light in the desired angular pattern. Adding (or retrofitting) specular reflectors to an existing light fixture is frequently implemented as a conservation measure.

Speech synthesizer: An electronic device which simulates speech to warn the driver of something wrong (such as an unclosed door).
Also see
Voice alert system

Speed

The average rate at which an object is traveling. Measured as a relationship of distance per time -- e.g., meters per second (m/s), kilometers per hour (kph or km/h), feet per second (ft/sec.), miles per hour (mph), or revolutions per minute (rpm).
The number of gears in a Transmission.

Also See
Basic Speed
Cornering speed
Cranking speed
Critical speed
Cruising speed
Cut-in speed
Engine speed limiter
Engine speed sensor
Engine speed
Five-speed transmission
Four-speed
Four-speed transmission
Four speed
Geared Speed
High speed direct injection
Idle speed
Idle speed adjustment
Idle speed screw
Idle speed stabilizer
Initial Stopping Speed
Low Speed
Low speed traction control
Motor Speed
Output speed
Piston speed
Road speed
Specific speed
Stall speed
Straight-line speed
Synchronous Speed
Three-speed
Three-speed transmission
Top end speed
Top speed
Two-speed

Speedability: The top speed a vehicle can attain as determined by engine power, engine governed speed, gross weight, driveline efficiency, air resistance, grade of road, and load.

Speed Actuator: See
Idle Speed Actuator

Speed adjustment: See
Idle speed adjustment

Speed brace: A drive handle in the shape of a crank; appropriate for fast operation but not having sufficient leverage for large nuts and bolts

Speed category: See
Speed rating

Speed circuit: See
Idle circuit

Speed control: Another name for Cruise control.
Also see
Idle Speed Control

Speed Control Motor: See
Idle Speed Control Motor

Speed control vacuum advance: A system which cuts off vacuum ignition advance when a car is cruising at low speeds, typically under 35 mph; for this purpose, a solenoid-operated valve is hooked into the distributor advance vacuum line, which is governed by a speed-dependent signal from a switch mounted on the transmission

Speed direct: See
High speed direct injection

Speed direct injection: See
High speed direct injection

Speed Drives: See
Adjustable Speed Drives

Speeder: A drive handle in the shape of a crank; appropriate for fast operation but not having sufficient leverage for large nuts and bolts

Speed limit: The maximum Speed that the law allows on a particular road. A speed limit is set for various factors such as school and playground zones; safety in negotiating curves and off ramps; national limits; fuel conservation; divided highways vs two-way traffic; construction zones; and city ordinances.

Speed limiter: See
Engine speed limiter

Speed nut

A self-locking device used especially to secure sheet metal screws; consists of a small steel plate with a hole and two arched prongs that engage with the screw thread; used extensively to attach plastic parts to a steel car body
Spring-steel clips used to hold floating drums and rotors in place during vehicle assembly.

Speedo: Abbreviation for Speedometer.

Speedo cable: See
Speedometer cable.

Speedometer: Instrument usually found on the Dashboard which is used to determine forward Speed of a vehicle in kilometers per hour or miles per hour.
Also See
Analog speedometer
Digital speedometer
HUD

Speedometer cable: A long specially constructed wire inside a Housing. The one end of the speedometer cable is inserted into the back of the Speedometer head and the other end is usually attached to the Transmission. When the speedometer Needle moves erratically or the cable makes noise, the cable needs to be lubricated with specially formulated Compound. Oil will cause it to stick.

Speedometer drive cable: See
Speedometer cable

Speedometer head: The instrument cluster which displays the road speed.

Speed rating

The maximum driving speed for which a tire is designed, indicated by a letter in the tire designation on the sidewall. The speed rating evolved gradually and is thus not directly proportional to the alphabetical order.

P = up to 150 kph (95 mph)
Q = up to 160 kph (100 mph)
R = up to 170 kph (105 mph)
S = up to 180 kph (113 mph)
T = up to 190 kph (118 mph)
U = up to 200 kph (125 mph)
H = up to 210 kph (130 mph) also called high speed thus the "H"
V = over 210 kph (over 130 mph) also called very high speed thus the "V"

Speed ratio: The ratio of the speed of the driving member of a mechanical drive to the speed of the driven member

Speed screw: See
Idle speed screw.

Speed-sensitive steering: A type of power-assisted steering which is light at low speeds and increasingly heavier at higher speeds, giving the driver more feel

Speed-sensitive wiper system: A system which increases blade pressure on the windshield as the car increases speed

Speed sensor: A device that measures the speed of a wheel or drive axle and sends the information in the form of a analog voltage signal to the ECU.
Also See
Engine speed sensor
Vehicle Speed Sensor
Wheel speed sensor

Speed stabilizer: See
Idle speed stabilizer

Speedster: A fast, sporty car model

Speed symbol: See
Speed rating

Speed-time Curve: See
Quadrilateral Speed-time Curve

Speed traction: See
Low speed traction control

Speed traction control: See
Low speed traction control

Speedway: Specialized sport run on short, oval dirt tracks with four riders from two teams in each race.

Spelter: Impure zinc containing about three percent lead and other impurities

Spent gas: The gases burnt during the previous firing cycle that remain in the combustion chamber of a two-stroke engine after the charge changing process has been completed and the ports have been closed by the piston. An excessive proportion of spent gas in the cylinder weakens the mixture available for combustion

Spherulitic graphite cast-iron: Cast iron in which the graphite formed during solidification is induced to form as insolated spheroidal particles rather than flakes.

SPFI: Acronym for single point fuel injection

Sphere: See
Glass sphere
Suspension sphere

Spherical combustion chamber: The combustion chamber of an internal combustion engine equipped with reciprocating pistons is ideally very compact in design, i.e., without gaps, grooves, edges, etc.; the most favorable design would thus be a sphere but the valves of a four-stroke engine make this impossible. The combustion chamber in diesel engines, however, is located in the piston crown, where it is in fact spherical

SPI

Acronym for Single point injection
Acronym for Serial Peripheral Interface

Spicer: A gearbox splitter which provides a second range of gears

Spider

Spider

On a Bicycle, the multi-armed piece to which the Chainwheels are bolted, usually welded to or part of the right Crankarm.
A four arm piece on a Constant velocity joint.
A central crosspiece linking the two yokes of a universal joint.
A cross-shaped wheel wrench with a different-sized box socket head on each of the four legs.
A Wheel spider
A type of sport vehicle. In the early 1900s it meant a light two-seater car. In the 1950s the word was revived by some Italian manufacturers for an open two seater Sports car. Also spelled spyder.

Also See
Alfa-Romeo
Planet spider
Wheel spider

Spider: Click image for books on
Spider

A model of automobile from Alfa-Romeo

Spider filter wrench: Spider wrench

Adjustable filter wrench that has two clamping legs driven by a gear mechanism for maximum range and gripping ability.

Spider gear: A small gear (usually in a set of two to four gears) mounted on a shaft pinned to the Differential case. They mesh with the Bevel gear on the ends of the axles and drive them.
Also see
Pinion gear.

Spigot: A short, cylindrical projection on one part designed to fit into a hole in another part, for location or retaining purposes (as for road wheels)

Spigot bearing: A British term for Pilot bearing. A small bearing in the center of the flywheel end of the crankshaft, which carries the forward end of the clutch shaft

Spigot mounting: Unlike stud-mounted wheels, spigot-mounted wheels incorporate a center hole in the wheel disc which is machined to provide a close-tolerance fit on the hub spigot for location

Spillover point: The location of the main circuit discharge in the venturi, which is always higher than the fuel level in the bowl so fuel won't run into the venturi when it shouldn't. When the spillover begins is determined by the size of the venturi and by the displacement of the engine pulling air through the carburetor. Also called Pullover point

Spin: To shape sheet metal by forcing it against a form as it revolves.
See
Bearing Spin
Wheel spin

Spindle

The machined shaft upon which the inside Races of the front wheel bearings rest. The spindle is an integral part of the Steering knuckle.
Another term for an axle, such as a pedal axle or a Bottom bracket axle.
That part of the front suspension system about which a front wheel rotates.
A shaft or pin about which another part rotates

Also See
Bottom Bracket Spindle
Steering spindle
Throttle spindle
Wheel Spindle

Spindle cap: A small metal cap on the front wheel bearing

Spine-back: See
Backbone frame

Spine frame: A frame with a single main structural member from which the engine is suspended

Spin galvanizing: A hot dip galvanizing process for small objects. The objects are immersed into the molten zinc in a perforated basket which, once the coating forms, is centrifuged at high speed so that the spinning action throws off the surplus zinc and ensures a clean profile

Spin imbalance: See
Radial runout

Spinner: A knock-off/on nut for central-locking wheels. Originally developed by the British company Rudge-Whitworth to enable racing car wheels to be changed quickly by knocking the nut on and off with a soft-headed hammer; the wheel is positioned by matching tapered faces within the wheel center and on its hub, the splines enabling driving or braking forces to be transmitted from hub to wheel; the spinner is a self-tightening nut with a left-hand thread for RH-side wheels and a right-hand thread for LH-side wheels; modern cars use large hexagon nuts.

Also See
Amputee spinner
Nut spinner
Palm spinner

Spinner handle: A screwdriver-type handle for use with sockets, used to quickly tighten and loosen fasteners

Spinner knob: Spinner knob

A device which is attached to a steering wheel to allow disabled people to steer a vehicle by the use of the knob.

Spinout: A race car that spins around due to being tapped, racing too close to another car, or clipping another while attempting a pass.

Spin regulation: See
Anti-spin regulation

Spin Sensors: See
Wheel Spin Sensors

Spiral: See
Bismuth Spiral

Spiral bevel gear: A Ring and pinion setup widely used in automobile Differentials. The teeth of both the ring and the Pinion are tapered and are cut on a spiral so that they are at an angle to the center line of the pinion shaft.
Also see
Bevel gear.

Spiral casing: See
Volute casing

Spiral-type glow plug: A glow plug having an exposed coil with a high number of turns

Spiral wrapped pin: A tube-like pin that is made by rolling a sheet of metal tightly together. Used as a Shear pin.

Spirit: Click image for books on
Spirit

An automobile manufactured by AMC
See
Aviation Spirit
White Spirit

Spirit level: A tool for testing if a surface is level (or vertical) using a glass tube containing an air bubble

Spirits: See
Methylated spirits

SPIS: Acronym for Safety Priority Index System

Spkrs: Abbreviation for speakers, as in dual rear spkrs.

SPL: Acronym for Smoke Puff Limiter

Splash: Ford Ranger's term for a Stepside truck.
Also See
Oil-combination splash and pressure system
Oil-splash system
Salt water splash
Splash shield

Splash and pressure: See
Oil-combination splash and pressure system

Splash and pressure system: See
Oil-combination splash and pressure system

Splash apron: See
Fender splash apron

Splashed graphics: A custom paintwork resembling paint drops and splashes on the body which look as if a can of paint had been spilled over the car; also available as stickers

Splash guard: See
Splash shield
Mud flap

Splash lubrication: Oil from the crankshaft journals, under pressure from the oil pump, is splashed onto the cylinder bores and piston pins to provide lubrication

Splash panel: A vertical closing panel mounted inside the wheel arch ahead of the rear edge of the front fender and/or hinge area to protect these areas from splash water and road dirt

Splash shield: A removable device found on Disc brakes to keep water, snow, and dirt from fouling the brakes. It also sends cool air to the inner side of the disc to help in heat dissipation.

Splash system: See
Oiling Splash System

Splash system, oiling: Method of lubricating moving parts by agitating or splashing oil in the crankcase.

Splash zone: The sections of a car body subject to extreme corrosion loads due to water splash

Splayed crankpins: The slight spreading apart of a crankpin in a V-type engine so that each rod has its own crankpin; this reduces vibration in some V-6 engines that have a 90° angle between the banks

Splayed spring: A design in which the leaf springs are placed at other than an 90° to the axle

Spline

A thin, narrow strip of metal
In order to secure one object on a shaft, longitudinal Grooves or splines are cut all around the shaft with matching grooves in the object. In this way the object slides on the shaft for installation so that both the object and the shaft rotate together.
Raised portions of a shaft which fit into corresponding grooves in a pulley or some sliding member. They can either permit end movement or can be used as permanent fastening.

Splined bottom bracket: Shimano's uniquely oversized, splined Bottom bracket spindle that is compatible only with newer style Shimano cranksets.

Splined hub: The hub of a driven plate in a clutch which is splined so that it can move along the gearbox input shaft

Splined joint: A Joint between two parts in which each part has a series of Splines cut along the contact area. The splines on each part slide into the grooves between the splines on the other part.

Splined shaft: A shaft having multiple grooves, or Keyseats, cut around its circumference.

Spline joint: Two mating parts that have a series of splines around their circumferences, one inner and one outer, to provide a longitudinally movable joint without any circumferential motion

Spline Nut: A nut having external splines or ribs which hold it in place when forced into a hole of slightly smaller diameter.

Spline Socket: A recessed socket in the head of a bolt or screw to develop greater torque or driving ease without rounding the recess.

Split: See
Asymmetrical power distribution
Diagonally split system
Diagonal split braking system
Equal power split
Fifty-fifty power split
Front-axle/rear-axle split
Front-axle and rear-axle split
Split rear axle housing
Torque split

Split bearing: See
Shell bearing

Split bearing attachment: See
Bearing separator

Split bench seat: A front seat arrangement in which the left side is independent from the right side. While a Bucket seat is shaped for an individual, split bench seats can still hold three people. Most are split 60/40 where the smaller portion is for the Driver. It avoids the disadvantage of the bench seat in that the Driver can position his seat differently from the passenger.

Split brake system: A service brake system having two or more separate fluid, electrical, mechanical or other circuits which upon failure in any circuit retains full or partial brake actuating capability.

Split braking: See
Diagonal split braking system

Split braking system: See
Diagonal split braking system

Split collar: See
Collet

Split crankcase: A crankcase of an engine which is divided horizontally near the center of the crankcase.

Split electrode spark plug: A spark plug with a V-shaped side electrode

Split folding rear seats: Rear seats which may be folded down in two sections, thus combining some extra luggage space with the possibility of a passenger sitting in the back of the car

Split-friction road surfaces: Differing road surfaces (such as ice and tarmac) offering differing tire adhesion

Split hydraulic brake system: Service brake system with two separate hydraulic circuits to provide braking action in one circuit if other one fails

Split Lens: See
Billet Split Lens

Split-lit-type rear main seal bearing: A two-piece neoprene seal; easier to install and has less friction than a rope-type main seal

Split loom: Flexible, corrugated conduit used to bundle wires into a harness

Split manifold: An Exhaust manifold that has a longitudinal Baffle placed near its center. An Exhaust pipe leads out of each half.

Split-phase motor: Motor with two stator windings. Both windings are in use while starting. One is disconnected by centrifugal switch after motor attains speed. Motor then operates on other winding only.

Split pin: A metal pin for securing a nut or rod, whose ends are bent backwards after insertion.
Also see
Cotter pin

Split point: The pressure at which a brake proportioning valve begins to limit hydraulic pressure to the rear brakes.

Split propshaft: See
Divided propshaft

Split rear axle housing: A rear axle housing made up of several pieces and bolted together. The housing must be split apart to remove the Differential. Compare Banjo rear axle housing

Split rear seats: Rear seats which may be folded down in two sections, thus combining some extra luggage space with the possibility of a passenger sitting in the back of the car

Split rim: A rim which is made of two or three pieces and uses a demountable flange.

Split ring lock washer: Split ring lock washer

A coiled, hardened, split circular washer with a slightly trapezoidal wire section.

Split Rivet: A small rivet having a split end for securing by spreading the ends.

Split screen: A divided windshield on the original Morris Minor

Split single: A two-stroke engine with two pistons that share a single combustion chamber

Split skirt: Split skirt

The piston skirt is manufactured to be either partially or completely split. When the piston warms and begins to expand, the split closes instead of binding in the cylinder.

Split skirt piston: A precursor of the modern solid piston skirt, with a narrow slot in one side of the piston to allow for expansion

Split spray: An incorrect setup of a spray gun, giving a spray pattern that is heavy at the top and bottom but narrow in the middle

Split system: Refrigeration or air conditioning installation which places the condensing unit outside or away from the evaporator. Also applicable to heat pump installations.

Also See
Diagonally split system
Triangle split system

Split-system master cylinder: See
Tandem master cylinder

Splitter: See
Beam Splitter
Nut splitter

Splitting: See
Ball joint separator
Lane Splitting

Splitting chisel: An extremely flat chisel used for body work and panel beating

Splitting lanes: The action of straddling the center line between two lanes of traffic so that following vehicles cannot pass on either side. This is a discourteous procedure unless it is the action of a police officer to slow down traffic because of an accident some distance ahead.

Splitting the cases: Taking the motorcycle transmission cases apart to repair the motor.

Splitting tool: See
Ball joint separator

Split type: See
Split rear axle housing

Split washer: See
Spring lock washer

Split-window Beetle: The original VW Beetle with a two-part rear window split vertically; produced up to 1953

Spoiler: An aerodynamic wing-shaped device attached to a vehicle (usually under the front Bumper or on the decklid) to either reduce Drag or induce Downforce on the vehicle. So called because it spoils the normal flow of air over or under the vehicle.
Also See
Boot spoiler
Ear
Front spoiler
Rear spoiler
Roof spoiler
Trunk spoiler
Whale tail

Spoke

One of several wires used to hold the Hub in the center of a wheel rim and to transfer the load from the perimeter of the wheel to the hub and on to the Frame.
Generally stainless steel, the spokes connect the hub to the rim on a wheel and provide structure. Most wheels have the spokes pass through holes in the hubs and then thread into spoke nipples seated in the rim. Tightening the spoke nipples creates tension in the wheel to maintain structural integrity and keep the wheel true.

Also see
Wire spoke

Spoke assembly: See
Cast spoke assembly

Spokes: See
Spoke.

Spoke steel type: See
Motor wheel type.

Spoke wheel: A styled, cast or forged alloy wheel with a wheel spider which incorporates a spoke design. Spoke wheels can be distinguished according to the respective number of spokes; many alloy spoke-type wheels, however, have a wheel spider with 28, 30, 32, or 34 spokes which are arranged in different angles and in a criss-cross pattern these are referred to as cross-spoke wheels.

Also See
Cast spoke wheel
Cross-spoke wheel
Wire spoke wheel

Spoke wrench: A tool for securing or removing Spokes by turning the Nipple.

Sponge: See
Car sponge

Sponge rubber valve: A sponge-rubber-lined valve plate attached to a bimetallic strip, which controls the air intake temperature to the carburetor in some BL cars. The bimetallic strip moves the plate up or down according to temperature, in its extreme positions, the sponge rubber seals either the cold air intake or the hot air intake

Spongy brake pedal: Air in hydraulic lines, distortion or stretching of connecting parts, or swelling of hydraulic hose may allow pedal to be spongy or springy instead of solid.
Also see
Spongy pedal

Spongy lead: Pure lead which serves as the active material in the charged negative plates of a battery.
Also see
Lead peroxide

Spongy pedal: When there is air in the Brake lines, or shoes that are not properly centered in the Brake drums, the Brake pedal will have a springy or spongy feeling when the brakes are applied. The pedal should normally feel hard when applied.

Also See
Soft pedal

Spool: See
Valve spool

Spool balance valve: A Hydraulic valve in Automatic transmissions that balances incoming oil pressure against spring control pressure to produce a steady pressure to some control unit.

Spool valve: A Hydraulic control value shaped somewhat like a spool upon which thread is wound.

Spoon

A tire-iron tool used to remove a tire (especially a bicycle or motorcycle tire) from its rim. Usually two or three spoons are necessary to do the job. Using a flat blade screwdriver instead of a spoon may puncture the tube.
A tool used to turn star wheel adjusters and thus to adjust the brake lining-to-drum clearance.

Also See
Body spoon
High crown spoon
Inside pry spoon
Spring beating spoon
Surface spoon
Surfacing Spoon

Sport: Originally meant something that was different from the normal. Thus a sports car was a vehicle that was different from a general transportation car. Sports as a game (i.e., hockey, baseball, etc.) is an activity that is different from the normal routine of work.
Also see
Dual Sport

S-port: A special carburetor port for ported vacuum

Sport and Imperial phaeton: Similar to the phaeton, but with extra equipment or refinements, such as wire wheels, Trunk rack, and ultra-modish paint treatments and Finish. The Imperial type indicates a Tonneau or second Windshield in front of the rear seat passengers.

Sportbike

A motorcycle type which originally began as a Cafe racer. The rider is bent forward for better flow of the air (as opposed to the upright position of a touring bike). Also called a crotch rocket because of the strain it places on the rider's crotch and because of its very fast speed.
A motorcycle designed for optimal speed and handling characteristics, often with extensive bodywork.

Sport coupe: In other respects similar to the Coupe, it has a Rumble seat in the rear deck and a small compartment for storage of golf clubs.

Sport roadster: In addition to being a roadster, it has provision for a Rumble seat in the rear deck, along with a golf locker for storage.

Sports car: Term commonly used to describe a relative small, low slung car with a high performance engine and excellent handling. Originally, sports cars were faster than sedans; today, many sedans can easily outperform sports cars in terms of top speed as well as acceleration

Sports racer: A two-seat race car with enclosed wheels.

Sportside: Dodge's term for a stepside truck

Sportster: See
Sports car

Sports tourer: A Bicycle whose structure, geometry, and Components are designed to make it a compromise between one suitable for racing and one suitable for loaded touring -- good for general pleasure riding.

Sport tourer: A motorcycle that combines the comfort and carrying capacity of a touring bike with the handling and power of a sportbike with larger fairings and hard, lockable luggage.

Sport utility vehicle: A vehicle built on a truck chassis but is configured much like a station wagon. Some examples are Blazer, Jimmy, Bronco, Explorer, Ram, and Cherokee

Sporty driving style: A manner of handling a vehicle in which the driver turns corners fast, brakes and accelerates hard, uses high revs in every gear, and shifts down before corners.

Spot: A small disc attached to a brake actuating lever.
Also See
Blind spot
Cathode Spot
Flat spot
Front-end Blind Spot
Hard Spots
High spot
Hot spot
Low spot
Spot magnetic electric brake

Spot efficiency: See
Atmospheric dust spot efficiency

Spot-Face: To finish a round spot on a rough surface, usually around a drilled hole, to give a good seat to a screw or bolthead; cut usually 1.5mm deep.

Spot faced: On a connecting rod, a bolt head seating surface that is machined so it describes a radius on the inboard-side of the bolt head as viewed from the top of the bolt head

Spot glazing: Filling minor imperfections (sand scratches).

Spot lamp: See
Spotlight

Spotlight: An auxiliary light used to shine a narrow beam of light.

Spot magnetic electric brake: An electric brake design in which the electromagnet is a small disc (spot) attached to an actuating lever.

Spot Paving: A paving treatment that provides large asphalt patches for bad areas. It is a maintenance tactic used for aging pavement to hold it over until a major improvement can be undertaken. When the treatment is complete, there will be scattered spots along the roadway where new asphalt has been applied. The work is sometimes followed with a surface treatment.

Spotting: See
Water spotting.

Spotting in: The paint respraying of very small areas

Spot weld: Fastening parts together by fusing, at various spots. Heavy surge of electricity is passed through the parts held in firm contact by Electrodes.

Spot welding: A type of resistance welding in which two pieces of metal are joined at a series of points (spots) by means of heat (usually electrically generated) and pressure; the most important welding method in auto body construction

Spot-weld drill: See
Spot-weld remover

Spot-welded flange: A sheet metal strip forming a flange at the edge of panels joined by Spot welding

Spot-weld remover

A special drill bit used to drill out weld spots on sheet metal material without damaging the panels.
A tool for use with a hand drill; features reversible cutting blade to cut out weld spots without damaging the sheet metal material; the cut depth can be varied, e.g., to release the upper panel only

Spout: See
Tailpipe

SPOUT: Acronym for Spark Output Signal

Sprag brake: A sprag is a stick (of wood or metal) which is inserted into gears or even into the dirt to stop the motion of something.

Sprag clutch: A Clutch that will allow rotation in one direction but that will lock up and prevent any movement in the other direction.

Spray: See
Dry-spray
Gravity-feed spray gun
Plasma spray process
Pressure-feed spray gun
Split spray

Spray arc: Gas metal arc process which has an arc voltage high enough to continuously transfer the electrode metal across the arc in small globules.

Spray bell: A dome-shaped, rotating paint spray element

Spray booth: A closed section in a painting line in which paint is sprayed on workpieces or body shells

Spray chamber: See
Salt spray chamber

Spray coating: An application method for chemical conversion coatings

Spray cooling: Method of refrigerating by spraying expendable refrigerant or by spraying refrigerated water.

Spray flap: See
Mud flap

Spray gun: An apparatus shaped like a pistol which delivers an atomized mist of liquid.

Also See
Airless spray gun
Compressed-air spray gun
Gravity-feed spray gun
Pressure-feed spray gun
Suction-feed spray gun

Spray gun nozzle cleaning unit: A special cleaning unit for paint shops which holds several spray guns in such a position that the nozzle is soaked in thinners

Spraying: See
Airless spraying
Air Volume Spraying
Cold spraying
Electrostatic spraying
Hot spraying
Metal spraying
Robot spraying
Zinc spraying

Spraying booth: A closed section in a painting line in which paint is sprayed on workpieces or body shells

Spraying viscosity: The viscosity required to make paint suitable for spraying, i.e., neither too thick nor too thin

Spray mist: A fogging caused in the course of spray painting; part of this settles as overspray on adjacent panels and nearby objects.

Also See
Overspray
Mask

Spray pattern: The shape of the jet of spray leaving a spray gun

Spray process: See
Plasma spray process

Spray testing: See
Salt spray testing

Spread: See
Bearing spread
Overall gear ratio

Spread axle

A trailer axle, usually 6 to 9 feet ahead of another axle and located near the center of the trailer.
A tandem axle assembly spaced farther apart than the standard spacing of 54 inches. The U.S. federal bridge formula favors trailer axles with an eight or nine foot spread by allowing higher weight than on tandems with standard spacing. Also called spread tandem

Spreader

A hand-held tool used to apply body filler to a damaged area prepared for filling.
A hydraulic jack with ends designed to reach behind dented double panels and to press them back into shape by the hydraulic action of the wedge-shaped ends.
A device attached to the back of a dump truck to evenly distribute sand or sand/salt mixture on icy roads.

Also See
Anti-rattle spring
Tire Spreader
Zero-velocity spreader

Spreader spring: A cross-shaped part made of spring steel sheet which applies radial pressure to the brake pads to prevent rattling.
Also see
Anti-rattle spring

Spread Tandem: A two-axle assembly with the axles spaced to allow maximum axle loads permitted by existing regulations. Distance between centers of axles of a spread tandem has generally been over 50 inches.
Also see
Spread Axle

Spring: Spring

Three types of springs are used on vehicles for various purposes: Compression spring, Leaf spring, and Extension spring

Also See
Advance Spring
Air bellows
Air spring
Anti-rattle spring
Bending Spring
Brake shoe return spring
Brush spring
Buffer Spring
Cantilever spring
Cart spring
Clutch diaphragm spring
Clutch spring
Coil spring
Contact spring
Damper springs
Detent ball and spring
Diaphragm spring clutch
Diaphragm spring
Door hold-open spring
Extension Spring
Flat spring
Float Bumper Spring
Garter spring
Gas spring
Hairpin valve spring
Helical spring lock washer
Helper spring
Inside spring caliper
Leaf Spring
Locating spring
Longitudinal leaf spring
Meshing spring
Multileaf spring
Negative Spring
Outside spring caliper
Overload spring
Over-travel Spring
Parabolic spring
Piston spring
Progressive rate spring
Progressive valve spring
Progressively wound valve spring
Quarter-elliptic leaf spring
Retainer spring tool
Retaining Spring
Retracting Spring
Return Spring
Rubber spring
Shoe Return Spring
Single-leaf spring
Single rate spring
Splayed Spring
Spreader spring
Suspension spring
Tensioning spring
Throttle return spring
Torsion bar
Transverse leaf spring
Valve spring
Variable rate springs
Variable spring
Zigzag Spring

Spring and damper settings: Suspension settings for springs and or struts. Stiffer settings provide better handling with a bumpier ride. Softer settings give a smoother ride but compromise performance.

Spring And Retainer: See
Hold-down Pin Spring And Retainer

Spring balance: An instrument for measuring weight or force which does so by the elasticity of a spiral spring.

Spring bar: In a 5-bar convertible roof mechanism, it is an additional bar between the main bar and the rear window; spring loaded, it assists the main bar in shaping the roof; a similar effect can be achieved by spring-steel leaves embedded in the canvas

Spring beating: A metalworking process for removing pressure ridges in body panels in which a Spring beating spoon is laid on the ridge area and is gradually moved across the ridge while the spoon surface is hammered with a body hammer

Spring beating spoon: A light pressed-steel blade designed specially for beating on ridges; the spoon is placed directly on the ridge and sharp blows with a hammer are delivered to the back of the spoon, spreading the force over a large area

Spring-biased: See
Spring loaded

Spring booster: A device used to beef up sagging springs or to increase the Load capacity of standard springs.

Spring bow: In a 5-bar convertible roof mechanism, it is an additional bar between the main bar and the rear window; spring loaded, it assists the main bar in shaping the roof; a similar effect can be achieved by spring-steel leaves embedded in the canvas

Spring bracket: See
Spring hanger

Spring brake: Emergency or auxiliary brake system utilizing a spring load as a force for braking. May be automatically actuated by low air pressure or mechanically controlled for use as a parking brake.

Spring caliper: See
Inside spring caliper
Outside spring caliper

Spring cap: See
Valve spring cap

Spring choke: See
Thermostatic spring choke

Spring clip

A fastening device made of an incomplete circle of spring steel, e.g., for covers.
A rebound clip which holds the spring leaves of a leaf spring together and to keep them in alignment.
A fastener used to provide a screw hole for a sheet metal screw; certain variants of this fastener may be moved slightly at their mounting to provide a certain degree of adjustment.

Also see
Speed nut

Spring clutch: See
Coil spring clutch
Diaphragm spring clutch

Spring collar: See
Valve spring collar

Spring compressor: A tool used to restrain coil springs for safe removal and installation. They are available in a variety of shapes, as manual or hydraulic designs; the most common type consists of two steel jaws running on a threaded screw which securely hook into the coil spring; turning a nut reduces the distance between the jaws and compresses the spring. This type of spring compressor is always used in pairs, e.g., to remove MacPherson strut springs.

Also See
Valve spring compressor

Spring depressor: See
Valve spring depressor

Spring divider: A divider with a spring for accurate setting

Springer fork: A motorcycle suspension system that uses large, exposed springs to dampen the impact of road irregularities.

Spring eye: Spring eye

A cylindrical hole formed by bending the end of a leaf spring around, for attachment to the vehicle

Spring hanger: A rubber-bushing bracket on a vehicle chassis on which a leaf Spring eye is mounted.

Also See
Shackle

Springing: A term for Suspension.

Also See
Air suspension

Spring lifter: See
Valve spring lifter

Spring loaded: A device held in place, or under pressure from a spring or springs. Also called Spring biased

Spring lock: See
Helical spring lock washer

Spring lock washer

A toothed, spring steel washer used as a locking device.
A hardened coil wire having a slightly trapezoidal section after forming which functions as a spring take-up device to compensate for developed looseness and the loss of tension between the parts of an assembly and to prevent the nut from turning.

Also see
Helical spring lock washer

Spring mounting: See
Spring hanger

Spring rate: Rate of deflection versus amount of load applied. In other words, how much force is needed to bend a spring a given distance.

Spring seat: Support on which the spring is anchored.
Also see
Valve spring seat

Spring shackle: See
Shackle

Spring steel: A heat treated steel having the ability to stand a great amount of deflection and yet return to its original shape or position.

Spring tool: See
Retainer spring tool

Spring type brake actuator: A unit that uss the stored energy in a spring to actuate the brake.

Spring washer: A warped-looking washer, typically used to prevent rattling by spring-loading certain movable threaded connections

Spring windup: The curved shape assumed by the rear Leaf springs during hard Acceleration or braking.

Sprint: See
Alfa-Romeo.

Sprocket: A Disc with teeth on its circumference for driving a Chain, a general term that applies both to Chainrings and to Freewheel Cogs.

Also See
Camshaft drive sprocket
Camshaft sprocket
Crankshaft sprocket
Driven sprocket
Drive sprocket
Overlay Sprocket

Sprocket wheel: See
Sprocket

Sprung mass: See
Sprung weight

Sprung weight: This refers to the weight of all the parts of the vehicle that are supported by the Suspension system. Unsprung weight includes wheels and tires, brake assemblies, the rear axle assembly and other structural members not supported by the springs. Unsprung weight can be reduced with Independent rear suspension because the Differential, and in some cases the brakes, can be attached to the body. Also called sprung mass.
Also see
Unsprung weight

SPS: Acronym for Service Programming System

Spud: See
Orifice Spud

Spur differential: A differential in front-wheel drive vehicle which uses spur gears rather than bevel gears, since input and output shafts are not at right angles.
Also see
Bevel differential

Spur gear: Spur gear

A gear on which the teeth are cut parallel to the shaft. They are used only for reverse gear in modern transmissions because they are noisier than Helical gears. However, they are cheaper to machine and require less power to turn than helical gears do. Also called Straight-cut gear.

Spurt hole: A small hole in the Connecting rod big end that indexes (aligns) with the oil hole in the crank Journal. When the holes index, oil spurts out to lubricate the Cylinder walls. Also called squirt hole

Spyder: In the early 1900s, a light two-seater car. In the 1950s the word was revived by some Italian manufacturers for an open two seater Sports car. Also spelled Spider.