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g: A unit of measurement for lateral acceleration, or "road-holding." One "g" is equivalent to 981 cm (32.2 feet) per second every second, the rate at which any object accelerates when dropped at sea level. If a car were cornering at 1.0 g -- a figure that very few production cars are able to approach -- the driver's body would be pushing equally hard against the side of the seat as against the bottom of it. 

G7: Seven industrial countries consisting of the United States, Japan, Germany, France, the United Kingdom, Italy and Canada, whose leaders have met at annual economic summits since 1975 to coordinate economic policies. 

gage: American term for "gauge." 

gal.: Abbreviation for "gallon." A US gallon (3.785 liters) is 20% smaller than an Imperial gallon (4.546 liters). 

gallery: A channel or tube usually found within the engine block for the transfer of fluid or gas. See oil gallery. 

gallon: A US gallon (3.785 liters) is 20% smaller than an Imperial gallon (4.546 liters). 

galvanometer: An instrument used to measure the pressure, amount of, and direction of an electric current. 

gap: [1] The distance between the center terminal (electrode) and the outer terminal (electrode) through which the spark must travel in a spark plug. Also see spark plug gap and air gap. [2] The distance between the points in contact breaker points. See point gap. [3] The distance between two vehicles travelling down the road as they go in the same direction. Generally a safe distance is a minimum of two seconds behind the vehicle in front. [4] The distance between the two ends of piston rings. See piston ring end gap. 

gapper: A device for determining the distance between two metal contacts. See feeler gauge. 

gapping: Adjusting the distance between the electrodes of a spark plug or the points of contact breaker points. Also see plug gapping. 

gas: [1] A non-solid material. It can be compressed. When heated, it will expand; and when cooled, it will contract. (Such as air.) [2] A common term for gasoline. [3] A term for LPG or propane. Also see bottled gas. [4] A term referring to the exhaust gases. See exhaust emissions. 

gas burner: Competition vehicle with engine set up to operate on standard pump gasoline instead of an alcohol, nitro, etc., mixture. Also called "gasser." 

gas-driven generator: a generator which turned by a gas engine. 

gas filter: A device for screening the gasoline to remove the impurities. See fuel filter. 

gas gage: See gas gauge. 

gas gauge: An instrument, usually located on the dashboard or center console, which indicates the amount of fuel in the fuel tank. Most gauges have a needle which fluctuates between "E" (empty) and "F" (full). Others show a digital readout of how many gallons or liters left in the tank. Also called "fuel gauge." 

gas metal-arc welding: Welding using a continuously fed consumable electrode and a shielding gas. Also called "sigma welding." 

gas pedal: The device actuated by the operator's foot for increasing or decreasing the amount of fuel entering the combustion chamber. Also called "throttle pedal." See accelerator. 

gas pockets: Cavities in weld metal caused by trapped gas. 

gas tank: The container for holding or storing fuel. See fuel tank. 

gas tungsten-arc welding: Welding using a tungsten electrode and a shielding gas. 

gas turbine: An internal-combustion rotating engine with one main moving part: the rotor with pinwheel-like blades attached. Air is compressed by the first rows of blades and delivered to the combustion chambers, from which the exhaust is directed to pass the remaining blades and to generate the power. Power is extremely smooth due to the absence of explosions and reciprocating parts. 

gasket: A material made of asbestos, cardboard, cork, paper, rubber, or soft metal placed between two metal parts to insure proper sealing. See base gasket, blown head gasket, and head gasket. 

gasohol: A blend of gasoline and ethanol alcohol that usually is 90% gasoline and 10% ethanol. Ethanol is the alcohol found in intoxicating beverages. It may attack rubber and plastic parts of fuel systems not designed to handle alcohol-blended fuels, but it is not poisonous to human beings like wood alcohol or methanol. 

gasoline: A hydrocarbon fuel used in the internal combustion engine. Also see ethyl gasoline, oxygenated gasolines, and reformulated gasolines. 

gasoline pump: !!! Definition under construction !!!. 

gasser: A vehicle which uses gasoline in the engine to run. See gas burner. 

gassing: The small hydrogen bubbles rising to the top of the battery electrolyte during battery charging. 

gate: [1] The slotted guide for the gearshift of an internal combustion engine. [2] The slotted guides in a shift drum. [3] A tailgate. 

GATT: Acronym for General Agreement on Tariffs and Trade. 

gauge: This is the British and Canadian spelling while in the United States it is sometimes spelled without the "u" (gage). [1] An instrument that registers the quantity of a substance, e.g., fuel gauge , ammeter, voltmeter, temperature gauge, oil gauge, oil pressure gauge, vacuum gauge. [2] A tool for measuring clearances, pressures, sizes, etc. See B & S gauge, compression gauge, dial gauge, and feeler gauge. 

gauntlet: !!! Definition under construction !!!. 

Gaylord: The 1955-57 models are milestone cars. 

GCW: Acronym for gross combination weight. 

gear: Wheel-like part with teeth cut into the rim. When one gear meshes with another gear, it causes the second gear to drive the other and in this way transmits power. When the gears are different sizes (different number of teeth on each gear) the mechanical average is changed. Also see axle end gears, bevel gear, camshaft gear, cluster gear, constant mesh gears, crankshaft gear, flywheel ring gear, helical gear, herringbone gears, high gear, hypoid gear, idler gear, intermediate gear, low gear, passing gear, planet gears, reverse idler gear, ring gear, sliding gear, spider gear, spiral bevel gear, spur gear, steering gear, straight-cut gear, sun gear, timing gear, wide-step gearing, and worm gear. 

gearbox: The device in the drivetrain consisting of an input shaft, a system of gears, and an output shaft that multiplies engine torque. A manual transmission consists of a clutch assembly plus a gearbox; and automatic transmission generally consists of a torque converter plus gearbox. Also see constant mesh gearbox, planetary gearset, and rack and pinion gearbox. 

gear grease: A heavy liquid grease that fills the differential and manual transmission to lubricate the gears. Also called "differential grease." 

gear indicator: A display which shows the particular transmission gear that has been selected. 

gear lever: A device which is attached to the side of a steering column or to the center console which will allow the operator to change the gears of the transmission. Also see left hand gear lever. 

gear oil: A heavy oil which is rated at 80 to 100 weight viscosity used in enclosed units containing gears. This oil infrequently or rarely needs changing. 

gear pump: !!! Definition under construction !!!. 

gear ratio: The relationship between the number of turns made by a driving gear to complete one full turn of the driven gear. If the driving gear turns four times to turn the driven gear once, the gear ratio would be 4 to 1. In most instances, the gear ratio is not even like 4:1 because the same teeth would be meshing with each other. Thus a ratio of 4.11:1, for instance, means that a particular tooth on one gear may eventually mesh with every one of the teeth on the other gear. Changing the tire size will change the effective gear ratio. 

gearing: The ratio between the drive gear and the driven gear. See alpine gearing and half-step gearing. 

gear selector: The device for choosing the desired transmission gear. See gearshift. 

gearset: A group of two or more gears used to transmit power. 

gearshift: A device which allows the operator to move the transmission gears into various configurations. Most often the gearshift is located on a lever on the steering column or on a lever on the floor between the driver and front passenger. Some older Chryslers had pushbutton controls on the dash. 

gearshifter: A device which allows the operator to move the transmission gears into various configurations. Most often the gearshift is located on a lever on the steering column or on a lever on the floor between the driver and front passenger. Some older Chryslers had pushbutton controls on the dash. 

gel coat: A thin layer of plastic resin covering fiberglass panels. 

general Agreement on Tariffs and Trade: (GATT) Signed in 1947, the GATT was a formal multilateral agreement aimed at expanding and liberalizing world trade. The World Trade Organization which is the successor to the GATT came into existence on January 1, 1995. 

generalized Preferential Tariff: (GPT) system of non-reciprocal tariff preferences for the benefit of developing countries. It grants duty-free or preferential entry to imports for eligible developing countries up to a certain dollar value or import percentage limit. 

generator: [1] A mechanism which generates or produces some substance, i.e., electric generator, acetylene generator. [2] An electromagnetic device for producing direct current electricity. It was replaced by an alternator in the early '60s. Its problem was that it recharged the battery only at high speeds. Also called a "dynamo." Also see alternator and third brush. 

GHGs: Acronym for "Greenhouse Gases." 

gib head key: See gib-head key. 

gib-head key: A special bar of any length like a flat key or square key, but one end is specially shaped to prevent the key from going all the way through. 

girl's bike: A bicycle where the horizontal top bar (of a "boy's bike") is angled down from the steering tube down to the bottom bracket and is usually parallel with the down tube. See ladies' frame. 

Giuletta: See Alfa Romeo. 

Giulia: See Alfa Romeo. 

GL: A term referring to gold line tires marketed in the late '60s and early '70s. 

glad hands: A separable mechanical connector used to join air line hoses when combination vehicles are coupled together. 

glass pack muffler: A straight through (no baffles) muffler using fibreglass packing around a perforated pipe to deaden exhaust sound. 

glaze: A highly smooth, glossy finish on the cylinder walls. As the piston rings rub up and down the cylinder, the rings polish the cylinder wall. Cylinder wall glazing reduces sealing efficiency. The only cure is to have the cylinder deglazed. 

glaze breaker: An abrasive tool used to remove the glaze from cylinder walls prior to the installation of new piston rings. Also called "deglazer." 

glazing: Use of special putty to fill minor imperfections when doing body repair. Also see spot glazing. 

g-loads: !!! Definition under construction !!!. 

global Positioning Satellite: !!! Definition under construction !!!. 

gloss: The ability of a paint to reflect images when polished. 

glove: See barrier cream 

glovebox: !!! Definition under construction !!!. 

glow plug: An electrical element located in the combustion chamber of a diesel engine which helps to heat up the air in the chamber so that the diesel will be ignited more quickly. Often they are connected in series so that when one becomes defective the others are inoperative. 

glow Plugs: !!! Definition under construction !!!. 

glycol: See ethylene glycol and antifreeze. 

glycote: See poly-glycotes. 

glycotes: See poly-glycotes. 

GM: Acronym for "General Motors Corp." 

GMC: Acronym for "General Motors Corporation." 

good will warranty: Normal warranty specifies that a product is covered for manufacturer's defects for a period of time or distance of use. If the item has gone beyond the normal warranty, the dealer may offer some warranty in order to keep your business. The dealer may pick up the costs for parts and labor, or just the labor, or 50% of the overall costs, or just a nominal sum. 

gouging: Cutting of a groove in the surface of a metal using a gas cutting torch of an arc-air cutting outfit. 

governor: A device designed to automatically control the speed or position of some part. Governors are used to prevent an engine from exceeding its maximum rpms. They are also used on rental vehicles to prevent operators from speeding. 

GPM: Acronym for "gallons per minute." 

GPS: Acronym for "Global Positioning (via) Satellite." 

GPT: Acronym for "Generalized Preferential Tariff." 

Graham-Paige: Only the Custom body of 1925-1948 with required application are classic cars. 

grand Touring Prototype: (GTP). 

granny gear: Colloquial term for the tiny inner chainring on a triple chainring crankset of a bicycle. Needed for climbing steep hills especially with a loaded bicycle. 

Gran Turismo: (GT) A car which combines the features of both the sedan and sports car. It features excellent engineering and road handling with relative comfort. Made in two-seater and four-seater models with cramped rear seats. 

grand Touring: (GT) See Gran Turismo. 

gravity: The attractive force exerted by one body on another. All bodies which have mass have this property. The pull of the earth upon objects so that they fall at the rate of 981 cm (32.2 feet) per second every second. Also see center of gravity, g, and specific gravity. 

gravity, center: The force which causes a body to fall to the earth. See center of gravity. 

gray Market Vehicles: !!! Definition under construction !!!. 

grease: A lubricant which reduces the friction between moving pieces of metal and also prevents moisture from causing metal to rust. See gear grease and lube grease. 

grease fitting: A device that seals in and allows the addition of more grease, or some other type of lubricant, to cushion two moving parts, allow them to move freely, and prevent them from wearing each other away. Found on ball joints, steering knuckles, tie-rod ends. Also called "zerk fitting." 

grease gun: A small, hand-operated pump that can be loaded with grease and used for lubricating the grease fittings on a vehicle. Adapters can be attached to the grease gun so that grease can be forced even into sealed bearings. 

grease pencil: A writing device which writes in grease or wax. It is used to mark tires because it can be easily rubbed off. 

grease seal: A circular metal disk covered in rubber or plastic with a center hole, an edge on the outside circumference, and another edge on the center hole with a spring to retain tension on the shaft that fits into the hole. It is used to keep grease and oil from leaking out and protects bearings from dirt and water. Also called "oil seal." 

green flag: !!! Definition under construction !!!. 

green flag with yellow diagonal stripe: !!! Definition under construction !!!. 

greenhouse: The glass area of a car or truck. 

greenhouse gases: (GHGs) Group of gases which individually act to trap solar energy near the earth. GHGs for which emission levels have been estimated are carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), sulphur hexafluoride (SF₆), carbon tetrafluoride (CF₄), carbon hexafluoride (C₂F₆) and hydrofluorocarbons (HFCs). 

green tire: The complete rubber/fabric/steel tire just before being cured. 

grey market: the grey market describes the purchase by intermediaries of product which is not supplied to them by the "authorized" distribution channel of the supplier. Thus, a warehouse club in Canada that sells a stereo bought in the U.S. or elsewhere from other than the manufacturer is supplying grey market goods. While grey market products are frequently the same as would be available from conventional channels in Canada, the grey market assumes responsibility for service or repair where the manufacturer declines this support. 

grid: The lead screen or plate to which the battery plate active material is attached. 

grill: Alternate spelling of "Grille." 

grille: A grating or crosswork of bars usually as an ornamental cover of the radiator which allows air to cool the engine. 

grind: To remove metal from an object by means of a revolving abrasive wheel, disc, or belt. Also see valve grinding and valve seat grinding. 

grinder: A device to remove metal from an object. See brake shoe grinder. 

grip: !!! Definition under construction !!!. 

groove: A channel or gouge in metal (see piston ring groove) or in the tread of a tire. 

groove cracks: Splitting or cracking of the rubber (undertread) at the base of the grooves, between tread ribs. Primarily caused by growth in textile casings. 

groove insert: See top ring groove insert. 

grooving: The cutting of a tread design into tread rubber where a design does not already exist. Also altering an original design, i.e., cross-grooving to increase traction. 

groove weld: A welding rod fused into a joint which has the base metal removed to form a V, U, or J through at the edge of the metals to be joined. 

gross combination weight: The weight of a truck and trailer combination and its entire contents. 

gross margin: The return an intermediary achieves on the selling price of the article. That is, if the intermediary buys a product for $1 and sells it for $1.50, the margin is calculated. For example, .50 divided by $1.50, or 33%. 

gross ton: 2240 pounds. Also called "long ton." 

gross train weight: Same as gross combination weight. 

gross vehicle weight: (GVW) Maximum legal weight at which a vehicle can be operated. The total weight of a fully equipped truck and payload. 

ground: Terminal of battery that is connected to the metal framework of the vehicle so that the frame acts as a conductor of electricity. In North America, the negative terminal is grounded. In British terms, it is called "Earth." Also see cam-ground piston. 

ground and polish: To cut and polish a crankshaft bearing surface to precision specifications. 

ground effect: The phenomenon that occurs when the airflow between a moving object and the ground creates downforce. 

ground strap: A wire cable or braided wire strap to transfer electricity. It can be found between the engine block and the chassis because the engine is isolated from the chassis by rubber mounts. Also called battery strap. See ground wire. 

ground wire: The wire which goes from the negative post of the battery to the frame on negative ground vehicles. Another ground wire may be a thick wire or braided wire cable which connects the engine to the frame. Since many engines are rubber mounted, there may be no metal contact between the engine and the frame apart from the ground wire which may also be called the ground strap. In British terms, it is called "earth wire." 

group of seven: (G7) seven industrial countries consisting of the United States, Japan, Germany, France, the United Kingdom, Italy and Canada, whose leaders have met at annual economic summits since 1975 to coordinate economic policies. 

growler: An instrument used in testing starters and generator armatures. 

growth: See tire growth. 

GRRF: Acronym for "Groupe de travail en matière de Roulement et de Freinage" (i.e., Working Party on Brakes and Running Gear) 

GT: Acronym for "Gran Turismo" or "Grand Touring." 

GTO: Acronym for "Gran Turismo Omologato." 

GTP: Acronym for "Grand Touring Prototype." 

GTS: Acronym for "Global Tire Standard." 

GTW: Acronym for gross train weight. 

guarantee: A promise by the manufacturer to fix or replace a specific part if it does not last for a specific time period or distance. 

gudgeon pin: British term for a piston pin or wrist pin. 

guide: A device which allows a long shaft to do its job without flexing. See valve guide. 

guided send test: Bending a specimen in a definite way by using a fixture. 

gum: oxidized portions of the fuel that form deposits in the fuel system or engine parts. 

gum stock: Rubber compounds containing only the necessary ingredients for vulcanizing. Reinforcing fillers are not present in gum stock. Also see cushion gum. 

gun: See grease gun. 

gut: To strip the interior of the vehicle. May also refer to removing the internal baffles from a muffler. 

gutted muffler: A muffler with no silencing baffles. Makes a very loud sound. 

gutter: The recessed part on a truck rim base that holds the lock ring in place. 

gutter bevel: Truck rims are bevelled to provide for the gutter and this bevel matches a 28° taper at the inside of the cast spokes, holding the rim in place. 

GVW: Acronym for "Gross Vehicle Weight" -- the total weight of a fully equipped truck and payload. 

GVWR: Acronym for "Gross Vehicle Weight Rating" -- the standard or rating of a vehicle's carrying capacity.