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How To Talk Like a Car Guy: Automotive Vocabulary List for Dummies

Apr 25, 2016


Now that the weather’s nice car fanatics are out in full force, waxing, washing and tuning up their latest rides.  Many new drivers have hit the road and are on the scene as well.  They’ll gather in cruises, local shows and meets all the while “talking shop” and bragging about their latest custom upgrades to their rides.  Do you know what they are talking about when they say words like chassis, turbo, or center-locking differential?  While being around serious car aficionados can be intimidating, we’ve collected a cheat sheet of vocabulary words for those of you who are new to the car world and may want to get up to speed on automotive lingo, or simply just want to know what the heck everyone is talking about, or better yet, sound like you know what the heck you’re talking about…  Enjoy! 

ABS: Anti-Lock Braking System.  A system designed to prevent skidding, especially in wet conditions.  

Air Brakes: Usually found on heavy-duty trucks, using compressed air to operate.


Air Injection: A method for reducing exhaust emissions. The injection of fresh air into the engine exhaust ports, combined with the high heat present in the exhaust manifold, causes the burning up of leftover fuel vapors.

Alloy Wheels: Any non-steel road wheel. Mostly aluminum, but technically a mixture of two or more metals.

Anti-Roll Bar: A suspension component. A steel rod or tube that connects the left and right suspension members to resist roll or swaying of the vehicle. Improves handling.

A-pillar: Vertical roof support between the windshield and front edge of the front side window.


Aspect Ratio: The ratio between the width and sidewall (or height) of the tire. Tires with lower aspect ratios, usually found on sports models, provide superior handling but a harsher ride.

Automatic Transmission: A system that varies the power and torque to a drivetrain without the use of a foot-operated clutch.


Alternator: A device that converts mechanical energy into electrical energy for the purpose of charging the car battery.

ATF: Automatic Transmission Fluid. A liquid used within an automatic transmission to transfer the movement of the torque converter to the driveshaft.


B-pillar: Vertical metal roof support between front and rear side windows on the side of the vehicle

Ball Joint: A dynamic joint of ball-and-socket configuration used in the steering and suspension systems. 

Bench Seats: Full-length seat that runs along the rear width of the car cabin so that more than two passengers can sit there. 

Beltline:  This line can be found extending under the windows from the front and the back.  

Body Style: The type of exterior shell or shape to a vehicle (sedan, coupe, hatchback, etc.).

Brake Caliper: A hydraulic (liquid-pressured) piston assembly that holds disc-brake pads. 

Brake Pad: Used in a disc system, it is a replaceable piece of backing plate and additional friction lining. The Disc, a thick, round metal plate located behind each wheel, against which a set of brake pads are applied by a caliper during braking.

Brightwork: These are any function or aesthetic reflective additions to a car.  

Carburetor: Used in engines to mix petrol and air for delivery to the combustion chamber. 

Catalytic Converter: A component of the exhaust system that creates a heat- producing chemical reaction to convert potentially harmful combustion byproducts into carbon dioxide and water. 

Center-Locking Differential: On all-wheel drive vehicles, a third differential in addition to those for the front and rear axles. This third differential allows the front and rear wheels to turn at different speeds as needed for cornering on dry pavement. On slippery surfaces, it locks all four wheels together, either automatically or manually depending on the system, for greater traction.

Character Line: A strip around the vehicle that generally features to give the car a distinctive and noticeable appearance.  

Check valve: A safety valve which allows fuel, air or a vacuum to flow in only one direction.

Chassis: This is the part of the car in which the driver sits and to which the engine and suspension are attached. In modern Formula 1 cars the chassis is a monocoque design manufactured from carbon fibre.

Choptop: The result of the process of lowering the top of a car, usually as part of a customized design. 

Cladding: These are panels around the edges of the car edges that can be aesthetic or functional.  

Clearcoat: The transparent top coat of paint on many newer vehicles; designed to create a long-lasting, lustrous appearance.

Clutch: This drivetrain component is found between the engine and the transmission. It acts as a coupling device which is used to engage and disengage the transmission from the engine when shifting gears. It is necessary to do this joining and detaching because the engine is turning at a relatively high rate (thousands of revolutions per minute), and attempting to alter a gear ratio at this point could send various bits of transmission shrapnel careening about the occupant compartment.

Clutch Disk: Presses against the transmission flywheel to transfer power from the engine to the transmission.

Coefficient of Drag (Cd): A measure of the aerodynamic resistance of the vehicle body. The smaller the number, the more wind-cheating the body design and the greater likelihood that passengers won't have to endure wind noises. 

Combustion Chamber: The area at the top of ht engine cylinders where the fuel is introduced and either ignited or compressed. 

Compressor: A system used by some manufactures to improve the power of engines by forcing air into the combustion chamber at greater pressure. 

Cylinder:  One of a group of chambers in the engine within which the compression process takes place.  Most cars are either 4, 6, or 8, but powerful super cars have been known to be equipped with 10 or 12.  

C-pillar: The vertical metal roof support between the side edge of the rear windshield (also called the backlight) and the rear edge of the rear window. 


Cabin: The interior people-space within a car. For a truck its called a Cab. The ‘Greenhouse' is a term used in automotive circles to describe all of the windows enclosing the passenger compartment.

Cabriolet: A two-door small open car with a hand- retractable roof, being either a rag (cloth) top or hard top, usually seating four. 

Cam: An irregularly shaped disc or projection whose rotation creates a rocking motion in an adjacent part.

Camber: Inward or outward tilt of the wheels tyres. This adjustment affects how the vehicle holds the road and handles cornering.

Camshaft: A metal shaft supporting the cams that cause the open/close operation of the intake and exhaust valves. The camshaft turns at 1/2 the speed of the crankshaft and is connected to it either via gears, a timing chain or a timing belt. 

Carbon Brakes: Introduced by the Brabham Team in 1978, these offer improved performance and superior durability to the steel brakes they superseded. Carbon disc brakes operate at their best when heated to extremely high temperatures, up to 1000° centigrade. Therefore, they are not suitable for road going cars as there performance when cold is very poor. 

Carbon Fibre: This is an ultra-light, but extremely strong material that has been used to manufacturer vehicle parts for road an racing cars. It was introduced to the World of Formula 1 racing in the 1970's in the form of large but light wings. McLaren were the first team to use it to produce the whole monocoque of a Formula 1 car in 1981. 

Coil: A transformer used in the ignition system for stepping up the voltage of the electric current conducted through the spark plugs. This high level of “electrical pressure" is what causes the current to jump the gap at the tip of each spark plug and create the actual spark that ignites the fuel inside the cylinder. 


Coil Spring: A heavy-duty, spiraled metal component of the suspension system which forms a dynamic connection between the body of an automobile and its chassis. 

Compression: The stage prior to combustion during which the piston in a cylinder pushes down on the fuel vapor within to pressurize it. 


Compression Ratio: The ratio of the volume within an engine cylinder when the piston is at the bottom of its stroke, compared to the volume in the cylinder when the piston is at the top of its stroke. The higher the ratio, the more compression during combustion and the more powerful the engine. Eg- 8:3:1 

Combustion Chamber: Top section of the engine cylinder, where the air-fuel mixture is ignited by a spark plug. The explosion of the combustion pushes the piston down into the cylinder, producing the force that the transmission delivers to the drive wheels.


Constant-Velocity Joint (CV Joint): On front-wheel drive and all-wheel drive vehicles, a coupling that allows the front axle to turn at a constant speed at various angles when the vehicle turns. The CV joint is a shaft that transmits engine power from the transmission to the wheel.

Convertible: A medium-large sized car seating unto 5 people an having possibly 4 doors with a top that can be either lowered or removed. 

Coupe: Generally, a two-door car with close-coupled passenger compartment.


Coupe de Ville: A coupe with an enclosed, rear passenger section and an open driver’s section. 

Crankcase: The area inside the engine block where the crankshaft, piston rods and other moving parts operate and receive continuous lubrication. 

Crankshaft: The main shaft of an engine through which the power produced during combustion is transferred to the transmission (and ultimately the wheels) as torque. Its rotation results from the reciprocating motion of the pistons.

Cruise Control: A device that, when set by the driver, will hold the car at the chosen speed. 

Crumple Zone: Portions of a vehicle’s structure designed to buckle and fold in an impact, absorbing crash force rather than transmitting it to vehicle occupants. 

Cylinder Head: At the top of the engine block is the cylinder head which contains intake and exhaust valves. Air and fuel enter the cylinder head through the intake valves and spent leftovers are released after combustion through the exhaust valves

Damper: A device which reduces vibration.


Daytime Running Lights (DRL): These lights come on whenever the vehicle is turned on; they make the vehicle more visible to other drivers. Mandatory in Canada and standard equipment on many vehicles sold in the United States.

Decked: The process of removing the body trim or contour lines from the hood or trunk of a car, usually as part of a customized design.


Diesel: An internal combustion engine in which the air-fuel mixture is ignited by compression in the cylinder rather than by a spark. Diesel engines use diesel fuel rather than gasoline and tend to be more fuel-efficient and require less maintenance than gasoline engines, but it is more complicated to get them to run cleanly. Also used as a slang term: after turning off the ignition, the engine continues to run for a short period.

Differential: A mechanical gearbox or fluid coupling that allows wheels to rotate at different speeds. Usually located on an axle, it allows the outside wheels to turn faster than the inside wheels during cornering. Four-wheel-drive and all-wheel drive vehicles have two differentials, one for the rear axle and one for the front. all-wheel drive vehicles also may have a third or center differential on the drive shaft that runs between the front and rear axles. 

Diffuser: A rear outlet for expelling engine noise. 

Displacement: The volume displaced by an engine’s cylinders. Formerly measured in cubic inches, it is now more commonly expressed in liters.


Distributor: Part of the ignition (electrical) system. Delivers electricity from the ignition coil to the distributor cap and the spark plug wires in the correct firing order. (The firing order is that sequence in which each cylinder begins its power stroke.) The spark plugs ignite the fuel and air mixture in each cylinder thousands of times a minute, producing the explosion that pushes the piston down in the cylinder to power the vehicle. 

Downpipe: The pipe that joins the entire exhaust system to the exhaust manifold. 


Double Wishbone Suspension: A type of independent suspension in which the upper and lower support pieces, or members, look somewhat like a wishbone.

Dragster: A straight-line racing car where the engine is half exposed an the rear wheels are larger than the front wheels. Exotic booster fuels are usually added like nitro-gas. 

Drafting: A phenomena where two cars running nose to tail together can move faster than an individual vehicle.

Drive Axle: Connects the transaxle to the front wheels on a front-wheel drive vehicle.


Drive Range (EV): The distance an electric vehicle can drive without re-charging its batteries.

Disc Brakes:  A disc rotates with the wheels, straddled by a caliper that can squeeze the surfaces of the disc at the edge to slow the wheels.  

Drive Train:  All parts of a vehicle that create power and transmit that power to the wheels.  

Drum Brakes: A breaking system that uses a metal drum.  Brake shoes press against the drum to slow or stop the car.  

Engine Management System:  An extremely sophisticated computer which monitors the condition of the car’s engine at all times.  

Driveshaft: A long metal cylinder located between the transmission and the rear axle, in front-engine rear-wheel drive vehicles. The shaft is connected to the components on each end with a universal joint, which allows for movement up and down without bending the shaft.


EBD: Electronic Brake Distribution is a component used with ABS an usually a brake assist mechanism, for small powerful cars, like the new Mini of 1998. 

Electronic Mufflers: In an electronic muffler system, sensors and microphones in the exhaust system sense the pattern of exhaust pressure waves. This information is sent to an on-board computer that controls loudspeakers in the muffler. The computer operates the loudspeakers to generate sound waves that oppose and cancel the original exhaust sound waves produced by the engine.

Electronic Stabilization Program: (ESP) increases vehicle control in situations near the vehicle’s limits. It reduces the risk of skidding and helps to keep the vehicle on course. ESP recognizes the course desired and the car's reactions. Through brake application at individual wheels, it generates one-sided forces which help the car to move in the desired direction. The ESP program uses other driving aids and is permanently engaged.

Electronic Control Module (ECM): Electronic Control Module. The master computer responsible for interpreting electrical signals sent by engine sensors and for activating automated engine components and processes accordingly in order to produce optimum performance. 

Electronic Ignition: A system which uses an electronic unit as opposed to an older mechanical style distributor with points (contacts) to control the timing and firing of spark plugs. 

Electronic Valve Timing (EVT): System in which a computer controls the timing of the opening and closing of cylinder valves. 

Engine: The basic job of an engine is to take fuel and convert its energy to some usable mechanical form (burn gasoline to spin a shaft and, ultimately, the wheels). Usually made from alloy & block. Its Cubic Capacity number [cc] represents the interior fuel space within it. The higher cc# the greater power it generates. Most vehicles today are fitted with what is known as a 4-cycle internal combustion engine. The four cycles are: Intake, Compression, Power, Exhaust. 

Engine cooler: An air intake with behind it a large inducting fan, drawing air through a water cooled piping arrangement, thus preventing engine overheating, where the event is highly expected. 

Evaporative Emissions: Evaporated fuel from the carburetor or fuel system which mixes with the surrounding outside air.


Evaporator Core: Part of the climate-control system that contains a liquid refrigerant which turns to gas to absorb heat from the air.

Exhaust Manifold: A cast set of pipes or passages through which exhaust gases exit the engine cylinders on their way into the exhaust system.


Exhaust Valves: Devices that open passageways from the cylinders for exhaust gases to exit but which also close them during compression and combustion to maintain cylinder pressure.

Exhaust Gas Recirculation (EGR): Part of the emissions system, it recirculates exhaust gases into the intake manifold, cooling the combustion chamber. 

Exhaust:  The pipe which through the waste gasses from the combustion process are removed from the car engine.  

Factory standard: The basic design and options that make up the packaging of an entry-level vehicle. Basically a car bought off the lot with no upgrades or mods. 

Fan Belt: Transmits power from a crankshaft-driven pulley to an engine fan and other accessories. 

Final Drive Ratio: The reduction ratio of the transmission gear set furthest from the engine. In other words, the ratio of the number of rotations of the drive shaft for one rotation of a wheel. In general, a low final drive ratio results in better fuel efficiency, and higher final drive ratio results in better performance.

Four-Wheel Drive (4WD): A transfer case distributes power to both axles in order to drive all four wheels. Sometimes called All-Wheel-Drive in USA.

Fog lights: Two special headlights designed for cutting through foggy conditions along the road ahead. 


Firing Order: The sequence in which spark plugs fire and combustion takes place in the engine cylinders.

Flywheel: A large disc bolted to the rear end of the crankshaft. The flywheel is encircled by a ring gear whose teeth are designed to mesh with the pinion gear in the starter during the process of starting the engine.

Front Wheel Drive:  The power of the engine is transmitted to the front wheels by the driveshafts. 

Fuel Injection System: The pip through which the waste gasses from the combustion process are removed from the engine and car.   

Fuel: A combustible, vaporous mixture of air and gasoline which is ignited within an engine to produce power. “Fuel" is a term often used in reference to the gasoline itself.


Fuel Cell: The name for the fuel tank used in formula racing cars, that sits behind the driver an is reinforced with Kevlar.

Fuel Injection System: Injects fuel into the engine’s cylinders with electronic control to time and meter the fuel flow.

Fuel System: These systems are vast and countless, but today’s basic systems divide into two fundamental groups: carburetor systems and fuel Injection systems. Carburetor systems work by allowing the vacuum created by the engine in the intake stroke to pull fuel and air into the engine. Fuel Injection systems are more common these days. Sensors and computer controls monitor various engine speeds, air flows and throttle positions, and then tell the system what to do. A fuel pump is used to transfer the gasoline from the fuel tank to the injector (which is kind of like a spray nozzle).

Fuel Injector: Taking the place of carburetors in the 1980s, the fuel injector is an electrically controlled valve that delivers a precise amount of pressurized fuel into each combustion chamber. 

Gasket: A thin, expanding material used to seal the gaps and imperfections between hard, adjoining surfaces.


Gear Ratio: The ratio of teeth counts between meshing gears.

Gearbox: A metallic enclosure containing several cogs, each one affecting the effort in which the car moves. Each cog/gear has a different mph ratio per 1000rpm. Overall control maybe manual via the gear stick, automatic, or semi via a hand paddle. 

Grille:  The metal grate at the front which provides cooling to the vehicle as well as making it look pretty bad ass.  

Hardtop: A car designed to resemble a convertible in looks and feel but without a removable top. Hardtops do not have the fixed post between the side windows.

Halogen bulb: A special headlight form whose brightness power is greater than standard bulbs, though they cost more an last shorter.

Hairpin: A tight looping curve on a race track. 

Handling: The ease of vehicle steering and maneuverability around turns, up hills, etc.

Hatchback: A passenger car with a full-height rear door that includes a rear window. Usually has a rear folding seat. 

Horsepower:  The common unit of engine power.  One horsepower equals 550 foot-pounds per second.  In other words - one horsepower is the power needed to lift a 550-pound weight one foot in one second.

Hydraulic: An integral car component operated by means of liquid under pressure, as used in the braking system.

I-Beam Suspension: A suspension beam under the car that supports the body in the shape of a capital I.


Idle Speed: The speed of the engine at minimum throttle and the engine in neutral. 

Ignition System: The system responsible for generating and distributing the electrical spark needed to ignite fuel in the cylinders and for altering the frequency (timing) of that spark in relation to changes in engine speed. 

Inboard Air Jack: A device added to some racing cars which raises their chassis after making a pitstop, so quicker action can be taken on their maintenance. It is powered by a compressed air canister. 

Injectors: Devices which receive fuel at low pressure and shoot it into the engine cylinders at predetermined intervals under higher pressure. 

Intake Manifold: A cast set of pipes or passages through which fuel or air is directed into the cylinders. 

Intake Valves: Devices that open passageways for fuel vapor to enter the cylinders but which also close them to maintain cylinder pressure during compression and combustion. 

Independent Suspension: A suspension design that lets each wheel move up and down independently of the others. A vehicle can have two-wheel or four-wheel independent suspension; sportier models have four-wheel independent suspension. 

In-Line Engine: Cylinders are arranged side by side in a row and in a single bank. Most four-cylinder and some six-cylinder engines are in-line engines. In V-6, V-8 or V-12 engines, the cylinders are divided into two banks, each of which is angled away from the other in a 'V' pattern.

Intake Charge: The mixture of fuel and air that combusts in the engine to create power.  

Intercooler: Device that cools air as it leaves a turbocharger or supercharger before the air is blown into the engine air intake. Cooling makes the air denser and richer in oxygen, which lets the engine produce more power.


Interior Payload: The amount of space or material that can be carried inside the vehicle. 

Leaf Spring: Suspension made from thin, curved steel.  Absorption of bumps is increased by the curved shape.  

Lift Gate: The rear opening on a hatchback. Also called a tailgate or hatch door.

Live Axle: A solid axle that means when one wheel turns, the opposite wheel must also turn.  

Lowrider: Generally, a car on which the chassis has been lowered; however, other customizations are often present. Some American cars have a hydraulic mechanism that does this action during driving.


M+S Rating: A tire rating which indicates a tyre designed to perform well in mud and snow.

Manual Transmission: A transmission that varies the power and torque through a foot pedal controlled clutch and a floor-mounted or steering-shaft-mounted gear selection lever.

Master Cylinder: The primary component for pressurizing fluid in a hydraulic system. Used in the braking system, it supports a reservoir for holding brake fluid and is activated each time the driver depresses the brake pedal.

Max power: Two figure totals given in brake-horse-power by engine revs per minute. [bhp x rpm]. 


Max torque: The weight of force per foot, given in pounds, and the rpm level, e.g. 100 lb ft at 1000 rpm. 

Miles Per Gallon / MPG: Fuel economy measurement. Generally, a vehicle maker may offer mpg ratings for city driving, highway driving, and combined driving, so their is no definitive single measure overall. 


Muffler: A chamber in the engine exhaust system used to suppress exhaust noise and smooth exhaust pulsations. Also referred to as a "silencer". Motorbike an moped owners sometimes remove these to beef-up their sound.

Multi-Link Suspension: Independent suspension controlled with several link arms that restrict undesired motion of the suspension for a smoother ride and more precise handling.

Multi-Port Fuel Injection: An electronic fuel-injection method that uses individual injectors to spray fuel directly into each intake port, bypassing the intake manifold. Also called multi-point fuel injection. 

Nitro-methane: A mixture of nitric acid and methane which is used to fuel Top Fuel Dragsters and Hotrods; is also called nitro or top fuel. 

Octane: The hydrocarbon substance in gasoline that reduces engine knock or pinging, which is a noise caused by premature ignition of fuel in the cylinder combustion chamber. The higher the octane number, the less chance of premature ignition. High octane, which has a rating above 91, is useful only when recommended by the manufacturer.


Odometer: Indicates the number of miles a vehicle has been driven. You know, that thing they tried to tamper with in Ferris Bueller?

Overhang: The distance from one wheel to the end of the car where the front and rear bumpers reach.  

Overhead Cam (OHC): The camshaft is on top of the cylinder head on overhead-cam engines. Single overhead-cam (SOHC) engines have a single cam above the cylinder head. Dual overhead-cam (DOHC) engines have two cams above the cylinder head.  


(OHV) engine: An overhead-cam engine with overhead-valves, which means the intake and exhaust valves sit atop the cylinder head.

Oversteer: No, this doesn’t mean you steer too much.  It occurs when the rear tires lose adhesion under cornering. In motor sports, this is also called loose. Oversteer can lead to a spin if the driver doesn’t reduce acceleration.  

Overdrive: A transmission gear with a ratio below 1:1, which improves fuel economy by reducing engine revolutions per minute at highway speeds. On a five-speed manual transmission, the fourth and fifth gears are overdrive. On a four-speed automatic transmission, the fourth gear is overdrive. When an overdrive gear set is engaged, the output shaft turns at a higher rate than the input shaft, reducing engine revolutions at cruising or highway speeds. 

Oxygen Sensor: An emissions related device which senses the presence of oxygen in the exhaust. The voltage it puts out is interpreted by the main computer (ECM) along with other sensor input to determine automatic adjustment of the air/fuel mixture.

Pillar: These connect the roof of the vehicle to it’s body.  

Pinion: A t ape of gear that has small teeth that mesh with other larger gears.  Not unlike our Carponents logo.  

Piston: A solid, cylindrically shaped part that alternately compresses fuel vapor within a cylinder (the compression stroke) and is thrust downward (the power stroke) by the force of the explosion that results when the vapor is ignited. Rocker arms connect the pistons to the crankshaft. 


Piston Rings: Metal rings seated in grooves on the outside of a piston that are used to ensure a proper seal between the piston and the cylinder wall. Typically, three (3) rings are used: two (2) ensure proper compression is produced and one (1) prevents oil from leaking into the cylinder. 

Positive Crankcase Ventilation Valve: An emission device that routes oil pan vapors to the intake manifold to be burned during combustion. Also known as the PCV valve.

Power Steering: A steering system that uses a separate motor or engine power to reduce the effort necessary to turn the front wheels. 

Power Steering Fluid: Many power steering systems use hydraulic power. These systems use a power steering pump driven by a belt from the crankshaft. The pump moves fluid under pressure through hoses to the steering gear. The pressure is used in the steering gear to reduce steering effort. A reservoir for fluid is attached to the rear of the pump. 

Power-to-Weight Ratio: The maximum power output of the vehicle per unit mass. The higher the ratio, the more powerful the vehicle. In comparing several vehicles, this can be a better measurement than engine horsepower or torque because it considers the weight variable. In other words, a car that seems to have a powerful engine but is also heavy may have less get-up-and-go than a vehicle that has a similar or less powerful engine but also weighs less. 

Powertrain: A group of components used to power the wheels that are calibrated into either front or rear-wheel-drive.  

PSI: Acronym for pounds per square inch. A pressure measurement used in tire inflation and turbocharger boost.

Pushrod: A metal rod that transmits the motion of the camshaft to the valve actuators to open and close the valves. Used on engines with overhead valves but without overhead camshafts.


Quarter Panel: Sheet of metal panel that covers the front and rear quarters of the vehicle. 

R-134a: The environmentally safe refrigerant now used in air-conditioning systems. It requires a slightly bulkier condenser unit than the older R-12 type. Vehicles equipped with R-12 systems can be converted to use R-134a. Since Freon is now banned, expensive and hard to obtain, the conversion may be a good idea when an R-12-based system needs recharging, particularly if technicians detect a leak.


Roadster: An open car having a single seat for two or three passengers, with originally a rumble seat in the rear, usually a folding roof.

Rack and Pinion Steering: The steering wheel is connected to a pinion gear that meshes with a toothed bar, also called a rack or linear gear. As the pinion turns, the rack moves side to side, moving the steering linkage and causing the front wheels to turn left or right. The ends of the rack are linked to the steering wheel with tie rods.

Radiator: The copper or aluminum device in front of the engine through which hot engine coolant is circulated and cooled. The liquid is then recirculates back through the engine block to cool it.

Rear axel assembly: The drive shaft turns (spins) a set of gears within the rear axle assembly known as the differential, or rear differential. The differential changes the direction of power from the driveshaft out to the rear wheels via the rear axle. 

Rear Wheel Drive:  The power of the engine transmitted to the rear wheels only.  The front wheels are used for steering.  

Recall: A manufacturer calls in vehicles to repair defects, usually safety-related. Recalls may be voluntary, requested by the government, or mandated by NHTSA.

Redline: The point on the engine tachometer that indicates the maximum RPM the engine can safely withstand.


Release Fork: Disengages the clutch disc from the flywheel by pressing on the pressure plate release springs. 

Revs:  An engine revolution (rev) occurs every time the pistons in the car travel up and down the cylinders.  The more revs the more power.  

Rim: The outer edge of a bare wheel. A hub-cap sometimes sits within this.


Rocker Panel: The body panel that runs beneath a vehicle’s doors. 

Rotor: Shiny metal disk that brake pads squeeze to stop the vehicle; hence the name disc brakes.

RPM: Revs (engine revolutions) per minute.  

Scoop:  These vents protrude from the vehicle and allow cooling.  

Sedan: A fixed-roof car with at least four doors or any fixed-roof two-door car with at least 33 cubic feet of rear interior volume. 

Sequential Fuel Injection: Similar to multi-port fuel injection, but the injectors spray fuel into the individual intake ports exactly at the beginning of each cylinder’s intake cycle. The precise fuel control provides better engine performance. 


Semi-trailing-arm suspension: An independent rear-suspension system in which each wheel hub is located only by a large, roughly triangular arm that pivots at two points. Viewed from the top, the line formed by the two pivots is somewhere between parallel and perpendicular to the car’s longitudinal axis. 

Shift Interlock: On a vehicle with automatic transmission, a safety device that prevents the driver from shifting out of park unless the brake pedal is depressed.

Shift gate: The mechanism in a transmission linkage that controls the motion of the gearshift lever. The shift gate is usually an internal mechanism; however, in some transmissions: including Ferrari five-speeds and Mercedes-Benz automatics: the shift gate is an exposed guide around the shift lever.

Shock absorber: A device that converts motion into heat, usually by forcing oil through small internal passages in a tubular housing. Used primarily to dampen suspension oscillations, shock absorbers respond to motion; their effects, therefore, are most obvious in transient maneuvers.  

Short Block: The lower portion of an engine below the cylinder head. 

Side mount: A spare tire mounted on the side of a car, normally on the fender just above and behind the front wheel.


Single Overhead Cam (SOHC): An engine with a single overhead cam generally has one intake and one exhaust valve per cylinder; the single cam opens and closes both valves. See also Overhead Cam and Dual Overhead Cam. 

Steering Rods: The metal rods on each end of the steering rack that connect it to the front wheels via ball joints (tie rod ends).


Strut: A single, self contained pivoting suspension unit that integrates a coil spring with a shock absorber. Struts are used on front wheel drive automobiles. A suspension element in which a reinforced shock absorber is used as one of the wheel's locating members, typically by solidly bolting the wheel hub to the bottom end of the strut.

Spark Ignition (SI) Engines: Use petrol as the fuel to drive the car.

Spark Plugs:  Used in petrol engines to ignite the petrol and air mixture to allow the car to drive. 

Spoiler:  That fancy “wing” on the back of a car that some people add to look cool, but really has an important aerodynamic feature of preventing lift and keeping the car down on the road.  

Supercharger: An air compressed that increases power by forcing more air into an engine than it can intake on its own.  

Suspension:  System in a car that absorbs shock from the road and travel around corners safely.  

Swage Line: The body of the vehicle curvets in a signature way for either appearance or function.  

Torque: A measurement of the force with which the engine turns the wheels of the car.  The greater the torque the faster the car.  

Torque Converter: An enclosed device connected to the crankshaft that uses a turbine-based system and a thin fluid (ATF) to propel the movement of the automatic transmission mains haft. As opposed to an automobile equipped with a manual transmission and clutch that must be engaged/disengaged, this “fluid" connection between the engine and the wheels is what enables a car to come to a full stop with its automatic transmission still in gear. 


Torque Steer: The tendency of the front wheels on a front-drive vehicle to pull to the side under hard acceleration. 

Torque-to-weight: The amount of torque derived power effort, in pounds per foot, over the tonnage of the vehicle. 

Timing Belt: On overhead cam equipped engines, an external belt used to synchronize the operation of intake/exhaust valves with the compression/ignition process occurring in the cylinder head and engine block below. 


Timing Valve: A valve in a fuel injection pump which times the delivery of fuel.

Track:  This is the distance measured side-to-side between the base of the wheels.  

Transmission:  A gearbox with a number of selectable rations used to match the engine’s RPM and torque to differing vehicle requirements.  

Transmission: The transmission is used to take the high-speed, low-torque power of the engine and convert it to a lower-speed, higher-torque output, which ultimately turns the drive wheels. Transmissions come in a wide variety of choices, but they basically divide into three categories: Manual, Automatic, and Manumatic. Lower gears allow fast acceleration, higher gears provide better gas mileage. Manual transmission uses a system of gears to create the high torque output required from the engine's high speed input. A clutch is used to disengage the transmission from the engine when shifting gears. Automatic transmissions do the shifting for the driver. No clutch is required. The shifting is accomplished by a hydraulic oil system. Manumatic transmissions are a hybrid of manual and automatic transmissions. In most cases they require no manually operated clutch, but they allow for the driver to shift gears manually when desired.

Turbocharger: A device which uses the exhaust gases to drive a turbine which forces more air into the combustion chamber.  

Turbine: An integral piece of the turbocharger, this small fan drives the compressor. A rotor with vanes or blades which is driven by the movement of fluid or gases across its surface. The turbine wheel in a turbocharger spins as a result of exhaust gases. In a torque converter, a turbine is used to propel ATF within the unit.

Turbo Lag: The time it takes the turbocharger to kick in after the driver accelerates; the lag results because a turbocharger compressor is spun by exhaust gases in the exhaust manifold.

V-Type Engines: The cylinders of this engine are divided into two angled blanks forming a V. 

Universal joint: A joint that transmits rotary motion between two shafts that aren’t in a straight line. Depending on its design, a universal joint can accommodate a large angular variation between its inputs and outputs. The simplest kind of universal joint, called a "Hooke joint," causes the output shaft to speed up and slow down twice for every revolution of the input shaft. This speed fluctuation increases with the angular difference between the shafts.

Wheel Base: The distance between the center of the front wheels to the center of the rear wheels.  

Wheel Well: The open area in the body of the car where the wheels sit.  

V4: A vehicle with four cylinders. Never use this term.  Unless someone asks you how many cylinders your car has. Its uncool to refer to your car as anything less than a V6.  

V6: A vehicle with six cylinders. The cylinders are divided into two banks, each of which is angled away from the other at the top, forming a 'V'. Typically, this angle is 60 degrees on V-6 engines.

V8: A vehicle with eight cylinders. The cylinders are divided into two banks, each of which is angled away from the other at the top, forming a 'V'. Typically, this angle is 90 degrees on V-8 engines

V12: A vehicle with a dozen cylinders. The cylinders are divided into two banks, each of which is facing each other at the top, an slightly forms a 'V' shape. Typically this angle is 30 degrees on most V-12 engines. Occasionally two V6 engines can be combined to act as a V12.

Valve Train: The valves and camshaft(s) within an engine, and any parts attached to the valves, such as rockers and pushrods, to move them up and down.

Valves: Many overhead-cam engines, particularly multi-valve models, are described by the total number of intake and exhaust valves in the cylinder head. A 24-valve V-6 engine would have four valves per cylinder: two intake and two exhaust valves. A 16-valve V-8 engine has only the standard single exhaust and single intake valve for each of its eight cylinders.

Valve gear: The valve number per cylinder and the cam number plus its position. 

Valve float: A high-rpm engine condition in which the valve lifters lose contact with the cam lobes because the valve springs are not strong enough to overcome the momentum of the various valve train components. The onset of valve float prevents higher-rpm operation. Extended periods of valve float will damage the valve train.

Valve lifter: Also called a “valve follower”: the cylindrically shaped component that presses against the lobe of a camshaft and moves up and down as the cam lobe rotates. Most valve lifters have an oil-lubricated hardened face that slides on the cam lobe. So-called “roller lifters," however, have a small roller in contact with the cam lobe: thereby reducing the friction between the cam lobe and the lifter. 

Valvetrain: The collection of parts that make the valves operate. The valve train includes the camshaft(s) and all related drive components, the various parts that convert the camshaft's rotary motion into reciprocating motion at the valves, and the valves and their associated parts. 

Viscous coupling: A particular kind of fluid coupling in which the input and output shafts mate with thin, alternately spaced discs in a cylindrical chamber. The chamber is filled with a viscous fluid that tends to cling to the discs, thereby resisting speed differences between the two shafts. Viscous couplings are used to limit the speed difference between the two outputs of a differential, or between the two axles of a car.

Variable-Assist Steering: A power-steering system that varies the amount of assistance it provides according to driving conditions. It provides maximum assistance at low speeds for maneuvers such as turning into a parking space or turning a corner after leaving a stop light. It provides minimum assistance at cruising or highway speeds to provide greater vehicle stability.


Vehicle Identification Number (VIN): A seventeen-digit identification number, unique to each vehicle, which includes codes for the manufacturer, year, model, body, and engine specifications.

Vented Disc Brakes: A brake disc that has cooling passages between the friction surfaces.

V-Type Engine: In a V-6, V-8 or V-12 engine, the cylinders are divided into two banks, each of which is angled away from the other at the top, forming a ‘V’. Typically, this angle is 60 degrees on V-6 engines and 90 degrees on V-8 engines. 

Waste gate: A valve used to limit the boost developed in a turbocharger. A waste gate operates by allowing some of the engine’s exhaust flow to bypass the turbocharger's turbine section under certain conditions.

Water Pump: The pump that circulates coolant through the engine block, cylinder head and radiator. It is driven by the engine crankshaft.

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