Lost in a world of unfamiliar terms and jargon? Do you think your mechanic is speaking a foreign language when he explains what is wrong with your Buick? Well, he is really, if you don't have a grasp of the basic terms in the world of cars. We at AutoSpeak can help. We have gathered basic terms to help you understand better what is going on with your car.

Actual Cash Value

The amount of money invested in the purchase and repairs of a used vehicle. Also known as ACV, this represents the amount of out of pocket expense a dealer or broker is "into" a car.

Air Bag

The air bag, also known as a Supplemental Inflatable Restraint System, is a passive safety device, supplemental to safety belts, that inflates to provide a cushion to absorb impact forces during moderate to severe frontal collisions. This system can help to lessen the chance of contact with the steering wheel, instrument panel and windshield. The air bag is actuated automatically by sensors located in the front of the vehicle. To maximize effectiveness, seat and shoulder belts must always be used in conjunction with this system

Airfoil

An aerodynamic device designed to improve traction by increasing the downforce on the car. The use of airfoils (also called wings) increases the cornering capability and improves stability at speed, but often at the expense of additional aerodynamic drag.

Air Injection

A system that injects air into the exhaust ports of the engine for combustion of unburned hydrocarbons in the exhaust gases, thus producing "cleaner" exhaust emissions.

Alignment

Generally refers to wheel alignment, which is the proper adjustment of the car's front and rear suspension for camber, toe, caster and ride height.

A-Pillar

In the side view, the foremost roof support of a vehicle, located in most instances between the outer edge of the windshield and the leading edge of the front door upper. Also known as an A-Post.

Alloy Wheels

A generic term used to describe any non-steel road wheel. The most common alloy wheels are cast aluminum. Technically, an alloy is a mixture of two or more metals. These wheels are known for their light weight and strength.

All-Wheel Drive

Often confused with Four-Wheel Drive (4WD), this drive system features four, full-time active drive wheels to reduce wheel slippage and provide greater driver control over the vehicle. All-Wheel Drive automatically splits engine torque between the front and rear wheels as needed, improving on-road traction in unfavorable road conditions. Unlike Four-Wheel Drive, All-Wheel Drive is an on-road system and is not designed for off-road use. AWD does not require the driver to actively engage the system. It is operational at all times, and requires no switches, lights or visor instructions for system operation.

Anti-Lock Brake System (ABS)

On a vehicle equipped with Anti-Lock Brakes, the wheels are equipped with speed sensors. When a sensor determines that a wheel is decelerating so rapidly that lockup may occur, the electro-Hydraulic Control Unit (EHCU) is activated. The EHCU then modulates the brake pressure in the appropriate brake lines by means of the solenoid-operated valves. This is intended to prevent wheel lockup and help the vehicle maintain directional stability during potentially hazardous braking situations. (See also: Rear-Wheel Anti-Lock and Four-Wheel Anti-Lock.)

Automatic Locking Front Hubs

Found in some four-wheel drive vehicles, this allows the driver to engage, or "lock," the front axle hubs without leaving the vehicle.

Axle Ratio

The ratio between the rotational speed (RPM) of the drive shaft and that of the driven wheel. Gear reduction in final drive is determined by dividing the number of teeth on the ring gear by the number of teeth on the pinion gear.

B-Pillar

The roof support between a vehicle's front door window and rear side window, if there is one.

Balance Shaft

A shaft designed so that, as it turns, it counter rotates the rotational direction of the engine crankshaft in a manner that reduces or cancels out some of the vibration produced by the engine.

Ball Joint

A flexible joint consisting of a ball within a socket. Ball joints act as pivots which allow turning of the front wheels and compensate for changes in the wheel and steering geometries that occur while driving.

Base-Coat/Clear Coat

A paint system that adds a final clear-coat paint layer over primer and color coats to provide a deep, "wet-look" shine that resists fading.

Belted Radial Tires

A reinforcing bank, normally textile, fiberglass or steel, running around the circumference of a tire and strengthening the tread area.

Bias-Ply Tires

A type of tire in which the plies or layers of cord in the tire casing are laid diagonally, criss-crossing one another at an angle of 30 to 40 degrees.

Body-On-Frame Construction

A type of automobile construction in which the body structure is attached to a separate frame.

Bore

The diameter of an engine cylinder or bearing.

Brake Fade

A condition brought about by repeated brake applications, resulting in build-up of heat that causes a temporary reduction or fading of braking effectiveness.

Brake Horsepower (BHP)

The actual horsepower of an engine, measured by a brake attached to the driving shaft and recorded by a dynamometer.

Brake Linings

The replaceable friction material which contacts the brake drum in a drum brake system to slow or stop the car.

Brake Master Cylinder

A cylinder containing a movable piston activated by pressure on the brake pedal. The piston produces hydraulic pressure that pushes fluid through the lines and wheel cylinders. This forces the brake lining or pad against the drum or disc to slow or stop the car.

Brake Pads

In a disc system, they are the replaceable flat segments consisting of a rigid backing plate plus frictional lining that takes the place of the shoe and lining in a drum brake. Brake pads are sometimes referred to as brake pucks.

Brake Shoe

The arc-shaped carrier to which the brake linings are mounted in a drum brake. They also force the lining against the rotating drum during braking.

Brakes, Drum

A type of braking system that utilizes a metal drum mounted on a wheel to form the outer shell of a brake. The brake shoes press against the drum to slow or stop drum and wheel rotation for braking.

Brakes, Disc

A type of braking system in which brake shoes, in a vise-like caliper, grip a revolving disk mounted on a wheel to slow or stop disc and wheel rotation for braking.

C-Pillar

The roof support between a vehicle's rearmost side window and its rear window. Also known as a C-Post. On a vehicle with four side pillars, the rearmost roof support may be called a D-pillar.

CAFE

The acronym for Corporate Average Fuel Economy. This single mileage figure is determined by taking a sales weighted average of the fuel consumption for all models produced by a manufacturer. The minimum required figure is an established U. S. government standard. Manufacturers which do not meet the minimum standard are fined.

Caliper

In a disk brake, a housing for cylinder, pistons and brake shoes, connected to the hydraulic system. The caliper holds the brake shoes so they straddle the brake disc.

Camber Angle

The inward or outward angle which a front-wheel spindle makes with a vertical line, as viewed by either the front or the rear of the vehicle. Positive camber results when the top of the tire tilts out further than its bottom. The adjustment of this setting affects both tire wear and vehicle handling.

Camshaft

The shaft in the engine which is driven by gears, belts or chain from the crankshaft. The camshaft has a series of cams that opens and closes intake and exhaust valves as it turns.

Capitalized Cost

The price of the leased vehicle plus any other charges such as fees or taxes that become the cost basis for calculating the terms of a lease.

Caster Angle

The forward or backward tilt of the steering axis as viewed from the side. If the point of load is ahead of the point of contact, the caster angle is positive. The caster angle tends to keep wheels in a straight line. Proper caster adjustment improves both tire wear and fuel economy.

Catalytic Converter

Often simply called a "catalyst", this is a stainless steel canister that is part of a vehicle's exhaust system and contains a thin layer of catalytic material spread over a large area of inert supports. It induces chemical reactions that convert an engine's exhaust emissions into less harmful products prior to entering the environment.

Center of Gravity

Point where the weight of a vehicle appears to be concentrated and if suspended at that point would balance front and rear.

Closed Crankcase Ventilation (CCV)

A system in which crankcase vapors are discharged into the engine intake system (usually via the intake manifold) where they are burned during the combustion process rather than being discharged into the atmosphere.

Closed End Lease

A lease in which the lessee is not responsible for the value of a vehicle when the lease is done. Under this arrangement the lessee may return the vehicle at the end of the term and have no further obligation for the car. Also known as a "walk-away" lease.

Cold Cranking Amps (CCA)

A rating, measured in amperes. Used for comparing cranking strength of automotive batteries during extremely cold (0 F or lower) weather.

Combustion Chamber

The volume of space at the top of the cylinder where burning of the air/fuel mixture begins.

Composite Headlamps

Usually manufactured with replaceable halogen bulbs and separate hard acrylic or glass lenses. This type of lamp provides superior illumination compared to the long-conventional sealed beam unit.

Compression Ratio

The volume of the combustion chamber and cylinder when the piston is at the bottom of its stroke, divided by the volume of the combustion chamber and cylinder when the piston is at the top of its stroke. Higher compression ratios tend to increase engine efficiency.

Compressor (Air Conditioning)

The machinism is an air conditioner that pumps vaporized refrigerant out of the evaporator, compresses it to a relatively high pressure, and then delivers it to the condenser.

Condenser

A device for storing electrical energy. In A/C application, an air conditioning component used to remove heat from the inside of a vehicle.

Connecting Rod

The metal rod that connects a piston to the crankshaft.

Contact Patch

The area of a tire's tread that is in contact with the ground.

Control Arm

A suspension element that has one joint at one end and two joints at the other end, typically on the chassis side. Also known as a wishbone or an A-arm.

Coolant

The mixture of water and anti-freeze that picks up heat from the engine and transfers it to the air passing through the radiator. This transfer of heat keeps the engine operating within its optimum temperature rant preventing premature engine wear.

Cooling System

The system that removes heat from the engine by the forced circulation of coolant and thereby prevents engine overheating. In a liquid-cooled engine, it includes the water jackets, water pump, radiator, and thermostat.

Cost of Ownership

Several items enter into the calculation of how much it actually costs to own a vehicle. Understanding these items can help determine what is the best purchase for each person. Ownership costs are divided into fixed costs and running costs. Fixed costs are the same whether the car is used or just sits. These costs usually decrease each year. Running costs are variable and are incurred when the vehicle is used. Running costs could increase as the vehicle ages.

Crankcase

A case that encloses the crankshaft. In most engines, the oil pan and the lower portion of the cylinder block form the crankcase.

Crankcase

A shaft with one or more cranks, or "throws," that are coupled by connecting rods to the engine's pistons. The combustion process creates reciprocating motion in the rods and pistons which in turn is converted to a rotating motion by the crankshaft.

Crossmember

One of several horizontal members in a vehicle frame which join the side members and add to overall strength and stability.

Cylinder Block

The basic part of the engine to which other engine parts are attached. It is usually a casting and includes engine cylinders and the upper part of the crankcase.

Cylinder Head

The removable part of the engine that attaches to the cylinder block directly above the cylinders. The head is cast from aluminum or iron and houses the combustion chambers, the intake and exhaust ports, spark plugs and much or all of the valve train. It has oil and water passages for cooling and lubrication.

D-Pillar or D-Post

The vertical or sometimes diagonal roof supporting member located at the extreme rear of the roof or greenhouse structure on station wagons and some sedan models.

Diesel Engine

A diesel engine uses heavier weight components than gas engines to handle higher compression ratios. Typically, diesel engines run with greater efficiency and higher torque than similar size gas engines. These attributes lead to better fuel economy and towing performance. Diesel engines do not have spark plugs or carburetors. Instead glow plugs are used to preheat air in the cylinders to ensure easy starts. Once the engine is started, compression heats the fuel in the cylinders for combustion.

Dieseling

A condition in which gasoline continues to fire after the ignition has been shut off. In late-model engines, dieseling , or run-on, is caused by heat and the unusually high manifold pressure that result from retarding the spark at idle. In fuel-injected cars when the engine is turned off, fuel is automatically shut off, eliminating dieseling.

Differential

The gear assembly connected to the drive shaft that permits the wheels to turn at different speeds when going around a corner, while transmitting power from the drive shaft to the wheel axles.

Differential, Locking

The same attributes of a standard differential, except that when one wheel is slipping, the most torque is supplied to the wheel with best traction. A locking differential reduces the possibility of a vehicle becoming immobile when one driving wheel loses traction.

Directional Stability

A vehicle's ability to maintain a true course of travel despite bumps, crosswinds, uneven road surfaces.

Disc Brakes

Properly called caliper disc brakes, a type of brake that consists of a rotor that rotates at wheel speed, straddled by a caliper that can squeeze the surfaces of the rotor with brake pads near its edge. Disc brakes provide a more linear response and operate more efficiently at high temperatures and during wet weather than drum brakes.

Displacement

In an engine, the total volume of air or air-fuel mixture an engine is theoretically capable of drawing into all cylinders during one operating cycle. Generally expressed in liters or cubic inches. Engine displacement is equal to (bore) x (bore) x (stroke) x (number of pistons) x (.785).

Distributor

A component of the ignition system, usually driven by the camshaft that directs high-voltage surges to the spark plugs in the proper sequence.

Double Wishbone Suspension ("A" Arm Suspension)

A system of independent suspension in which each wheel is located on a "knuckle" that is connected by ball joints to an upper A arm and a lower A arm. Usually, the lower A arms are longer. This system provides minimal changes in track and camber when the suspension is under load, as when going over bumps or in hard cornering.

Drag Coefficient

A measure of the aerodynamic sleekness of an object. Drag coefficient is signified by "dc.: The lower the number, the greater the aerodynamic efficiency. The higher the drag coefficient, the more a car's engine must work to keep a given road speed. Also known as "CD" for coefficient of drag."

Drivetrain

The power-transmitting components in a car, including clutch, gearbox (or automatic transmission), driveshaft, universal joints, differential and axle shafts.

Dual Overhead Camshafts (DOHC)

A DOHC engine has two camshafts in each cylinder head; one camshaft actuates intake valves and the other actuates exhaust valves. The camshafts act directly on the valves, eliminating pushrods and rocker arms. This reduced reciprocating mass of the valve train enables the engine to build RPM more quickly. DOHC designs are typically high-performance, four valve per cylinder engines. (A four valve per cylinder two intake and two exhaust design helps the engine "breathe" more freely for increased performance.)

Dynamometer

A device which absorbs and measures the power derived by an internal combustion engine.

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Auto Terms E

Electrolyte

Any solution that conducts an electrical current, such as a mixture of sulfuric acid and distilled water found in automotive batteries.

Electronic Fuel Injection System

A system that injects fuel into the engine and includes an electronic control unit to time and meter the fuel flow.

Electronic Ignition System

An ignition system that uses transistors and other semiconductor devices as an electronic switch to turn the primary current on and off.

EPA Fuel Economy Rating

Comparative mileage figures generated from laboratory fuel-economy tests administered by the federal Environmental Protection Agency (EPA) using simulated weight and drag to approximate real driving conditions.

Exhaust-Gas Recirculation (EGR)

An exhaust-emission control system in which a portion of the exhaust gas is picked up from the exhaust manifold and sent back to the intake manifold t be reburned in the engine. Mixing exhaust gases with the fresh air/fuel mixture lowers the combustion temperature and reduces the formation of oxides of nitrogen in the exhaust.

Exhaust Manifold

The network of passages that gathers the exhaust gases from the various exhaust ports and routes them toward the catalyst, the muffler and the exhaust system.

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