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BA: An abbreviation for "British Association" which is a term used to describe a series of fine, small diameter threads for electrical and precision equipment

babbitt: An alloy of tin, copper, and antimony having good antifriction properties. Used as a facing for bearings.

babbitt metal: See babbitt

baby seat: A specially designed seating device (which is not generally standard equipment) to hold safely very young children (usually under the weight of 10 kilograms).

BAC: Acronym for "Blood Alcohol Content"

back axle: The rear axle

back axle ratio: See final drive ratio

backbone: See backbone frame.

backbone chassis: See backbone frame

backbone frame: A frame, having the cross-section of a rectangular box, that runs along the center of the vehicle and occupies the space between the seats. This box generally divides at the front, running along each side of the gearbox and engine up to a crossmember to which the front suspension pieces are attached. At the rear a similar triangular frame encloses the final-drive housing and provides attaching points for the rear suspension. Lightness combined with high torsional rigidity are features of this frame design, made famous by Colin Chapman with the Lotus Elan.

backfire: [1] Passage of unburned fuel mixture into the exhaust system where it is ignited and causes an explosion (backfire) prematurely. [2] Sometimes ignition takes place in the intake manifold by a flame from a cylinder because the intake valve leaks. Burning of the fuel mixture in the intake manifold may be caused by faulty timing, crossed plug wires, leaky intake valve, etc. [3] A welding term referring to a short "pop" of the torch flame followed by extinguishing of the flame or continued burning of the gasses

backfiring: Repeated backfires in the exhaust or the cylinders

backflow scavenging: see loop scavenging

backflushing: See flushing the cooling system.

backhand welding: Welding in the direction opposite to the direction that the gas flame is pointing. Also called "backward welding."

backing: Some material placed on the root side of a weld to aid control of penetration

backing pad: A rubber disc which is secured to a spindle which in turn is attached to a drill or other tool which rotates the spindle. An abrasive disc or polishing disc is secured to the backing pad.

backing plate: See brake backing plate.

backlash: The amount of "play" or clearance between two parts. In the case of gears, it refers to how much one gear can be moved back and forth without moving the gear into which it is meshed.

backlight: The rear window of a vehicle.

backlight heater: Heated rear window

backlight defogging system: Heated rear window

back panel: See rear panel

backplate: British term for brake backing plate

back pressure: The resistance to the flow of exhaust gases through the exhaust system. By rerouting the exhaust gases for noise suppression, a muffler causes back pressure, but a straight pipe alone causes only minimal back pressure. Some engines require back pressure, so that removing the exhaust system will cause internal damage.

backrest: The back (upright) part of the seat against which your back reclines

back-step welding: Welding small sections of a joint in a direction opposite the direction that the weld as a whole is progressing.

back up: To go in reverse

back up alarm: An annoying loud beeping which is repeatedly sounded when a vehicle (usually a large truck) is placed in reverse. It is designed to warn pedestrians behind the vehicle. The British term is "reversing warning signal"

back up light: A light which is located at the rear of the vehicle and is illuminated when the transmission is placed in reverse. The British term is "reversing light"

back-voltage: Voltage which opposes the current when the current in an inductive circuit changes and the magnetic field cuts the conductors. Also see self-induction back-voltage

backward welding: See backhand welding

BAC level: Blood Alcohol level

badge: An emblem with a manufacturer's name and/or logo on a plate to identify a model or component

badge engineering: When a manufacturer sells two identical vehicles but the model names are different, he is badge engineering. For example, General Motors may sell a vehicle as a Chevrolet or a Pontiac where the only difference is the model name, logo, and more or less chrome or other minor alterations.

badging: The tendency of a manufacturer to engage in badge engineering

baffle: An obstruction used to slow down or divert the flow of gases, liquids, sound, etc. They are found in the fuel tank, crankcase, muffler, and radiator.

baffle plate: A metal plate that acts as a baffle.

bake: A process of drying or curing paint by using heat

Bakelite: The trademark for a synthetic thermosetting plastic resin used in electrical parts because it is a good insulator. The name comes from its inventor, L. H. Baekeland, 1863-1944.

baking finish: Paint that requires baking in order to dry

baking temperature: The temperature at which a varnish or paint must be baked to develop desired final properties of strength and hardness

balance: [1] The state in which weight is evenly distributed. [2] The action of applying weights or drilling holes in something to establish even weight distribution so that vibration is reduced. See balance shaft, counter balance, crankshaft counter-balance, dynamic balance, harmonic balancer, spool balance valve, spring balance, static balance, tire balance, and wheel balancer.

balance control: A switching device on a stereo radio which adjusts the amount of sound coming from the left and right speakers or from the front and rear speakers

balanced crankshaft: A crankshaft with extended reinforcements to form counterbalancing or act as a vibration damper

balance disc: A disc-shaped device in a centrifugal pump which is attached to the pump shaft. The disc lifts when a force is applied to the underside of the disc allowing pressure to leak past until the axial forces are balanced

balanced engine: An engine in which all the reciprocating parts such as pistons and connecting rods are adjusted to exactly the same weight

balance patch: A factory installed patch used to bring a new tire within quality control balance tolerances before distribution and sale. It is placed inside the tire casing and looks much like a nail hole repair patch.

balance pipe: A tube which joins two or more carburetors to even out the flow difference.

balancer: See harmonic balancer and wheel balancer.

balance shaft: An engine will normally vibrate because of the up-and-down motion of the pistons which turn a crankshaft in one direction. A balance shaft rotates (often in the opposite direction) so that its vibration cancels some of the vibration of the engine. Sometimes an engine will have two balance shafts turning in opposite directions located on either side of the crankshaft.

balance weight: A lead weight attached to the rim of a wheel. See wheel weight.

balancing: [1] Dismantling engine and reassembling it to exact specifications and tolerances. This process may help to improve engine performance, smoothness, and reliability. Sometimes called "blueprinting." See balanced engine. [2] Keeping wheels in balance. See wheel balancing.

balancing weight: See wheel weight

bald tire: A tire on which the tread is all worn away. A slick also has no tread, but this is done deliberately for racing purposes

balk ring: A friction-regulated pawl or plunger used to make the engagement of gears easier. British spelling is "baulk ring"

ball: A sphere usually made of metal when used in automotive applications. See ball and spring, ball bearing, ball joint, and ball joint rocker arm, hitch ball.

ball-and-nut steering: See recirculating ball steering

ball and socket: See ball joint

ball and socket joint: See ball joint

ball and spring: See detent ball and spring.

ballast ignition system: An ignition system which uses a ballast resistor connected in series with the coil primary winding and which is bypassed when the starter is engaged so that the spark is more efficient under cold weather starting

ballasting: The addition of liquid or dry weight inside the tire to act as a counterbalance, to increase traction, reduce wheel spin, and dampen out bounce.

ballast resistor: (BAL RES) A resistor constructed of a special type wire, the properties of which tend to increase or decrease the voltage in direct proportion to the heat of the wire.

ball bearing: An antifriction bearing consisting of an inner and outer hardened steel race (or cage) separated by a series of hardened steel balls.

ball bearing puller: A tool for removing a ball bearing from a shaft or from a housing

ball cage: A circular frame which holds the balls in place in a ball bearing

ball end hexagon screwdriver: A tool that looks like an Allen wrench except it has a small ball at the very end. This arrangement allows it to work at various angles.

ball joint: A flexible joint using a ball and socket type of construction, used in steering linkage setups, steering knuckle pivot supports, etc. Their flexibility helps to compensate for the changes in the wheel and steering when turning or hitting a bump on the road. There are usually upper and lower ball joints attached to the upper and lower A-arms.

ball joint rocker arm: A rocker arm that instead of being mounted on a shaft, is mounted upon a ball-shaped device on the end of a stud.

ball joint separator: A tool for forcing out ball or tapered joints. One style is shaped like a two-prong fork with a wedge-shaped jaw which is struck with a hammer to separate the joint. Another style uses direct pressure from a screw or screw-activated lever action to split the joint.

ball joint steering knuckle: A steering knuckle that pivots on ball joints instead of on a kingpin.

balloon tire: A type of low pressure tire which was first introduced in the 1920s. Its width and height were the same which gave it a rounded shape. This style was used on bicycles as well as automobiles.

Ballot: The 1925-1948 model automobiles with required application are classic cars.

ball peen hammer: A hammer with two ends on the head. One is round and the other is flat. They are best used for hammering and shaping metal

ball socket: A recessed spherical well for receiving the ball in a ball joint

ball valve: A check valve in which a ball in a tube is used to control the flow of liquid.

BAL RES: Abbreviation for ballast resistor

band: Bands are like a metal belt which is in the shape of a circle where the two ends are close, but do not meet. They wrap around parts inside the transmission called "drums." The drums house the gears and clutches and freewheel until a certain gear needs to be applied. When first gear needs to be applied, the drum for first gear is locked up by the application of the band. By locking up the drum, the gears now drive the wheels rather than freewheel inside the drum. Also see brake band and power band.

band brake: See brake band

bands: See band.

bandwidth: The range of audio frequencies that an audio component (radio) can handle

B & S: bore and stroke.

B & S gage: Abbreviation for "Brown and Sharpe." A standard measure of wire diameter.

B & S gauge: Abbreviation for "Brown and Sharpe." A standard measure of wire diameter.

banger: [1] A colloquial term used to express the cylinders in an engine. Often used with a number such as "six banger." Also see four banger. [2] A British colloquial term for beater (an older, cheaper, well-worn car which is still usable).

banger racing: A competition of speed on small racing tracks where older cars are driven as fast as they can go and where bumping other racing cars is permitted (encouraged??)

banjo: [1] Besides being a musical instrument, this is a fitting which is shaped like a banjo. It has round end that is doughnut shaped with a tube coming out from one side. It is usually used to transfer fluid from the center hole of the round end and out the lateral tube. [2] A drum-shaped central part of an axle casing containing the differential. See rear axle housing, banjo type.

banking: The slope of a track from the wall to the apron, generally measured in the corners.

bar: [1] A unit of pressure. One bar equals 100 kilopascals or 14.5 psi. [2] A rod. See anti-roll bar, boring bar, stabilizer bar, torsion bar, traction bar, and wheelie bars.

bar clamp: A tool with a stationary head and a sliding foot for clamping purposes

bare shell: The shell of a car body in which all parts have been removed including doors, hood, and trunk lid

BARO: Abbreviation for barometric pressure sensor

barometric pressure sensor: A sensor found in the engine management system which detects the ambient barometric pressure so that precise fuel mixture can be maintained at different altitudes

barrel: [1] The air horn in the carburetor. In particular, it is that part where the throttle valve is located. If a carburetor has four openings with a throttle valve in each, it is called a "four-barrel carburetor." Also see carburetor barrel. [2] Another name for the cylinder.

barrel tappet: A hollow rocker arm shaped like a barrel

barrier cream: A special cream which is applied to your hands before working on a greasy engine. When the job is over, you can wash your hands and easily remove the grease stains. Also called "invisible glove" or "silicon glove"

barrier effect: The effect produced by coating metal to shield it from corrosion

barrier paint: A primer which is used on bare metal to prevent corrosion.

base: [1] The lowest supporting part of an upright member. [2] The bottom layer or coating in a series of paint coats

base and clear system: Paint finish which is made up of a colored base coat (usually a metallic finish) and clear lacquer coat

base coat: The first coat in a paint system. It is either the undercoat or primer or a colored coat which is covered by clear lacquer

base circle: As applied to the camshaft lowest spot on the cam, the area of the cam directly opposite the lobe. Also called cam heel

base gasket: The gasket directly below the cylinder and between the cylinder and crankcase. Also called "cylinder gasket."

base material: Any material (metal or plastic) which needs to be coated

base metal: [1] Metal that is under a coating or that needs to be coated. [2] Metal to be welded, cut, or brazed.

base model: The least expensive vehicle with the least amount of features as standard equipment. It has the smallest engine and often manual transmission as well as few power equipment. Base models constitute only a small percentage of the cars sold. Sometimes called a "stripper" or "stripped down" unit.

baseplate: A strong metal plate which is the main support for something

basic ignition setting: The ignition setting on a non-running engine according to the specifications. After the engine is running, the timing can be set more accurately

basic ignition timing: The ignition timing on a non-running engine according to the specifications. After the engine is running, the timing can be set more accurately

basic price: The price of a vehicle without including any optional accessories, taxes, delivery charges, etc.

basic timing: The ignition timing on a non-running engine according to the specifications. After the engine is running, the timing can be set more accurately

basket case: An old car which probably does not run. Often many engine and transmission parts have been removed and are either missing or stored in the trunk or a "basket"

bastard: A file (a tool) which has a coarse cut

bastard file: A file with a coarse cut

bat: A lump or collection of something. Also see fibreglass.

batch: [1] A number of things which are produced as a group. [2] A mixture of natural and synthetic rubber with other material such as fillers, chemicals, and vulcanizing agents in the production of tires

batch number: A number which may be added to a serial number to identify when the product was manufactured. In this way, when a problem occurs to some products of the same batch, action can be taken to correct or replace others from the same batch.

bath: A tub into which something is immersed

battery: An electrochemical device for producing electricity by converting chemical energy. The typical automotive lead-acid battery supplies the source of power for cranking the engine and also provides the necessary electrical energy for the ignition system. In addition, it can (for a limited time) furnish current when the electrical demands of the vehicle exceed the alternator or generator output. Also called the "storage battery."

battery acid: Electrolyte (usually sulphuric acid) in each of the battery cells

battery cap: Small caps which seal each battery cell

battery capacity: The amp-hour capacity

battery cell: Individual compartments in a battery which is filled with electrolyte. Six-volt batteries have three cells, 12-volt batteries have six cells

battery case: The box made of polypropylene holding several chambers (cells) which have lead plates and filled with electrolyte.

battery charge: The condition or state of the amount of electricity in a battery

battery charge indicator: An instrument which shows the state of charge in a battery

battery charger: An electric device which is plugged into an electrical outlet (e.g., 110 volt AC) and connected to the two terminals of the battery to restore the state of charge in the battery. One of leads coming from the charger is red and the other is black. The red lead is clamped on the positive post of the battery while the other is clamped on the frame of the vehicle.

battery charging: The process of renewing the battery by passing an electric current through the battery in a reverse direction.

battery charging station: With the advent of electric cars, there needs to be places where their batteries can be recharged periodically -- thus is born the battery charging station. Also called a "charging point."

battery clamp: A hold down device which secures the battery from moving around

battery compartment: A place in the vehicle where the battery is located. In cars and trucks it may be found under the hood (usually toward the front), under one of the seats, or in the trunk. In motorcycles it is found in the middle of the bike, under the seat

battery condition: See battery charge

battery connector: A plug on battery-powered vehicles to connect the batteries to the charging station

Battery Council International: A group which makes decisions related to battery composition and disposal.

battery cover: The top of the battery case. It has several holes (covered with caps) for access to the battery cells.

battery discharge controller: A device on a vehicle which is driven by an electrical motor. It triggers a warning indicator when the battery power drops below a certain level.

battery discharge indicator: An instrument on a vehicle which is driven by an electrical motor which indicates the percentage of the maximum charge of the battery

battery earth: British term for battery strap or ground strap

battery filler: A device with a long hollow tube with a rubber bulb at one end. It is used for inserting into a container of battery acid and sucking up the acid, then inserting into the battery cell to fill it. However, motorcycle batteries arrive from the manufacturer with no electrolyte (battery acid). Battery acid comes in a large plastic container with a rubber hose to which a metering clamp is attached. The container is usually placed on a higher shelf so that it is fed into the battery by gravity and regulated by the metering clamp

battery fill line: A horizontal line on the side of a translucent battery case which indicates the level to which you fill it with electrolyte. Usually there are two lines indicating a minimum level and maximum level.

battery fluid: See battery acid

battery hold down clamp: See battery clamp

battery ignition: Any system where the battery supplies the initial voltage to power the starter motor and fire the spark plugs

battery ignition system: See battery ignition

battery is flat: The battery does not have enough electrical power to start the car

battery is flat: The battery does not have enough electrical power to start the car

battery master switch: A control which disconnects the battery power from all the electrical components

battery post: The terminal on a battery to which the cable is attached. Older automobile batteries used a round post which stood up from the top of the battery. To avoid confusion, the positive post has a larger diameter than the negative. On newer batteries the post may or may not be abandoned in favor of a terminal on the side of the battery. On motorcycle batteries, the posts are usually flat with a hole for bolting the cables to them.

battery state indicator: See battery charge indicator

battery strap: [1] 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 ground strap. See ground wire. [2] A rubber strap with metal hooks at each end and is used to secure a battery in place, especially on motorcycles

battery terminal: [1] A battery post on the top of the battery or a lug with a hole on the side of the battery. [2] The clamp at the end of a battery cable

battery tester: [1] A voltage meter or hydrometer for checking the state of charge of a battery. [2] An instrument for checking the condition of the battery cells

battery tray: A metal or plastic on which the battery sits.

baulk ring: British spelling for balk ring

bayonet bulb: See bayonet cap

bayonet cap: A cylindrical base of an electric bulb, usually with two pins projecting on either side, which engage in J-shaped slots to lock the bulb securely in its socket.

bayonet fitting: See bayonet socket

bayonet socket: A socket for receiving a bayonet cap. It has two slots on either side (usually J-shaped) to accommodate the bulb's pins.

BBDC: Acronym for "before bottom dead center."

bbl: Abbreviation for "barrel," as in 4-bbl carburetor.

BCI: Acronym for "Battery Council International."

BDC: Acronym for "bottom dead center."

bead: [1] The portion of a tire which fits onto the rim of the wheel. On a tubeless tire, the contact of the bead with the rim seals the air into the tire. Bead heel, bead sole, and bead toe form a foot-like shape. Also see tire bead. [2] A small ball-like particle used in bead blasting or in some catalytic converters. [3] In welding, it is the appearance of the finished weld. It describes the neatness of the ripples formed by the metal while it was in a semi liquid state.

bead base: The part of the tire bead which is in contact with the rim bead seat

bead blaster: A cleaning device for removing paint and contaminants from an object. See bead blasting

bead blasting: A cleaning process which uses glass beads which are forced by air pressure against the object to be cleaned. This system removes paint and contaminants from objects which are awkwardly shaped.

bead breaker: A device used to remove a tire from its rim by releasing the tension the bead has upon the rim.

bead core: The ring of steel wires in the tire's bead. Also called bead wires

beaded edge: The edge of a body panel or upholstery panel wrapped around a wire or other stiffening item

beaded edge tire: An older form of high-pressure tire with projecting beads

beader: A power tool for forming beads on the edges of body panels

bead expander: A device used in the mounting of tubeless tires to prevent inflation air from escaping and bring the tire beads against the tapered bead seat area (rim).

bead heel: The portion of the tire bead in contact with the rim flange

beading: The action of forming a step in the middle of a panel (not at the edge) which creates a shallow indentation to reinforce the panel

bead movement: Movement of the bead on the rim caused by improper inflation, excessive loading, improper design, improper seating, or improper rim or tire size. Also called "bead rocking." See bead unseating

bead seat: The portion of the wheel rim below the rim flange providing radial support to the bead of the tire

bead seat mat: A seat cover made of a network of wood beads

beam point: A feathered rubber extension of the bead toe used where a flap is not required; protects the tube from chafing between bead toes and rim base.

bead seat diameter: The measurement of tire diameter, at the bead heel, where it seats on the rim. It is marked on the tire sidewall following section width.

bead separation: A situation where the bead comes off the wheel rim

bead toe: The bottom portion of the tire bead in contact with the rim bead seat

bead unseating: Shifting of the tire bead from its seat on the wheel rim which often leads to the removal of the tire. See bead movement

bead wires: Steel wires wound around the circumference and placed in the beads. Their tension prevents the beads from lifting over the rim flanges. Also called bead core

beam: See high beam and low beam.

beam axle: A rigid or dead axle which supports the non-driven wheels. See axle.

beam indicator: A light on the instrument panel which comes on when the high beams are activated. Also called "high beam indicator"

bear: To turn as in the expression, When you get to the corner, bear right.

bearing: [1] The area of a unit in which the contacting surface of a revolving part rests in order to minimize wear and friction between two surfaces. [2] An antifriction reducing device that is usually found between two moving parts. The babbitt bearings found between the connecting rod and the crankshaft are lubricated and cushioned with oil, and the front wheel bearings must be repacked with grease at regular intervals. Bearings can be ball or roller type. Also see antifriction bearing, ball bearing, big end bearing, carrier bearings, clutch pilot bearing, friction bearing, insert bearing, main bearing, needle bearing, precision insert bearing, roller bearing, sealed bearing, tapered roller bearing, throwout bearing, and thrust bearing.

bearing assembly: When more than one load needs to be supported, several bearings are used making up the bearing assembly. For instance, a crankshaft may have two bearings (one at each end) as well as a few more in the middle

bearing block: The two halves of metal which encase a bearing.

bearing cage: See ball cage

bearing cap: A rigid, semicircular part which encloses and holds the outer shell of a shell bearing

bearing clearance: The amount of space left between a shaft and the bearing surface, this space is for lubricating oil to enter.

bearing cone: [1] taper roller bearing. [2] The inner race in an adjustable axial or radial ball bearing

bearing cup: [1] Retainers, held in place by bolts and nuts, that hold the bearings in place. Also called bearing shell. [2] The bearing race that curves around the outside of a ring of ball bearings and works in conjunction with a cone.

bearing face: The bottom part of a nut or bolt head which clamps down on the surface of the part it is securing.

bearing housing: The cavity into which the bearing fits

bearing material: The metal layer which forms the surface of the wear part of the bearing

bearing puller: A tool used to remove bearings from a shaft by pulling them off. It has two or more arms which circle around the back side of the bearing and a center post which butts up against the end of the shaft. As the center post is screwed down, the arms pull the bearing toward the end of the shaft.

bearing race: In ball or roller bearings, it is one of the two steel rings on either side of the ball or roller

bearing separator: A tool used to separate double bearings or close-fitting gears when a conventional bearing puller cannot be used

bearing shell: One of a pair of thin semicircular steel cups lined with an alloy such as coper-lead or lead-indium, which together enclose a shaft or other rotating member, and are held in a circular housing which can be divided into two halves.

bearing spread: A diameter which is slightly greater than the housing into which a shell bearing is being placed. Thus the bearing is forced into place to reduce its movement. See interference fit

bearing surface: The area of the bearing that is in actual contact with the shaft or other supporting member

beast: A vehicle which performs very well.

beater: An old or collectible vehicle that is in drivable condition, but looks terrible inside and out, and probably is missing many original parts. Often used to describe a vehicle that is past the easy restoration stage but still contains many good driving miles. It is also a term for "urban combat car" and is usually used in conjunction with the word winter, as in winter beater, which is a vehicle that is so far gone, it is sacrificed to the salt covered roads of winter. It is a disposable collectible that is driven until it disintegrates. In other words, it looks as if someone had been beating it for quite a while. British term is banger.

bed: Any flat surface used as a support

bedding-in oil: British term for break-in oil

bed in: British term for break-in

beefed-up: [1] Colloquial term for making something stronger. [2] Colloquial term for modifying or improving something so it will work faster or more efficiently. Similar to souped up

Beema: Colloquial term for BMW

Beemer: Colloquial term for BMW

Beetle: Colloquial term for the original rear-engined Volkswagen

before bottom dead center: (BBDC) As the crankshaft rotates, it brings the piston down to a place just before it reaches bottom dead center.

before top dead center: (BTDC) As the crankshaft rotates, it pushes the piston up to a place just before the top of its movement.

before upper dead center: (BUDC) As the crankshaft rotates, it pushes the piston up to a place just before the top of its movement.

bell housing: Sometimes called "clutch housing." The metal covering around the flywheel and clutch (of a manual transmission) or torque converter assembly (of an automatic transmission).

belt: [1] A reinforcing band, normally textile, fiberglass, or steel, which runs around the circumference of a tire and strengthens the tread area. Also see cog belt. [2] A circular band which is used to transfer power from one component to another. For instance, a fan belt is used to transfer power from the engine to the alternator, water pump, and air conditioner compressor. See fan belt. [3] seat belt

belt anchor: The point where the end of the seat belt is attached

belt anchorage: The point where the end of the seat belt is attached

belt drive: In order to transmit power from a source to a destination, some kind of connection is needed. A bicycle, for instance, uses a chain drive to transmit the power from pedalling action to the rear wheel. A belt drive uses a leather or rubber belt to transfer power from one pulley to another thus increasing or decreasing the speed of rotation of the driven pulley through mechanical advantage. For instance the alternator is rotated by a belt (sometimes called the "fan belt") which is driven by a shaft which is directly attached to the crankshaft. Some motorcycle models (like Harley Davidson and Honda) have a belt drive to transmit power to the rear wheels. Since a belt drive requires no lubrication (in contrast with chain drive) it is one of the cleanest final drive systems.

belted bias tire: A tire which uses both cross-ply and radial-ply patterns with added belts (such as used on radial-ply tires) on diagonal body plies (as in cross-ply tires). As a result the tire has stiffer sidewalls than tires with just straight radial plies.

belted piston: A piston with a continuous steel band cast into the skirt below the rings for controlling skirt expansion.

belted tire: A tire with a stabilizing belt of two or more plies of steel, fiberglass, etc., running circumferentially around the tire between the carcass and the tread rubber. The carcass can be either radial or bias ply. See bias belted tire.

belt end: The part of the seat belt which has the bracket which is attached to the floor pan. Some cars attach this end to the car seat itself.

belt line: The horizontal line that runs around the body of the vehicle just below the bottom of the glass panels (greenhouse). The British term is "waistline"


belt retractor: A device which automatically pulls the seat belt back into its reel

belt sander: A power sanding tool with a rotating belt of sandpaper

belt slack: The looseness of a belt (either the drive type belt or a seat belt)

belt slip: When a drive belt is not as tight as it should be, it will slip on the pulley and thus will not transmit power. If a driven pulley is seized, the belt will also slip.

belt tensioner: A device consisting of an idler pulley which is usually located between the drive and driven pulleys. It can be adjusted to increase the tension on the belt.

belt transmission: See belt drive

belt up: A British term for buckle up

belt webbing: Strong fabric material used for seat belts

bench: [1] A workbench. [2] A test bed for studying or repairing an engine. Also see bench test

bench grinder: A power tool mounted on a workbench with one or two grinding wheels

bench seat: A front seat which runs from the left door to the right door. The alternative is bucket seats. Also see split bench seat.

bench test: A determination of the power output of an engine when it is mounted on a test bed. Also it can be checked for oil leaks, fuel consumption, emission levels, etc.

bench vise: A vise which is mounted on a workbench

bending pliers: Pliers with flat, smooth jaws used to hold sheet metal in place

bending strength: The ability of metal to resist bending

Bendix: See Bendix type starter drive.

Bendix drive: See Bendix type starter drive.

Bendix screw: A helical screw on the shaft of a starter motor

Bendix starter: A starter motor with a Bendix drive

Bendix type starter drive: A self-engaging starter drive gear, the gear moves into engagement when the starter starts spinning and automatically disengages when the starter stops. Also called inertia drive

Bentley: The 1925-1945 models are classic cars. The 1946-67 models are milestone cars.

Benz: The 1925-1948 models with required application are classic cars.

benzene: (C6H6) A constituent of gasoline

berline: A term used during World War I which describes a closed luxury vehicle with small windows. The passengers were able to see out; but their privacy was maintained because it was difficult to see in.

between wheel spacer: An obsolete circular metal plate having a bolt hole circle and center bore and fitting between the faces of disc wheels to provide additional dual clearance.

bevel: The angle that one surface makes with another when they are not at right angles.

bevel differential: A differential which has bevel gears for its main elements. This allows the input and output shafts to be at right angles to one another. Also see spur differential

bevel drive shaft: A shaft with a bevel gear at one end or both ends. It is used primarily for driving an overhead camshaft

bevel gear: A gear shaped like the wide end (frustum) of a cone, used to transmit motion through an angle. They are found in differentials. Also see spiral bevel gear.

bevel gear drive: A transmission which is used to drive one or more shafts which do not line up with the output shaft. Also called bevel gear transmission

bevel gear transmission: A transmission which is used to drive one or more shafts which do not line up with the output shaft. Also called bevel gear drive

bevel joint: A piston ring gap in which the two ends of the ring are tapered.

beverage holder: A circular clip located on the center console, door panel, or dashboard which is designed to hold a cup or bottle. Also called cup holder

bezel: The crimped edge of metal that secures the glass face to an instrument. A bezel can be either decorative or functional. Some bezels are threaded and secure switches and control buttons to the dash, console, or steering column.

bhp: Abbreviation for brake horsepower.

bias: The acute angle at which the cords in the tire fabric intersect the circumferential centerline of the finished tire. Also see brake bias.

bias belted tire: A type of tire construction in which there are bias plies as well as a belt of steel or synthetic (rayon, nylon, or fiberglass) cords between the carcass and the tread. The belt overlaps the bias plies and wraps around the circumference. The cords and belt cross each other at bias angles.

bias ply tire: A tire having two or more carcass plies arranged in a criss-cross manner and diagonally to the beads and travels approximately 1/3 the distance around the circumference before attaching to the other bead. Each cord in the next ply is arranged in the same manner, but in the opposite direction. Also called a "conventional tire" or "cross-ply tire"

bias tire: A type of tire construction in which the tire cords or plies run diagonally from bead to bead. Generally in passenger cars, there are two plies of fabric. In a P185/80D13 tire, the D indicates a bias-ply tire. Sometimes called a "conventional" tire.

bib: A leather or vinyl covering for the front of a vehicle.

bicycle: A two-wheel non-motorized vehicle in which the two wheels are not side-by-side but in line. Also called "bike." See all terrain bike, coaster, girl's bike, loaded tourer, mixte frame, mountain bike, penny-farthing, quadricycle, sports tourer, tandem, tourist, tricycle, unicycle, and velocipede.

bicycle carrier: A device which is attached to the rear bumper or to the roof of a vehicle to carry a bicycle

big-block: See big-block engine

big-block engine: A large V-8 engine produced in the '60s and '70s. It typically has a cast-iron block and head and is fed by a carburetor. Contrasts with small-block engine.

big end: The end of the connecting rod which fits around the crankpin

big-end bearing: See big-end bearing
big-end bearing: The bearing in the end of the connecting rod that attaches to the crankshaft.

big-end bolt: One of the bolts attaching the big-end cap to the connecting rod

big-end cap: The detachable end of the connecting rod which fits on the crankpin

Big Jim: A colloquial term for a device for opening door locks. It is a flexible metal strip about an inch wide and very thin and has a J-shaped end. It is inserted between the door window and the door frame to trigger the latch

big three: General Motors, Ford, and Chrysler.

bihexagon: A twelve-sided figure. Some nuts and bolt heads have twelve sides.

bihexagonal: Having 12 sides

bihexagon socket: A tool socket which fits 12-sided nuts and bolts

bike: A two-wheel vehicle -- either a bicycle or a motorcycle. See all-terrain bike.

BIL: Acronym for "Bilimportorenes Landsforening" (Norway). Also Acronym for "Bilindustrief”reningen" (Sweden)

bill of lading: The cost or the paperwork describing the cost of a vehicle's load or freight.

bimetallic corrosion: When two different metals are attached to each other, some electrons tend to move from one metal to the other. This action happens especially when there is a little moisture between the two pieces. Also see galvanic corrosion

Bimmer: Colloquial term for BMW

binder: The ingredient in a paint that holds the pigment particles together. Also see binders.

binder bolt: On a bicycle, the bolt used to fasten a stem inside a steerer tube or a seatpost inside a seat tube.

binders: Vehicle brakes.

binding: [1] The rubbing of brake shoes against the drum or of brake pads against the disc. [2] The strip material turned over along the edge of a carpet or mat

binnacle: The cluster of instruments and switches mounted in a circular casing on or near the steering column

biocide: A product which kills any fungus or microbes that may have contaminated diesel fuel.

biodegradable: A product which is capable of being decomposed by bacteria into harmless elements without danger to the environment.

bit: [1] A tool for boring or cutting which fits into a drill. [2] The tip of a screwdriver

bit adapter: A tool (like a screwdriver) with a hollow socket (instead of the blade) to accept a variety of bits

bite: [1] A vehicle's ability to adhere to the road (especially to a racing track). [2] The ability of a tool to secure itself to a fastener as in I want my wrench to get a good bite on that bolt.

bituminous paint: Black or dark colored tarry paint which contains bitumen. Used for the protection of exposed metal parts.

BL: Acronym for "British Leyland"

black and white checkered flag: A flag which is waved at the finishing line in races to indicate the winner.

black box: [1] A recording device which reveals conditions just prior to a crash. [2] A control unit

black chromium plating: An electroplating deposit of a black chromium layer for decorative purposes

blackening: See bulb blackening

black flag: A flag which is colored black and is waved at a race. It indicates that the driver must return to his pit for consultation. It means that the driver has violated a serious racing rule such as spilling fluid on the track or was speeding on the pit road.

Blackhawk: The 1925-1948 models are classic cars.

blackwall: Tires which do not have any white or red coloring. See whitewall and red line.

bladder: A hollow bag which can be inflated. In some instances, fuel tanks will become rusty inside. A possible cure is to install a bladder. This is done by flushing out the rust chips, applying an acid solution to remove any oil/gas residue, and coating the inside with a plastic compound. When done correctly, this plastic coating does not dissolve when it comes in contact with gasoline.

blade: [1] A straight narrow flat part like the end of a screwdriver or knife. [2] The part of a windshield wiper (blade rubber) which contacts the windshield. [3] One of the vanes of a rotor or impeller

blade connector: A plain metal tongue for forming electrical connections

bladed impeller: A rotating part of a centrifugal pump that has blades or vanes

blade rubber: The rubber strip that fits into the arm of a windshield wiper

blanking piece: A flat piece of metal which closes off a tube. Also called a "blanking plate"

blanking plate: A flat piece of metal which closes off a tube. Also called a "blanking piece"

blanking plug: A rubber stopper for filling in the holes of bodywork such as drain holes in the floorpan

blast cleaning: The removal of corrosion, dirt, paint, etc. by a blast of abrasive particles. Also see bead blasting and sand blasting

bleed: [1] To remove air bubbles from hydraulic lines and components of a system. Also see air bleed, air bleed screw, and compensating jet. [2] To reduce the air pressure in tires that have been run, warmed up, and thus increased from their starting pressure -- an action which should be avoided.

bleeder: The valve or screw used to vent the air out of a liquid-filled system. See brake bleeder and pressure bleeder.

bleeder screw: A screw used to release the air from a system like the brake system. Also see idle air bleed screw.

bleeder valve: The device which vents air from the brake system.

bleed screw: A screw used to release the air from a system like the brake system. Also see idle air bleed screw.

bleed valve: The device which vents air from the brake system.

bleeding: [1] A lower (older) color coming through a fresh coat of paint. [2] The action of venting air from a liquid-filled (hydraulic) system. [3] Reducing the air pressure in tires that have been run, warmed up, and thus increased from their starting pressure -- an action which should be avoided.

bleeding a system: Remove air bubbles from a brake system, a fuel injection system, or a cooling system so that they won't impede the flow of liquid through that system.

bleeding the brakes: This refers to the removal of air from the hydraulic system, bleeder screws are loosened at each wheel cylinder, (one at a time) and brake fluid is forced from the master cylinder through the lines until all air is expelled.

blem: An abbreviation for blemish.

blemish: A tire with a slight imperfection in appearance that will not affect tire life or safety. Also called a "blem."

blind rivet: A pop rivet

blind spot: An area not visible from the driver's seat. It is usually the area behind the rear quarter and not visible in the mirrors. When approaching another vehicle in a lane beside you, avoid being in its blind spot. Also do a shoulder check before switching lanes to check for vehicles in the blind spot

blister: [1] A bubble on a paint surface. [2] A localized bubble on the surface of a tire, normally caused by a separation between plies or between surface rubber and a ply.

blistering: The formation of bubbles on the paint surface.

BLM: Acronym for the "Bureau of Land Management."

BLMC: Acronym for "British Leyland Motor Corporation"

block: That part of the engine containing the cylinders. Also see cylinder block, EN-block, brake pad, block heater, die, monoblock, rubbing block, and sanding block.

block heater: A devices which, during very cold weather, keeps the engine warm when the vehicle is not being used -- thus making cold starts easier. The free end is plugged into 110 volt AC wall socket. It is especially important for starting diesel engines at very low temperatures.

blocking ring: See balk ring

block sanding: The process of using a wooden block wrapped in sandpaper to sand the material.

blood alcohol content: The amount of alcohol in the bloodstream as a result of drinking liquor

blood alcohol level: The amount of alcohol in the bloodstream as a result of drinking liquor

bloom: A surface film on rubber, caused by the migration to the surface of sulphur, wax, or other unreacted ingredients of the compound. It may be protective to the tire and detrimental only if appearance is a major factor.

blooming: A formation of an undesired thin surface film or a milky white haze or mist on paintwork. It is caused when paint is applied during humid, cold conditions as moisture is trapped in the wet film

blow: To become defective either by leaking or burning through

blow back: Because of a sticky valve or the intake valve closing late, some of the air-fuel mixture is blown back through the carburetor

blowby: The mixture of fuel-air which is lost past the piston rings and causes fumes that form acid and sludge in the crankcase and smoking from the oil filer hole. Generally there is a loss of engine power. Most are removed through the PCV system.

blow-by: The mixture of fuel-air which is lost past the piston rings and causes fumes that form acid and sludge in the crankcase and smoking from the oil filer hole. Generally there is a loss of engine power. Most are removed through the PCV system.

blowdown: The escape of gases between the opening of the exhaust valve and the piston reaching bottom dead center, or in a two-stroke engine between exhaust port opening and transfer port opening.

blowdown period: In a two-stroke engine, it is the time between the exhaust port opening and the transfer port opening which should be sufficiently long enough to allow time for the cylinder pressure to drop below the crankcase pressure, so that the exhaust gases can be expelled more easily

blower: [1] Also called a "supercharger" or "turbocharger." This is a pump which forces air into the cylinders at higher than atmospheric pressure. The increased pressure forces more air into the cylinders than what would be drawn in normally. In this way the engine can burn more fuel and thus produce more power. There are two main types of blowers: the turbocharger, which uses some of the waste heat energy in the exhaust gases to drive a compressor and pump the air; and the belt-driven or shaft-driven supercharger which uses engine power to pump air. [2] A fan for an interior heating and ventilating system or even for an air-cooled engine

blow gun: A paint spray gun with a wide nozzle which is fed by air pressure. It is used to blow out crevices in material that is otherwise hard to reach.

blowlamp: A British term for blow torch

blown: [1] An engine equipped with a turbocharger or supercharger. [2] An engine which is ruined. Usually the piston is seized. Also see blown head gasket.

blown head gasket: A gasket that has a break between the opening for the cylinder and an opening for the coolant. The coolant will leak into the combustion chamber. This condition can be diagnosed by a loss in coolant and white smoke out the exhaust.

blowoff valve: A one-way valve that opens to the atmosphere above a certain set pressure to relieve excessive internal pressure buildup; often used with a turbocharger installation to limit boost pressure to the engine.

blow out: To clean a dirty or blocked pipe by blowing compressed air through it

blowout: A sudden rupturing of tire body, causing complete loss of air pressure which flattens the tire.

blow-out: A sudden rupturing of tire body, causing complete loss of air pressure which flattens the tire.

blow-over: A respray of doubtful quality, often poorly prepared and carelessly masked.

blowpipe: Another term applied to the oxyacetylene torch

blow torch: A tool which is attached to a bottle of flammable gas. The gas is ignited to give an intense flame for brazing and soldering. The British term is "blowlamp"

blue book: A listing of the current prices for used cars, based on age, condition, and optional equipment. Available at banks, loan offices, libraries, and insurance companies.

blueing: The blue color that appears on chrome pipes when subject to intense heat. In some cases, it can be removed; but most often it is permanent.

blueprinting: Dismantling engine and reassembling it to exact specifications and tolerances. This process may help to improve engine performance, smoothness, and reliability. Sometimes called "balancing."

blue smoke: The color of the exhaust which indicates that the fuel mixture is too rich

blushing: The formation of a whitish or misty appearance on the finish color.

BMC: Acronym for "British Motor Corporation"

BMEP: Acronym for brake mean effective pressure

BMW: Acronym for "Bayerische Motoren Werke." The 1925-48 models 327, 328, 327/328, and 335 are classic cars. The 507 models for 1957-59 are milestone cars.

BMW roundel: The little black, blue, and white BMW checkerboard logo.

board: A printed circuit board

board test: A test of a printed circuit board

boat trailer: A trailer for carrying a boat

bodge: A British term to describe work that is done poorly or with defective materials

bodily harm: Physical injury to a person caused by an accident

bodily injury: Physical injury to a person caused by an accident

body: [1] The main portion of an automobile. Often it refers just to the outside shell. [2] The main part of a housing. [3] The shank of a bolt. [4] In welding, it refers to the main structural part of a regulator.

body assembly: The building up of the automobile body from its various components

body builder: A person who builds automobile bodies, i.e., coachbuilder.

body-colored: Something that is painted the same color as the body. Also see color-coded

body component: Any structural part that makes up the body of a vehicle.

body construction: The manufacturer of a vehicle body

body file: When patching hole in a body panel and filling it with body putty, a body file which is a hand tool) is used for smoothing the putty to conform to the contour of the body

body filler: A substance (often with the name Bondo) which is a paste used to fill minor imperfections in a body panel. It hardens and is shaped to fit. It can also be painted to match the rest of the vehicle.

body flange: A point on the body where two panels overlap, forming a small step

body framing: An assembly of the body components

body glass: The windshield, backlight (rear window), and side windows of a vehicle

body hammer: A hammer with a large flat pounding surface for removing dents

body-in-white: In the process of building a vehicle, this is a body shell after everything is welded but before it is painted

body jack: A hydraulic tool for pushing or pulling body panels into shape

body lead: An alloy of lead and tin which is used to fill dents and seems in a body panel to establish a smooth surface. When heated it flows easily to fill the imperfections

body panel: The sheet metal that forms the outside body pieces.

body putty: A malleable material designed to smooth on dented body areas, upon hardening, the putty is dressed down and the area painted. Also called "bondo."

body rattle: A noise in the bodywork usually cased by loose parts, badly fitting doors, hood, or trunk lid

body repair: After a vehicle has suffered an accident or has corroded panels, the body needs to be repaired to bring it back to like-new condition

body roll: The rocking or tilting motion of a vehicle when it goes around the corner

body sealer: A tar-like substance which is used to seal body joints

body shell: The bare skeleton of a vehicle with all the wheels, doors, hood, trunk lid, etc. removed

body shop: A service outlet specializing in vehicle body repair work.

body side molding: A protective stripe along each side of the vehicle running from the leading edge of the front fender, along the door panel(s) to the rear end of the back fender. It may be solid plastic or rubber attached directly to the panels while others are attached to a metal strip which in turn is attached to the panels.

body spoon: A tool with a flat contoured working surface like a spoon. It is used to slap out dents and is sometimes used in place of a dolly when it is too difficult to reach behind the panel

body stripe: A decorative stripe applied to a motorcycle fuel tank or the outside of a car to enhance the appearance. Sometimes model names are also part of the stripes.

body styling kit: An additional set of bolt-on parts (like spoilers, air dams, fender skirts, laker pipes, wings) which are intended to improve the looks, performance, and efficiency

body tub: The bare body shell (minus the doors, trunk lid, hood, fenders) which is lowered onto the chassis at the time of assembly

bodywork: The complete body structure mounted on the chassis of a vehicle with a separate chassis, and the complete sheet metal panel for unibody vehicles.

bog: A hesitation usually experienced when starting out.

bogie: An assembly of four wheels on two axles with common suspension, usually on heavy commercial vehicles, trailers, and older Ski-Doos

bogie wheel: One of the suspension wheels on an older Ski-Doo

boil: The process of change from a liquid to a gas through the application of heat.

boiling point: The exact temperature at which a liquid begins to boil or changes to a gas (i.e., vaporizes). The boiling point of a liquid decreases with increasing altitude, and increases with pressurization. The coolant in a modern radiator/coolant system can be as high as 260°F (127°C). See dry boiling point and wet boiling point.

bold-up: The application of retread or repair rubber.

bolster: [1] A supporting brace. [2] The act of supporting

bolt: A securing device upon which a nut is threaded. It usually has a nut-type head. It is usually measured not so much by the size of the wrench required to secure the bolt; but by the diameter of the threads, the thread pitch, the length of the bolt under the head, and the strength of the bolt. See binder bolt.

bolt and nut: A pair of objects with matching screw threads. When either the bolt or the nut is turned, it moves with great force. Often used as fixing devices. The nut is the circular piece that looks like a ring with threads on the inside hole. The bolt is the shaft with threads. Also see pivot bolt.

bolt hole: The hole in metal through which a bolt must be inserted or screwed in place. See wheel bolt hole.

bolt hole circle: See wheel bolt hole circle.

bolt-on: Accessories which are easily secured to an automobile with just a few bolts rather than having to be welded in place. Usually done by the owner.

bolt-on fender: A fender which is secured with bolts rather than being welded in place

bolt-on goodies: Accessories which are easily secured to an automobile, but are often for show rather than function

bolt-on kit: A group of parts available in one package which the owner can attach himself.

bolt-on wing: British term for bolt-on fender

bomb: A vehicle which is in very poor shape, "The car is a bomb and not worth a nickel." In contrast, it can mean a vehicle which has great acceleration, "The car flew down the track like a bomb."

bond: [1] A state of adhesion. [2] The act of connecting two components by means of a glue or adhesive [3] The junction of the weld metal and the base metal

bonded brake lining: brake lining that is attached to the brake shoe by an adhesive rather than by rivets.

bonding agent: A material which provides adhesion

bonding method: A procedure of joining two components with adhesive

bondo: See body putty.

bone: See A bone, T-Bone, backbone frame herringbone gears wishbone.

bonnet: British term for vehicle hood.

bonnet badge: British term for hood badge

bonnet bump rubber: British term for hood bump rubber

bonnet bumper: British term for "hood bumper" or hood bump rubber

bonnet landing panel: British term for hood landing panel

bonnet liner: British term for hood liner

bonnet lock: British term for hood lock

Bonnet pin: British term for hood pin

bonnet pin kit: British term for hood pin kit

bonnet release: British term for hood release

bonnet stay: British term for hood rod

bonnet support: British term for hood rod

bonnet tape: British term for hood tape

book: See blue book.

booming: [1] A noise caused by interruptions to the flow of air such as an open windows. [2] Low pitched resonance, especially in the exhaust. [3] Thumping sound coming from large stereo woofers

boost: [1] The amount of positive pressure created in an intake system above normal atmospheric pressure by a turbocharger or supercharger. Normal atmospheric pressure is 14.7 psi. A blower providing 10 psi boost increases the pressure to 24.7 psi. Boost is sometimes measured in atmospheres where one atmosphere equals 14.7 psi. Thus 24.7 psi is about 1.7 atmospheres. [2] The action of jump starting one battery from another. [3] To increase power, charge, or pressure, etc.; or to amplify volume, audio sound, etc.

boost control valve: See blowoff valve

booster: [1] A radio device which amplifies the signal or the audio output to the speakers. Because of its size it is mounted in the glovebox, under the dash, in the center console, under the seat, or in the trunk. [2] A device incorporated in vehicle system (such as brakes and steering), to increase the pressure output or decrease amount of effort required to operate, or both. See brake booster, power booster, spring booster, and vacuum booster.

booster battery: A second battery used in commercial vehicles to give a little more power when starting.

booster cable: See jumper cables

booster coil: A secondary ignition coil which increases the intensity of the spark

boost gauge: An instrument which indicates boost pressure

boost pressure: Pressure in the intake system of a supercharged engine when the supercharger operates. See the first definition of boost.

boost sensor: A sensing device in a supercharger. It is located in the choke tube which sends a signal to the ignition control unit according to pressure conditions. In turn, the control unit adjusts the ignition timing for the best performance.

boost valve: A valve in a hydraulic system which increases the pressure

boot: [1] British term for trunk. [2] The rubber or plastic cover located at either end of the spark plug cable to insulate the connections between the cable ends and the spark plug and distributor terminal. Always grasp the cable by the boot when removing it. [3] The protective cover of the ball joint that holds the grease. [4] The covering around the CV joint. [5] A simple protective device (sometimes a piece of tube, tire, etc., cut to size) placed between the casing and tube. It offers temporary protection for the tube against pinching by an injury in the casing. It is not a repair of the injury and is unsafe to use. [6] A denver boot, which is a device which clamps on the wheels of a parked car to immobilize it.

booted: A vehicle which has been disabled by a denver boot is said to be "booted."

booted version: British term for trunk model

boot handle: British term for trunk handle

bootlid: British term for trunk lid

boots: See boot.

boot spoiler: British term for trunk spoiler

bore: [1] The cylinder hole itself. [2] The diameter or width of the cylinder. [3] As a verb, it means to cut a circular hole.

bored: To increase the diameter of the cylinder. Also see stroked.

bore diameter: The diameter of the cylinders. It is usually measured in either inches or millimetres. When a cylinder is bored out because of scored walls, it is increased by "ten thou" of an inch (0.01") or 0.25 mm.

bore-stroke ratio: The relation between the diameter of the cylinder bore and the length of the stroke of the piston. If the stroke is longer than the cylinder bore diameter then the engine is called a long stroke engine. If the stroke is shorter than the cylinder bore diameter then the engine is called a short stroke engine. If the stroke is the same as the distance of the cylinder bore diameter then the engine is called a square engine

boring bar: A machine used to cut engine cylinders to a specific size. As used in garages, to cut worn cylinders to a new diameter.

boring: Renewing the cylinders by cutting them out to a specified size, a boring bar is used to make the cut.

boss: An extension or strengthened section that holds the end of a pin or shaft. For example, the holes in the piston through which the piston pin is placed would easily break the thin walls of the piston when under pressure. The area around the hole (on the inner side of the piston) are strengthened to prevent breakage. This area is the piston boss.

bossing mallet: A hammer with a pear-shaped wooden head used for shaping and stretching metal over a sandbag or wooden block.

botch: [1] A repair job which is very poorly done. [2] To do a repair job poorly

botched-up job: A colloquial term for a poor repair which will not be permanent.

bottled gas: (LPG) (liquefied petroleum gas or propane) gas compressed into strong metal tanks. The gas, when confined in the tank, under pressure, is in liquid form.

bottle jack: A hydraulic lifting device which is in the shape of a bottle

bottleneck: A traffic situation where the road narrows to the point where traffic is excessively slowed

bottom: [1] The lowest point. [2] To lower something. [3] To reach the end of its travel (i.e., bottom out). [4] To make contact with the road

bottom bracket: The cylindrical part of a bicycle frame that holds the crank axle, two sets of ball bearing, a fixed cup, and an adjustable cup.

bottom dead center: (BDC) The lowest point of the piston and connecting rod travel in a cylinder. In a horizontally opposed engine, it is sometimes called the outer dead center. Opposite to top dead center

bottom dumps: Trailers that unload through bottom grates.

bottom end: [1] All the moving parts in the crankcase and their bearings. [2] The lower range of engine revolutions

bottom end gasket kit: All the gaskets below the base gasket (crankcase gaskets and inspection cover gaskets) and all the O-rings and replaceable spacers in the bottom end of an engine. Also see top end gasket kit.

bottom gear: The lowest gear in a transmission.

bottoming: [1] A situation where the suspension reaches the end of its travel. [2] A situation where the lowest part of the chassis touches the ground, especially on a bump

bottom out: To reach the end of its travel.

bottom tank: In a thermosyphon water-cooling system, this is the bottom radiator tank. Also see header tank and radiator tank

bounce: [1] When referring to valves, it indicates a condition where the valve is not held tightly closed in the seat even though the camshaft has not opened it. Also called "flutter." [2] When referring to a distributor, it indicates a condition where the points make erratic contact when they should remain closed. [3] When referring to suspension, it indicates an up-and-down motion called "jounce" and "rebound." You can test it by pushing down and releasing a corner of a vehicle

bound electron: See b.

bound electrons: Electrons in the inner orbits around the nucleus of the atom, they are difficult to move out of orbit.

bourdon tube: A circular, hollow piece of metal that is used in some instruments, pressure on the hollow section causes it to attempt to straighten, the free end then moves a needle on the gauge face.

bowden cable: A wire control cable within a sheath and used for activating the clutch, choke, or accelerator

bowed: A bent shape.

bowl: See float bowl.

bowser: A tanker used for refuelling military ground vehicles or airplanes

bow wow: A vehicle in very bad shape. A dog.

bow-wow: A vehicle in very bad shape. A dog.

box: [1] Colloquial term for a transmission. [2] See E-box. [3] A silencer

boxed rod: connecting rod in which the I-beam section has been stiffened by welding plates on each side of the rod.

boxer engine: A horizontally opposed engine.

box member: A structural part made as a box section

box section: A closed panel structure of square cross section which is used to strengthen a vehicle's underbody

box spanner: A British term for a hollow tube with a socket at each end and two holes through which a bar can be inserted to turn the wrench. The bar is called a T-bar; but the British call it a tommy bar

box van: A British term for a cube van with a large cargo box behind the driver's cab.

box wrench: A tool designed to secure or remove a bolt or nut. Each end of the wrench fits around the bolt head or nut. British term for "ring spanner." In contrast, see open end wrench.

boxy: A derogatory description of a car that has square angles instead of smooth curved lines.

boy racer: A low-cost car without much sophistication or performance; but it does have a very sleek and sporty appearance.

B-pillar: The center body pillar on sedans. It connect the sills and provides roof support. Sometimes referred to as simply post, as in 1957 Chevy two-door post. On a true hardtop design these pillars are missing, leaving uninterrupted glass area along the sides of the car. Also called "B-post."

B pillar: See B-post.

B post: B-post.
B-post: The center body post on sedans. It connect the sills and provides roof support. Sometimes referred to as simply post, as in 1957 Chevy two-door post. On a true hardtop design these pillars are missing, leaving uninterrupted glass area along the sides of the car. Also called "B-pillar."

brace: A support beam to give reinforcement between two objects.

bracing: [1] To stiffen something by using a brace. [2] A brace

bracket: a support device which is often a right-angled shape.

braided hose: A rubber hose which is covered in a woven material or braided wire. Used for various hoses under the hood.

brake: [1] To slow down a vehicle. [2] The mechanism that converts motion (kinetic energy) into heat energy through friction. The most common instance is found in the wheels of cars where the brake shoes or disc pads are designed to press against the brake drum or brake disc. Also see anti-lock brake system, bonded brake lining, cantilever brakes, dual brakes, emergency brake, hub brake, inboard brakes, jake brake, juice brakes, mechanical brakes, parking brake, power brakes, primary brake shoe, primary forward brake shoe, prony brake, rim brake, rollercam brakes, self-energizing brake shoe, servo action brakes, and U-brakes.

brake adjuster: A device which moves the drum shoes closer to or further apart from the drum.

brake adjusting spanner: A British term for brake wrench

brake adjusting wrench: A wrench which is used to adjust the brake shoes

brake anchor: A steel stud or pin upon which one end of the brake shoes is either attached to or rests against. The anchor is firmly affixed to the backing plate.

brake, anti-lock: See anti-lock brakes.

brake antiroll device: See brake anti-roll device.

brake anti-roll device: A unit installed in the brake system to hold brake line pressure when the vehicle is stopped on an upgrade, when the vehicle is stopped on the upgrade and the brake pedal released, the anti-roll device will keep the brakes applied until either the clutch is released or as on some models, the accelerator is depressed.

brake backing plate: A rigid metal (steel) plate, located inside the brake drum, on which the wheel cylinder, brake shoes, and other brake parts are mounted. The braking force applied to the shoes is absorbed by the backing plate.

brake band: A band, faced with brake lining, that encircles a brake drum, it is used on several parking brake installations. It differs from brake shoes in that brake shoes squeezes against the inside surface of a drum while a brake band squeezes against the outside surface of a drum.

brake bias: The front/rear distribution of a vehicle's braking power. For the shortest stopping distance, brake bias should match the vehicle's traction at each end during hard braking brake modulation -- the process of varying pedal pressure to hold a vehicle's brakes on the verge of lockup. Ideally, the brakes will unlock with only a slight reduction in the pressure needed to lock them. Typically, however, a considerable pressure reduction is required.

brake bleeder: A valve attached to each wheel brake. This valve can be opened and closed to allow air to be removed or bled from the brake lines.