Radiator Glossary of Terms
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Backfire
The sudden combustion of gases in the intake or exhaust system that results in a loud explosion.
Backing Plate
Steel plate on which wheel cylinders(s), brake shoes and other drum brake parts are mounted.
Backlash
The clearance or play between two parts, such meshed gears.
Backspacing
The distance from the back edge of a wheel rim to the back of the center section.
Bakelite
A heat resistant, plastic insulator material commonly used in printed circuit boards and transistorized components.
Balance
The equal distribution of the mass of the tire and wheel assembly for smooth driving. Balance is achieved by fitting weights to the wheel rim to offset uneven weight distribution of the tire or wheel.
Ball Bearing
A bearing made up of hardened inner and outer races between which hardened steel balls roll.
Ball Joint
A flexible coupling in a vehicle's suspension that connects the control arm to the steering knuckle. A ball joint is so named because of its ball-and-socket construction. Some are designed to never require grease while others should be lubed every six mon
Ballast Resistor
A resistor in the primary ignition circuit that lowers voltage after the engine is started to reduce wear on ignition components.
Barometric Pressure
The pressure exerted by the weight of the earth's atmosphere, equal to one bar, 100 kilopascals, or 14.7 psi (often rounded off to 15 psi) at sea level. Barometric pressure changes with the weather and with altitude. Since it affects the density of the ai
Barometric Pressure Sensor
A device that senses barometric pressure for the engine control system. May be combined with a Manifold Absolute Pressure (MAP) sensor.
Battery
The battery is a storehouse of electrical energy for starting the engine. All cars and light trucks today have a 12-volt battery. Most are also maintenance-free, meaning you don't have to add water to them periodically. Some even have built-in charge indi
Bead
An inextensible hoop of high tensile steel wires that anchors the plies and conforms to the rim seat to hold the tire onto the wheel rim.
Bead Seat
The inner ledge portion of the wheel rim where the tire bead rests adjacent to the flange.
Bearing
A friction reducing, supportive device usually located between a stationary part and a moving part.
Belts
The plies of tire cords beneath the tread that determines the tire's diameter and stabilizes the tread by resisting deformation from cornering, braking, and centrifugal forces.
Bias-Ply
A type of tire construction utilizing plies that run diagonally from one bead to the other. One ply is set on a bias in one direction, and succeeding plies are set alternately in opposing directions crossing each other. Some times called a cross-ply tire.
Bimetal Temp Sensor
Any sensor or switch made of two dissimilar types of metal that bend when heated or cooled due to the different expansion rates of the alloys. These types of sensors usually function as an on/off switch.
Bleeding
Method of purging air from a brake system's hydraulic lines and cylinders. Air is compressible and contaminates brake fluid. It is released via a "bleeder valve" on each wheel cylinder.
Blending
The mixing of base stocks and additives to produce a lubricant with specified properties.
Blowby
Combustion gases, composed of water vapor and unburned fuel, that leak past the piston rings into the crankcase during normal engine operation. These gases are removed by the PCV system to prevent the buildup of harmful acids in the crankcase.
Body Roll
The leaning or tipping of a vehicle's body to one side when turning sharply. This reduces traction and increases tire scuff due to undesirable alignment changes. Body roll is controlled primarily by a sway bar, but the stiffness of the springs and shocks
Bonded Lining
Brake lining (friction material) attached to the brake shoe with adhesive.
Brake Balance
The ratio of braking force distributed between the front and rear wheels.
Brake Bleeding
This is the process of removing air bubbles from the brake system by pumping fluid through the lines. Air bubbles are bad because they compress when pressure is applied resulting in a low or spongy feeling pedal. The correct procedure for bleeding the bra
Brake Disc
The basis of a disc brake system: a round metal disc which rotates with the road wheel and, in order to generate braking power, is clamped by a caliper holding two friction linings (pads).
Brake Drum
The basis of a drum brake system. It is a circular metal component that rotates with the road wheel. A set of brake shoes that are fixed in position and act on the drum by expanding.
Brake Fade
A reduction in brake power due to lessening of friction between the brake shoes and drum or pads and disc. Brake fade often occurs from heat buildup due to repeated or prolonged brake application.
Brake Feel
Sensation transmitted to the driver during a braking action via the brake pedal.
Brake Flushing
An operation where the brake system is flushed with alcohol or brake fluid to remove water, dirt and other contaminants. Fluid is placed in the master cylinder and forced through the lines and wheel cylinders, exiting at the cylinder-bleed screws.
Brake Hose
Flexible rubber (or synthetic) hose used to join hydraulic brake components.
Brake Line
Rigid tubing which links various hydraulic components in a brake system.
Brake Lines
The system of hoses and tubes where brake fluid flows through from the master cylinder to the brakes at each wheel. Leakage caused by fluid seeping from cracks in brake lines can cause loss of brake power.
Brake Lining
Common name for Friction Material.
Brake Master Cylinder
The component in the hydraulic brake system in which the brake fluid is stored.
Brake Pad
A brake shoe and lining assembly used with disc brakes.
Brake Fluid
The brake system uses a glycol-based hydraulic fluid. The fluid is "hygroscopic," which means it tends to absorb moisture over time (never leave a can of brake fluid open for this reason). Moisture lowers the boiling point of the fluid and causes internal
Brake Job
A typical brake job includes replacing the brake linings (new disc brake pads and shoes), resurfacing the rotors and drums, adding fresh brake fluid and bleeding the system, and inspecting/replacing any other worn components (usually at extra cost). If ro
Brake Rotors
The flat disk-like plates that provide the friction surface in a disc brake. When hydraulic pressure is applied to the caliper, the brake pads are squeezed against both sides of the rotor producing friction and heat. Some rotors have cooling fins between
Brake Shoe
The backing for the brake lining. The term is, however, usually applied to the assembly of the brake backing and lining.
Brake Squeal
The annoying high-pitched screech that's sometimes heard when braking. A common ailment on many disc brake-equipped cars, it is caused by vibration between the brake pad and rotor. It causes no harm, but metallic scraping sounds should be investigated bec
Brakes
The brake system uses hydraulic pressure to stop the vehicle when you step on the brake pedal. Pushing the pedal down pumps fluid from the master cylinder to the brakes at each wheel. This squeezes the brake linings against the rotors and drums, creating
BTU
Abbreviation for British Thermal Units. One BTU is the amount of heat it takes to heat one pound of water one degree Fahrenheit. The energy value of various fuels is often expressed in so many BTUs per gallon. Gasoline, for example, has around 120,000 BTU
Bump Steer
The tendency of a vehicle to suddenly veer or swerve to one side when hitting a bump or dip in the road. The condition is caused by uneven toe changes that occur as a result of the steering linkage or rack not being parallel with the road surface. This ca
Bump Stops
Rubber bumpers (often cone or wedge shaped) on the chassis that limit suspension travel. "Bottoming out" the suspension means hitting the bump stops.
Bushing
A liner, usually removable, for a bearing; an anti-friction liner used in place of a bearing.
Bypass Filter
A filter that constantly filters oil flowing through the engine.

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