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Fa    Fe     Fi    Fl     Fo     Fr     Fu

Fan Clutch  The fan clutch is a small fluid coupling with a thermostatic device and controls a variable-speed fan. It ensures that the fan will rotate at just the right speed to keep the engine from overheating, and reduces drive to the fan when it is no longer needed. The fan clutch has a fluid coupling partly filled with silicone oil designed for just that purpose. When the temperature of the air passing through the radiator rises, the heat alerts a bimetal coil spring to "uncoil" or expand. When it expands, it allows just a little more oil to enter the fluid coupling, so the fluid coupling starts to rotate the fan. If the air coming through the radiator is cool, the opposite happens; the coil spring contracts, the oil leaves the fluid coupling and the fan slows. Slowing the fan when it is not needed reduces fuel consumption, makes less noise and saves engine power. Sometimes a flat bimetal strip spring is used instead of a coil spring; it bows out and in when the temperature rises and drops, letting oil in and out of the fluid coupling.

Fast Idle The higher speed, 1,100 to 1,500 rpm, at which an engine idles during warm-up, when first started.

Fast-Idle Cam  A cam-shaped lever on the carburetor that provides fast-idle action when the engine is cold.

Fast-Idle Screw A screw in the carburetor linkage to adjust fast-idle speed.

Fast Idle Solenoid  A solenoid operating in conjunction with an automatic choke to open the throttle slightly when the choke is in operation

Fast Lane: 

The outside lane (far left lane in North America, etc. or the far right lane in Britain, Australia, etc.).

Also called the "passing lane" 

Feeler Blade A thin strip or blade of hardened steel, ground to an exact thickness, used to check or measure clearances between parts.

Filler Cap (Brake Fluid Reservoir Cover) The cap on the brake fluid reservoir has a hole for air, or is vented, to allow the fluid to expand and contract without creating a vacuum or causing pressure. A rubber diaphragm goes up and down with the fluid level's pressure, and keeps out any dust or moisture.


[1] A thin metal object projecting from a surface and is used to dissipate heat. It is found on radiators and air-cooled engines.

[2] Wings and airfoils used to improve a vehicle's aerodynamics, stability, or possibly aesthetics.

Final Drive This is the end of the drive train before power is transmitted to the wheels. In a typical car, the engine (or electric motor) transmits its power through some sort of clutch into a transmission. Then the power is transmitted to differential gears that adjust the engine speed to the most efficient use intended. These final drive differential gears are either at the front axle or rear axle, depending on the vehicle's layout. A typical family car or one intended for high speeds will have a low numerical ratio, to give it speed and good fuel efficiency. A truck or performance car is likely to have a high numerical ratio for better pulling power or for better acceleration

Final Drive Gear The last gear in a drivetrain before the driven wheels. Usually it is in the differential.

Firewall  The partition dividing the engine compartment from the passenger compartment on a car or truck.

Firing Oder  The order in which the engine cylinders fire, or deliver their power strokes, beginning with the number one cylinder.

The spark plug in each cylinder fires in a particular order, which is unique to the engine design.
 For example, the firing order for a small-block or big-block Chevy V8 or a Chrysler V8 is 1, 8, 4, 3, 6, 5, 7, 2.

Fluid Coupling On a manual transmission, there is a mechanical connection between the engine and transmission through the clutch. On an automatic transmission a fluid coupling provides a viscous fluid to connect the engine output and the transmission. It transfers engine torque to the transmission input shaft through the use of two units with vanes (called a "torus") operating very close together in a bath of oil. The engine drives one torus causing it to throw oil outward and into the other torus which then begins to turn the transmission input shaft. A fluid coupling cannot increase torque above that produced by the crankshaft. Buick's Dynaflow is an example of this kind of coupling.

Flywheel  A large, heavy iron or steel disc attached to the rear of an engine crankshaft in order to provide sufficient centrifugal force to smooth the power impulses from the cylinders

Four Stroke Cycle (Four-Stroke Cycle)  An internal-combustion engine that requires two revolutions per cylinder or four piston strokes to achieve a power stroke: internal stroke, compression stroke, power stroke, exhaust stroke. More efficient than the two-stroke-cycle engine

Four Wheel Drive
Four-Wheel Drive  (4WD) A type of drive system in which both front wheels are connected to its own differential and axles, and both back wheels are connected to its own differential and axles. Between these two differentials there is a transfer case which allows you, in the case of part-time four wheel drive, to switch between two-wheel drive and four-wheel drive. In full-time four-wheel drive power is sent to both differentials.

Frame (Chassis)  The basic structure of the vehicle is the frame and it provides a good anchor point for the suspension system. There are two types of frames; integral frames, or 'unibody', and conventional frames. A conventional frame is basically a 'one-piece' frame; or two 'one-piece' frames fastened together. These frames are extremely rigid to keep all the parts of the car in perfect alignment, which are attached to it. It is constructed of heavy steel and welded or cold riveted together. Cold riveting keeps the rivets from shrinking after they cool off. The integral, or unibody, frame is just the opposite. With this type of frame, the body parts are used to structurally strengthen the entire car, and all of the sections are welded into one piece. Sometimes the parts of the body and the suspension system are attached and reinforced. Also, some unibody frames have partial front and rear frames for attaching the engine and suspension members.

Free play  The amount of travel before any action takes place. The "looseness" in a linkage, or an assembly of parts, between the initial application of force and actual movement. For example, the distance the brake pedal moves before the pistons in the master cylinder are actuated.



front apron: The panel behind and below the front bumper, joining the bottom ends of the front fenders

Front Axle The axle to which the front wheels are attached


front-axle/rear-axle split: A dual-circuit braking system in which one circuit brakes only the front axle while the other circuit brakes only the rear axle.

Front Axle and Rear Axle split
Front-Axle and Rear-Axle split
A dual-circuit braking system in which each circuit brakes both the front axle and the rear axle


front bumper: A guard which protects the front of a vehicle. See bumper and rear bumper.


front differential: differential in the front axle of a four-wheel drive vehicle


front end: body area incorporating the leading edge of the fenders, the headlights, radiator grille and bumper, i.e., the full area that makes up the frontal appearance of the car


front end alignment: See front-end alignment.


front-end alignment: The adjustment of the camber and caster of the front wheels. See alignment.


front-end impact: An impact as the result of a head-on collision


front engine: A vehicle with its engine located at the front of a vehicle above the front suspension. This is the most common layout, which may be combined with either rear-wheel or front-wheel drive. Also see mid-engine car and rear engine


front fender: body section covering the front wheels, originally separate; but now in most cars faired in and part of the body shell


front fork: See fork.


front forks: See fork.


front nose section: The front section of a car's body that uses one single structure to make up the front end, i.e., including the radiator grille surrround, both fenders, front apron, etc. front panel: A panel joining the front fender and forming a mounting for the headlights, grille, and air ducts into the engine compartment, which is often identical with the front apron where no separate apron is fitted below the front panel. Also see lower front panel


front pillar: See a-pillar


front pipe: The first section of the exhaust system from the exhaust manifold to the silencer (or front silencer where there are two). Also see twin front pipe


front-seat: The closed position of a stem type service valve to isolate the compressor. The system should never be operated with the valves in this position


front seat: seat in the front of passenger cabin for the front seat passenger


front seats: The front passenger's and driver's seats


front silencer: first and main silencer in an exhaust system where there are two


front spoiler: The air deflector on the front of a car, aerodynamically designed to cut the wind resistance around the car, for improved handling control, stability, traction, and better fuel economy


front suspension: The springs, shock absorbers, linkages, etc. which support the front wheels. See independent front suspension.


front triangle: Actually a quadrilateral with one short side, it is the section of a bicycle frame that consists of the head tube, the top tube, the seat tube, and the down tube. Also called "main triangle."


front wheel drive: See front-wheel drive.


front-wheel drive: (FWD) A vehicle that is pulled by its front wheels rather than being pushed by its rear wheels. The driveshaft and center floor hump is eliminated in front-wheel drive cars. The engine is located over the driving wheels so that it gains better traction in snow. Wear on the front tires can be severe.


front wheel tire clearance: The distance between the tire and the closest point on the vehicle laterally, longitudinally and vertically, checked lock to lock and all intermediate points.


front wing: British term for front fender 







Front Suspension  The springs, shock absorbers, linkages, etc. which support the front wheels.

See independent front suspension.

Front Wheel Drive (front-wheel drive)

(FWD) A vehicle that is pulled by its front wheels rather than being pushed by its rear wheels. The driveshaft and center floor hump is eliminated in front-wheel drive cars. The engine is located over the driving wheels so that it gains better traction in snow. Wear on the front tires can be severe.

Fuel A combustible material used to produce energy. One of the essential factors in a combustion engine (Fuel, Air, Proper proportion of mixture, compression, timing, spark).

Fuel Air Mixture (Fuel-Air Mixture)

A combination of vaporized fuel and air which is brought into the cylinder through the carburetor or fuel injectors. When it is compressed and ignited, it produces the power needed to drive the engine.

Fuel Air Ratio  The amount of fuel in comparison with the amount of air. This is the reciprocal of the air-fuel ratio.

Fuel Delivery System  The various components that move fuel from the gas tank to the engine. This typically includes a fuel pump, a considerable length of fuel line (hard tubing) and a fuel filter. Once the fuel reaches the engine compartment, it travels through the fuel injection system and into the engine to get burned along with air during the combustion process (or, in older or race vehicles, through one or more carburetors and into an intake manifold).

Fuel Filter A device that removes impurities from the fuel before it gets to the carburetor. It is usually found near the carburetor in the fuel line that comes from the fuel pump (in-line fuel filter), or inside the carburetor (integral fuel filter) or fuel pump (integral fuel filter). This unit must be cleaned or replaced on a regular basis, usually once a year or it will become clogged and restrict fuel to the carburetor.

Without a filter, the jets and orifices in the carburetor will become clogged.

Fuel Gauge An instrument, usually located on the dashboard or center console, which indicates the amount of fuel in the fuel tank. Most gauges have a needle which fluctuates between "E" (empty) and "F" (full).

Others show a digital readout of how many gallons or liters left in the tank. Also called "gas gauge."

Fuel Injection (FI)  A fuel system that uses no carburetor but sprays fuel either directly into the cylinders or into the intake manifold just ahead of the cylinders. It uses an electronic sensing device to deliver the correct amount into the combustion chamber. Throttle-body injection locates the injector(s) centrally in the throttle-body housing, while port injection allocates at least one injector for each cylinder near its intake port.

Older throttle body injection (TBI) systems that appeared on cars and trucks in the '80s were essentially electronically controlled carburetors, which squirted fuel into the intake manifold, rather than apportioning it to each individual cylinder.

Fuel Injectors  The part of a fuel injection system that squirts fuel into an engine. When a vehicle has been modified for significantly enhanced airflow in the intake system, it sometimes is necessary to swap to higher-flow fuel injectors, so they can deliver sufficient fuel to maintain the ideal air/fuel ratio.

Fuel Line The metal, plastic, or rubber hose or pipe through which the fuel passes from the fuel tank to the fuel pump to the carburetor or fuel injector nozzle.

Fuel Mileage A measurement or calculation of the number of miles per amount of fuel - usually measured in miles per gallon.

Fuel Mixture A mixture of gasoline and air. An average mixture, by weight, would contain 16 parts of air to one part of gasoline.

 See air-fuel mixture.

Fuel Pump  The fuel pump has three functions: to deliver enough fuel to supply the requirements of an engine under all operating conditions, to maintain enough pressure in the line between the carburetor and the pump to keep the fuel from boiling, and to prevent vapor lock. Excessive pressure causes the carburetor float needle off its seat its seat resulting in high fuel level in the float chamber, leading to high fuel consumption. Highest pressure occurs at idling speed and the lowest at top speed.

Fuel Tank  The fuel tank stores the excess fuel until it is needed for operation of the vehicle. The fuel tank has an inlet pipe and an outlet pipe. The outlet pipe has a fitting for fuel line connection and may be located in the top or in the side of the tank. The lower end is about one-half inch above the bottom of the tank so that collected sediment will not be flushed out into the carburetor.

The bottom of the tank contains a drain plug so that tank may be drained and cleaned.

Fuse  An electrical device which protects a circuit against accidental

 overload. The typical fuse contains a soft piece of metal which is calibrated to melt at a predetermined current flow (expressed as amps) and break the circuit.

Fusible link A circuit protection device consisting of a conductor surrounded by heat-resistant insulation. The conductor is smaller than the wire it protects, so it acts as the weakest link in the circuit. Unlike a blown fuse, a failed fusible link must frequently be cut from the wire for replacement.

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The objective of this Web Page is to familiarize you with basic auto maintenance
-  in some common emergencies -
not to make you an expert in auto mechanics

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