Cars - http://maxpages.com/carsinhistory/D

Distributor cap: An insulated cap containing a central terminal or tower with a series (one per cylinder) of terminals or towers that are evenly spaced in a circular pattern around the central terminal or tower, the secondary voltage travels to the central terminal or tower where it is then channelled to one of the outer terminals or towers by the rotor. The cap also keeps dirt and moisture out of the distributor.

Distributor hold-down clamp: A metal bracket at the base of the distributor that has a nut or bolt which can be loosened to allow the distributor to be moved on its shaft to readjust ignition timing or to open the points for gapping.

Distributor shaft: The metal shaft inside the distributor that has a cam wheel which revolves with the shaft and forces the points to open. A spring causes the points to close.

Dive: The action of the front of the vehicle to point downward (or dip) during braking. The opposite is squat. Also see anti-dive, anti-lift, anti-squat, and brake dive.

DIY: See do-it-yourself market.

Dnf: !!!.

Doble: The 1925-1948 models are classic cars.

Dodge: The 1967-70 Coronet R/T models are milestone cars. The 1968-70 Charger R/T and Daytona models are milestone cars.

Dog: 1. Man's best friend. 2. A vehicle in very bad shape, which may not be man's best friend. 3. A lug or protrusion on an object.
DOHC: Acronym for "double-overhead camshaft." Refers to an engine with two overhead camshafts. See double overhead cam and engine type

Do-it-yourself market: (DIY) The vehicle maintenance and repairs conducted by the vehicle owner or friend/relative who purchase auto parts from a retail outlet.

Domestic: a vehicle produced in Canada, United States or Mexico.

Door: The side panels of a vehicle which permit the occupants to enter or leave the passenger compartment. In most cases the doors open so that the hinge is toward the front of the vehicle. When the hinge is toward the back of the vehicle, they are called "suicide doors."

Door rates: the hourly rates charged by dealers on standardized units of service work. Hourly rates may or may not correspond to an actual hour of work.

Doosy: See Duesy.

Dorris: The 1925-1948 models are classic cars.

Dos-a-dos: Back to back seating on older cars where the driver and front passenger faced forward; but the two rear passengers faced rearward.

DOT: Acronym for "Department of Transportation" -- an American federal agency.

DOT 3: This brake fluid has a glycol base. It is clear or light amber in color. Its dry boiling point is 401° minimum and wet boiling point of 284° minimum. It will absorb 1 to 2 percent of water per year depending on climate and operating conditions. It is used in most domestic cars and light trucks in normal driving. It does not require cleaning the system and it can be mixed with DOT 4 and DOT 5.1 without damage to the system. The problem with it is that it absorbs moisture out of the air and thereby reduces its boiling point. It can also damage the paint on a vehicle.

DOT 4: This brake fluid has a borate ester base. It is clear or light amber in color. Its dry boiling point is 446° minimum and wet boiling point of 311° minimum. It is used in many European cars; also for vehicles in high-altitude, towing, or high-speed braking situations, or ABS systems. It does not require cleaning the system and it can be mixed with DOT 3 without damage to the system. The problem with it is that it absorbs moisture out of the air and thereby reduces its boiling point. It can also damage the paint on a vehicle.

DOT 5: This brake fluid generally has a silicone base. It is violet in color. Its dry boiling point is 500° minimum and has no wet boiling point in federal DOT 5 specifications. It is used in heavy brake applications, and good for weekend, antique, or collector cars that sit for long periods and are never driven far. It does not mix with DOT 3, DOT 4, or DOT 5.1. It will not absorb water and will not damage the paint on a vehicle. It is also compatible with most rubber formulations. The problem with it is that it may easily get air bubbles into the system which are nearly impossible to remove, giving poor pedal feel. It is unsuitable for racing due to compressibility under high temperatures. If as little as one drop of water enters the fluid, severe localized corrosion, freezing, or gassing may occur. This can happen because water is heavier and not mixable with silicone fluids. It is unsuitable for ABS.

DOT 5.1: This brake fluid has a borate ester base. It is clear or light amber in color. Its dry boiling point is 500° minimum and wet boiling point of 356° minimum. It is used in severe-duty vehicles such as fleets and delivery trucks; towing vehicles, and race cars. It can be mixed with DOT 3 or DOT 4 without damage to the system. It maintains higher boiling point than DOT 3 or DOT 4 fluids due to its higher borate ester content. It is excellent for severe duty applications. The problem with it is that it costs more than other fluids and there is limited availability. It also absorbs moisture out of the air and thereby reduces its boiling point. It can also damage the paint on a vehicle.

DOT number: The symbol DOT on a tire means it meets or exceeds Department of Transportation safety standards. Following DOT are a maximum of eleven numbers. E.g., "DOT FT TW A2NX 092." ("DOT" = meets or exceeds federal standards; "FT" = identifies manufacturing plant; "TW" = the code for tire size; "A2N" or "A2NX-3" or optional 4 digits = manufacturer's code to identify the characteristics of the tire; "092" = Week of mfg., in this case, 9th week of 1972. Prior to May 22, 1971 the manufacturer's plant was identified by only three numbers (Example DOT 129). Retreaded tires must also have a new serial number and can be determined by the letter "R" following DOT letters.

Double-barrel carburetor: Two throttle openings or barrels from the carburetor to the intake manifold. Also see four-barrel carburetor, and single-barrel carburetor.

Double clutch: See double clutching.

Double clutching: Vehicles with manual transmission and no synchromesh have difficulty shifting from one gear to another. With synchromesh, shifting is accomplished by depressing the clutch pedal and moving the gearshift selector from one gear to the next. Without synchromesh, shifting is not smooth unless you double clutch. Here you depress the clutch pedal, shift to neutral, lift up on the clutch pedal, blip the throttle (accelerator), then depress the clutch pedal again and shift to the next gear. While this action seems complicated, you can get used to doing it to avoid the grinding noise heard in non-synchromesh transmissions.

Double flare: The end of the tubing, especially brake tubing, has a flare made so that the flare area uses two wall thicknesses. This makes a much stronger and safer joint in bicycle tubing.

Double cap nut: (Budd mounting) A type of securing device which consists of an inner cap nut (sleeve nut) and an outer cap nut. It is the most common method for mounting disc wheels in dual.

Double leading brake shoe: A system of braking where two hydraulic plungers and separate pivots create better braking when the vehicle is going forward; however it is not very effective when the vehicle goes in reverse. Also see single leading brake shoe.
Double overhead cam: (DOHC) An engine with two camshafts located above the cylinders. One drives the intake valves and the other operates the exhaust valve. In a single overhead cam engine (SOHC), one cam has enough lobes to drive both the intake and exhaust valves. The DOHC engine is considered to be a very sophisticated and more efficient engine; but is sometimes more difficult to adjust the valves. See engine type.

Double wishbone: !!!.

Dowel pin: A pin (steel or wood), passed through or partly through, two parts to provide proper alignment and to prevent movement between them. Sometimes called "locating pin."

Downdraft carburetor: A carburetor in which the air passes downward through the carburetor into the intake manifold. Contrasts with sidedraft carburetor.

Downforce: A vertical force directed downward, produced by airflow around an object such as the body of a vehicle.

Downgearing: See downshifting.

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

Downshifting: Manually shifting to a lower gear in order to use the engine compression to assist in reducing the vehicle's speed. Also called "downgearing."

Downtime: Downtime occurs when a vehicle is being repaired (esp. a commercial vehicle), it cannot fulfil its function. There is a loss in both potential proceeds from its use as well as the salary of its operators.

Down tube: the tube running from the headset to the bottom bracket, one part of the main triangle on a bicycle frame.

Dr: Abbreviation for "door," as in 2-dr. car-dics.htm#Sedan">Sedan."

Drafting: The action of following closely behind a faster vehicle so as to take advantage of the aerodynamic effect which causes both the vehicles behind and the one in front to move faster. See slip stream.

Drag: 1. To accelerate a vehicle from a standing start, over a course one-fourth mile in length. 2. Used by some drivers when referring to challenging another driver to an acceleration race. 3. Air resistance. See aerodynamic drag.

Drag coefficient: (Cd) A number used in calculating the aerodynamic drag acting on a vehicle. The drag coefficient is a function of factors like the shape of the vehicle, airflow through the vehicle for ventilation and cooling. The number is determined in a wind-tunnel or by coasting tests performed on the vehicle. The lower the drag coefficient the less drag on the vehicle and the more aerodynamic is the vehicle. A sleek vehicle has a drag coefficient, or "Cd," of about 0.30; a square, flat plate's is 1.98. Also signified by Cx.

Drag link: A steel rod connecting the pitman arm to one of the steering knuckles. On some installations the drag link connects the pitman arm to a center idler arm.

Drag race: A competitive match between two vehicles in which they race over a 1/4 mile course.

Drag wheel: Special steering wheel used on some dragsters. Often consists of a crossbar spoke and a portion of rim on each end.

Dragster: A vehicle especially built for drag racing.

Drain plug: See oil drain plug.

Draw: 1. To form wires by pulling the wire stock through a series of hardened dies. 2. The process of removing the hardness from a piece of metal. 3. The amount of electrical load or electrical requirement.

Draw filing: draw-filing.

Draw-filing: Filing by passing the file, at right angles, up and down the length of the work.

Dream car: A one-of-a-kind futuristic, experimental automobile usually appearing at auto shows to stimulate interest in the manufacturer's products. Much design benefit spurs from dream cars and many reach the production stage.

Drift: See four-wheelDrift and tire deviation angle.

Drill: A tool used to bore holes. Also see letter drills, number drills, and twist drill.

Drilled: An expression used to describe a hole which has been cut into a crankshaft to allow oil to be fed to the main bearings on the connecting rod throws.

Drill press: A nonportable machine used for drilling.

D ring: See D-ring.

D-ring: A D-shaped ring found on many models of bicycle shift levers, used to adjust the level of tension on the inner parts of the lever.

Drivable: The condition of a vehicle which may have many mechanical and appearance problems, but it has an engine which runs and wheels that turn, etc. so that it can be operated and driven.

Drivability: The general qualitative evaluation of a powertrain's operating qualities, including idle smoothness, cold and hot starting, throttle response, power delivery, and tolerance for altitude changes.

Drive fit: A condition of fit (contact) between two parts that requires pressure to force the parts together. Usually the shaft is slightly larger than the hole so that they must be pounded or forced or driven together. Also called "force fit," "press fit," or "interference fit."
Drive pinion: The shaft that takes power from the clutch into the gearbox. See clutch shaft and hypoid gear

Driveline: Everything in the drivetrain except the engine and the transmission.

Driver: 1. A collectible vehicle which is too good to treat as a beater and not quite good enough to show. It is a presentable old car or truck that is used for everyday purposes. It is maintained as though it were a late-model vehicle. With care, it could be easily restored to show car condition. 2. A person who operates the controls of a vehicle to regulate its speed and direction. 3. A tool used to insert something like a fastening device (e.g., screwdriver). 4. Also see drivers.

Driver evaluation: !!!.

Drivers: Colloquial term for "drive axle tires." Also see rim drivers.
Driveshaft: The shaft connecting the transmission output shaft to the differential pinion shaft. It transmits power from the transmission to the differential. It is found primarily on rear-drive vehicles. There is usually a universal joint on either end.

Drive shaft: See driveshaft.

Driveshaft safety strap: A metal strap or straps, surrounding the driveshaft to prevent the shaft from falling to the ground in the event of a universal joint or shaft failure.

Drive train: 1. This term refers to the entire moving part of the car: Engine, clutch, transmission, driveshaft, differential, axles, and sometimes the wheels. 2. The derailleurs, chain, freewheel, and crankset of a bicycle.

Drivetrain: 1. This term refers to the entire moving part of the car: Engine, clutch, transmission, driveshaft, differential, axles, and sometimes the wheels. 2. The derailleurs, chain, freewheel, and crankset of a bicycle.

Driving light: !!!.

Drop: The vertical distance from the horizontal line connecting the two wheel axles and the bottom bracket, one way of determining the location of the bottom bracket in relation to the rest of the bicycle frame. Also see drops.

Drop center rim: A one-piece rim with a deep center section which is lower than the two outer edges, this allows the bead of the tire to be pushed into the low area on one side while the other side is pulled over and off the flange.

Drop center rim taper: A passenger rim where both bead seats are tapered 5° or a tubeless truck rim where both bead seats are tapered 15°.

Drop forged: A part that has been formed by heating the steel blank red hot and pounding it into shape with a powerful drop hammer.

Drophead: See drophead coupé.

Drophead coupe: This is a two-door automobile which has the appearance of a convertible, but the roof is fixed in place. In Europe, it is called a "cabriolet."

Dropout: A slot in the frame into which the rear wheel axle fits. Also see fork tips.

Dropout hanger: A threaded metal piece that extends below the right rear dropout of a bicycle, used as a mount for the rear derailleur.

Dropped axle: A front axle that has been altered so as to lower the frame of the vehicle, consists of bending the axle downward at the outer ends.

Drops: The lower, straight portion of a turned-down-type handlebar set.

Drum: A cylindrical container. Housing for transmission gears where the bands are located. See brake drum, brake drum lathe, and drum brake.

Drum brake: A type of brake using a shallow drum-shaped metal cylinder that attaches to the inner surface of the wheel and rotates with it. When you press down on the brake pedal, curved brake shoes with friction linings press against the inner circumference of the drum to slow or stop the vehicle. Also see brake drum.

Drum brakes: See drum brake.

Dry ballast: A form of ballasting where a fine powder of barium sulphate is inserted inside the tire. It is sometimes referred to incorrectly as "Lead" ballast because of one brand name, "Ledballast."

Dry battery: See dry cell.

Dry boiling point: The temperature at which fresh brake fluid from a new container will boil. See wet boiling point and DOT 3.

Dry cell: A battery (like a flashlight battery) that uses no liquid electrolyte.

Dry charged battery: A battery with the plates charged but lacking electrolyte, when ready to be placed in service, the electrolyte is added.

Dry friction: dry friction exists when the rubbing parts have no other substance between them and are clean of other materials (i.e., no grease or oil). Opposite to wet friction.

Dry liner: When a cylinder sleeve is pressed into a bore and the cooling fluid does not contact the outside of the sleeve, the engine has a dry liner. Also see liner.

Dry sleeve: A cylinder sleeve application in which the sleeve is supported in the block metal over its entire length, the coolant does not touch the sleeve itself. Also see wet sleeve.

Dry spray: dry-spray.

Dry-spray: atomized paint that does not dissolve into the material being sprayed. It is caused by holding the gun too far from the work, too much air pressure or a solvent that evaporates too fast.

Dry sump: A lubrication system in which the engine's supply of oil is not contained in the crankcase (sump) but is pumped to the engine from an external container. This system allows the crankcase to be reduced in size and the engine to be installed lower in the chassis, and eliminates the oil starvation most conventional oiling systems suffer when subjected to the accelerative, braking, and cornering forces generated by a racing car.

DS: Acronym for "Diesel Severe" oil for use in under adverse conditions in diesel engines.

Dual axles: See tandem axles.

Dual bead tire: Heavy service and large truck tires using two or more sets of bead wires in each bead rather than one.

Dual brake: See dual brakes.
Dual brakes: A brake system that uses a tandem or dual master cylinder to provide separate brake system for both front and rear of vehicle. In the event of a loss of hydraulic fluid, one system may still work because it is independent of the other system. Often the front left brake is linked with the right rear brake. Likewise the right front brake is linked with the left rear brake. Some cars like the Rolls-Royce, link the two front brakes with the right rear brake, and the two front brakes with the left rear brake.

Dual braking system: See dual brakes.

Dual breaker points: A distributor using two sets of breaker points to increase the cam angle so that at high engine speeds, sufficient spark will be produced to fire the plugs.

Dual carbs: Two carburetors on the same engine.

Dual carburetors: Two carburetors on the same engine.

Dual drive: 1. Tandem axles, both powered directly by the engine. 2. Colloquial term for twin screw.

Dual Ghia: The 1956-58 models are milestone cars.

Dual mounting: Two tires mounted together on each side of an axle of several types: cast spoke type, disc wheel type (held on by double cap nuts or inner cap nuts and outer cap nuts), Chevrolet type, motor wheel type

Dual overhead cam engine: !!!.

Duals: 1. Two sets of exhaust pipes and mufflers -- one for each bank of cylinders. 2. Two tires on each end of an axle.

Dual spacing: A measurement in inches (or millimeters) from the center of the tread of one tire, to the center tread of the other tire in dual, which provides clearance between duals for air circulation.

Duct: A tube through which air, gas, or liquid is conducted. See NACA duct.

Duesenberg: The 1925-1948 models are classic cars.

Duesy: Expression to indicate quality, as "It's a duesy." The word is derived from the high quality Duesenberg automobiles.

Dummy lights: !!!.

Dump body: A large truck's metal body which is generally hinged at rear and dumped by hydraulic means. The size is generally given in cubic yard water level capacity.

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Page Updated Sun May 20, 2001 8:08pm EDT