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T: A letter rating for tires to indicate that they are theoretically rated for speeds up to 190 kph (118 mph), as in P220TR15.The next higher rating is H and the one lower rating is S

tach: tachometer.

tachograph: Instrument to record, on a graph, vehicle trip information such as mph, rpm, "stop" and "go" periods.

tachometer: (tach) A device used to indicate the speed of the engine in rpm. The tachometer is mounted on or near the dashboard (some even appear on the hood and others in a heads-up display on the windshield). It helps the driver to know the optimum rpm for changing gears on manual transmissions. A tachometer is also a diagnostic device which a mechanic uses to determine idle speed and other carburetor and running settings.

tack: A term used to describe the sticky quality of a rubber compound.

tack coat: The first coat of enamel that is allowed to dry until "tacky" usually about 10-30 minutes, depending on the amount of thinner used. The surface is "tacky" when it will not stick to the finger when light pressure is applied.

tack rag: A cloth impregnated with a non-drying varnish that is used to pick up dust and dirt particles.

tack weld: Small weld used to temporarily hold together components of an assembly.

tail: See kamm tail.

tailgate: [1] On a truck it is the fold down access door to the truck bed. On a station wagon, it is the rear door. [2] As a verb, to follow closely behind another vehicle.

tail pipe: exhaust pipe which runs from the muffler to the rear of the vehicle. and is open to the atmosphere, through which the exhaust gases are routed into the atmosphere.

take foot off the accelerator: The action of easing up on the accelerator completely so that there is only a minimal amount of fuel entering the engine thus the engine will slow down

take foot off the gas pedal: The action of easing up on the gas pedal completely so that there is only a minimal amount of fuel entering the engine thus the engine will slow down

take foot off the throttle pedal: The action of easing up on the throttle pedal completely so that there is only a minimal amount of fuel entering the engine thus the engine will slow down

Talbot Lago: All 150C models are classic cars.

Talbot: All 105C and 110C models are classic cars. The 1946-54 Lago 4.5 models are milestone cars.

talc: Powder lubricant to prevent sticking between tube and tire.

tandem: [1] A bicycle that provides seats, bars, and pedals for two or more riders, one behind the other. [2] A tractor-trailer truck.

tandem axle: See tandem axles.

tandem axles: A combination of two axles having a common suspension.

tandem drive: Two powered axles in combination.

tank: A container into which any liquid can be held. Also it may even be empty such as a vacuum tank. Also see cylinder, expansion tank, fuel tank, and vacuum tank.

tap: [1] To cut threads in a hole or tube. [2] The fluted tool used to cut the threads.

tap and die set: A set of taps and dies for internal and external threading, usually covers a range of the most popular sizes.

taper: A gradual narrowing. Also see worm and taper pin.

tapered roller bearing: An antifriction bearing using a series of tapered, hardened steel rollers operating between an outer and inner hardened steel race.

tape weight: See adhesive weight.

tappet: The screw used to adjust the clearance between the valve stem and the lifter or the rocker arm. Also see bucket tappet, cam follower, roller tappets, and valve tappet.

tappet noise: Noise caused by the lash or clearance between the valve stem and rocker arm or between the valve stem and valve lifter.

tar: A black, sticky substance made from petroleum. It is useful for patching cracks in the road. However, when driving over it, the wheels kick up particles of it on a vehicle's painted surface. See bug and tar remover.

tare weight: The weight of a truck, exclusive of its contents, but including gas, oil, etc., ready to roil. Also called "curb weight."

targa: A removable-roof body style popularized by Porsche that is similar to a convertible except that it incorporates a fixed, roll-bar-like structure running from side to side behind the front seats.

tariff: A duty or tax imposed on imports.

tar remover: See bug and tar remover.

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

T-bar: A rod which is inserted into the holes of a box spanner. The British term is tommy bar.

taxi: A vehicle used for transporting people for hire.

t Bone: [1] Model-T Ford car. [2] To hit another vehicle against its side.

t-Bone: Model-T Ford car.

t-boned: Hitting another vehicle on its side.

t-connector: Any connector in the shape of the letter "T" -- often referring to a hollow unit. For example, the line coming from the windshield washer pump is connected to the bottom part of a "T" and the crossbar at the top sends the fluid to the two nozzles (one on each side of the windshield). It differs from a Y-connector in that the crossbar is straight across while the Y-connector has a V-shape crossbar.

TDC: Acronym for "top dead center."

tear it down: See pull it down.

teflon: A plastic with excellent self-lubricating (slippery) bearing properties.

tele: Abbreviation for "telescoping steering wheel."

telescoping steering wheel: (tele) A steering column which can be shortened or lengthened to provide the most comfortable driving position.

temper: To effect a change in the physical structure of a piece of steel through the use of heat and cold.

temperature control: See automatic temperature control.

temperature gage: See temperature gauge.

temperature gauge: An instrument for measure the temperature of the coolant in engine block.

tempered glass: See laminated windshield.

template: A pre-cut pattern, usually metal, used to determine the contour of a buffed tire. Also see buffing template.

tensile strength: [1] Regarding a tire, it is a measurement of the greatest longitudinal stress a tire cord can bear without breaking. [2] Maximum pull stress in psi a specimen is capable of developing.

tension: A pulling or stretching stress applied to an object. Also see high tension leads, and low tension leads.

terminal: [1] A connecting point in an electric circuit. [2] When referring to the battery, it would indicate the two battery posts. Also see negative terminal, positive terminal, and primary terminal.

terminal tower: The terminals at the top of the distributor cap into which the spark plug wires fit. Also called "distributor tower"

tether kill switch: A safety device used on snowmobiles and personal watercraft. One end is attached to the operator's wrist and the other end is plugged into a special switch. When the operator falls off his vehicle, the tether pulls out of the switch causing the engine to die.

tetrachloride: See carbon tetrachloride.

tetraethyl lead: a lead compound used as an additive to increase the octane rating and reduce the knock or detonation tendencies of gasoline. Also see lead free.

t Ford: Model-T Ford car.

t-Ford: Model-T Ford car.

TFT: Acronym for "Thin Film Technology."

t-handle socket: A tool in which a socket has been welded to a long rod (about 8 to 10 inches). At the other end of the rod, a crossbar has been welded. Thus it is formed in the shape of the letter "T". In some instances it speeds up the removal and installation of bolts.

t head: See T-head engine and engine type.

t-head: See T-head engine and engine type.

t head engine: See T-head engine.

t-head engine: An engine in which the arrangement of the valves on either side of the combustion chamber creates a "T" configuration. Usually the intake valves are on one side and the exhaust on the other. The modern crossflow cylinder heads are variations on this old concept. But the original design is not in current use.

thermal: See British Thermal Unit, thermal efficiency, and thermal reactor.

thermal deterioration: Loss of strength of carcass cords due to heat generated in a tire.

thermal efficiency: The percentage of the heat developed in the burning fuel charge that is actually used to develop power determines thermal efficiency. When fuel is combusted in an engine not all the fuel is converted into power. Some is lost in overcoming friction and some escapes down the tail pipe in the hot exhaust gases so this percentage is always less than 100%. Efficiency will vary according to engine design, use, etc. If an engine uses a great deal of the heat to produce power, its thermal efficiency would be high. Also see adiabatic engine.

thermal equilibrium: The point at which the rate of cooling becomes equal to the rate of heat generation in a tire. Also called "heat balance."

thermal reactor: A high-volume thermally isolated chamber replacing the exhaust manifold and providing a place for high-temperature afterburning of exhaust pollutants. Found on all Mazda rotary engines and some piston engines (BMW for example) as well.

thermostat: A temperature sensitive device used in the cooling system of an engine to control the flow of coolant between the cylinder block and radiator. It is set into the engine block and shuts off the circulation of water until the temperature of the water reaches the point at which the thermostat is set to open. Because automotive internal combustion engines operate more efficiently when their temperature is maintained within narrow limits, the thermostat closes off the flow of coolant from the engine to the radiator until the engine has reached the desired operating temperature. Other thermostats are used in the electrical circuit of the vehicle heating system to control the amount of heat supplied to the passengers, in the manifold heat control system that preheats the air-fuel mixture going to the cylinders, and in the automatic choke.

thermostatic coil choke: A sensing device mounted on the carburetor that automatically controls the choke butterfly valve by sensing the heat of the exhaust manifold. Also see choke.

thermostatic spring choke: A sensing device that automatically controls the choke butterfly valve by sensing the heat of the exhaust manifold. Also see choke.

thinner: The solvent used to thin lacquers and enamels to the proper consistency for application.

third brush: A generator in which a third, movable brush is used to control current output.

third hand: A tool used on bicycles to squeeze the brakes together against the rim so that adjustments can be made to the cable.

Thompson rotovalve: A type of valve which rotates as it opens and closes.

thou: An abbreviation for "thousandth" or one divided by a thousand; a small measurement representing 1/1000th of an inch as in Ten thou (0.01) is equal to 0.25 mm."

thread: The spiral grooves on a screw, bolt, or nut. See left-hand thread and right-hand thread.

three-quarter race camshaft: A description of the custom camshaft indicating the type of lobe grinding which, in turn, dictates the type of use. Other grinds are one-quarter race, full-race, street-grind, etc.

3-spd: Abbreviation for "three-speed," either manual transmission or automatic transmission.

three speed: A transmission which has three forward gears.

three-speed: A transmission which has three forward gears.

three-speed transmission: A transmission which has three forward gears.

three way catalytic converter: See three-way catalytic converter.

three-way catalytic converter: A pollution control device which reduces all three noxious substances: HC, CO, and NOx.

throat of a fillet weld: Distance from the weld root to the weld face.

throttle: The device that controls the vacuum created in the venturi of the carburetor. The greater the vacuum, the richer the fuel-air mixture. The throttle enables the engine to run on a richer mixture and produce more power for high-speed driving. It consists of a throttle arm, located on the outside of the carburetor and connected to the gas pedal (or throttle twist grip on a motorcycle), which in turn activates a throttle butterfly valve at the base of the carburetor barrel, where it joins the intake manifold.

throttle arm: The lever that actuates the throttle.

throttle body: A housing containing a valve to regulate the airflow through the intake manifold. The throttle-body is usually located between the air cleaner and the intake plenum.

throttle body fuel injection: A form of fuel injection in which the injectors are located at the engine's throttle body, thereby feeding fuel to more than one cylinder. Such an arrangement saves money by using fewer injectors; but because it routes both fuel and air through the intake manifold, it eliminates some of the tuning possibilities offered by port fuel injection.

throttle butterfly: A valve in the throat of the carburetor which regulates the amount of the flow of gasoline. See throttle valve.

throttle pedal: The gas pedal which operates the throttle butterfly through a series of linkages.

throttle valve: A valve in the carburetor. It is used to control the amount of air-fuel mixture that reaches the cylinders. Usually consists of a flat round disc mounted on a shaft so that it can be tilted at various angles in the carburetor throttle valve body. It is connected by suitable linkage to the accelerator pedal.

throw: [1] The offset portion of the crankshaft designed to accept the connecting rod. Also see crankpin. [2] The distance from the center of the crankshaft main bearing to the center of the connecting rod journal. The piston stroke is twice the throw distance.

throwing a rod: The action of breaking a connecting rod. Often the rod will force its way out of the side of the engine resulting in major damage which is expensive to repair. In most cases the rod breaks because of the lack of enough oil to cool the rod.

throwout: See throwout bearing and clutch throwout fork.

throw-out: See throwout bearing and clutch throwout fork.

throw-out bearing: See throwout bearing.

throwout bearing: A part of the clutch, activated by the clutch pedal, that allows the clutch to disengage. If you allow the vehicle to idle in gear with the clutch pedal depressed, instead of shifting to neutral gear, you can wear out the throwout bearing. Also called the "clutch release bearing." Also see free pedal play.

throw-out fork: See clutch throwout fork.

throwout fork: See clutch throwout fork.

thrust: To surge powerfully upward or press outward. See camber thrust, piston thrust, thrust bearing and thrust washer.

thrust bearing: A bearing with flanges on its two sides that prevents a shaft such as the crankshaft from moving endwise. In the engine crankshaft assembly these flanges are a close fit to the two sides of the crankpin. If the crankshaft tends to shift one way or the other the crankpin sides come up against the flanges preventing excessive endwise movement.

thrust washer: A bronze or a hardened steel washer placed between two moving parts. The washer prevents longitudinal movement and provides a bearing surface for the thrust surfaces of the parts.

Thunderbird: The 1955-57 and 1958-60 models are milestone cars.

tie-down: A device for securing a load usually made of straps and hooks.

tie rod: A rod, or rods, connecting the steering arms together. It links the pitman arm and the idler arm to the steering knuckle arms. When the tie rod is moved, the wheels pivot.

tie rod arm: See steering arm.

tie rod end: See tie rod ends.

tie rod ends: A type of ball joint which transfers the movements of the steering wheel to the wheels. Grease fittings or ball joints located on the ends of the steering linkage.

tier 1 Supplier: manufacturer to the vehicle assemblers who are responsible for delivery of the finished assembly, product development and continued technology renewal.

tier 2 Supplier: producer of parts providing value-added to minor sub-assembly.

tier 3 Supplier: supplier of engineered materials and special services, such as rolls of sheet steel, bars and heat treating, surface treatments.

TIG: Term used to describe gas tungsten arc welding (tungsten inert gas).

tilt: Abbreviation for "tilt steering wheel."

tilt steering wheel: (tilt) A steering wheel which moves up or down or which can be set at a different angle. In this way, the driver can find the most comfortable position and also allows easier entry and exit from the vehicle.

timing: One of the essential factors in a internal combustion engine (Fuel, Air, Proper proportion of mixture, compression, Timing, spark). When the piston is in the compression stroke, both valves must be closed. If one or more is open, the valve timing is out. Perhaps a timing belt or timing chain has jumped a tooth. If the spark does not arrive at the correct moment, the engine is out of time. If this ignition timing is only slightly off, the engine may run with less efficiency.

timing belt: A toothed belt driven by the crankshaft and operates the camshaft. It causes the valves to open and close at the proper time. When an engine is rebuilt, it is important to line up the crankshaft sprocket and camshaft sprocket before applying the belt. When the belt breaks, often a valve will remain open and be hit by the rising piston causing the valve to bend and other internal damage.

timing chain: A drive chain driven by the crankshaft and operates the camshaft. It causes the valves to open and close at the proper time. When an engine is rebuilt, it is important to line up the crankshaft sprocket and camshaft sprocket before applying the chain. When the chain often a valve will remain open and be hit by the rising piston causing the valve to bend and other internal damage.

timing gear: Both the gear attached to the camshaft and the gear on the crankshaft. They provide a means of driving the camshaft. This system is used where long life and hard service are expected as in commercial vehicles and race cars. Using gears is generally a noisier method than using a timing chain or a cog belt to drive the camshaft.

timing gears: See timing gear.

timing light: A stroboscopic unit that is connected to the secondary circuit to produce flashes of light in unison with the firing of a specific spark plug. By directing these flashes of light on the whirling timing marks, the marks appear to stand still. By adjusting the distributor, the timing marks may be properly aligned, thus setting the timing. Xenon timing lights have the advantage over neon lights because they are more visible in daylight.

timing mark: See timing marks.

timing marks: [1] Marks or notches, usually located on the vibration damper, used to synchronize the ignition system so that the plugs will fire at the precise time. [2] One tooth on either the camshaft or crankshaft gear will be marked with an indentation or some other mark. Another mark will be found on the other gear between two of the teeth. The two gears must be meshed so that the marked tooth meshes with the marked spot on the other gear.

Tin Lizzie: An affectionate name for the Model T Ford of which 15,007,033 were built.

tinning: coating a piece of metal with a very thin layer of solder.

tire: The rubber part of the wheel which contacts the ground. The construction can be bias-ply, bias-belted, or radial. The plies are made of rayon, nylon, and polyester. Belting can be fiberglass, steel, or kevlar. The rest of the tire is hard rubber. Also see knobby tires, pneumatic tire, sew-up tire, tubular tire, and wired-on tire.

tire aging: The deterioration of rubber properties by oxidation over a period of time.

tire balance: Because tires turn at relatively high speeds, they must be carefully weighted so that they do not bounce or vibrate when they rotate. Two basic kinds of balancing are static balance and dynamic balance.

tire bead: That portion of the tire that bears against the rim flange. The bead has a number of turns of steel wire in it to provide great strength.

tire casing: The main body of the tire exclusive of the tread, tube, etc.

tire clearance: See vertical tire clearance, longitudinal tire clearance, lateral tire clearance, and front wheel tire clearance.

tire deviation angle: An angle formed by the direction of travel of a vehicle and the steered direction (that which the wheels are pointing). It is produced by distortions within the tire, due to external forces. Not to be confused by actual slipping or skidding. Also called slip angle.

tire dressing: Paint, black glossy or dull finish, to improve appearance of tire sidewalls.

tire gage: See tire gauge.

tire gauge: An instrument for determining the pressure in a tube or tire.

tier growth: The stretching of textile tire cord materials due to heat and loss of strength, resulting in the casing increasing in size.

tire iron: A tool for removing a tire from the rim of a wheel. Also see spoon.

tire jack: A device which is used to lift one corner of a vehicle so that a wheel can be removed and replaced in the event of a flat tire. See jack.

tire lever: A tire iron.

tire paint: A black paint, compatible to tire bodies, used to enhance the appearance of a tire after retreading.

tire plies: The layers of nylon, rayon, etc., cloth that are used to form the casing. Most vehicle tires are two ply with a four ply rating. Two ply indicates two layers of cloth or plies.

tire ply: See tire plies.

tire roll-off: A condition in which the bead unseats because a tire was run while flat. Also, the sudden loss of air due to side forces, such as hard cornering, combined with underinflation. The safety ledge on passenger rims (a necessity for tubeless mountings) guards against a roll-off.

tire rotation: Moving the front wheels to the rear and the rear to the front to equalize any wear irregularities in the tires.

tire sidewall: That portion of the tire between the tread and the bead.

tire Size Markings: Those designations that appear on the side of a tire to indicate its basic dimensions; width, and rim diameter.

tire spreader: Any device, manual or hydraulic, used to spread tire beads for inspection, repair, service, etc.

tire store: retail outlet selling and installing tires and often offering other vehicle repair services.

tire tread: That part of the tire that contacts the road.

tire unbalance: A tire that is not weighted properly can cause vibration. The condition is exaggerated by centrifugal force which increases as speed is increased and by the distance the heave spot is from the wheel axis.

tire valve: A small valve, mounted on the wheel rim of a tubeless tire, that allows air to be added to the tire with an air hose and allows air to be withdrawn from an over-inflated tire by pressing on the little stem at the end of the valve. Some tire valves have little caps to protect against leaks and keep dirt from fouling the valve. On tires with inner tubes, the tire valve is mounted on the inner tube. There are two kinds of valves used: Presta and Schrader.

TISC: The Industry Safety Council.

T-joint: Joint formed by placing one metal against another at an angle of 90 degree. The edge of one metal contacts the surface of the other metals.

TMPH: Acronym for "Ton Mile Per Hour." A system devised to ascertain the working capacity of earthmover tires; it is a supplement to the normal load and inflation tables.

toe: See brake shoe toe, heel and toe, toe control link, toe-in, toe-out, toe-out on turns, toe steer, and tooth toe.

toe control link: A lateral link in a multilink suspension designed to control a wheel's direction as the suspension moves up and down.

toe in: See toe-in.

toe-in: An adjustment of the front wheels where the distance from the center of the left wheel to the center of the right wheel is less at the front of the wheels than at the back of the wheels. A slight amount of toe-in is usually specified to keep the front wheels running parallel on the road by offsetting other forces that tend to spread the wheels apart. The major force is the backward thrust of the road against the tire tread while the vehicle is moving forward. Other factors include play in the tie-rod assembly and allowance for angular changes caused by wheel bounce or variations in road conditions. Toe-in is measured in fractions of an inch or millimeters

toe of weld: Junction of the face of the weld and the base metal.

toe out: See toe-out.

toe-out: An adjustment of the wheels where the front of the wheels is further apart than the back. Generally toe-out is not desirable. Toe-out is measured in fractions of an inch or millimeters. See toe-in.

toe out on turns: See toe-out on turns.

toe-out on turns: When the vehicle negotiates a curve, the inner wheel turns more sharply and while the wheels remain in this position, a condition of toe-out exists.

toe steer: The changes in the direction of a wheel that occur without driver steering input. Toe steer can be caused by ride steer or by deflections in suspension components caused by the stresses of cornering, accelerating, and/or braking on smooth and bumpy roads.

toggle switch: A switch that is actuated by flipping a small lever either up and down or from side to side.

tolerance: The amount of variation permitted from an exact size or measurement. The actual amount from the smallest acceptable dimension to the largest acceptable dimension.

tommy bar: A rod that fits in a box spanner

ton mile per hour: (TMPH) A system devised to ascertain the working capacity of earthmover tires; it is a supplement to the normal load and inflation tables.

tonneau: See tonneau cover.

tonneau cover: A cover of leather or other soft pliable material used for protecting the interior of a convertible when the soft top is down. The cover snaps to the dash, sides and rear of the vehicle and often has a zipper allowing the driver to operate the vehicle while the passenger side of the vehicle remains covered.

tool: [1] As a noun, it is any device which assists in the installation or removal of a component. [2] To work material by turning, milling, grinding, polishing, drilling, punching, boring, shaping, shearing, pressing, or planing. [3] As a colloquial verb, it is the action of motion as in We were tooling down the highway when we saw you.

tooling: Set of required standard or special tools needed to produce a particular part. It includes jigs, fixtures, gauges, and cutting tools; but excludes machined tools. Also see tool.

tooth heel: The wider outside end of the tooth in the differential ring gear.

tooth toe: The narrower inside end of the tooth in the differential ring gear.

top cap: When retreading a tire, new tread rubber is added to the buffed casing, covering only the crown area. Also see full cap.

top dead center: (TDC) Highest point of piston and connecting-rod travel in a cylinder; the ends of the compression and exhaust strokes in a four-cycle engine.

top end gasket kit: The gaskets that apply to everything from the base gasket up (e.g., base gasket, head gasket, manifold gaskets, carburetor mounting gaskets) as well as all the O-rings and replaceable spacers. Contrasts with the bottom end gasket kit.

top end speed: The maximum speed which a vehicle can attain. This may differ from the maximum speed allowed by the law and from the recommended maximum speed of a vehicle. In some vehicles, governors are installed to limit the speed so that top end speed is not attained. Others may use warning lights or flashing speedometer readings (i.e., on digital displays) or even warning sounds. Also see bury the needle and red line.

top off: Fill a partially filled container to full capacity.

top ring groove insert: A piston ring that has a nickel-iron or comparable metal insert cast into the piston heads. The top ring groove is cut into this metal. As the top ring grooves in aluminum pistons pound out of shape, this insert groove will prolong the useful life of the piston and ring.

top tube: On a bicycle, the horizontal tube that connects the seat tube with the head tube.

top up the battery: Determine if the electrolyte is at the correct level and add distilled water to bring it up if necessary

torch: The mechanism which the operator holds during gas welding and cutting, at the end of which the gases are burned to perform the various gas welding and cutting operations.

Toronado: The 1966-67 Toronado models are milestone cars. Sometimes you will see this car incorrectly spelled "Tornado" in classified ads.

torpedo: An open sports vehicle generally with an unbroken design line from the hood to the back of the car.

torque: Turning or twisting force such as the force imparted on the drive line by the engine. Usually measured in lb-ft. It differs from work or power in that torque does not necessarily produce motion. Basically, the magnitude of a torque acting on a body is the product of the magnitude of a force and its force arm (perpendicular distance from the axis of rotation of the body to the line of action of the force). This product is called the moment of the torque about the axis or the torque. Also see self-aligning torque.

torque converter: A unit in an automatic transmission, quite similar to the fluid coupling, that transfers engine torque to the transmission input shaft. It also cushions the flow of power. Unlike the fluid coupling, the torque converter can multiply engine torque. This is accomplished by installing one or more stators between the torus members. In the torque converter the driving torus is referred to as the "pump" and the driven torus as the "turbine." The engine drives the impeller which in turn impels fluid against the vanes of a turbine connected through transmission gears to the driveshaft of the automobile. The stator redirects oil flow from the turbine to boost impeller action and multiply engine torque.

torque multiplication: Increasing engine torque in the automatic transmission through the use of a torque converter.

torque rods: See stabilizer.

torque sensitive limited slip differential: !!! Definition under construction !!!.

torque steer: A tendency for a car to turn in a particular direction when power is applied. Torque steer is common in front-drive cars because reaction forces created in the half-shafts can generate uneven steering forces in the front tires.

torque tube drive: The method of connecting the transmission output shaft to the differential pinion shaft by using an enclosed driveshaft. The driveshaft is enclosed in a torque tube that is bolted to the rear axle housing on one end and is pivoted through a ball joint to the rear of the transmission on the other. The driving force of the rear wheels is transferred to the frame through the torque tube. This method was used on older cars in an attempt to get rid of the twisting forces of engine torque on the suspension and driveshaft.

torque wrench: A tool used to draw nuts, cap screws, etc., up to a specified tension by measuring the torque (turning force) being applied.

torsion bar: A long spring steel rod attached in such a way that one end is anchored while the other is free to twist. One end is fastened to the frame at one end and to a suspension part at the other. If an arm is attached, at right angles, to the free end, any movement of the arm will cause the rod or bar to twist the bar's resistance to twisting provides a spring action. The torsion bar replaces both coil and leaf springs in some suspension systems. The main advantage of the torsion bar over the coil spring in the front suspension is the ease of adjusting front suspension height.

torsion bar suspension: A suspension system that makes use of torsion bars in place of the leaf or coil spring.

torsional vibration: A twisting and untwisting action developed in a shaft. It is caused either by intermittent applications of power or load.

torsion spring: See torsion bar.

torus: The inner surface of a hollow doughnut-shaped structure, especially found in automatic transmissions. See fluid coupling.

totalled: A car accident in which a vehicle has sustained severe damage so that the cost to repair it is more than what the vehicle is worth. In this case, it is written off

total quality management: (TQM) A management technique to improve the quality of goods and services, reduce operating costs and increase customer satisfaction.

toughened glass: See laminated windshield.

tourer: British term for touring car See loaded tourer, sports tourer, and AC Buckland Open Tourer.

touring bike: [1] A motorcycle that comes from the manufacturer with saddlebags and a trunk. [2] A bicycle that has been equipped with saddlebags (often over the front wheels as well as the rear).

touring car: A vehicle with a body longer than the phaeton style, but very similar to it. It permits the use of auxiliary seats in the rear passenger compartment. It was an open car with seats for four or more passengers. Early models had no side weather protection but later were fitted with detachable side screens and curtains. Made until about 1930.

touring triple: A triple chainring crankset designed to provide the wide range of gears needed for loaded bicycle touring.

tourist: A cyclist who takes short or long excursions by bicycle, often carrying several panniers containing clothing and camping equipment.

town car: The same as the Imperial sedan without the rear quarter windows or a roof over the front compartment.

TQM: Acronym for "Total Quality Management."

TRA: Tire and Rim Association.

track: Front track is the distance between the center of the left front wheel and the center of the right front wheel when the vehicle is set to its normal ride height and wheel alignment specifications. Rear track is the distance between the center of the left rear wheel and the center of the right rear wheel. They are not always the same.

tracking: The alignment of the vehicle with respect to axle centers of a vehicle being in the same plane, rear tires following front tires and trailer following the tractor, in the attitude designed. Correct tracking is when the rear wheels of a vehicle follow the same line as the front wheels.

track rod: See panhard rod.

traction: The force of adhesive friction exerted by a body on the surface on which it moves. Also see liquid traction.

traction bar: articulated bar or link attached to both frame and rear axle housing to prevent spring windup (with resultant wheel hop) during heavy acceleration or braking. Also see panhard rod.

traction control, low speed: A system that helps prevent front-wheel spin on slippery or gravel surfaces during acceleration at speeds up to 40 kph (25 mph).

traction differential: See limited-slip differential.

traction engine: A steam or diesel engine used for hauling heavy vehicles on roads or over difficult terrain.

traction limited grade: Steepest negotiable grade where traction is the limiting factor.

tractor: Truck portion of combination or train. Also called "semi," "semi-tractor," "truck tractor," or "tractor-trailer."

tractor-trailer: See tractor.

trail braking: A driving technique in which the driver begins to brake before entering a turn and then continues to brake as he eases into the corner. As cornering forces build, the driver gradually feathers off the brakes -- trading braking power for cornering grip. By increasing the vertical loading -- and thus the traction -- at the front tires, trail-braking can improve a car's turn-in.

trail distance: The distance from the point at which the cornering force acts to the center of the wheel or steering axis.

trailer: [1] Platform or container on wheels pulled by a truck or tractor. [2] Distance between fifth wheel pin and center of rear axle (or center between tandems). [3] A unit which contains camping equipment and is pulled behind a vehicle. Also see soft-top trailer and hard-top trailer

trailer towing package: See trailer-towing package.

trailer-towing package: An optional equipment which usually includes a heavy-duty suspension, a larger radiator, a transmission cooler, and a rear bumper with a trailer hitch. This improves handling and allows a vehicle to haul a heavy trailer.

trailing arm: Type of independent rear suspension in which the pivot axis is exactly across the vehicle, or perpendicular to the longitudinal axis. This means the wheels are always upright relative to the body and hence leaning with the body in a corner. Widely used at the rear of front-wheel-drive cars. Also see semi-trailing arm.

trailing brake shoe: The brake shoe that is installed facing the rear of the vehicle. Also called secondary brake shoe or reverse brake shoe.

trailing link: A suspension link that is aligned to resist longitudinal motions in a wheel; it is mounted to the chassis ahead of the wheel.

train: See drivetrain, powertrain, valvetrain, and wind trainer.

trainer: See wind trainer.

tramp: [1] A hopping motion of the front wheels usually caused by incorrect balance or when a high inflation tire has been run empty. [2] The action of rapidly depressing the throttle pedal. Also see axle wind up or axle tramp.

tranny: Colloquial name for "transmission."

trans: Abbreviation for "transmission."

transaxle: A drive setup in which the transmission gearbox, clutch, final drive, and differential are combined into a single unit connected directly to the driveshaft. It is used mostly in rear-engine cars like the Corvair, but is also found in some front-wheel drive cars and some performance cars where a front engine/rear transaxle gives better overall balance (such as the Alfa Romeo Alfetta).

transceiver: A radio device able to transmit and receive radio waves.

transducer: A device for transferring power which is generated in one system to another system in the same or a different form, e.g., electrical to mechanical.

transfer: See decal

transfer case: An auxiliary device in a 4-wheel-drive vehicle that allows power to be delivered to both axles. Normally the transfer case incorporates a shifting device so that the front drive can be disconnected, if desired, for running on pavement. Also see four-wheel drive.

transfer port: A channel in the block of a two-stroke engine where the air-fuel mixture enters the combustion chamber and exits out another transfer port after it burns.

transformer: An electrical device with an arrangement of copper coils with an iron center, used to increase or decrease electrical voltage. A vehicle ignition coil transforms the voltage from 12 volts to upward of 20,000 volts.

transistor ignition: A form of ignition system which uses transistors and a special coil. The conventional distributor and point setup is used, but the points merely serve to trigger a transistor which switches the heavy primary current. With the transistor unit, the voltage remains constant, thus permitting high engine rpm without resultant engine "miss." Transistors are much more efficient switches at high engine speeds and in addition they don't burn, pit or change gap spacing. The advantages of these systems include greatly increased point life, generally better starting because of improved contact condition and voltage output not greatly affected by breaker point dwell time which results in better high-rpm performance. Also point life is greatly extended as the transistor system passes a very small amount of current through the points.

transmission: A device (full of gears) that uses gearing or torque conversion to effect a change in the ratio between engine rpm and driving wheel rpm. When engine rpm goes up in relation to wheel rpm, more torque but less speed is produced. A reduction in engine rpm in relation to wheel rpm produces a higher road speed but delivers less torque to the driving wheels. Also see auxiliary transmission, automatic transmission, five-speed transmission, infinitely variable transmission, manual transmission, progressive transmission, standard transmission, and synchromesh transmission.

transmission adapter: A unit that allows a different make or year transmission to be bolted up to the original engine.

transmission, automatic: See automatic transmission.

transmission, conventional: See standard transmission.

transmission fluid: (ATF) A superthin oil that fills the automatic transmission system so that it can run on hydraulic pressure. It can also be used in some power-steering pumps. It is sometimes used to clean the inside of a carburetor.

transmission housing: The outer shell which contains the transmission gears.

transmission, standard: See standard transmission.

transverse arm: A suspension arm not split into two separate sections as is an A-arm. Often used as the bottom locating link with MacPherson strut suspension. Also called "lateral arm." Also see MacPherson strut.

transverse cable: See stirrup cable.

transverse engine: An engine that is mounted laterally (i.e., left to right) between the drive wheels (rather than longitudinally -- front to back), often found on cars with front-wheel drive.

transverse leaf spring: A leaf spring that is mounted so that it is at right angles to the length of the vehicle.

transverse mount: See transverse engine.

trap: [1] The area over which the vehicle is raced for timing purposes. [2] A pedal on a bicycle into which the foot is locked in place. See rattrap.

traps: See trap.

travel: The distance an object can move. See clutch pedal free travel.

travel trailer: A unit which is pulled behind a vehicle. It is enclosed and contains all the conveniences of home: sleeping room, showers, toilets, cooking, dining, and relaxing. Some have a slide-out feature which enlarges the living, dining, sleeping, or cooking areas.

tread: [1] The distance between the two front or two rear wheels. [2] Portion of the tire which contacts the roadway. [3] The pattern of the outside circumference surface of a tire. Also see asymmetrical tread, directional tire, symmetrical, and wide treads.

tread bar: Raised portions of rubber that make up me tread of the tire, separated by grooves that are arranged laterally, providing traction in the forward or rearward direction.

tread block: Raised portions of rubber that make up part of the tread pattern They are often present in the shoulder area and are more or less rectangular in shape.

tread depth: The measurement from the bottom cm of the tread groove to the top of the tread expressed in 32nds of an inch.

tread rib: The continuous raised portions of rubber that run circumferentially (straight or in a zigzag pattern) making up the tread on the tire.

tread roller: A roller, either manual or power, used to help apply me tread rubber, remove trapped air and obtain adhesion. Also see stitching.

tread separation: Pulling away of the tread from the tire casing.

tread squirm: The flexibility in the tire tread between the surface of the tread and the tire carcass. Snow tires, with their small, deep, unsupported tread blocks, have a large amount of tread squirm. Slick racing tires, which have no tread pattern, have very little squirm.

tread wear indicator: See tread-wear indicators.

tread-wear indicator: See tread-wear indicators.

tread wear indicators: See tread-wear indicators.

tread-wear indicators: Bars of hard rubber that appear across the treads of a tire. They are 1/16" above the base of the tread. They become visible when the tread has been worn down so that only 1.5 mm (a sixteenth of an inch) of tread is left.

tree: See christmas tree.

trials: A type of ATB cycling competition that tests riders not on speed but on ability to maintain balance while navigating a bicycle around and over numerous obstacles such as rocks, trees, and steep, slippery terrain.

triangle: See front triangle and rear triangle.

triangle split system: See dual brakes -- especially the picture.

triangle-split system: See dual brakes -- especially the picture.

triangulation: The arrangement of the stabilizing tread plies whereby their cords form tiny triangles in the Michelin 'X. radial truck tire.

trick: !!! Definition under construction !!!.

tricycle: A three wheeled vehicle (usually pedal-powered) where there is a single front wheel and two rear wheels. A three-wheeled, early-type open automobile using bicycle wheels and a steel-tube frame. Also see trike.

tri-drive: A vehicle having three rear driving axles.

trike: A tricycle. Sometimes a motorcycle that has been converted to a three-wheeled unit. Sometimes the rear two wheels are powered by a small automobile engine.

trim: Nonfunctional metal or plastic molding, frames, and other decorative additions to vehicle bodies and interiors.

trim level: vehicle designation assigned by vehicle manufacturers that represent specific equipment packages.

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