| Tailpipe |
A
piece of steel exhaust tubing at the tail of a vehicle usually extending
from the muffler. The tailpipe is usually the furthestmost piece
of exhaust pipe. On vehicle with mufflers mounted mid-vehicle, tailpipes
frequently rot out because they don't get as warm and evaporate
moisture out as well. |
|
|
| Taper
roller bearing |
Roller
bearings in which the rollers are larger at one end than at the
other. The whole bearing assembly is roughly cone-shaped and fits
into a tapered bearing race. By using shims or tightening an adjuster
nut, the bearing can be pressed into the cone to eliminate freeplay.
Tapered roller bearings are used as front wheel bearings on rear
wheel drive vehicles, and in differentials and transmissions. |
|
|
| Tappet |
Another
term for lifter. See lifter. |
|
|
| Taxi |
Derived
from taximeter, an instrument invented by Wilhelm Bruhn in 1891
which automatically recorded the distance traveled and/or the
time consumed. Enables fares to be accurately measured. Taxicab
comes from taximeters + cabriolet. Cabriolet is a two-wheeled,
one-horse carriage with a folding rear leather top which was a
popular type of carriage used as taxis in 19th century London.
The first motorized taxi service was operated by Drosch-kenbesitzer
"Dotz" in the spring of 1896 in Stuttgart, Germany.
The next year, a rival service was begun by Friedrich Greiner.
|
|
|
|
T-bar roof |
A
semiconvertible roof design pioneered by General Motors that debuted
on the 1968 Corvette. Features removable overhead panels above the
driver and passenger which attach to the windshield frame and a
center bar connecting the windshield and rear portion of the roof.
The panels can be fiberglass or transparent (smoked) plastic. Stronger
design than a true convertible design. Also called a "T-top"
because when the panels are removed the windshield and center connecting
bar form the shape of a capitol "T". |
|
|
| TBI |
See
Throttle-body injection. |
|
|
| TDC |
See
Top dead center. |
|
|
| Temper |
A
metal's hardness, or hardening metal by heat-treating, or hammering/pressing
cold metal. |
|
|
| Tempered
glass |
A
type of safety glass used in automobiles which is created by heat
treating. Used on the sides and rear windows of automobiles. Heat
treating glass creates a strong, yet brittle outer layer that, when
damaged, shatters into small squarish pieces generally no larger
than a fingernail. Cuts received from tempered glass are usually
surface lacerations -- typically far less severe than deep cuts
that result when contacting large shards produced by broken glass
which is untempered. |
|
|
| Tensile
strength |
A
material's resistance to stretching. Tensile strength is measured
in pounds per square inch (lb/sq. in). |
|
|
| Terminal
post |
A
post on a car battery where the battery cables connect to. The positive
terminal (+) is known as the anode, the negative (-) is called the
cathode. Battery terminals are made of lead and are prone to corrosion,
especially the positive terminal. It may be one of the most frequent
causes of an engine not cranking. Yearly cleaning and the use of
anticorrosion washers are helpful. |
|
|
| Test
track |
A
facility usually consisting of a high-speed banked oval track, road
coarse, and or a skid pad where manufacturers test production vehicles
and prototypes. Not generally accessible to the public. Also called
Proving grounds. |
|
|
| Tetraethyl
lead |
A
lead compound that was added to gasoline until the 1980's to increase
a fuel's octane rating and lubricate valve seats. Lead has been
phased out of gasoline in an effort to reduce people's exposure
to lead which has been shown to lead to serious health problems
after prolonged exposure.
|
|
|
| T-head
engine |
An
engine design used on engines of some vintage automobiles where
all the intake valves were on one side of the cylinders and the
exhaust valves are on the other side. After about 1915 other designs
took over. |
|
|
| Theft
alarm |
A
system using sensors and a loud buzzer designed to alert others
and scare would-be thiefs away. Also called Theft deterrent. |
|
|
| Thermal
efficiency |
The
ratio of work done by an engine verses the total amount of heat
contained in it's fuel. The ratio is always less than 1:1 because
not all of the heat contained in the fuel is converted into power.
Some is used up to overcome friction, some goes out the exhaust
as unburned gasses. |
|
|
| Thermal
reactor |
A
kind of afterburner chamber used in place of an exhaust manifold
on some rotary engines. Produces cleaner exhaust output. |
|
|
| Thermister |
A
resistor whose resistance changes proportional to temperature. Used
in temperature gauges and thermo switches (electric fan). |
|
|
|
Thermostat
|
A
device used in automotive cooling systems which is essentially
a heat-controled valve which regulates coolant flow to the radiator
and thus regulates engine temperature. Engineers design engines
to operate most efficiently in a specific temperature range. Upon
startup, the thermostat is closed which blocks or reduces coolant
flow to the radiator until engine coolant has reached operating
temperature. This helps the engine warm up quickly.
Thermostats
of different designs are used in other places in a typical automobile;
in the passenger compartments to control heating and ventilation
temperatures; in a carburetor to regulate the choke; and in a
car's breather to direct warm air off an engine's exhaust manifold
so it receives preheated air.
|
|
|
| Three-way
catalyst |
A
catalytic converter which converts engine exhaust gasses of carbon
monoxide, nitrogen and hydrocarbons into less harmful, less polluting
gasses. |
|
|
| Throttle |
The
accelerator pedal. Also can be the lever on the carburetor or throttle
body injection which the accelerator cable connects to. |
|
|
| Throttle
body (injection) (TBI) |
A
carburetor-style fuel injection system which uses two fuel injectors
to supply fuel to all an engine's cylinders. For more info, see
Fuel injection. |
|
|
| Throttle
plate/ valve |
Flat,
rounded plates in a carburetor that basically act like an air valve
to vary the amount of air which flows through the carburetor (and
into the engine). Controls engine speed. Throttle plates mount to
a rod which connect via a cable to the gas pedal. When the accelerator
is pushed, the cable causes the rod (and throttle plate(s)) to turn
open/close and vary engine speed. |
|
|
| Throw |
The
distance from the center of the crankshaft main bearing to the center
of the connecting rod bearing journal. The piston stroke is twice
the length of the throw (as the crankshaft revolves the throw moves
above and below the crankshaft). |
|
|
| Throwout
bearing |
A
bearing inside the clutch assembly which pushes the release fingers
and disengages the clutch when the pedal is pushed. Also called
Clutch release bearing. |
|
|
| Thrust
bearing |
A
bearing with flanges that prevents a shaft from moving laterally.
Also, a bearing design where the bearing carries a load that is
pressed against it. |
|
|
| Thrust
washer |
A
hardened metal washer, usually of a measured thickness, which accepts
a heavy load and prevents lateral movement of gears or a shaft.
Commonly used between gears in a transmission. |
|
|
| Tiedowns |
A
device that can be used to hold cargo or tarps in place. Can be
cord, or stretchable rubber bands such as bungee cords. |
|
|
| Tie
rod |
A
rod used in a vehicle's steering system which connects and transmits
steering motion from the rack-and-pinoin rack to the steering knuckles.
On vehicle's with a recirculating ball-type steering box, a center
link/drag link (trucks) is used. Tie rods connect from the center
link/drag link to the steering knuckles. Tie rods are usually contain
a threaded end so they can be adjusted to set proper tow. |
|
|
| Tilt
steering wheel |
A
feature that allows the driver to raise or lower the steering wheel's
height. |
|
|
| Timed
injection |
See
Pulsed injection. |
|
|
| Timing |
The
point at which the intake and exhaust valves open/close and when
the spark plugs fire in relation to the crankshaft (and therefore
pistons) position. In order to gain optimum power and efficiency,
critical engine parts and processes must occur at a precise time.
Timing is measure in crankshaft degrees. Modern vehicles use computers
to adjust timing so it is always correct. |
|
|
| Timing
belt |
A
wide, cogged or toothed, flat belt which drives the camshaft from
the crankshaft. Used most commonly on overhead cam engines where
the camshaft is considerably further away from the crankshaft
than a traditional V6 or V8 pushrod engine with a single camshaft.
One
downside of belt is that they have a definite lifespan. If not
changed, usually around 60,000 miles, they can break, often resulting
in serious engine damage.
|
|
|
| Timing
chain |
A
drive chain which connects the camshaft to the crankshaft. |
|
|
| Timing
gears |
A
system of gears which allows the crankshaft to drive the camshaft.
Used mostly on race cars, street rods and commercial vehicles where
severe conditions require a heavy-duty timing system. Noisier, but
more durable than timing chains or belts. |
|
|
| Tip
plate |
The
vertical plates on the outer ends of an aerodynamic wing used on
race cars. Controls turbulence around the outer edge of the wing.
Also referred to as the End plate. |
|
|
| Tip
seal |
Special
seals used at the three outer edges of a rotary engine's rotor to
prevent compressed gas leakage in the combustion area. Also transfers
combustion heat to the rotor to the engine block. Used in Wankel
rotary engines. The equivalent of piston rings in a typical internal
combustion engine. Also known as Apex seals. |
|
|
| Tire(s)
|
A
rubber component which fits on a vehicle's wheel and contacts the
road surface and supports a vehicle's weight. A tire carcass is
made up of belts of fine steel, or cord imbedded in rubber with
a thick tread pattern molded on it's outer edge. Automotive tires
are of the tubeless type -- they create an air-tight seal to the
wheel and are usually inflated to around 32-35 psi. Combining different
carcass and tread designs can produce a wide variety of tires such
as, high speed performance tires, mud & snow, all-season, winter,
off road and racing tires. |
|
|
| Tire
bleach |
A
timesaving product used by auto dealers and detailers that can be
sprayed onto tires to clean dirt off whitewalls or raised lettering.
Leaves the whitewalls or raised lettering particularly white. |
|
|
| Tire
bulge |
The
region at the base of a tire where the sidewalls flex outward due
to vehicle weight. An underinflated tire will exhibit greater bulge.
Also see Loaded section height. |
|
|
| Tire
depth gauge |
A
measuring device usually in the shape of a "T" that can
be pressed onto a tire to quickly determine the distance between
the top of the tread and base of the tread. Used by auto and tire
dealers to determine a tire's tread life and whether tires are due
for rotation. |
|
|
| Tire
dressing |
See
Dressing. |
|
|
| Tire
foam |
See
Tire bleach (above). |
|
|
| Tire
grading |
See
Uniform tire quality grading. |
|
|
| Tire
iron(s) |
Heavy-duty
steel bars and rods used to remove or install a tire from or onto
a wheel. Sturdy steel bars are required in order to pry a tire's
bead over a wheel rim. |
|
|
| Tire
patch |
The
area of a tire's tread that contacts the ground. Also referred
to as the Footprint or Contact patch.
Also,
a flat piece of thin rubber which can be adhered on the inside
of a tire to patch a small hole.
|
|
|
| Tire
plug |
A
thin strand-like strip of rubber, or soft rubber-coated cord which
can be inserted into a small hole in a tire to seal an air leak.
Requires a special tool. The advantage of a tire plug is the speed
and ease which a tire can be repaired. Simply mount the strand in
the tool and insert into the tire's hole, twist and carefully remove
the tool. Great for repairing small holes like those made from nails.
A properly plugged tire which did not suffer any cord or sidewall
damage can remain sealed for it's entire service life. |
|
|
| Tire
pressure gauge |
An
air pressure gauge that can be pressed onto a tire valve stem
to determine air pressure inside a tire. Most tire pressure gauges
are of the pencil type and are graduated in both pounds per square
inch (psi) and kilopascals (kpa).
**
To convert the English unit of pounds into it's metric equivalent
of kilopascels, multiply pounds by 6.895.
|
|
|
| Tire
ratings |
Numbers
and letters printed on the sidewall of tires that list it's size,
weight rating, speed capacity and other information. As an example,
a tire which has P225/70VR15 is a metric tire that has a cross section
width (sidewall to sidewall width) of 215 millimeters and an aspect
ratio of 70 which is the ratio of a tire's height to it's width
(in this case the tire's height is 70% of it's width). The "V"
indicates a maximum speed of 149, and is a Radial (R) constructed
tire which fit's a 15" diameter rim. |
|
|
| Tire
rotation |
Moving
tires to different locations on the vehicle to equalize treadwear
and increase tire life (can substantially increase tread-life).
Although there are a variety of different tire rotation schemes,
all have their merits. Here are the most popular:
1.
Move front tires to rear, cross rear tires when moving to front.
2. Cross front tires when moving to rear, move rear tires straight
ahead.
3. Move front tires straight back, and rear tires forward, keeping
on same side of car (least popular routine).
4. Spare tire rotation: Cross rear tires as move to front, move
one front tire straight back to rear, move other front tire to
spare tire compartment. Install spare tire on rear.
|
|
|
| Tire
scrub |
Tire
scuffing or slipping caused by a variety of factors. Can be caused
by turning a corner too sharply, or having misaligned steering
such as incorrect toe, or worn steering parts which can cause
the wheels to scuff. Tire scrub is particularly common on rear-wheel-drive
vehicles when making sharp slow speed turns. Ackerman steering
is term for compromise steering geometry which allows the outer
wheel to turn a larger circle when making turns to reduce tire
scrub.
Tire
scrub can also occur on some four-wheel-drive vehicles when turning
on dry pavement. Driveline and tire binding can occur which causes
the tires to slip or hop.
See
Ackerman steering, Caster, Camber and Differential.
|
|
|
| Tire
stager |
See
Stager. |
|
|
| Tire
valve |
A
cone-shaped one-way valve inside a tire's valve stem which allows
air to be inserted into the tire, but prevents air from escaping.
Often referred to as a Schrader valve, named after it's inventor.
Also see Valve stem. |
|
|
| Tire
width |
See
Section width. |
|
|
| Toe |
Steering
geometry where tires are angled slightly inwards toward the center
of the vehicle. Most manufacturers specify a tow setting of a couple
degrees at the front wheels, meaning the leading edge of the front
wheels is actually closer than the rear edge (they point inwards).
This compensates for rolling resistance and play in the suspension
joints and bushings which tend to pull the wheels back slightly
while driving. |
|
|
| Toe
board |
See
Floorboard. |
|
|
| Toe
control |
A
rear suspension design that actively adjusts tow to compensate for
slight changes in toe due to suspension flex and braking. The Mazda
RX-7 and some Mercedes and Porsche models incorporate such a design.
Maintains correct steering geometry during hard cornering and braking. |
|
|
| Toe
steer |
Undesirable
steering resulting from minor changes in toe that occur during cornering
and braking on some vehicles. Suspension compression resulting from
body roll can cause the front or rear wheels to tow in or out during
cornering which can lead to increased understeer or oversteer. Exacerbated
by worn suspension components. |
|
|
| Tolerance |
An
allowable amount of measure that a part can deviate from a nominal
standard and still be considered 'acceptable'. |
|
|
| Tonneau
cover |
A
removable cover which can be installed on a convertible when it's
top is down to cover the passenger compartment and protect from
rain. A typical tonneau cover is made from vinyl, waterproof canvas
or leather and attaches from the front of the dash to the rear
of the passenger compartment. Many have region around the driver
which can be unzipped so a driver can operate the automobile in
inclement times.
A
new type of tonneau cover is available for pickup trucks. However
it is used to prevent rain from entering the box rather than the
passenger area. Usually fastened with snaps, or can also be retractable
or a rigid lift-up design.
|
|
|
| Tool
box |
A
box, usually metal or plastic, which can be installed in the bed
of a pickup truck. Spans the entire width of the box. Generally
has lockable covers which can be lifted up on each side of the box
for access to tools. |
|
|
| Top
Dead Center (TDC) |
The
highest point of travel of a piston and connecting rod in an engine's
cylinder. Occurs on the end of the compression and exhaust strokes.
TDC is almost always indicated by a timing mark on an engine's harmonic
balancer. TDC is often used to properly position a crankshaft when
installing new timing components. The opposite is Bottom Dead Center
(BDC) where the piston and rod are at their lowest point of travel.
|
|
|
| Top
gear |
See
High gear. |
|
|
|
Torch ignition |
A
combustion system that uses two combustion chambers for each cylinder.
A small combustion chamber and spark plug is located off to the
side of the normal combustion chamber. During combustion, the smaller
combustion chamber contains a rich air/fuel mixture while the large
combustion chamber contains a very lean air/fuel mix. Ignition first
occurs in the small chamber; the rich air/fuel mix ignites easily
and a flame (like a "torch") spreads into the larger chamber
and ignites the lean air/fuel mix in that chamber which would otherwise
be prone to misfire. Similar to a Stratified Charge ignition system.
Overall, a leaner air/fuel mix can be burned which produces lower
emissions and cooler combustion temperatures. Also see Stratified
Charge. |
|
|
| Torque |
Turning
or twisting effort which is usually measured in ft-lb or Newton-meters
(metric). Engine torque is measure at the crankshaft on an engine
dynamometer. |
|
|
| Torque
converter |
A
device which mounts between the motor and transmission and acts
like a hydraulic clutch, torque multiplier, hydraulic pump and cushions
the flow of power from the motor to the transmission. Torque converters
mount to an engine's flywheel, are doughnut-shaped, made of steel,
filled with transmission fluid and contain three finned parts inside:
an impeller, turbine and stator. . The impeller is driven by the
motor, the turbine is connected to the transmission input shaft.
The stator is the middle component. As the engine (and torque converter)
rotates, hydraulic fluid inside flows between the vanes of the three
elements in such a way to increase engine torque. |
|
|
| Torque
converter lockup clutch |
A
mechanism found in modern torque converters which locks the torque
converter's impeller and turbine together at a certain speed to
essentially eliminate slippage between the engine and transmission.
Increases fuel economy. Most torque converters lock up at speeds
over 40 mph. |
|
|
| Torque
(horsepower) curve |
A
graphic representation of an engine's torque and how it varies with
crankshaft speed. Measured by a dynamometer. Torque (horsepower)
are plotted on a graph at different engine speeds (rpm) and connected
to form a visual representation of the engine's torque (horsepower)
for purposes of experimenting with different performance parts or
comparing to other engines. Also see Horsepower, Engine Dynamometer.
|
|
|
| Torque
peak |
Maximum
torque output of an engine. Represented as the highest point on
it's torque curve. |
|
|
| Torque
steer |
A
characteristic on many front-wheel-drive automobiles where the front
wheels tend to pull one way or the other during hard acceleration.
Causes the steering wheel to pull. Most pronounced on vehicles that
use unequal-length front axleshafts (which is often necessary with
front wheel drive designs). Engine torque becomes unevenly applied
to the ends of driveshafts (wheels) of different length shafts. |
|
|
| Torque
tube |
A
rear divetrain feature that appeared on the rear axles of vintage
automobiles. A long, heavy-duty steel tube was attached to the front
of the rear differential which supported the driveshaft. Consequently,
only one universal joint was required -- at the front of the driveshaft.
Such vehicles had a smooth ride because the springs only had to
support the vehicle's weight and did not have to be firm enough
to withstand twisting torque or braking torque. |
|
|
| Torsen
differential |
Torsen
differential. A type of torque-sensing differential limited-slip
system noted for smooth engagement. Sometimes referred to as a Torsen-Gleason
differential. Also see Zexel-Torson. |
|
|
| Torsen-Gleason
differential |
See
Torsen differential (above). Also see Zexel-Torson. |
|
|
| Torsion |
Twisting
of an object by two forces which are equal and opposite in direction. |
|
|
| Torsional
rigidity |
The
strength of an automotive chassis or body and it's resistance to
twisting forces. Measured in lb/degree of twist. |
|
|
| Torsion
bar |
A
long, rounded, spring-steel bar used in some vehicle's suspension
in place of coil springs to support a vehicle's weight and allow
suspension flex. A torsion bar hooks to the frame at one end, and
a suspension component at the other end - usually a lower A arm.
When the suspension flexes, the bar is twisted rather than compressed
like a coil spring. One advantage of such a system is it's compact
nature over coil springs. |
|
|
| Tossable
|
A
handling term used by road testers that describes quick responsiveness
and how well a vehicle can negotiate sharp sudden curves, U-turns
and slalom course. |
|
|
| Touring
car |
A
term which manufacturers applied to an open-top automobile that
had two or four-doors and could seat at least four occupants. Could
have a folding top for inclement situations, but not necessarily. |
|
|
| Tow
bar |
An
A-shaped metal frame which when connected between two vehicles
allows the lead vehicle to tow another vehicle without the necessity
of a driver in the towed vehicle to steer or apply the brakes.
Towbaring allows the transport of a vehicle over long distances.
When towbaring, the lead vehicle pulls the trailing vehicle and
also steers it. When the lead vehicle turns, it pulls the front
end of the trailing vehicle in the direction it is turning which
causes the front wheels of the trailing vehicle to steer in the
same direction. The vehicle being towed follows the lead vehicle.
Primary
downfalls of towing are severely reduced braking and handling.
Since the trailing vehicle cannot do any braking, the lead vehicle
must brake for the weight of both vehicles, which can double or
triple stopping distances. Secondly, handling is compromised because
the sideways pulling necessary to steer the nose of the trailing
vehicle reduces traction at the rear end of the lead vehicle leading
to severe oversteer conditions around corners. In addition, braking
around corners can be a tricky, white-knuckle experience. If care
is not observed, jackknifing is a distinct possibility.
The
best towbaring results come when using a lead vehicle which is
much heavier (particularly in it's rear) than the vehicle being
towed. Also, a vehicle with dual rear wheels (more traction) reduces
handling and traction problems.
|
|
|
| Tow
chain/strap |
A
durable chain or piece of heavy-duty strap or nylon rope used for
extracting stuck vehicles, or towing disabled vehicles to safety.
Tow straps usually contain metal hooks at each end and are preferred
because they allow some flexing and help 'slingshot' a vehicle from
a stuck position. |
|
|
| Track |
The
distance measured between the center of a pair of tires. |
|
|
| Track
bar |
Another
term for panhard rod. See Panhard rod. |
|
|
| Track
link |
A
semi-trailing-arm rear suspension design and patented by BMW. Adds
a helical motion to the wheel's normal swinging motion. Reduces
toe and camber changes as the wheel moves up and down from body
roll, braking and when encountering bumps. |
|
|
| Track
rod |
Another
name for a panhard rod. See panhard rod. |
|
|
| Traction |
How
well a tire adheres to the road surface. Affected by environmental
elements such as water, mud ice, sand on the road, and tread design.
Traction control systems found on some vehicles help prevent slippage
during acceleration in slippery conditions. |
|
|
| Traction
control |
A
computer-controlled system that reduces wheel-spin in slippery conditions
in order to increase stability and control. Typical system automatically
reduces throttle opening and pulses the brakes to eliminate wheel
spin during acceleration. In many ways, it's similar to an ABS system
using many of the same parts only applied to acceleration instead
of braking. |
|
|
| Trail
braking |
A
driving technique applied by race car divers which allows them to
negotiate corners faster than traditional braking techniques. The
brakes are applied before entering a corner and slowly released
once cornering forces build up. That leaves more gripping power
at the tires for cornering some of which would otherwise be used
for braking. |
|
|
|
Trailing arm |
A
suspension link used on the rear suspension of many front-wheel-drive
vehicles which secures a wheel to the vehicle chassis. In a trailing
arm suspension, the wheel attaches to the rear of the arm, thus
'trailing' the arm. Trailing arms are typically positioned parallel
to the length of the automobile which allows the wheel to remain
vertical during cornering and suspension flex. |
|
|
| Trailing
shoe |
The
rearward shoe in a drum brake system. Through self-energization
it wedges against the drum with greater force than hydraulic pressure
is pressing it. |
|
|
| Trailing-throttle
oversteer |
An
undesirable handling condition in which sudden oversteer can occur
in a rear-wheel-drive cars when the throttle is suddenly released
during hard cornering. As the throttle is released some weight shifts
forward removing weight from the rear tires which can cause a loss
of traction and sudden oversteer. Sometimes called Lift-throttle
oversteer. |
|
|
| Tramlining |
See
Nibble. |
|
|
| Trammel
bar |
A
bar which is used to adjust toe-in or toe-out. Measures between
the front and rear of a pair of tires. |
|
|
| Tramp |
A
condition similar to, but not as severe as, wheel hop where torque
transmitted to the wheels causes the rear axle to rotate back/fourth
on it's own centerline and makes the wheels hop up and down but
not actually leave the pavement. Also see Wheel hop and Axle windup. |
|
|
| Tranny |
Slang
for transmission. See Transmission (below). |
|
|
| Transaxle |
A
driveline component which combines a transmission and axle in one
unit. The transmission, differential, clutch and final drive ratios
are all in the transaxle unit. Used in all front wheel drive vehicles
and most rear-engine vehicles. |
|
|
| Transfer
case |
An
additional gearbox used on most four-wheel-drive trucks which splits
(transfers) power both front and rear wheels. Most transfer cases
can be switched by means of a lever or electric solenoid between
rear-wheel-drive and four-wheel-drive. Many also have an additional
"lower" gear for greater pulling power. Some include a
differential for "full-time" four-wheel-drive systems
which allows the front and rear driveshafts to spin at different
speeds and eliminates binding in the driveline which can occur when
driving a four-wheel-drive on dry pavement. |
|
|
| Transistorized
ignition |
An
electronic ignition system where ignition points send a signal to
a transistor to switch on/off current to create spark at the plugs.
Was an early form of electronic ignition which served to prolong
the life of ignition points. Ignition points tend to pit and wear
over time. |
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|
| Transmission |
The
main driveline device which hooks to the engine and contains different
gear ratios, a reverse gear and multiplies engine torque to drive
the vehicle's wheels. In low gears when the vehicle is accelerating
engine torque is multiplied. At higher speed torque is traded for
higher wheel speeds and lower engine speed. Manual transmissions
include a clutch, automatic transmissions use hydraulic fluid and
a torque converter to interface between the engine and transmission.
Many modern transmissions have an overdrive gear for better economy
at cruising speeds. |
|
|
| Transmission
cooler |
A
device, usually made of aluminum with thin continuous tubes and
cooling fins, similar to an automobile radiator, but smaller, used
to cool transmission fluid. Heat is an automatic transmission's
enemy and quickly damage or ruin a transmission if overheated. Manufacturers
usually pass transmission fluid through part of the radiator to
cool the fluid. In heavy-duty applications, an auxiliary miniature
radiator is mounted in front of the vehicle's radiator for purposed
of increased transmission fluid cooling capacity. Aftermarket transmission
coolers are available at automotive parts stores and are a good
addition when towing and hauling. |
|
|
| Transmission
mounts |
Rubber
and steel mounts similar to engine mounts which support the transmission.
Helps reduce transmission of noise and vibration to the chassis.
In a typical rear-wheel-drive vehicle one or two transmission
mounts supports the rear of the transmission. (The engine and
transmission are bolted together so there are usually two mounts
at the engine and one or two at the rear of the transmission.)
Also
see Engine mounts.
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|
|
| Transmission
tunnel |
The
'humped' portion in the center of the floorboard and extends from
the firewall to the rear of the passenger compartment on most cars.
Originally was necessary to provide room for the transmission on
rear-wheel-drive automobiles, but more recently, although it has
become reduced in size on modern vehicles, it still serves as an
important structural support design. |
|
|
|
Transverse
arm
Transverse link
|
See
Lateral arm. |
|
|
| Transverse
engine |
Positioning
the engine perpendicular to the vehicle's centerline. Used on nearly
all front-wheel-drive vehicles. Produces a short, compact engine
compartment and also aligns the crankshaft with the transmission
shaft and drive axle which eliminates additional gears to change
direction of powerflow. |
|
|
| Transverse
leaf spring |
A
leaf spring used for suspension that is mounted perpendicular to
the centerline of the vehicle such as was found on many vintage
automobiles. A single transversely-mounted leaf spring was used
to suspend both ends of a single axle. The design was revived in
the form of a fiberglass leaf spring which was used to suspend the
front/rear of some modern Corvettes. |
|
|
| Trap
oxidizer |
A
device fitted to the exhaust of some diesel motors which traps and
re-oxidizes soot and particulate combustion byproducts. Results
in cleaner diesel exhaust emissions. |
|
|
| Tread |
A
thick layer of rubber on the outer edge of a tire that contains
a pattern of grooves and blocks for increasing traction on pavement
or any other surface. Tire manufacturers design tread to move water
away from a tire to prevent hydroplaning, grip better in mud/snow,
provide good braking and keep noise at a minimum at high speeds.
Heat is generated at the tread of a rolling tire. Wider tread dissipates
heat into the tire better. |
|
|
| Tread
depth |
The
height of a tire's tread measured from the bottom of the tread grooves
to the top of the tread. Measured in 32nds of an inch. As tires
wear tread depth decreases which reduces a tire's ability to move
water away from it's surface and also reduces it's grip in mud/snow.
Most states have laws which specify minimum tread depth. Tire manufacturers
mold band, called Wear bands across the width of tires, usually
3/32" which show when a tire has worn out and must be replaced.
|
|
|
| Tread
grooves |
Lines
or grooves in a tire's tread which serve to help channel water from
a tire to prevent hydroplaning and increase a tire's traction in
slippery conditions. |
|
|
| Tread
squirm |
Tire
flex which occurs from having tall unsupported blocks of rubber
tread such as with snow tires. Tall rubber tread blocks can actually
bend from vehicle weight and cornering forces during cornering reducing
responsiveness. Racing slicks have very little squirm. |
|
|
| Trip
computer |
A
handy electronic device found in many modern automobiles which calculates
vehicle speed, distance, time and fuel use. Generally a microprocessor
is connected to the car's fuel system, speed sensors, engine and
clock. Common information includes fuel used, distance until empty,
average fuel economy, instant fuel economy, miles driven since last
refill, and sometimes trip completion calculator (requires initial
input of trip distance). |
|
|
| Trunk |
A
storage compartment at the rear of a car. Usually the spare tire
is located inside the trunk. On mid or rear-engine automobiles,
the front storage area is considered the trunk. |
|
|
| Trunk
lid |
A
lift-up, hinged door or body panel which covers and provides access
to the trunk. Seal on the trunk lid or around the outer edge of
the trunk prevent water from entering. |
|
|
| T-top |
See
T-bar roof. |
|
|
| Tube |
Generally
refers to a rubber inner tube used in tires. Nearly all passenger
tires are tubeless but some large truck tires require inner tubes. |
|
|
| Tubeless |
Tires
which do not require an inner tube to hold air pressure. Nearly
all passenger car and truck tires are of the tubeless tire design.
The inner rim rim of the tire, known as the "bead", forms
an airtight seal to the wheel rim when mounted on a wheel. Both
the bead and the rim must be clean and free of rust scale or defects
to form a lasting airtight seal. |
|
|
| Tuck-in |
An
undesirable handling condition associated with front-wheel-drive
cars in which the nose of the vehicle tends to "tuck in"
towards the inside of a curve when suddenly releasing the accelerator
during hard cornering. Tractive forces which were used for pulling
the vehicle straight ahead are redirected to cornering allowing
the vehicle to suddenly corner harder. Reduces understeer. Tuck-in
is not the same as oversteer. |
|
|
| Tuck-under |
See
Turn-under and Tumblehome. |
|
|
| Tumblehome |
A
styling term that describes part of the outer curvature of an automobile.
When looking at a vehicle straight-on, most vehicles exhibit an
outward curvature (narrower at the top/bottom than middle). Usually
the widest part is at the vehicle's belt line. In the design world,
the portion above the belt line that curves in from vertical is
termed the tumblehome. The curve from vertical below the belt line
is called turn-under. |
|
|
| Tuned
intake/exhaust system |
An
intake and exhaust system which are specially "tuned"
to take advantage of air pulses in order to increase airflow from
the intake manifold into the combustion chamber harness exhaust
pulses to help move combusted gasses out of the combustion chamber
through the exhaust system. A better breathing engine increases
power because more air can go through the cylinders and less energy
is required to draw in and expel gasses. Tuning is done by adjusting
the length and diameters of intake runners, header and exhaust pipes
and choosing an efficient muffler chamber design. |
|
|
| Tune-up |
A
general term for routine maintenance and readjusting timing, spark
gap and carburetor adjustments to achieve optimal engine performance.
With most modern vehicles, a general tune-up consists of replacing
the spark plugs, and usually changing the oil and air/oil/fuel filters
and toping off all fluids. Modern fuel injection systems rarely
require adjusting. A more thorough tune-up might include changing
the distributor cap and replacing spark plug wires. |
|
|
| Turbine |
A
disc-shaped device with vanes which can be used to turn a shaft
if acted upon by the force of a gas or liquid. Turbines are used
inside turbo chargers and inside torque converters. |
|
|
| Turbo |
See
Turbocharger. |
|
|
| Turbocharger |
A
device which uses energy from an engine's exhaust to increase power
output. Turbochargers consist of two turbine units connected by
a shaft; one connected to the exhaust, another to the engine's intake.
A control system regulates boost (intake pressure) to prevent engine
damage. Exhaust gasses rotate the exhaust turbine, which in turn,
spins the other turbine that forces air into the engine's intake
manifold. A turbocharger does not consume energy like a supercharger,
it makes use of otherwise wasted energy in an engine's exhaust system
to increase power output. Also see Supercharger. |
|
|
| Turbodiesel |
A
diesel engine fitted with a turbocharger. Used to increase a diesel
engine's power output (generally achieve 10% greater fuel economy).
A diesel engine with a turbocharger is more stable than a gasoline
motor with a turbo, because diesel motors do not use a throttle
valve to regulate speed like gas engines (diesel engine speed is
determined by fuel regulation). |
|
|
| Turbo
lag |
A
power delay associated with turbochargers. The time between when
the accelerator is pressed and when power increase from the turbo
system kicks in. A gasoline motor uses a throttle to restrict airflow
into the motor. When running at low speeds, little air is flowing
through the cylinders and through the exhaust. When the accelerator
is pressed, enough air must first pass through the cylinders and
through the exhaust side of the turbocharger before it can spin
the intake side of the turbocharger to increase air into the engine.
More pronounced at slower engine speeds. |
|
|
| Turbo
muffler |
A
low-restriction performance muffler which has at least one baffling
chamber. Yields increased engine performance, greater power and
responsiveness by reducing back pressure in the exhaust system.
Coupled with quality header pipes and larger-than-stock diameter
pipe can produce a low restriction exhaust system that can substantially
increase power. A stock exhaust system is usually the greatest source
restriction which reduces an engine's 'breathability'. Generally,
a performance exhaust system is one of the best performance upgrades
one can make in terms of power increase. Also see Glass-pack muffler,
Exhaust collector, and Exhaust header. |
|
|
| Turn-in |
A
handling term which describes the transition between driving straight
and cornering. How well a vehicle make a quick and smooth transition
is reflective on it's suspension, tires and steering. Wide tires,
a stiff anti-roll bar and quick ratio steering improve a vehicle's
turn-in. |
|
|
| Turn
indicator |
See
See Turn signal. |
|
|
| Turning
circle |
See
turning radius. |
|
|
| Turning
diameter |
See
Turning radius. |
|
|
| Turning
radius |
The
diameter of the smallest circle needed by a car to make a 360 degree
turn. Two popular turning radius measurements are curb-to-curb and
wall-to-wall. Curb-to-curb measures the circle at the vehicle's |
