| Washboard |
A
road which is rippled similar to ripples in an old fashioned manual
washboard. A potentially dangerous road surface because tires tend
to bounce over the surface significantly reducing traction. More
common on gravel roads, especially approaching stop signs. |
|
|
| Wastegate |
A
valve used on turbochargers to limit turbo boost. The valve diverts
exhaust gasses either around the exhaust turbine or into the air. |
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|
| Water
injection |
A
seldom used process of injecting a small amount of water (or alcohol/water
mix) into the air stream near the carburetor to mix with the air/fuel
mixture. The idea is that the water evaporates as it enters the
engine and cools the incoming air/fuel mix leading to a more dense
air/fuel charge, which should lead to high volumetric efficiency.
Also,
allows the use of lower-octane fuel because the air/fuel charge
is cooler and suppresses detonation.
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|
|
| Water
jacket |
Cavities
and passages inside the engine block and cylinder head where coolant
circulates. The passages are part of the metal casings. Coolant
which pumped throughout the passages absorbs heat from around the
cylinders and valves and moves it to the atmosphere once it reaches
the radiator. |
|
|
| Water
pump |
A
pump usually mounted on the front of an engine and driven by a belt
off the crankshaft which forces coolant through water passages,
the heater core and radiator. |
|
|
| Watt
linkage |
A
linkage system used to prevent lateral movement of a live, rear
axle; similar in effect to a panhard rod but without the negative
effects of bumpsteer associated with a panhard rod. A watts linkage
uses three links; two laterally located links, each one with an
end fastened to each side of the frame. A third, nearly vertically
located link connects to the horizontal links and is mounted on
the back of the axle housing. I is allowed to pivot at it's center.
The watts linkage effectively prevents side-to-side movement of
the rear axle, but does not produce bumpsteer from body lean or
suspension flex.
Another
version of the watts linkage consists of two horizontal bars,
each mounted near the outer ends of each axle tube and connecting
to a nearly vertical link which is mounted to and pivots on a
bracket mounted to the frame.
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|
|
| Weather
strip |
Rubber
seals around the outside of doors, windows and the trunk lid which
prevent moisture and air from entering the passenger compartment.
Also reduces wind noise. Also called Weatherstripping. |
|
|
| Wedge-shaped
combustion chamber |
A
combustion chamber where the head forms a taper to the top of the
piston; the area being taller near the valves. Resembles a wedge
when looked at from a cross-sectional perspective. The wedge produces
a quench area away from the valves. A quench area is a relatively
narrow region away from the larger combustion area where most of
the combustion gasses reside. Less combustion occurs in the quench
area allowing it to stay cooler thus drawing heat away from the
larger, primary combustion area, producing an overall cooler combustion
chamber. As a result, detonation risks are lowered meaning higher
compressions can be used resulting in greater power. |
|
|
| Weight
distribution |
The
percentage of a car's total weight which is carried by it's front
or rear wheels. Weight distribution greatly affects handling. The
closer to 50/50 (front/rear) distribution the better handling. Most
front-engine production automobiles have a much greater weight bias
at the front wheels. Mid-engine designs more closely approach the
50/50 mark. |
|
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| Weight
transfer |
A
shifting of a vehicle's weight that occurs when braking (towards
front), cornering (towards side) and accelerating (towards rear).
|
|
|
| Western-style
mirrors |
Large
protruding mirrors, usually supported by three or four mounting
legs, used on many large pickup trucks. Similar to mirrors used
on large semi tractors. Allow better visibility particularly when
trailering. Also called West coast mirrors or Big rig mirrors. |
|
|
| Wet
liner |
A
removable cylinder that is inserted into an engine and directly
cooled by coolant. By contrasts, a dry liner inserts into a cylinder
and is cooled by conduction between the liner and cylinder. Wet
liners are used widely in commercial diesel engines. |
|
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| Wheel |
A
circular device, usually made of stamped steel or cast aluminum
that attaches to the hub of an automobile. A tire mounts to the
wheel. |
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| Wheel
adapters |
A
steel device that contains mounting holes that allows it to be bolted
to a vehicle's axle or wheel hub, and studs arranged in a different
pattern that allow a rim of a different bolt pattern to be bolted
to. Commonly used by off-roaders and street rodders to mount modern
wheels of a common bolt pattern to older vehicles with unusual bolt
patterns. Also used as a spacer to widen the stance of a vehicle. |
|
|
| Wheel
alignment |
Correctness
of steering and suspension geometry according to manufacturer specifications.
Poor wheel alignment can be caused by worn or damaged bushings,
ball joints, struts or bent suspension linkages and may lead to
wandering or accelerated tire wear. When technicians perform a wheel
alignment they first inspect/replace worn parts, then make adjustments
to return caster, camber and toe angles to meet specifications.
Also see: Caster, Camber, Toe and Steering geometry |
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| Wheel
arch |
The
arch of a fender around a wheel. Serves a function of styling and
functionality. Also see Wheel lip and Wheel well. |
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| Wheel
balancing |
The
process of attaching wheel weights to the outer edge of a wheel
to eliminate vibrations caused by an out-of-weight tire/wheel
assembly. For decades the normal method was to balance tires statically
(not moving) on a bubble balancer. The tire/wheel assembly was
set horizontally on a the bubble balancer and weights were carefully
arranged on the rim until the tire reaches horizontal. Although
good balancing could be achieved, it was imprecise and didn't
correct for lateral movement.
Now,
tires are balanced dynamically on a computerized spin balancer
which more precisely corrects for both vertical out-of-balance
conditions as well as lateral vibrations. Wheels are removed from
the car and placed on the balancer and spun vertically. The computerized
balancer detects out-of-roundness and tells the technician exactly
where on the rim to place the weights and exactly how heavy each
weight should be. The result is a better balanced tire which wears
longer and reduces suspension and driveline wear.
|
|
|
| Wheelbase |
The
distance from the center of the front wheels (axle) to the center
of the rear wheels (on same side of car). Vehicles with a longer
wheelbase are typically more stable and easier to regain control
of in slippery conditions, but have a larger turning radius and
are less nimble. |
|
|
| Wheel
bearings |
Ball,
roller or tapered roller bearing assemblies used on a vehicle's
axles and wheel hubs to support the weight of a vehicle and allow
it to roll smoothly. |
|
|
| Wheel
cylinder |
A
part used in a drum brake system that pushes the brake shoes apart
and caused the vehicle to stop. One wheel cylinder is used for each
wheel. The wheel cylinder is mounted to the brake backing plate
and connected to the master cylinder via a steel brake line. Inside
each wheel cylinder are two small pistons that ride in a machined
bore. When the brake pedal is pressed, pressurized brake fluid from
the master cylinder rushes into the wheel cylinder forcing the pistons
outward. This forces the brake shoes outward against the rotating
drum causing the vehicle to stop. Also see: Master cylinder, Brake
backing plate and Vacuum assisted brakes. |
|
|
| Wheel
hop |
An
condition in which a wheel rapidly and violently moves (hops) up
and down leaving the pavement surface, usually occurring during
hard acceleration. Caused by torsional twisting of the axle (axle
wind-up), insufficient shock dampening, weak springs, or incorrect
shock location. |
|
|
| Wheel
housing |
See
Wheel well. |
|
|
| Wheel
lift |
An
undesirable condition that occurs during cornering where an inside
wheel lifts off the pavement. |
|
|
| Wheel
lip |
The
edge of the fender which forms the wheel arch. The wheel lip may
be flared as a matter of styling or to prevent water, mud and debris
from being thrown onto the vehicle. Also see: Wheel arch and Wheel
well. |
|
|
| Wheel
offset |
The
position of a wheel's vertical plane in relation to it's mounting
hub. If the wheel is moved further away from the hub is has a positive
offset. If it is moved closer towards the center of the vehicle
it has a negative offset. Purchasing aftermarket rims or using spacers
can alter a wheel's offset. |
|
|
| Wheel
patter |
Short,
fast wheel movements that occur when encountering small bumps like
tar strips or uneven lateral cracks in the pavement. Also known
as Bump-thump. |
|
|
| Wheel-rim
flange |
The
portion of the wheel rim that contacts the tire's bead |
|
|
| Wheel
slip |
Wheel
slippage that occurs during hard cornering but not out of control.
See Slip angle, Oversteer and Understeer. |
|
|
| Wheel
spin |
A
rotating tire which spinning faster than it's directional speed.
Has lost traction. |
|
|
| Wheel
tramp |
Another
term for wheel hop. See Wheel hop and Axle windup. |
|
|
| Wheel
travel |
The
maximum amount of vertical movement of a vehicle's wheels. Determined
by suspension geometry and the distance between the locating arms
and bumpstops. More wheel travel allows a vehicle to smoothly traverse
large road bumps and rough surfaces faster and with greater passenger
comfort. Wheel travel is a tradeoff between nimble handling and
ability to comfortably traverse large bumps. |
|
|
| Wheel
well |
The
area above the wheels that extends from the fender's wheel arch
to the chassis. The front wheel well typically contains a contoured
metal or plastic arched panel which fits inside the wheel well and
protects the engine compartment form splashing water, mud and thrown
rocks. Since rust commonly occurs in this region most manufacturers
apply a generous amount of undercoating. |
|
|
|
Windage
tray
|
A
thin metal panel which can be mounted below the engine's crankshaft
in high-performance and race engines to reduce oil splashing onto
the crankshaft's counterweights which yields increased engine power.
Also prevents oil foaming at high speeds. |
|
|
| Window
regulator |
The gear mechanism behind a manual window crank that actuates the
mechanism that raises and lowers side windows. |
|
|
| Windscreen |
The
British word for windshield. See Windshield. |
|
|
| Windshield |
The
front window that spans the width of the vehicle. Laminated glass
is used for windshields. It consists of two panes of glass with
a tough clean plastic layer between. Also see: Laminated glass and
Tempered glass. |
|
|
| Windshield
wipers |
An
electromechanical system consisting of a switch, electric motor,
linkages, arms and thin rubber blades for cleaning the windshield.
When activated, the electric motor causes the wiper arms to sweep
across the windshield. Thin rubber strips fitted in the wiper arms
squeegee water, mud, snow and road debris off the windshield. Although
most automobiles have two windshield wipers mounted low on the front
windshield, many sport utility vehicles and minivans also have a
wiper mounted on the rear door to keep the rear window clean. |
|
|
| Wind
tunnel |
A
test device or facility which simulates windflow in a controlled
environment. Used by automobile designers and racing organizations
to observe and measure airflow around automobiles in order to increase
their aerodynamic characteristics which result in higher speed,
increased fuel economy and better handling. Airflow is usually generated
by a large fan or turbine. Streams of smoke can be released in the
flowing air to visually observe airflow and turbulence. The most
accurate wind tunnels have a moving ground plane. |
|
|
| Wind
wander |
A
vehicle which is pushed or wanders off coarse due to head winds
or crosswinds or turbulence cause by tractor trailers (called Wake
turbulence). Requires steering correction to maintain coarse. Usually
a result of vehicle design, aerodynamics and alignment and suspension.
Front-engine vehicle are typically less prone to wind wander than
rear engine vehicles. |
|
|
|
Wind wing |
A
name for a hinged front quarter window which could be opened for
ventilation. So called because they tended to protrude like wings
when opened. Not used on modern vehicles. Also known as a vent window,
or vent wings. |
|
|
| Wing |
A
horizontally mounted panel resembling an upside-down airplane wing
used on race cars and sports cars to increase downforce on the front
or rear end. Increases traction and improves cornering at high speeds.
Also see: Airfoil, Spoiler, Skirt and Ground effects. |
|
|
| Wiper
arms |
Metal
arms with pivot points which move across the windshield to clear
water away for increased visibility. Rubber wiper blades (see below)
attach to the wiper arms. |
|
|
| Wiper
blades |
Hinged
metal assemblies which contain thin rubber strips with a flat edge
that mount to wiper arms and squeegee water from the windshield. |
|
|
| Wiper
delay |
A
feature that allows the wiper arms to operate intermittently. |
|
|
| Wiper
motor |
A
multi-speed electric motor which operates the wiper arm assembly. |
|
|
| Wiper
motor relay |
An
electric relay that controls the wiper motor and controls wiper
delay functions. |
|
|
| Wiring
harness |
An
arrangement of bundled color-coded wires which is routed through
a vehicle and carries electric current to the engine and all electrical
parts of the automobile. An automobile's equivalent of a circulatory
system. |
|
|
| Wishbone |
A
link used in independent suspension systems similar in function
to an A-arm, but Y-shaped; resembles a wishbone. The shorter legs
of the wishbone link attach to the chassis; the single leg attaches
to the knuckle. A rugged suspension design. Also see: A-arm and
Independent front suspension. |
|
|
| W-link |
A
type of locating system similar to a panhard rod used to prevent
lateral movement of a live rear axle. |
|
|
| Wood
alcohol |
Another
term for methanol. See Methanol. |
|
|
| Worm-and-sector
steering |
Another
term for recirculating ball steering. A worm gear inside of the
steering box moves a sector when the steering wheel is rotated.
For more information, see Recirculating ball-and-nut steering. |
|
|
| Worm
gear |
A
long gear in the shape of a screw. The teeth of the worm gear can
mesh with the teeth of a traditional round gear to transfer motion
to a right angles of the worm gear. |
|
|
| Wrist
pin |
Another
term for piston pin. See Piston pin. |
