An articulating, rotating shaft used in independent-suspension systems that transmits power from the final drive unit (differential) to a power wheel. Used in independent rear suspension and front-wheel drive. Two are required; one for each side.

A sealed-beam headlamp with a small inner bulb filled with halogen which surrounds a tungsten filament. Halogen headlamps may increase luminous intensity at the road surface by 50 to 80 percent, as compared to the long-conventional sealed-beam headlamp systems. Many halogen headlamp systems incorporate high-beam and low-beam in one element, enhancing their serviceability.

A crank handle for manually starting internal combustion engines. Used till about 1930. Now obsolete.

A general term covering all the aspects of a car's behavior that are related to its directional control.

When extreme pressure must be placed on the brake pedal to stop the car. Have brakes serviced promptly.

The hazard relay controls the flashing of the hazard warning lights.

A charge assessed by many collision repair facilities to dispose of wastes associated with repairing your vehicle in an environmentally appropriate way. Some insurance companies refuse to pay this charge.

The head gasket seals the cylinder head to the engine block. It is subject to tremendous pressures, and often fails if and when an engine overheats.

The digital projection of pertinent instrument data onto the lower portion of the windshield on the driver's side. The driver does not have to take his eyes off the road to read his instrument panel.

The measure of a spark plug's ability to dissipate heat from its firing end. The higher the heat range, the hotter the plug fires.

The heater core is a miniature radiator that sits in the dashboard. When the heater is turned on, it opens the heater valve which lets hot coolant into the heater core, which then warms the air coming into the vehicle's interior.

The heater ducts are the tubes that connect the heater fan to the vents in your vehicle's dashboard.

The heater fan is the interior fan that controls the speed of air being introduced into the interior.

The heater valve is controlled by the interior heating controls. When you turn on your vehicle's heat, the valve opens and allows hot coolant to enter the heater core, which then warms the air entering your vehicle's interior.

Vehicle (truck) weighing from 26,001 to 33,001 lbs. Also included off-highway trucks.

A performance-oriented technique of down-shifting while braking that requires the driver to use all three pedals of a manual-transmission car simultaneously. To perform a heel-and-toe downshift, the driver brakes with the toe of his right foot and: while continuing to brake: uses the heel or the side of the same foot to blip the throttle and raise engine rpm as he downshifts. The left foot operates the clutch pedal in the normal fashion. The sequence is as follows: brake with the right toe; depress the clutch with the left foot; shift to neutral; while continuing to brake, blip the throttle with the side or the heel of the right foot to raise rpm; shift to a lower gear; let the clutch out; release the brakes. The technique is difficult to master, but after practice it can be performed in less than a second. This process is best for smooth power flow and long transmission life.

An extremely rigid articulating joint, commonly known as a 'spherical rod-end,' used in any precision linkage. Heim joints are often used in the suspension links of race cars because they locate wheels very precisely.

A gear in which the teeth are cut at an angle to the shaft. The advantage is that there are usually two teeth meshing at all times, making for smoother and quieter operation. Helical Gear A type of gear in which the teeth are cut at a slanting angle to the gear's circumference. A helical design produces an even, constant tooth loading in a gearset, thereby reducing noise.

A term used to describe any engine that has hemispherical combustion chambers in its cylinder head. Although a four-valve design is more efficient, a hemi head provides room for a pair of large valves and offers good breathing characteristics. Used in many sports and racing cars.

A hemispherically shaped combustion chamber at the top of the engine cylinder. The hemispheric shape provides improved efficiency because the forces of the explosion are directed to the piston by the curved surface of the combustion chamber.