An abbreviation for:
Low, one of the forward gear positions of a transmission.
Liter, a unit of metric liquid measure.
A term used for L-head engine.
L-Head Engine
An engine with intake and exhaust valves in the block, parallel to the pistons and cylinders.
A Bosch pulsed, electronic, fuel-injection system that uses input on the volume of intake air to calculate fuel delivery.
LA Kit
A reconditioned crankshaft that is supplied with the appropriate bearings and an installation kit.
An identifying mark or trademark of a nationally recognized testing lab that is attached to signify that the item has been tested and meets appropriate standards.
A method used to mend cracks in cylinder heads and blocks using threaded repair plugs side-by-side and overlapping each other.
A type of paint that dries by solvent evaporation that must be rubbed out to produce a gloss.
Ladder Bars
A device attached to the chassis or frame at one point and to the rear axle at two points on a drag-race car to reduce rear-axle windup.
Ladder Chassis
A conventional frame design that consists of two side rails, not necessarily parallel, connected to each other by a series of cross members like a ladder.
Ladder Frame
A term used for ladder chassis.
The incorrect operation of a shock absorber because of aeration due to the mixing of air with oils, causing the shock absorber to produce a poor ride.
To fail to keep up; to fall behind.
A dry lake used for high-speed performance trials.
Lakes Pipes
Straight exhaust pipes with no muffler.
A hot rod with minimal frontal area and fully exposed wheels designed for lakes competition.
An abbreviation for lowest achievable level.
The Greek letter L.
A term used by engineers to represent the air/fuel ratio.
A European auto maker's term for the oxygen sensor.
Lambda Control
Using a lambda, sensor-controlled computer to adjust the air/fuel mixture.
Lambda Sensor
A European auto maker's term for the oxygen sensor.
Lambda Sond
The first closed-loop, fuel-injection system to appear in production, developed jointly by Robert Bosch and SAAB.
Laminar Airflow
The smooth, continuous movement of one layer of gas or liquid over another.
The movement of a body of air/fuel mixture through the intake manifold and ports as it flows over the boundary layer.
A structure consisting of two or more layers of material, such as fiberglass.
To fabricate a structure of two or more layers of material, such as fiberglass.
Laminated Case
A container, such as a safety fuel cell, with walls of two or more layers of material.
Laminated Core
An assembly of steel sheets for use as an element of a magnetic circuit having the property of reducing eddy-current losses.
A device to convert electrical energy to radiant energy, which is normally visible light.
That part of a piston between the ring grooves that separates and supports the rings.
Land Speed Record (LSR)
The maximum speed obtained by:
A wheel-driven, internal-combustion engine vehicle.
A thrust-driven jet or rocket engine vehicle.
A semi-convertible car with a folding top over the rear passenger compartment.
Landau Bar
Ornamental ogee or S-shaped trim sometimes applied to C-pillars or sail panels.
Landau Iron
A term used for landau bar.
Landau Top
A passenger-car top partially covered with vinyl to give it a convertible-like appearance.
Landing Gear
Retractable supports for a semi-trailer to keep the trailer level when the tractor/truck is detached from it.
A complete trip around an oval track or road course.
To gain a full lap over the second place competitor.
Lap Joint
A joint between two overlapping members in parallel planes.
Lap Weld
A welding process between two overlapping members in parallel planes.
A valve-grinding process using a paste-like grit on the face of the valve.
Lapping Compound
A paste-like grit used for lapping valves.
An acronym for light amplification by stimulated emissions of radiation.
A device that produces a concentrated, coherent light beam by stimulated electronic or molecular transitions to lower energy levels.
The clearance between two parts.
Lash-Pad Adjusters
Small round metal pieces of various thickness used to adjust valve clearance.
Late Apex
Getting to the inside of a turn later than usual due to a late entry into the corner.
Latent Heat
The amount of heat required to cause a change of state of a substance without changing its temperature.
Latent Heat of Condensation
The quantity of heat given off while changing a substance from a vapor to a liquid.
Latent Heat of Evaporation
The quantity of heat required to change a liquid into a vapor without raising the temperature of the vapor above that of the original liquid. Also known as latent heat of vaporization.
Latent Heat of Fusion
The amount of heat that must be removed from a liquid to cause it to change to a solid without causing a change of temperature.
Latent Heat of Vaporization
A term used for latent heat of evaporation.
Lateral Acceleration
The centrifugal force that tends to push a vehicle sideways, toward the outside of a turn.
Lateral Link
A suspension component used to reduce side-to-side movement of a wheel.
Lateral Runout
A tire that has excessive variations in width; the measured amount of sideways wobble on a rotating tire.
Lateral Weight Transfer
The momentary shift of a vehicle weight from the inside tires to the outside tires, or outside to inside, due to cornering forces.
A good start off the starting line in drag racing.
Lay a Patch
The same as to lay rubber.
Lay a Sscratch
The same as to lay rubber.
Lay on It
To go fast.
Lay on the Iron
To cut to the inside of another car on a turn, forcing it away from the apron or apex and out of the groove.
Lay Rubber
To leave streaks of rubber on the pavement during rapid acceleration. Also lay a patch and lay a scratch.
Lay the Crank
A reconditioned crankshaft supplied with the appropriate bearings and an installation kit.
Lines scribed on a piece of material or metal as a guide in bending or forming.
An abbreviation for liquid crystal display.
Le Mans
A road-racing circuit in France.
Le Mans Start
A method of starting a race by having the drivers stand across the track and, at the start signal, race to their vehicle, jump in, belt up, start their engines, and take off.
To be out in front.
Lead Sled
A term used for kustom or kemp.
A car with excessive amounts of lead or body filler over mediocre, sheet-metal work.
Lead Sulfate
A hard, insoluble layer that slowly forms on the plates of a discharging battery that may be reduced only by slow charging.
Leaded Gasoline
Gasoline to which a small amount of tetraethyl lead is added to improve engine performance and reduce detonation, a practice no longer allowed due to EPA regulations.
A person who drives faster than necessary.
Leading Link
A component of the suspension system that is attached to the chassis behind the wheel and positioned to resist fore-and-aft movement of the wheel.
Leading Shoe
A brake shoe in a nonservo brake that pivots around a fulcrum in the direction of normal drum rotation. Also known as forward shoe.
Leaf Spring
A rear, vehicle-suspension spring featuring one or more flat leaves of spring steel with graduated lengths. It has an eye at one end to connect to the vehicle frame and it is connected to the axle with a U-bolt.
Leaf-Spring Bushing
Bushings that are used to dampen noise and vibration from the road to the frame of the car.
Leaf-Spring Center bolt
A bolt passed through a hole in the center of each spring leaf for holding the leaves together. The bolt head is used to locate the spring position on the axle-housing.
Leaf-Spring Hanger
The vehicle frame-attachment bracket for the front eye of the rear leaf spring that allows the spring to pivot.
Leaf-Spring Shackle
The small arm, or swing attachment for the rear of the leaf spring located between the frame and spring eye. It allows the spring to shorten and lengthen during normal driving conditions.
Leaf-Tip Insert
Small, replaceable pads of plastic, rubber, or composition placed between spring leaves near their ends to promote slippage between the leaves during flexing.
Leak Detector
A device using visual or audible signals to indicate a leak.
A dye-type fluid that may be injected into a system that will indicate the presence of a leak.
Leak Find
A trade name for a dye solution that can be injected into a system to find difficult leaks.
Leakage Current
A small amount of current that flows through insulation when a voltage is present and heats the insulation due to it's resistance, resulting in a slight power loss.
Leakdown Test
A test using 100 psi (689.5 kPa) air pressure injected in each cylinder via the spark-plug hole or injector port to determine the leakage past the rings, gaskets, or valves.
A vehicle not well prepared.
A vehicle leaking oil or coolant.
A term often used for lean mixture or lean out.
Lean Burn
A Chrysler electronic engine control that appeared in the mid 1970s. It maintains precise control of the spark timing to allow a very lean mixture to burn properly, reducing emissions using an analog computer.
Lean Misfire
A condition caused by a vacuum leak or open EGR valve that results in an air/fuel mixture too lean to sustain combustion, causing one or more cylinders to pass unburned fuel into the exhaust system, resulting in an increase in hydrocarbon (HC) emissions.
Lean Mixture
An air/fuel mixture with too much air.
Lean on It
A term often used for lay on it or lay on the iron.
Lean Out
To increase the portion of air or decrease the portion of fuel in an air/fuel mixture.
To decrease the portion of nitro in a fuel mixture.
Lean Roll
To turn carburetor idle-mixture screws in enough to effect a slight rpm drop, causing a leaner mixture.
Leaner and Later
Early calibration strategies for air/fuel mixture and ignition timing to reduce HC and CO formation.
A drag-race driver that red lights by leaving the line too soon.
Left-Hhand Thread
A thread pattern on a bolt or nut that requires it to be turned to the left or counter-clockwise for tightening.
Leg It
To go fast.
Leg out of Bed
A connecting rod that has broken through a cylinder block wall.
A vehicle, generally a new one, with several defects or a defect that can't be resolved.
Lemon Law
Federal and state laws that assure customer satisfaction for repairs to new vehicles by the dealer or replacement by the manufacturer.
Length-to-Diameter Ratio
The ratio of a coil-spring wire diameter to its overall length, a measure of the spring's effectiveness.
To be on a horizontal plane.
The amount of liquid in a system.
Level Control
A term used for automatic level control.
The trade name for the shatterproof, heat-resistant clear plastic used in race-car rear windows.
An electronic fuel-injection system by Bosch that uses a mass airflow sensor with a digital control unit.
An abbreviation for lower heating value.
The cylinder head on a flathead or L-head engine.
Life Expectancy
The anticipated longevity of a part, assembly, or component.
The amount of the opening of a valve.
The amount of rise generated by a lob of the camshaft.
An upward force caused by the airflow around a vehicle.
Lift It
Get off the throttle.
Lift Kit
A suspension package designed to raise the vehicle body above the frame and tires.
Lift-Throttle Oversteer
A loss of grip on the drive wheels of a rear-drive vehicle when the throttle is lifted during fast cornering causing the rear of the vehicle to swing toward the outside of the turn.
A rear luggage compartment that is an extension of the passenger compartment with access gained through an upward-opening, hatch-type door.
A part between the camshaft and push rod on an OHV engine.
A part between the camshaft and valve stem on an OHC engine.
Also known as follower.
Lifter Bore
The hole in which a valve lifter is located.
The rear opening of a hatchback or liftback.
Light it Off
Start an engine.
Light the Rugs
To smoke the drive tires at the start of the race.
Light the Weenies
Same as light the rugs.
Light Up
To perform a burn out.
Light-Duty Vehicle
Any motor vehicle rated at 8,500 pounds (3,856 kilograms) GVWR or less, having a curb weight of 6,000 pounds (2,722 kilograms) or less, and having a frontal area of 45 square feet (4.2 square meters) or less.
Light-Off, Mini-Oxidation Catalytic Converter
A small catalyst mounted just behind the exhaust manifold that gets hot very quickly after the engine is started, so that it begins working in time to neutralize much of the extra pollution that is produced during cold running.
The timing lights at the end of a drag strip.
Lightweight Leaf Spring
A fiber-composite spring.
Lightweight-skin Spare Tire
A bias-ply, compact spare tire with a reduced tread depth to provide about 2,000 miles (3,218 kilometers) of tread life; designed for emergency use only, and driving speed limited to 50 mph.
Lime Deposits
A condition that exists in a cooling system when the lime, present in water-based coolants, comes out of solution and coats the engine's water passages.
Limited-Production Option (LPO)
An item of new car equipment available for a limited market, such as a high-performance police package.
Limited-Slip Differential
A differential having special friction mechanisms tending to keep both rear-axle shafts rotating at the same speed, regardless of unequal tire-to-road surface friction.
Limited-Slip Differential Gear Oil
A specially formulated gear oil required in limited-slip differentials because of the extreme pressures on the clutch cones or clutch plates and discs.
Limiting Valve
A term used for front-axle limiting valve.
The maximum and minimum values designated for a specific element.
Short for limousine.
A chauffeur-driven formal sedan having a glass partition separating the driver from the passengers.
A bus or van used to carry people to and from an airport or train station.
Line Contact
The contact made between the cylinder and the torsional rings, usually on one side of the ring.
The contact made between the valve and the valve seat.
Line Job
Beating a drag competitor from the start.
Line Mechanic
A mechanic who works on the repair line at a dealership.
A mechanic who is skilled in a particular automotive system.
Line Pressure
The base pressure established in a transmission by the pump and pressure regulator valve.
The pressure present in a line or hose.
Line Ream
To ream bearings or bushings to size after they have been installed.
Line Static Pressure
A 10 to 15 psi (69 to 103 kPa) hydraulic pressure maintained in a drum-brake system when the brakes are not applied to keep pressure on wheel-cylinder cup lips in order to seal fluid in, as well as air and dirt out.
Line-and-Hose Tape
A type of insulation tape.
Line-Setting Card
A card provided by the vehicle manufacturer that lists its specifications and equipment.
Line-Setting Tag
A tag provided by the vehicle manufacturer that lists its specifications and equipment.
Linear EGR
An AC Rochester EGR system using a linear motor to move the valve's pintle in small steps, which provides precise control of recirculation.
Linear-Rate Coil Spring
A coil spring with equal spacing between the coils, one basic shape, and constant wire diameter having a constant deflection rate regardless of load.
The synthetic, gum-rubber material bonded to the inner surface of the tire to seal it.
A sleeve used to repair a worn cylinder.
An insert used to repair a worn valve guide.
Short for streamliner.
Lines of Force
A term used for magnetic lines of force.
The friction material attached to the drum-brake shoe or disc-brake pad that contacts the brake disc or drum when the brakes are applied.
A lever or rod to transmit movement from one part to another.
The portion of a chain's structure that connects two adjacent joint or pitch centers.
Link Plate
A side plate of a pin link or a roller link in a roller chain.
A series of levers or rods used to transmit movement from one part to another part.
Linkage Power Steering
A type of steering system that has a power assist connected directly to the steering rods.
Liquid Cooling
A method of engine cooling that relies on coolant circulation through water jackets inside the cylinder head and block, then on to a radiator to maintain proper operating temperature.
Liquid Line
The line connecting the receiver-drier outlet with the expansion-valve inlet.
The line from the condenser outlet to the receiver-drier inlet is sometimes called a liquid line.
Liquid-Coolant Circulation
A term used for coolant circulation.
Liquid-Cooled Engine
An engine that is cooled by circulating coolant around the cylinders and through passages in the heads.
Liquid-Crystal Display (LCD)
A type of alpha-numerical readout display on some instruments using a liquid-crystal film sandwiched between glass plates that become opaque when an electrical current is applied.
Liquid-Filled Gauge
A mechanical instrument that is filled with a clear liquid to damp out oscillations that could affect accuracy.
Liquid-Vapor Separator
An evaporative emissions or fuel-supply-system control component that allows vaporized fuel to return to the fuel tank, where it condenses for reuse. Uncondensed vapors flow through tubing into the charcoal canister.
The lowest temperature at which a metal or an alloy is completely liquid.
Liquified Natural Gas (LNG)
Methane gas (CH4) that has been converted to a liquid by chilling.
Liquified Petroleum Gas (LPG)
A predominately propane gas (C3H8) that contains some butane gas (C4H10) that is compressed to a liquid state.
A term used for condenser.
A metric unit of liquid measure.
An absorbent paper strip impregnated with a purple-colored matter that turns blue if dipped into an alkaline solution and red if dipped into an acid solution.
Little Eend
The smaller end of a connecting rod.
Live Axle
An axle through which power is applied via a differential and half shaft.
An abbreviation for liquified natural gas.
Lo Po
Low performance.
The demand for power placed on an engine.
The cargo of a truck or other vehicle.
The amount of weight placed on a tire.
The heat quantity imposed on an air conditioner.
The fuel for a drag racer, such as nitro.
Load Range
A term used for load rating. The weight a tire will support at a given inflation pressure.
Load Rating
A term designating the maximum weight that a particular tire is designed to support, usually related to a specific air pressure.
Load Test
A starter-motor test in which the current draw is measured under normal cranking load.
A battery test whereby the battery is loaded for testing.
Load-Carrying Ball Joint
The lower ball joint on low-mounted coil springs or torsion bars or the upper ball joint on high-mounted, coil-spring suspensions; compression or tension loaded, supporting the weight of the vehicle.
Load-Leveling Sshock Absorber
Inflatable shock absorbers, often used with an electronic height-control system, that are pressurized with air to increase their load-carrying capability.
Load-Proportioning Valve (LPV)
A device used to distribute hydraulic pressure to the front and rear brakes based on the vehicle load.
An enrichment of the air/fuel mixture to the point of rough idling, usually resulting in black smoke from the exhaust.
That concentric part of a camshaft that causes the valves to open and close by actuating a valve lifter.
Lobe Centers
The number of degrees of a camshaft between intake and exhaust lobes.
Local Preheating
The preheating of an isolated or specific portion of a structure.
Location Table
A term used for component location table.
Lock Nut
A nut that is designed to lock when tightened or torqued.
A second nut that is screwed down tightly against the first nut.
Lock Pin
A pin used in some ball sockets to keep the connecting nuts from working loose, and on some lower ball joints to hold the tapered stud in the steering knuckle.
Lock Washer
A split-type of washer that helps prevent a bolt or nut from working loose.
The number of turns required to turn the front wheels from one extreme to the other.
Locked Rear End
A rear axle without a differential where both rear wheels turn at the same speed on curves as well as on a straightaway.
A term used for locking rear end.
Locking Hubs
A dog clutch in a wheel that permits it to be disengaged from the axle shaft and made free-wheeling when a driving force is not required, such as when being towed.
Locking Rear End
A final drive differential that acts as a locked rear end on the straightaway, but allows one wheel to be free-wheeling on curves.
Locking Torque Converter
A hydraulic torque converter in an automatic transmission having a mechanical clutch that locks at cruising speeds.
A metal washer-like device with tabs that may be bent around a nut or bolt head to prevent them from turning.
A manual adjustment mechanism that allows adjustment of free travel of a lever or rod.
The point at which braking power overcomes the traction of the vehicle's tires and skidding occurs, causing loss of control, long stopping distances, and flat-spotting of the tires.
Lockup Clutch
A type of clutch in which the torque converter turbine is locked up with the engine, eliminating slippage.
Lockup Torque Converter
A fluid clutch designed with a clutching assembly in an automatic transmission to improve coupling efficiency at a predetermined vehicle speed.
A trade name for a line of sealants and adhesives that are popular in the automotive industry.
Long Arm
The throw of a crankshaft after it has been stroked.
Long Block
An assembled engine block that contains all of the components from the intake manifold to the exhaust ports.
Long Gear
A final drive with a low gear ratio providing high gearing.
Long, Short Arm Suspension
A front suspension system where the upper control arm is shorter than the lower control arm, allowing each wheel to compensate for changes in the road surface while not greatly affecting the opposite wheel in a manner that allows the wheel and tire assembly to rise and fall vertically as it goes over bumps.
The cargo area of a long-wheelbase pickup truck.
Longest Leaf
A term used for the main leaf.
A spin in track racing, usually deliberate to avoid an accident.
Loop Scavenging
A method used to remove the exhaust gases from the cylinder in a two-stroke engine.
Formed eyelets with minimal gaps at the ends of extension springs.
The tendency of a vehicle to oversteer.
A slick track or driving surface.
Loose Roller Clutch
A one-way clutch which has the rollers individually placed between the cam and race, not located by a gauge.
A big, high-performance engine that idles roughly due to a high profile cam.
Lose Fire
To stall an engine.
Lost Foam Casting
A casting method using a model part made of styrofoam.
Loud Pedal
An accelerator.
Slotted openings in a hood or body panel to admit or emit ambient air.
A vertical blind-type shutter to reduce or block airflow through a device, such as a radiator.
Love Taps
The bumping and shoving that often occurs when cars are running in a closely packed group in circle-track racing.
Lover Cover
The scattershield between the driver's legs in a front-engined, single-seat drag car.
Low Beam
A headlamp intensity for use when meeting or following another vehicle.
Low End
Low engine speed.
Low End Power
The engine horsepower output during the first 25–30% of engine rpm range.
Low Gear
A speed obtained from a planetary gear set when the internal gear is held and power is applied to the sun gear, producing an increase in torque.
Low Gearing
A drive ratio that provides maximum output at a low road speed.
Low Head
A term used for low-head pressure.
Low Maintenance Battery
A conventional, vented lead-acid battery that requires periodic maintenance.
Low Pedal
A condition where excessive clearance, at some point in the braking system, or a low fluid level, causes almost full pedal movement for the application of the brakes.
The clutch-pedal position of a Model T when engaged in low gear.
Low Rider
A vehicle with small wheels so that it has been lowered as much as possible.
Low Risers
Standard-height cylinder heads developed in the early 1960s by Ford for 406, 427, and 428 cid engines.
Low Side
A term used for suction side.
Low-Head Pressure
The high-side pressure that is lower than expected for a given condition.
Low-Lead Fuel
A gasoline that contains less than 0.018 ounces (0.5 grams) per gallon (3.785 liters) of tetraethyl lead, no longer sold in this country due to the environmental impact.
Low-Loss Fitting
A fitting designed to close automatically or manually to prevent fluid or vapor loss when used at connection points between hoses, service valves, vacuum pumps, recovery, or recycle machines.
Low-Mounted Coil Spring Suspension
A type of suspension having a coil spring located above the lower control arm, with the top end of the spring contacting the car frame, found primarily on vehicles having a separate or stub frame.
Low-Pressure Control
An electrical or mechanical device used to control pressure in the low side of a system.
Low-Pressure Cutoff Switch
An electrical switch that is activated by a predetermined low pressure to open a circuit during certain low-pressure periods.
Low-Pressure Line
A hose or line used to carry low pressure vapor, liquid, or air.
Low-Pressure Side
Usually refers to the return side of a fluid or air system having a low pressure.
Often referred to as suction side.
Low-Pressure Switch
A switch that is actuated due to a fall in pressure.
Low-Pressure Vapor Line
A term used for suction line.
Low-Side Pressure
The pressure in the low side of an air conditioning system, from the evaporator inlet to the compressor inlet, as may be noted on the low-side pressure gauge.
Low-Side Service Valve
A device located on the suction side of the system that allows the service technician to check low-side pressures or perform other necessary service operations.
Low-Speed System
A circuit in the carburetor that provides fuel to the air passing through it during part-throttle, low-speed operation.
Low-Suction Pressure
Pressure that is lower than normal in the suction side of the system due to a malfunction of the unit.
To reduce the ride height of a vehicle by modifying its suspension.
Lower A-Arm
The lower member of a double A-arm suspension system.
Lower Control Arm
A front suspension component connected between the pivoting attachment point on the car frame and the lower ball joint, which is fastened to its outer end.
Lower End
The crankshaft, main bearings, and connecting rod bearings assembly in an engine.
Lower Entry
The bottom of a wet cylinder sleeve in an engine block.
Lower Entry Sleeve
A cylinder sleeve used to repair a lower entry.
Lower Heating Vvalue (LHV)
The latent heating value of water that is exhausted as steam.
Lower Mount
A support for the engine or transmission that is below the crankshaft centerline.
Lower Radiator Hose
The radiator hose from the outlet of the radiator to the inlet of the water pump.
Lowering Block
A device that may be used to reduce the riding height of certain vehicles.
Lowest Achievable Level (LAL)
A term used to define the lowest amount of emission permitted for any substance considered toxic or otherwise hazardous.
An abbreviation for liquified petroleum gas.
An abbreviation for limited-production option.
An abbreviation for load-proportioning valve.
An abbreviation for land speed record.
A United States version of a Bosch pulsed-electronic, fuel-injection system having a lambda sensor.
A substance, usually petroleum based, used to coat moving parts to reduce friction between them.
The new synthetic product poly alkaline glycol (PAG) and ESTER used with new refrigerants.
A term often used to identify an organic mineral-based grease or oil product.
Lubrication Guide Book
A specially prepared publication, detailing required lubrication services with related information for each make and model of automobile.
Lubrication Interval
Manufacturer's recommended mileage and/or time limit when periodic lubrication services should be performed as a part of a preventative maintenance program.
Lubrication System
The oil pump, filter, hoses, lines and passages in an engine that facilitate the oiling of all moving parts.
Lug Bolt
A hex-headed, threaded bolt used to hold the wheel on a vehicle.
Lug Nut
A hex-sided, threaded device used to hold the wheel on a vehicle having lug studs.
Lug Stud
A threaded protrusion used with a lug nut to hold the wheel on a vehicle.
Running an engine at less than normal rpm, causing it to balk.
Lumbar Support
A seat support for the lumbar portion of the occupant's body.
A large, heavy engine.
To severely damage or destroy something, such as an engine.