Cars - http://maxpages.com/carsinhistory/R

R: Letter designation for tires to indicate that they are radial as in P185R13 tire..

Race: 1. The inner or outer ring that provides a contact surface for the balls or rollers in a bearing. 2. A competition (usually based on speed) between two vehicles. See drag race and race camshaft.

Race camshaft: A camshaft, other than stock, designed to improve engine performance by altering cam profile. Provides increased lift, faster opening and closing, earlier opening and later closing, etc. Race camshafts are available as semi-race or street grind, three-quarter race camshaft or full race. Grinds in between these general categories are also available.

Rack and pinion: See rack and pinion gearbox.

Rack and pinion gearbox: A type of steering system with a pinion gear on the end of the steering shaft. The pinion engages a long rack (a bar with a row of teeth cut along one edge). When the steering wheel is turned, the pinion turns and moves the rack to the left or right. This movement is carried through tie rods to the steering arms at the wheels.

Rack and pinion steering: See rack and pinion gearbox.

Radar detector: !!!.

Radial: See radial engine and radial tire.

Radial cracking: Cracking of sidewall rubber running perpendicular to the tire beads. May result from underinflation or exposure to ozone.

Radial engine: An engine with a number of cylinder arranged in a circle around the crankshaft center line. A design often used for aircraft engines.

Radial ply: The ply or plies used in tire in which the cords run at right angles to the bead and parallel to the tire radius. See radial tire.

Radial runout: A tire assembly that does not form a true circle; the radii of the circle are not equal. Most usual causes are bent wheel (out of round) or tire not mounted properly (beads not seated).

Radial tire: A type of tire construction which has the main carcass plies or cords which run at right angles to the bead and parallel to the radius. By itself, this construction is very weak because when the bias angle is smaller, the structure is stiff. However, the radial tire has a very large bias angle. In order to strengthen the tire, a belt surrounds the circumference. This belt is made of low-angle plies (usually about 15 degrees). In this way, the tread area is stiff and the sidewall are flexible. In this way they can act independently of each other. In a P185/80R13 tire, R indicates a radial tire.

Radiation: The transfer of heat from one object to another when the hotter object sends out invisible rays or waves that upon striking the colder object, cause it to vibrate and thus heat.

Radiator: A device that cools the liquid in the cooling system by allowing it to circulate through a series of water channels, which are exposed to air ducts. Also see rodding the radiator and heat exchanger.

Radiator cap: See pressure cap.

Radiator fill hole: An opening at the top of the radiator through which new water and coolant can be added. The pressure cap seals the fill hole.

Radiator pressure cap: See pressure cap.

Radio: Automobile radios began to appear in vehicles in 1928.

Radius: See loaded radius, free radius, and radius rods.

Radius rod: See radius rods.

Radius rods: Rods or arms which is part of the suspension, usually a live rear axle. They are attached to the axle and pivoted on the frame. They are used to keep the axle at right angles to the frame (i.e., prevent lateral movement) and yet permit an up and down motion. On some cars like the Triumph Spitfire, they are used to help locate the swing axles.

Rag: See tack rag.

Ragtop: convertible.

RAI: Acronym for "Nederlandse vereniging de Rijwiel-en-Automobiel Indusrie" (Netherlands).

Rail: A dragster built around a relatively long pipe frame. The only body panels used are around the driver's cockpit area.

Rail, shift: See shift rails.

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

Rake: The angle at which a rod is attached. See fork rake.

Raked: Ground clearance, at either front or rear of the vehicle, reduced or increased, thus giving the vehicle a tilted appearance.

Ram air: !!!.

Ram induction: Using the forward momentum of vehicle to scoop air and force it into carburetor via a suitable passageway.

Ram intake manifold: An intake manifold that has very long passageways that at certain speeds aid the entrance of fuel mixture into the cylinders.

R&D: Acronym for "Research & Development".

Rasp: 1. A tool like a file with coarse teeth used to prepare a tire for section repair and for buffing prior to retreading. 2. The action of using a rasp tool.

Ratchet: A feature of a special wrench which allows you to turn the handle in one direction to tighten a nut or bolt, but turning it in the opposite direction does nothing but position the handle back where you started and leaves the wrench on the nut or bolt. Likewise you could set the wrench to loosen a nut or bolt. Also see socket wrench.

Rated horsepower: SAE horsepower.

Ratio: A fixed relationship between things in number, quantity or degree. For example, if the fuel mixture contains one part of gas for fifteen parts of air, the ratio would be 15 to 1. See a/f ratio air-fuel ratio aspect ratio compression ratio final drive ratio fuel-air ratio gear ratio power-to-weight ratio rear axle ratio steering overall ratio steering ratio.

Rattrap: The type of bicycle pedals that have thin metal plates with jagged edges running parallel on each side of the pedal spindle.

RAVE valve: A device used on two-stroke engines which automatically alters or varies the exhaust port size. It stands for Rotax adjustable variable exhaust.

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

Rayon: A synthetic fiber.

Rdstr.: Abbreviation for "roadster."

Reactor: See stator and thermal reactor.

Rear axle housing: See banjo type and split type.

Rear axle housing, banjo type: A rear axle housing from which the differential unit may be removed while the housing remains in place on the vehicle. The housing is solid from side to side.

Rear axle housing, split type: A rear axle housing made up of several pieces and bolted together. The housing must be split apart to remove the differential.

Rear axle ratio: The number of times the rear wheels turn compared to a particular transmission speed. The higher the rear axle ratio, the slower the engine can run and still allow the vehicle to achieve a given speed. Also called "Final axle ratio."

Rear suspension: The axles, springs, and linkages which control the movement of the rear wheels. See independent rear suspension.

Rear triangle: A bicycle frame triangle formed by the chainstays, seatstays, and the seat tube.

Rear-wheel drive: !!!.

Rebound: The action of a shock absorber to spring back to its fully extended state. The opposite of rebound is jounce.

Rebuild: To disassemble a particular device, clean it thoroughly, replace worn parts, and reassemble it. Also called "overhauling."

Recap: See retread.

Recharge: The action of bringing a product back to its full or original level. Recharging a battery brings the voltage back to its recommended level. Recharging the air conditioner means filling the system with refrigerant.

Reciprocating action: A back-and-forth or up-and-down movement such as the action of the pistons.

Reciprocation: A back-and-forth or up-and-down movement such as the action of the pistons.

Recirculating ball: See recirculating-ball-and-nut steering.

Recirculating ball and nut steering: See recirculating-ball-and-nut steering.

Recirculating-ball-and-nut steering: A very popular type of steering gear. It uses a series of ball bearings that feed through and around and back through the grooves in the worm gear and nut on the steering shaft. The turning forces are transmitted through these ball bearing to a sector gear on the pitman-arm shaft. When the steering wheel is turned, the worm gear on the end of the steering shaft rotates and the movement of the recirculating balls causes the ball nut to move up and down along the worm. Movement of the ball nut is carried by teeth to the sector gear which in turn moves with the ball nut to rotate the pitman-arm shaft and activate the steering linkage. The balls recirculate from one end of the ball nut to the other through a pair of ball return guides. This system is also called ball-and-nut steering or worm-and-recirculating-ball steering.

Recirculating ball worm and nut: See recirculating-ball-and-nut steering.

Recirculation: See exhaust-gas recirculation.

Recovery system: See coolant recovery system and vapor recovery system.

Rectifier: A device used to change AC (alternating current) into DC (direct current). Some small motorcycles use a single diode for this purpose (half-wave rectifiers), the overwhelming majority use four diodes connected in a bridge which yields full-wave rectification. Also see diode.

Recumbent: !!!.

Red Flag: !!!.

Red line: 1. Top recommended engine rpm. If a tachometer is used, it will have a mark (red line) indicating maximum rpm. Some tachometers mark the red line with a colored sector. Others have two lines: the lower one marking the maximum allowable sustained engine rpm, the higher line indicating the absolute maximum rpm. 2. (RL) Tires with a red concentric line which were marketed in the late '60s and early 70s.

Reducer: The solvent that is used to thin enamel.

Reed valve: A one-way valve used in a two-cycle engine. It is made of a flat strip of metal that lies on the floor of the crankcase over a hole connected to the carburetor. As the piston moves up, the vacuum developed in the crankcase lifts the reed valve off the hole. The vacuum causes the fuel-air mixture to flow from the carburetor into the crankcase. Then, as the piston starts to move down, pressure increases in the crankcase pushing the reed valve down, closing the hole and sealing the crankcase.

Reel: A revolving, often cylindrical device for winding up or letting out cord, wire, or strap. See inertia reel.

Refit: closure of a plant for the purpose of plant conversion or retooling.

Reformulated gasoline: Fuel with less volatility and reduced levels especially of toxic hydrocarbons.

Reformulated gasolines: Fuels with less volatility and reduced levels of especially toxic hydrocarbons.

Refrigerant: The liquid used in refrigeration systems to remove heat from the evaporator coils and carry it to the condenser. It absorbs and gives up heat as it changes from a liquid to a gas to a liquid. Freon-12 was a common automotive refrigerant, but it has been replaced by C134.

Refrigerant-12: The name applied to refrigerant generally used in automotive air conditioning systems and refrigerators. Also called freon-12.

Registration: motor vehicle ownership that is filed with the province/state.

Regrooveable tire: See special mileage tire.

Regrooving: The act of cutting new tread grooves into the crown of the tire after the original tread is worn down. A practice which is legally forbidden in many places.

Regular gasoline: !!!.

Regulator, voltage: See voltage regulator.

Regulator: A device to reduce and control pressure in gas or liquid.

Reinforcement: Any material, usually rubber and fabric, vulcanized to the tire to return strength to the cord body upon an injury.

Relay: An electro-magnetically operated switch used to make and break the flow of current in a circuit. As low amperage current is passed through one circuit of the relay, it switches a greater current through another line. For example, when installing auxiliary lights with a heavy draw, the stock light switch may not be able to take the current. Thus a relay is installed so that when the light switch is turned on, low current is sent to the relay. The relay closes the circuit of heavy wiring directly from the battery to the lights. Also called "cutout" and "circuit breaker."

Release finger: See clutch semi-centrifugal release fingers.

Release fingers: See clutch semi-centrifugal release fingers.

Relief valve: See pressure relief valve.

Relieve: To remove, by grinding, the small lip of metal between the valve seat area and the cylinder and removing any other metal deemed necessary to improve the flow of fuel mixture into the cylinders. Porting is generally done at the same time.

Remanufacturing: The process of taking a used part and returning it to original equipment (OE) specifications through disassembly and cleaning of the core, testing, and remachining or replacement of worn components.

Remote Keyless Entry: !!!.

Remover: A chemical or compound used to clear away unwanted material. See bug and tar remover.

Renault: The 45 HP models of 1925-1948 with required application are classic cars.

Reo: The 1931-33 Royale 8-31, Royale 8-35, Royale 8-52, and Royale Custom 8 and 1934 N1, N2, and 8-52 are classic cars.

Repair gum: See cushion gum.

Replacement market: all products and services used in the repair and maintenance of vehicles.

Repro: Abbreviation for "reproduction."

Reproduction: Parts or complete vehicles that have been manufactured to closely follow or exceed original specifications, materials, and performance. Also called "repro" or "repros." These parts often are so perfect that not even a concours judge can tell that they are not NOS or OEM.

Research & development: R&D expenditures (product and process development).

Resin: 1. A secretion from trees used in varnishes, printing ink, and plastic as a binder. 2. A synthetic product with some of the same physical properties as the plant secretion. 3. A liquid plastic used in body work.

Resistance: 1. An opposing force. 2. A measure of a conductor's ability to retard the flow of electricity. Also see air resistance.

Resistor: A device placed in a circuit to lower the voltage. It will also decrease the flow of current. Also see ballast resistor.

Resistor spark plug: A spark plug containing a resistor designed to shorten both the capacitive and inductive phases of the spark. This will suppress radio interference and lengthen electrode life. Using a non-resistor spark plug may also damage a CDI box.

Resleeve: See re-sleeve.

Re-sleeve: This is a term used of the piston cylinders. The old cylinder inserts are completely removed and new inserts or sleeves are pressed in. This action is done when the cylinder cannot be rebored. Also see cylinder sleeve.

Resonator: A small muffler-like device that is placed into the exhaust system near the end of the tail pipe. It is used to provide additional silencing of the exhaust.

Restoration: The act of working on a vehicle with such care as to bring it back to its original condition (including original parts, paint, chroming processes, etc.) rather than merely rebuilding or repairing one.

Restraint: A device used to halt the movement of something. See head restraint.

Restrictor plate: !!!.

Retard: 1. To set the ignition timing so that a spark occurs later or less degrees before TDC. It involves adjusting the camshaft, distributor spark, or valve operation. In this way, the spark plugs fire or the valves open later in the cycle. Also see spark retard. The opposite of advance. 2. The device for doing this action.

Retainer: A device which holds something in place. See valve keeper.

Retread: 1. A means of extending the life of a tire that has worn its original tread, yet still has a sound carcass. The casing is prepared by buffing off tread rubber and vulcanizing new tread rubber stock in its place. 2. A casing to which tread rubber has been affixed to extend the useable life of the tire after the original tread has been worn out.

Retreading: See retread.

ReVere: The 1925-1948 models are classic cars.

Reverse brake shoe: See trailing brake shoe.

Reverse-Elliot type axle: A solid bar front axle on which the steering knuckles span or straddle the axle ends.

Reverse flush: Cleaning the cooling system by pumping a powerful cleaning agent through the system in a direction opposite to that of normal flow.

Reverse idler gear: A gear used in the transmission to produce a reverse rotation of the transmission output shaft.

Reversion: Excessive heating of a cured rubber compound leading to deterioration of its physical properties.

Revolutions per kilometer: (RPK) A measurement of the number of times a tire turns in one kilometer of travel.

Revolutions per mile: (RPM) A measurement of the number of times a tire turns in one mile of travel.

Revolutions per minute: (RPM) The speed the engine crankshaft is turning. Also see RPM.

Rev range: !!!.

RH: Acronym for "right hand," as in RH drive. For all vehicles, left and right are from the perspective of sitting in the driver's seat.

RHD: Acronym for "right-hand drive."

Rib: The continuous raised portions of rubber that run circumferentially (straight or in a zigzag pattern) making up the tread on the tire. Also the term applies to various raised surfaces circling the sidewall, i.e., guide rib.

Ricardo principle: An arrangement in which a portion of the combustion chamber came in very close contact with the piston head. The other portion, off to one side, contained more space. As the piston neared TDC on the compression stroke, the fuel mixture was squeezed tightly between the piston and head thus causing the mixture to squirt outward into the larger area in a very turbulent manner. This produced a superior mixture and allowed compression ratios to be raised without detonation.

Rich mixture: !!!.

Ride height: A measurement between the ground and some fixed reference point on a car's body. The exact location of the fixed point varies among manufacturers. This dimension can be used to measure the amount of suspension deflection or the height of the body from the ground.

Ride steer: A generally undesirable condition in which a wheel steers slightly as its suspension compresses or extends. Also called "bump steer."

Ridge: An edge or ledge or lip which protrudes beyond the normal face of an object. See piston ring ridge and burr.

Riding the clutch: A situation where the driver rests his foot on the clutch pedal while the vehicle is being driven. This action can cause undue wear on the clutch plates because they may be rubbing against each other ever so slightly.

Right: When referring to the side of a unit, the right side is always from the perspective of operation. In other words, when sitting in the driver's seat or when riding a bicycle or when pushing a mower, the right side is the operator's right hand side. In other words the left or right side is determined by facing the rear of the unit.

Right hand thread: See right-hand thread.

Right-hand thread: The common direction (clockwise) which is used to secure a nut to a bolt. Also see left-hand thread.

Rigid axle: A simple non-independent suspension, consisting of a rigid transverse member with wheel hubs solidly bolted to it. The axle can be attached to the body by leaf springs, or by a combination of suspension arms and links.

Riley: The 1925-1948 models with required application are classic cars. The 1945-55 2.5 (RMA, RME) models are milestone cars.

Rim: 1. On a bicycle, the metal or wooden hoop of a wheel that holds the tire and tube and the outer ends of the spokes. 2. On a truck, the metal assembly consisting of a base and either a side ring or a side and lock ring combination, which are removable from one side for tire mounting. The opposite side has a fixed flange to retain the tire. Note: Passenger and tubeless rims do not have removable side and lock rings. Also see drop center rim and safety rim.

Rim brake: Any type of brake that slows or stops a wheel by pressing its pads against the sides of the wheel rim.

Rim drivers: Riveted or welded metal blocks or extrusions on both sides of the valve slot to prevent valve damage due to rim slippage on cast spokes.

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Page Updated Sun May 20, 2001 8:08pm EDT