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for the old n new alike... (technical terminologies)

Started by sonic1, January 21, 2004, 02:31:56 AM

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SAE: Society of Automotive Engineers
The professional association of transportation-industry engineers. The SAE sets most auto-industry standard for the testing, measuring, and designing of automobiles and their components.

Scrub radius
The distance from the point where the steering axis intersects the ground to the longitudinal line that runs through the center of the tire's contact patch. Also called "steering offset."

As used by Car and Driver, the term "sedan" refers to a fixed-roof car with at least four doors or any fixed-roof two-door car with at least 33 cubic feet of rear interior volume, according to measurements based on SAE standard J1100.

Semi-elliptic leaf spring
A slightly curved leaf spring that is attached to a car's body at its ends and to a suspension component near its middle. One of the two body attachments is a shackle, which allows for changes in the spring's length as it flexes up and down.

Semi-trailing-arm suspension
An independent rear-suspension system in which each wheel hub is located only by a large, roughly triangular arm that pivots at two points. Viewed from the top, the line formed by the two pivots is somewhere between parallel and perpendicular to the car's longitudinal axis.

Series (tire)
The numerical representation of a tire's aspect ratio. A 50-series tire has an aspect ratio of 0.50.

Shift gate
The mechanism in a transmission linkage that controls the motion of the gearshift lever. The shift gate is usually an internal mechanism; however, in some transmissions: including Ferrari five-speeds and Mercedes-Benz automatics : the shift gate is an exposed guide around the shift lever.

Shock absorber
A device that converts motion into heat, usually by forcing oil through small internal passages in a tubular housing. Used primarily to dampen suspension oscillations, shock absorbers respond to motion; their effects, therefore, are most obvious in transient maneuvers.


Single-rate spring
A spring with a constant spring rate. For example, if a 100-pound force deflects the spring by one inch, an additional 100 pounds will deflect it one more inch, and so on until the spring either bottoms or fails.

A large area of smooth, flat pavement used for various handling tests. Roadholding is measured by defining a large-diameter circle (Car and Driver uses 300 feet) on the skidpad and measuring the fastest speed at which the car can negotiate the circle without sliding off.

Slip angle
The angular difference between the direction in which a tire is rolling and the plane of its wheel. Slip angle is caused by deflections in the tire's sidewall and tread during cornering. A linear relationship between slip angles and cornering forces indicates an easily controllable tire.

A slang for an automatic transmission.

Single overhead camshaft: an SOHC engine uses one camshaft in each cylinder head to operate both the exhaust valves and the intake valves.

Space frame
A particular kind of tube frame that consists exclusively of relatively short, small-diameter tubes. The tubes are welded together in a configuration that loads them primarily in tension and compression.

An aerodynamic device that changes the direction of airflow in order to reduce lift or aerodynamic drag and/or improve engine cooling.

The opposite of dive, squat is the dipping of a car's rear end that occurs during hard acceleration. Squat is caused by a load transfer from the front to the rear suspension.

Steering axis
The line that intersects the upper and lower steering pivots on a steered wheel. On a car with a strut suspension, the steering axis is defined by the line through the strut mount on top and the ball joint on the bottom.

Steering feel
The general relationship between forces at the steering wheel and handling. Ideally, the steering effort should increase smoothly as the wheel is rotated away from center. In addition, the steering effort should build as the cornering forces at the steered wheels increase. Finally, the friction built into the steering mechanism should be small in comparison with the handling-related steering forces.

Steering gain
The relationship between yaw and the steering wheel's position and effort. All three should be proportional and should build up smoothly.

Steering geometry
The group of design variables outside the steering mechanism that affect steering behavior, including camber, caster, linkage arrangement, ride steer, scrub radius, toe-in, and trail.

Steering response
A subjective term that combines steering feel and steering gain.

Straight-line tracking
The ability of a car to resist road irregularities and run in a straight line without steering corrections.

The distance between the extremes of a piston's travel in a cylinder.

A suspension element in which a reinforced shock absorber is used as one of the wheel's locating members, typically by solidly bolting the wheel hub to the bottom end of the strut.

The space in the engine block under the crankshaft into which the oil drains from its various applications.

An air compressor used to force more air into an engine than it can inhale on its own. The term is frequently applied only to mechanically driven compressors, but it actually encompasses all varieties of compressors-including turbochargers.



A removable-roof body style popularized by Porsche that is similar to a convertible except that it incorporates a fixed, roll-bar-like structure running from side to side behind the front seats.

A housing containing a valve to regulate the airflow through the intake manifold. The throttle-body is usually located between the air cleaner and the intake plenum.

Throttle-body fuel injection
A form of fuel injection in which the injectors are located at the engine's throttle-body, thereby feeding fuel to more than one cylinder. Such an arrangement saves money by using fewer injectors; but because it routes both fuel and air through the intake manifold, it eliminates some of the tuning possibilities offered by port fuel injection.

Toe-control link
A lateral link in a multilink suspension designed to control a wheel's direction as the suspension moves up and down.

The intentional nonparallel orientation of opposite wheels. Toe-in is measured by subtracting the distance between the front edges of a pair of tires from the distance between the rear edges of the same pair of tires. The toe-in dimension is positive when the fronts of the tires are turned toward the center of the car.

Toe steer
The changes in the direction of a wheel that occur without driver steering input. Toe steer can be caused by ride steer or by deflections in suspension components caused by the stresses of cornering, accelerating, and/or braking on smooth and bumpy roads.

The rotational equivalent of force, measured in pound-feet.

Torque converter
A particular kind of fluid coupling with a third element added to the usual input and output turbines. Called ""the stator,"" this additional element redirects the churning fluid against the output turbine, increasing torque. This torque increase, however, is achieved at the expense of rpm and efficiency.

Torque steer
A tendency for a car to turn in a particular direction when power is applied. Torque steer is common in front-drive cars because reaction forces created in the half-shafts can generate uneven steering forces in the front tires.

Torsion bar
A spring consisting of a long solid or tubular rod with one end fixed to the chassis and the other twisted by a lever connected to the suspension.

Traction control
An electronic control system that prevents wheelspin by detecting when a driven wheel is about to break traction, and then reducing engine power and/or applying the appropriate brakes to prevent it.

A driving technique in which the driver begins to brake before entering a turn and then continues to brake as he eases into the corner. As cornering forces build, the driver gradually feathers off the brakes: trading braking power for cornering grip. By increasing the vertical loading : and thus the traction: at the front tires, trail-braking can improve a car's turn-in.

Trailing arm
A suspension element consisting of a longitudinal member that pivots from the body at its forward end and has a wheel hub rigidly attached to its trailing end. A sufficiently rigid trailing arm can provide all of a wheel's location. In that case it is similar to a semi-trailing arm, except that its pivot axis is exactly perpendicular to the car's longitudinal center line.

Trailing link
A suspension link that is aligned to resist longitudinal motions in a wheel; it is mounted to the chassis ahead of the wheel.

A transmission and a differential combined in one integrated assembly.

A gearbox with a number of selectable ratios, used to match the engine's rpm and torque to differing vehicle requirements.

Tread squirm
The flexibility in the tire tread between the surface of the tread and the tire carcass. Snow tires, with their small, deep, unsupported tread blocks, have a large amount of tread squirm. Slick racing tires, which have no tread pattern, have very little squirm.

Tube frame
A car frame made up of rigid tubing welded together. Tube frames are easier to manufacture in small quantities than unitized frames.

The term that describes the convex curvature on the side of a car body.

Tuned intake and exhaust systems
Intake and exhaust systems that, by harnessing the pressure pulses and resonances inside the various passages and chambers of the intake and exhaust manifolds, increase the flow of intake charge into and out of the combustion chambers.

A supercharger powered by an exhaust-driven turbine. Turbochargers always use centrifugal-flow compressors, which operate efficiently at the high rotational speeds produced by the exhaust turbine.

Turbo lag
Within a turbocharger's operating range, lag is the delay between the instant a car's accelerator is depressed and the time the turbocharged engine develops a large fraction of the power available at that point in the engine's power curve.

The moment of transition between driving straight ahead and cornering.



A handling condition in which the slip angle of the front tires is greater than the slip angle of the rears. An understeering car is sometimes said to push, because it resists turning and tends to go straight.

Unitized construction
A type of body construction that doesn't require a separate frame to provide structural strength or support for the car's mechanical components. A unitized body can employ monocoque construction, or it can utilize strong structural elements as an integral part of its construction.

Universal joint
A joint that transmits rotary motion between two shafts that aren't in a straight line. Depending on its design, a universal joint can accommodate a large angular variation between its inputs and outputs. The simplest kind of universal joint, called a "Hooke joint," causes the output shaft to speed up and slow down twice for every revolution of the input shaft. This speed fluctuation increases with the angular difference between the shafts.


Valve float
A high-rpm engine condition in which the valve lifters lose contact with the cam lobes because the valve springs are not strong enough to overcome the momentum of the various valvetrain components. The onset of valve float prevents higher-rpm operation. Extended periods of valve float will damage the valvetrain.

Valve lifter
Also called a "valve follower": the cylindrically shaped component that presses against the lobe of a camshaft and moves up and down as the cam lobe rotates. Most valve lifters have an oil-lubricated hardened face that slides on the cam lobe. So-called "roller lifters," however, have a small roller in contact with the cam lobe: thereby reducing the friction between the cam lobe and the lifter.

The collection of parts that make the valves operate. The valvetrain includes the camshaft(s) and all related drive components, the various parts that convert the camshaft's rotary motion into reciprocating motion at the valves, and the valves and their associated parts.

Viscous coupling
A particular kind of fluid coupling in which the input and output shafts mate with thin, alternately spaced discs in a cylindrical chamber. The chamber is filled with a viscous fluid that tends to cling to the discs, thereby resisting speed differences between the two shafts. Viscous couplings are used to limit the speed difference between the two outputs of a differential, or between the two axles of a car.



Waste gate
A valve used to limit the boost developed in a turbocharger. A waste gate operates by allowing some of the engine's exhaust flow to bypass the turbocharger's turbine section under certain conditions.

Wheel hop
An undesirable suspension characteristic in which a wheel (or several) moves up and down so violently that it actually leaves the ground. Wheel hop can be caused by many problems, including excessive unsprung weight, insufficient shock damping, or poor torsional axle control.


The rotation about a vertical axis that passes through the car's center of gravity.


Zero-offset steering
A steering system whose geometry has a scrub radius of zero. This configuration minimizes the steering effects produced during acceleration (with front drive) or braking on varying traction surfaces.

sana marami kayo matutunan... ako sobrang dami... kahit wala akong alam talaga... ehehhehe

:D :D :D ;D ;D ;D


Quote from: sonic1 on February 24, 2004, 10:53:00 PM
A tuned-in front suspension characteristic that converts braking-induced forces in the suspension links into a vertical force that tends to lift the body, thereby reducing dive under braking.

Nice write-up but I have to disagree here.  BMW uses brake torque from the rear to reduce dive by use of cleverly designed rear suspension angles.



very informative...... kulang nalang ata sizes ng gulong at rims baka pwede kayong mag post nun......


Hi newbie here

really sorry to butt in but im just curious what a servo is and where is it located?



it is located at the throttle body of the efi, this are one of the major problems mitsubishi has specially in lancer or cyclone engine. we had this problem then, nagbabago yung menot, taas baba sya, in honda naman cya yng map sensor  
==<<Life is Short, Dive Hard!!!>>==


Quote from: Lester on September 09, 2004, 10:20:09 PM
Hi newbie here

really sorry to butt in but im just curious what a servo is and where is it located?


According to Webster:

Noun 1. servo - control system that converts a small mechanical motion into one requiring much greater power; may include a negative feedback system
Synonyms: servomechanism, servosystem

Adj. 1. servo - of or involving servomechanisms
Synonyms: servomechanical


Just a guess for the meaning of some Hondas. ;D

ESi - Extra Special injection
VTi - Variable Timing injection
VTi-S - VTi Special
VTi-L - VTi Luxury
SiR - Super injected Racing

Now for Mercedes. :D

A - Affordable
C - Compact
E - Executive
S - Superior

SL - Spyder Luxury
SLK - SL Kompressed
CL - Coupe Luxury
CLK - CL Kompressed

ML - Mountaineer Luxury

CLS - Compact Lowered Sedan ???
The EK is the birth of the genuine Civic Type R.


Quote from: squalastic on October 25, 2004, 12:44:58 AM
Just a guess for the meaning of some Hondas. ;D

ESi - Extra Special injection
VTi - Variable Timing injection
VTi-S - VTi Special
VTi-L - VTi Luxury
SiR - Super injected Racing

I read this glossary of terms sa super street:

B17A - USDM DOHC VTEC Motor of 92 Integra GS-R
B18A/B - USDM NON-DOHC VTEC Motor of 90's integra RS/LS
B18C1 - US/JDM DOHC VTEC Motor of 94's integra gs-r
CTR - Civic Type R
Integ/Teg - Integra
C/R - Compression Ratio
ECU - Electronic Control Unit
Frankenstein/Mini-Me - LS/VTEC Motor
GS-R - DOHC VTEC Motor on Integs
H22A - US/JDM DOHC VTEC Motor on Prelude
Hybrid - vehicle with motor swap
ITR - Integra Type R
LS - non-VTEC Motor
RS - base model of non-VTEC Integ
SiR - Sports Injected Race
VTEC - Honda's Variable Valve Timing and lift Electronics Control
ZC - JDM SOHC and DOHC Motor found on early Civics and Integs
ESi - Electronic Sports Injected (Ito sabi ng nka-chat ko sa Yahoo na taga-U.K.)
My EG-8

[img width=250 heig


Some BMW technicals:

ValveTronic : Variable valve timing and lift. This is infinitely variable as it is actuated by electronic motor controlled by ECU. Used to adjust power output from low to medium throttle. Not used in WOT!.

Servotronic: Electronically controlled hydraulic power steering. Typical PS is purely hydraulically driven. BMW uses eletric motors to control the steering feel based on a series of parameters. Available since 1987!.

Fly-By-Wire eletrionic throttle. Electrically actuated throttle butterflies that repond to electrical impluse as opposed to traditional cable actuated throttle. New E60 M5 can go from idle throttle position to WOT in 120 ms. Yes. Milliseconds!.

Active Steering: Electrically/Electronically operated steering system with variable ratios that respond to different programmed conditions. Controlled by eletric motors with direct mechanical gears , sensors and ECU.

X-Drive: Infinitely variable torque split 4 wheel drive. Front/Back, left and right with Computer control. Detect wheelspin within 150 ms!.

M Cars: Motorsport steet legal BMW performance cars using standard body shells with custom suspension, drive trains, engine, brakes and wheels. M3, M5, M6 are examples. Still factory build at designated plants.

DSC: Dynamic stability control. An advance version of Traction control using a multitute of sensors.


Newbie here!!! :D
I saw some tire querries. maybe it will help you to check this thread:

Let's speak tire side marks:
205/55/VR15 0r 205/55R15 84V
205=tire width
55=tire height
VR=Speed rating
15=Rim size
84V(or without V)=Load Index

Speed ratings:
M 81 mph 130 km/h  
N 87 mph 140km/h Temporary Spare Tires
P 93 mph 150 km/h  
Q 99 mph 160 km/h Studless & Studdable Winter Tires
R 106 mph 170 km/h H.D. Light Truck Tires
S 112 mph 180 km/h Family Sedans & Vans
T 118 mph 190 km/h Family Sedans & Vans
U 124 mph 200 km/h  
H 130 mph 210 km/h Sport Sedans & Coupes
V 149 mph 240 km/h Sport Sedans, Coupes & Sports Cars
W 168 mph 270 km/h Exotic Sports Cars
Y 186 mph 300 km/h Exotic Sports Cars
  285/35ZR19 99Y 186 mph, 300 km/h
  285/35ZR19 (99Y) in excess of 186 mph, 300 km/h

Load Index/Pounds/Kilograms
71 761 345                                      
72 783 355                                       92 1389 630
73 805 365                                       93 1433 650
74 827 375                                       94 1477 670
75 853 387                                       95 1521 690
76 882 400                                       96 1565 710
77 908 412                                       97 1609 730
78 937 425                                       98 1653 750
79 963 437                                       99 1709 775
80 992 450                                     100 1764 800
81 1019 462                                   101 1819 825
82 1047 475                                   102 1874 850
83 1074 487                                   103 1929 875
84 1102 500                                   104 1984 900
85 1135 515                                   105 2039 925
86 1168 530                                   106 2094 950
87 1201 545                                   107 2149 975
88 1235 560                                   108 2205 1000
89 1279 580                                   109 2271 1030
90 1323 600                                   110 2337 1060
91 1356 615

Another very important marking is the UTQG(Uniformity Tire Quality Grade) Standards:
Treadwear - This shows how long your tire will last and how sticky it can be. (0-500 or more)
Traction Grades  Asphalt g force  Concrete g force
      AA                  Above 0.54               0.41
        A                  Above 0.47               0.35
        B                  Above 0.38               0.26
        C               Less Than 0.38            0.26

Temperature Grades       Speedsi n mph
             A                            Over 115
             B                     Between 100 to 115
             C                     Between 85 to 100

Hope this will help you purchasing tires.
Happy riding! 8)

Quote from: Nacho Libre on August 31, 2008, 11:23:06 PM
...Some people get too hung up on hardware and technology and for

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