Glossary of Terms Used In Pinpoint Tests
Light AccelerationIncrease in speed at less than half throttle.
Heavy Acceleration
Half to full throttle increase in speed.
WOT
Wide open throttle
Ambient Temperature
The surrounding or prevailing temperature. Usually the temperature in the service area or outdoor depending on where the testing is taking place.
Articulation
Vertical movement of the front wheel driveshaft and joints relative to the frame of the vehicle to which they are attached.
Belt Chirp
An intermittent noise usually at idle caused by belt misalignment.
Belt Squeal
A continuous noise caused by a frozen accessory or insufficient tension.
Boom
A cycling, rhythmic noise often accompanied by sensation of pressure on the eardrums.
Bound Up
Refers to a stressed, rubber-mounted component that transmits any noise, vibration and harshness (NVH) that would normally be absorbed by the mount. (See Neutralize).
Brakes Applied
When the vehicle is stationary and the transaxle is in DRIVE (D), the service brakes are applied with enough force to prevent vehicle movement.
Camber
Angle formed between front wheel knuckle axis and horizontal as viewed from in front of the vehicle.
- Camber is positive when the wheel tops are farther apart than the wheel bottoms.
Caster
Angle formed between the shock absorber upper mount and lower ball joint centerline axis or the kingpin axis and a vertical axis as viewed from the side of the vehicle. Caster is considered positive when the top of the kingpin axis is behind the vertical axis.
Chuckle
Refers to the noise that occurs on the coast driving phase; usually caused by excessive clearance due to differential gear wear or by a damaged tooth on the coast side of the final drive ring gear or the final drive sun gear.
Clunk
Due to excessive final drive ring gear backlash, elongation of the differential pinion shaft holes in the differential case, or missing side gear or pinion gear thrust washers. If none of these conditions exist, clunk may be caused by a loose fit of the front wheel driveshaft joints to the side gear splines.
Coast/Deceleration
Slowing of the vehicle by releasing the accelerator at cruise and allowing the engine to slow the vehicle without application of the brakes.
Coast/Neutral Coast
Engine/transaxle taken out of gear by placing the gear shift lever in NEUTRAL (N) or by depressing the clutch pedal.
CPS
Cycles per second.
Cruise
Steady highway speed. neither accelerating nor decelerating. with even pressure applied to the accelerator pedal on level ground.
Deceleration
Slowing of the vehicle by releasing the accelerator at cruise and allowing the engine to slow the vehicle without applying the brakes.
Drivetrain
Includes all power transmitting components from the engine to the wheels, including clutch, transaxle, and front wheel driveshaft and joints.
Engine Imbalance
A component in the engine which is normally smoothly balanced is now causing a noticeable vibration in the vehicle.
Engine Misfire
One or more cylinders in the engine fail to fire at the proper time.
Engine Run-up Test
Operation of the engine through normal rpm range with the vehicle sitting still and the gear shift lever in NEUTRAL (N). Used for engine and accessory vibration check.
Flexible Coupling
A flexible joint in the exhaust pipe located between the three way catalytic converter (TWC) and muffler, designed to eliminate binding conditions in the exhaust system and eliminate exhaust NVH.
Float
A cruise drive mode in which the throttle setting matches the engine speed to road speed. resulting in very gradual deceleration.
Gravelly Feel
A grinding or growl in a component similar to the feeling experienced while driving on gravel.
Harshness
A harder than usual behavior of a component. like riding in a vehicle with overinflated tires.
Hose Clamp
Screw-type hose clamp.
Hz
Hertz (cycles per second).
Imbalance
Out of balance. More weight on one side of a rotating component causing shake or vibration.
Inboard
Toward the centerline of the vehicle. (See Outboard).
Isolate
To separate from the influence of other components.
Knock
Caused by a gear tooth damaged on the drive side of the final drive ring gear which can be corrected by grinding the damaged area.
Neutral Engine Run-Up Test
Operation of the engine through normal rpm range with vehicle sitting still, transaxle in NEUTRAL (N). Used for engine and accessory vibration check.
Neutralize (Normalize)
To return to an unstressed position. Used to describe various mounts and exhaust system hangers. (See Bound Up).
NVH
Noise, vibration, harshness.
Outboard
Toward the outside of the vehicle, rather than toward the centerline. (See Inboard).
Pumping Feel
A very slow vibration that results in a movement of vehicle components similar to pumping the service brakes slightly.
Radial/Lateral
Radial is in the plane of rotation. Lateral is at 90 degrees to the plane of rotation.
Road Test
Operation of the vehicle under conditions designed to re-create the problem condition.
Runout
Out-of-round or wobble.
Shake
Low-frequency vibration, usually results in visual movement of components.
Tip-In Moan
A light moaning noise heard when the vehicle is lightly accelerated, usually between 40-80 kph (25-50 mph).
TIR
Total indicator runout.
Tire Deflection
Bending of the tire body during rotation.
Tire Force Vibration
Tire vibration caused by variations in tire construction, resulting in a vibration when the tire rotates against the pavement. (This condition may even be present on perfectly round tires.)
Tires - Flat Spots
Commonly caused by letting the vehicle stand while the tires cool off. Can usually be corrected by operating the vehicle again until the tires are warm. Also, regular wear patterns in the tire tread resulting from wheel-locked skids or a defective tire.
Two-Plane Balance
Radial and lateral balance.
Vibration
Regular movement of a component that results in a sound or feel of movement.