ASE A4 flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Recirculating ball steering gear

A steering gear in which a ball nut rides on recirculating ball bearings along a worm shaft, moving a sector shaft that swings the pitman arm.

Ackermann steering geometry

Geometry in which the inner front wheel steers a sharper angle than the outer wheel so both wheels roll on arcs sharing a common center, reducing tire scrub.

Included angle

The sum of steering axis inclination and camber. It is not adjustable, so an out-of-spec value indicates a bent knuckle, spindle, or strut.

Steering wheel free play

The amount the steering wheel can be rotated before the front wheels respond, measured at the rim with the wheels straight ahead. Excess indicates worn linkage or gear.

Power steering relief pressure

The maximum pump pressure produced when the steering is held against a stop, typically 1,000 to 1,500 psi, limited by the pump's pressure relief valve.

Electric power steering torque sensor

A sensor that measures torsional deflection of the steering column shaft from driver input, allowing the control module to command proportional assist motor current.

Idler arm function

On parallelogram steering linkage, it supports the end of the center link opposite the pitman arm. Worn idler bushings allow toe change and cause wander.

MacPherson strut

A suspension unit combining a coil spring and damper that also locates the wheel. Camber is adjusted by moving the strut-to-knuckle joint.

Load-carrying ball joint check

A ball joint that supports vehicle weight is checked for axial (vertical) play with the vehicle's weight resting on it, using a dial indicator or pry bar.

Spring rate definition

The force in pounds required to compress a spring one inch. It increases with larger wire diameter, fewer active coils, or smaller mean coil diameter.

Stabilizer bar link noise

Worn sway bar links or bushings produce clunking or rattling over bumps. Verify play by prying components with the suspension at normal ride height.

Control arm bushing preload

Rubber bushings must be tightened with the suspension at normal ride height. Tightening at full droop twists the rubber and causes early failure.

Air suspension height sensor

A sensor that reports ride height to the control module, which runs the compressor and solenoid valves to maintain the programmed trim height at each corner.

Worn strut symptoms

Excessive rebound, cupped tire tread, nose dive during braking, longer stopping distance, and fluid leakage. Lost gas charge reduces damping control.

Camber angle definition

The inward or outward tilt of the wheel top from vertical. Negative camber tilts the top inward and wears the inner tread edge; positive camber does the opposite.

Caster angle definition

The forward or rearward tilt of the steering axis viewed from the side. Positive caster, top rearward, increases straight-line stability and steering effort.

Toe setting definition

The difference between front and rear measurements across a pair of tires. Toe-in means the fronts are closer together; excess toe causes feathered tread wear.

Thrust angle

The average rear toe direction relative to the vehicle centerline. A nonzero thrust angle causes dog tracking and an off-center steering wheel.

Alignment adjustment order

Set tire pressure and ride height first, then caster and camber, then toe last, because toe readings change whenever camber or caster is adjusted.

SAI and included angle

Steering axis inclination is the front-view tilt of the steering axis. Included angle equals SAI plus camber and changes only when parts are bent.

Memory steer

A condition where the vehicle continues to turn after the steering wheel is released, caused by binding strut bearings, ball joints, or column universal joints.

Tire size P225/60R16

225 mm section width, 60 aspect ratio meaning sidewall height is 60 percent of width, radial construction, and a 16-inch rim diameter.

Positive wheel offset

The wheel mounting face is outboard of the wheel centerline. This reduces track width and affects scrub radius, bearing load, and steering feel.

Tread wear indicator

Raised bars molded into the tread grooves at 2/32 inch (1.6 mm), the legal minimum tread depth in most jurisdictions. They appear when replacement is due.

Static versus dynamic balance

Static balance corrects a one-plane up-and-down imbalance. Dynamic balance uses two planes to correct side-to-side rocking of the wheel assembly.

Tire conicity pull

A tire built with offset belt layers that pushes sideways like a cone, causing a steady pull. Cross-swapping the front tires reverses the pull direction.

DOT date code

The final four digits of the DOT tire serial number. The first two digits are the week of manufacture and the last two are the year.

Lug nut torque sequence

Tighten lug nuts in a star or crisscross pattern in progressive stages to the specified torque so the wheel seats squarely and evenly on the hub.

Speed-related vibration diagnosis

Vibration that varies with road speed points to wheels, tires, runout, or driveline. Vibration that varies with engine RPM in neutral points to engine or converter.

CV joint click diagnosis

Clicking or popping during turns under acceleration indicates a worn outer constant velocity joint, most often after a torn boot has released its grease.

Wheel bearing noise test

A growl that changes volume when the vehicle is swerved left versus right identifies a bearing on the loaded or unloaded side, confirmed with a wheel shake.

ADAS recalibration after alignment

Camera and radar systems referenced to the vehicle thrust line may require static or dynamic recalibration whenever ride height, ride attitude, or alignment angles change.