ASE A4 Suspension and Steering flashcards

On a vehicle with a solid rear axle, individual toe is generally not adjustable. Significant discrepancies in individual rear toe readings, even if total toe is within spec, indicate a bent or damaged axle assembly.

• Individual rear toe not adjustable on solid axles.
• Split individual toe implies a bent axle.
• Requires repair or replacement of the axle.

Memory trick: Solid axle, toe's a mess; if split, it's bent, no less!

Excessive free play in a manual steering gear, specifically in the pitman arm shaft before the arm moves, indicates excessive lash between the worm gear and sector gear, which can often be corrected by adjusting the sector shaft lash.

• Lash is clearance between internal gears.
• Causes 'dead spot' or free play in steering.
• Adjusted via sector shaft screw on steering gear.

Memory trick: Lash in the sector, adjust the screw to fix the wander.

The angle between the vehicle's geometric centerline and the thrust line (the direction the rear wheels are pointing). It indicates whether the rear axle is parallel to the front axle and perpendicular to the centerline.

• Positive thrust angle: rear axle points right.
• Negative thrust angle: rear axle points left.
• Ideally, thrust angle should be 0 degrees.
• Impacts steering wheel centering and 'dog-tracking'.

Memory trick: Negative thrust means the rear is 'thrusting' left, like a left hook.

A loud squawking or squealing noise, especially when turning the steering wheel under load, is a key indicator of a slipping power steering pump drive belt.

• Noise under load (turning).
• Accompanied by increased steering effort.
• Caused by loose or worn belt.

Memory trick: Squawking steer? The belt's too loose, my dear!

Excessive lateral runout or warpage of brake rotors causes pulsation or vibration felt through the brake pedal and/or steering wheel, especially during braking.

• Primary symptom is vibration/pulsation during braking.
• Can cause minor vibration at speed even when not braking.
• Often exacerbated by heat from heavy braking.

Memory trick: Brake vibration means check the rotors.

Axial (in-and-out) play in an inner tie rod end leads to a 'dead spot' in the steering, making the vehicle feel loose and causing wander due to inconsistent toe settings, especially at speed.

• Allows rack movement without wheel response.
• Causes 'dead spot' and loose steering feel.
• Prevents accurate toe adjustment, causing wander.

Memory trick: In-and-out play makes steering feel like a dead zone.

A power steering pressure hose that has internally collapsed or kinked, restricting the flow of high-pressure fluid from the pump to the steering gear, leading to reduced power assist.

• Causes heavy steering, especially at low speeds.
• Reduces the effective hydraulic pressure at the steering gear.
• Requires replacement of the hose.

Memory trick: Collapsed hose means less pressure for the steer.

Wear or damage to the internal components of a rack-and-pinion steering gear, such as the pinion bearings, rack teeth, or internal bushings, resulting in grinding noises and/or excessive play.

• Causes metallic grinding noise, especially when turning.
• Noise is often felt through the steering wheel.
• Requires replacement or rebuild of the steering rack.

Memory trick: Grinding gear is an internal fear.

Caster is the forward or rearward tilt of the steering axis when viewed from the side. It influences steering stability and returnability, and unequal caster can cause a vehicle to pull.

• Positive caster: top of steering axis tilts rearward.
• Negative caster: top of steering axis tilts forward.
• Vehicle pulls to the side with less positive caster.
• Caster helps maintain straight-line stability.

Memory trick: Less positive caster lets the wheel 'fall back' and pull you to that side.

On suspensions with shim-adjustable upper control arms, removing shims from the front pivot reduces negative camber (or increases positive camber), while adding shims increases negative camber (or reduces positive camber).

• Shims at upper control arm pivots affect camber AND caster.
• Removing shims at front pivot decreases negative camber.
• Adding shims at front pivot increases negative camber.
• Equal shim changes at both pivots primarily affect camber.

Memory trick: Shims at front, camber's sway, remove to push the top away.

A rattling noise from the steering column area, often caused by loose mounting bolts, worn U-joints, or internal column components.

• Heard over bumps or with slight steering wheel movement.
• Often a mechanical noise, not related to power assist.
• Can be localized by checking mounting points and shaft connections.

Memory trick: Rattling column means check the connections.

Tie rod ends contain ball joints that can wear over time, leading to excessive play in the steering linkage and causing clunking noises or loose steering.

• Connects steering rack/gear to steering knuckle.
• Contains a ball joint for articulation.
• Wear causes play, noise, and alignment issues.

Memory trick: Linkage clunks when its ball joint is loose, like a rusty gate.

A procedure performed during alignment setup to eliminate measurement errors caused by wheel runout or improper sensor mounting.

• Crucial for measurement accuracy.
• Involves rotating the wheels.
• Compensates for non-concentricity.

Memory trick: Runout compensation ensures a true spin.

Tie rod adjusting sleeves can have standard (right-hand) threads on both ends, or a combination of right-hand and left-hand (reverse) threads, which affects the direction of toe adjustment when turning the sleeve.

• Standard (right-hand) thread: clockwise tightens/shortens.
• Left-hand (reverse) thread: clockwise loosens/lengthens.
• Most sleeves have right-hand threads on both ends.
• Some designs use opposing threads for intuitive adjustment (turn to move wheel in desired direction).

Memory trick: Threads dictate direction: righty-tighty, lefty-loosey, unless it's a reverse twist!

Unequal caster (caster split) causes a vehicle to pull to the side with less positive caster. The remedy is to adjust the caster on the affected side(s) to bring them within specification and minimize the side-to-side difference.

• Unequal caster causes a pull.
• Pull is towards the side with less positive caster.
• Caster also affects steering returnability.
• Adjust to bring both sides within spec and reduce split.

Memory trick: Balance the caster, balance the pull.

Thrust angle is the direction the rear wheels are pointing relative to the vehicle's centerline. It is adjusted by altering the toe of the rear wheels, especially on independent suspensions.

• Positive thrust angle: rear axle points to the right.
• Negative thrust angle: rear axle points to the left.
• Corrected by adjusting individual rear toe settings.

Memory trick: Thrust's a twist, correct the rear, make the centerline crystal clear.

Toe adjustment involves symmetrically changing the angle of the front wheels relative to the vehicle's centerline, affecting tire wear and steering response.

• Positive toe (toe-in) means the front of the wheels are closer together.
• Negative toe (toe-out) means the front of the wheels are farther apart.
• Adjustments are made by lengthening or shortening tie rods.

Memory trick: Toe's direction, spec's your guide; too out, bring it in; too in, open wide.

Wear within the worm gear, ball nut, or rack teeth of a manual steering gearbox can cause excessive free play even after proper sector shaft adjustment.

• Manifests as excessive steering wheel free play.
• Not resolved by sector shaft pre-load adjustment alone.
• Requires gearbox overhaul or replacement.

Memory trick: Adjusted pre-load, still loose? Internal wear!

Excessive play in the inner tie rod end's ball and socket joint can cause clunking noises during turns and a loose steering feel.

• Causes clunking during turns.
• Can be felt as steering play.
• Directly affects steering linkage integrity.

Memory trick: Clunking when you turn? Check the tie rod, it's a lesson to learn!

Excessive movement or looseness in a tie rod end, typically causing clunking noises, loose steering, and uneven tire wear.

• Can be inner or outer tie rod ends.
• Causes clunking/popping noises, especially on turns or bumps.
• Leads to vague steering feel and compromised alignment.

Memory trick: Loose linkage means direct replacement.

Steering Axis Inclination (SAI) is a non-adjustable angle. A significant difference in SAI between the left and right sides typically indicates a bent or damaged component in the steering or suspension system.

• SAI is a fixed, non-adjustable angle.
• Determined by the vehicle's design (knuckle, strut).
• Split SAI often points to structural damage from impact.

Memory trick: SAI's fixed, a split's a clue, component damage, often new.

A popping or clicking noise heard when turning the steering wheel, particularly at low speeds, often indicates a worn or damaged strut bearing.

• Allows strut to rotate with steering.
• Can cause noise when turning.
• Often mistaken for steering linkage issues.

Memory trick: Noisy turns might mean a strut's concern.

The difference between the left and right caster angles. A small split is acceptable, but excessive split can cause a vehicle pull.

• Influences steering stability and returnability.
• Affects steering effort.
• Should be within manufacturer's specified tolerance (typically 0.5 - 1.0 degree).

Memory trick: Both the individual and the difference must be in the green.

Significant deviations in Included Angle, especially when accompanied by out-of-spec camber, often point to a bent spindle or steering knuckle, as SAI (part of IA) is non-adjustable.

• IA = SAI + Camber.
• SAI is fixed by design.
• IA issues imply damage if camber cannot explain it.

Memory trick: IA + Camber = SAI, if IA is off, check for bent metal.

Caster is a primary contributor to steering stability and returnability. Insufficient positive caster leads to light, wandering steering, poor return-to-center, and sometimes heavy steering effort, while excessive positive caster can make steering heavy.

• Positive caster provides self-aligning torque.
• Insufficient positive caster: poor returnability, light steering.
• Excessive positive caster: heavy steering, good returnability.
• Zero or negative caster: unstable, poor returnability.

Memory trick: Caster is like a shopping cart wheel: too little, it wobbles; too much, it's hard to turn.

When a diagnostic trouble code indicates a 'circuit malfunction' for a sensor, the initial diagnostic step involves inspecting the electrical connections and wiring related to that sensor.

• DTCs often point to specific circuits.
• Check physical connections first.
• Wiring integrity is crucial for sensor operation.

Memory trick: Circuit fault? Check the wires, and the connections are tight!

Intermittent communication errors between an EPS control module and other vehicle modules (e.g., BCM) typically indicate a fault in the CAN bus wiring, connectors, or network integrity, requiring inspection of these components.

• DTCs point to network issue.
• Look for wiring damage, corrosion, loose pins.
• CAN bus is critical for module communication.

Memory trick: Communication broken? Check the wires and connectors.

For MacPherson strut suspensions without factory-installed camber adjustment, an aftermarket camber bolt kit is used to provide adjustability, typically by replacing a strut-to-knuckle bolt with an eccentric.

• Many MacPherson struts have fixed camber.
• Out-of-spec camber requires component replacement or aftermarket solution.
• Camber bolt kits provide limited adjustment range.

Memory trick: MacPherson's strut, if no adjust, a camber bolt is a must trust.

After all alignment adjustments are made and verified to be within manufacturer specifications, the final crucial step is to perform a road test to confirm proper vehicle handling and steering wheel centering under real-world conditions.

• Verify all angles are in spec.
• Ensure steering wheel is centered.
• Road test confirms dynamic performance.
• Check for pulls, drifts, and feedback.

Memory trick: Specs are green, now hit the scene!

Caster split refers to an imbalance in caster angle between the front wheels. A vehicle will typically pull towards the side with the numerically lower (less positive) caster.

• Less positive caster on a side causes a pull to that side.
• Caster aids steering stability and returnability.
• Equal caster is crucial for straight-line tracking.

Memory trick: Caster's difference, pull's direction, less positive guides to its section.

Toe is the inward or outward pointing of the wheels when viewed from above. Incorrect toe settings are a primary cause of rapid and uneven tire wear.

• Toe-in: front of wheels closer together than rear.
• Toe-out: front of wheels farther apart than rear.
• Excessive toe-in causes outer edge wear.
• Excessive toe-out causes inner edge wear.

Memory trick: Toe-in pinches the outside, toe-out stretches the inside.

If an alignment angle that is specified as non-adjustable is found to be outside manufacturer specifications, it indicates a physical defect in a suspension component, requiring inspection, repair, or replacement.

• Non-adjustable means no built-in adjustment.
• Out-of-spec implies physical damage or wear.
• Requires inspection of related components.
• Common culprits: bent control arm, worn bushing, damaged subframe.

Memory trick: No knob to turn? Then it's a broken internal concern!

Intermittent loss of electric power assist that resolves with an ignition cycle or short drive, despite sound wiring, often points to a failing EPS control module.

• Power assist is intermittent.
• Resolves with ignition cycle/driving.
• Wiring appears visually good.
• Indicates internal module fault.

Memory trick: EPS flickers, then it's fine? Module's brain might be offline!

Warped or uneven brake rotors are a common cause of steering wheel vibration and pulsation, especially when the brakes are applied.

• Causes steering wheel vibration.
• Most noticeable during braking.
• Related to rotor runout or thickness variation.

Memory trick: Braking shakes? Rotors are usually the culprits, for goodness sakes!

On independent rear suspensions, thrust angle is corrected by adjusting the individual toe settings of the rear wheels to align the rear thrust line with the vehicle's geometric centerline.

• Positive thrust angle means rear points right.
• Negative thrust angle means rear points left.
• Adjust individual rear toe to correct.

Memory trick: Positive thrust means right rear needs a push back.

Steering Axis Inclination (SAI) is the inward tilt of the steering axis when viewed from the front. Out-of-specification SAI, especially when camber is acceptable, often points to a bent control arm or spindle.

• SAI is a non-adjustable angle on most vehicles.
• Out-of-spec SAI indicates bent/damaged components.
• Commonly affected by bent control arms or strut towers.
• Aids in diagnosing collision damage.

Memory trick: SAI is the lean of the pivot; if it's off, a bone (arm) is likely bent.

If alignment angles are within specification but a vehicle still pulls, common causes include uneven tire pressure, worn suspension components, brake drag, or radial tire pull.

• Always check tire pressure first.
• Inspect for worn parts.
• Consider brake issues.

Memory trick: If alignment is fine, check the tires or the parts that bind.

The process of ensuring the steering wheel is perfectly straight before performing front toe adjustments to prevent an off-center steering wheel after alignment.

• Crucial step before toe adjustment.
• Prevents cosmetic and functional issues.
• Often done with a steering wheel holder.

Memory trick: A crooked wheel needs a straight start.

Camber is the inward or outward tilt of the wheel when viewed from the front of the vehicle. A vehicle tends to pull towards the side with more negative camber or less positive camber.

• Positive camber: top of the wheel tilts outward.
• Negative camber: top of the wheel tilts inward.
• Unequal camber side-to-side causes a steering pull.
• Pull is towards the side with more negative camber.

Memory trick: Negative camber pulls you down and in, just like a sad mood.

Deteriorated steering gear mounting bushings allow the steering gear to shift, introducing play into the steering system. This causes a vague steering feel and vehicle 'wander,' requiring constant corrections to drive straight.

• Gear movement absorbs steering input.
• Results in imprecise steering.
• Causes vague feel and highway wander.

Memory trick: Loose mounts make the steering wander like a lost ship.

Out-of-specification toe or thrust angle on a solid rear axle usually indicates a bent axle housing or worn/damaged axle locating components, as these angles are typically non-adjustable.

• Toe and thrust are fixed on solid axles.
• Discrepancies mean damage or wear.
• Requires component repair/replacement, not adjustment.

Memory trick: Solid axles don't adjust; they bend or break.

Caster split refers to a difference in caster angle between the left and right front wheels. A vehicle will typically pull towards the side with less positive caster.

• More positive caster on one side will cause the vehicle to pull to the opposite side.
• Caster helps with steering returnability and straight-line stability.
• Unequal caster (split) can lead to steering pull.

Memory trick: Caster's lean, where it's more, the car pulls to the other shore.

Steering Axis Inclination (SAI) is a non-adjustable angle formed by the steering axis and true vertical. Discrepancies between sides or being out of specification usually indicate bent or damaged suspension components.

• SAI is a diagnostic angle, not adjustable.
• Side-to-side differences point to bent components.
• Bent strut, steering knuckle, or control arm are common culprits.

Memory trick: SAI's off-kilter, danger's near; bent metal's the culprit, make it clear.

Total toe is adjusted by shortening or lengthening both tie rods equally to move the front wheels in or out simultaneously, maintaining steering wheel center.

• Shortening tie rods reduces toe-in (increases toe-out).
• Lengthening tie rods increases toe-in (reduces toe-out).
• Equal adjustment keeps steering wheel centered.

Memory trick: Too much 'in' means shorten both out.

When hydraulic power steering is stiff only when cold and improves as the engine warms, the most likely cause is incorrect power steering fluid type or viscosity, which affects fluid flow at low temperatures.

• Fluid viscosity changes with temperature.
• Wrong fluid can be too thick when cold.
• Check fluid specification against manufacturer recommendations.

Memory trick: Cold makes the fluid thick, like molasses.

A valve within the power steering pump that regulates fluid flow and pressure based on engine speed and steering input, ensuring appropriate power assist.

• Regulates fluid output to the steering gear.
• Responds to engine RPM and steering demand.
• Malfunctions can cause variable steering effort.

Memory trick: Low speed, high effort? Check the flow's hidden valve!

A partially collapsed power steering pressure hose restricts high-pressure fluid flow, causing heavy steering, especially when cold, which may slightly improve as fluid warms.

• Heavy steering, worse when cold.
• Slight improvement as engine warms.
• Restricts high-pressure fluid delivery.
• Fluid level and appearance normal.

Memory trick: Cold, heavy steer, then a bit better? Pressure hose might be a letter-getter!

A condition where steering assist is lost or reduced in only one turning direction, often caused by internal faults within the steering gear/rack, such as a sticking control valve or a leaking piston seal.

• Pump pressure is typically normal when tested.
• Indicates a problem within the steering gear's directional hydraulic circuit.
• Requires steering gear repair or replacement.

Memory trick: One-sided hard steer? Gear's internal error!

A squealing or chirping noise from the power steering system, especially during quick steering inputs or cold starts, often indicates a loose, worn, or glazed power steering pump drive belt that is slipping under load.

• Caused by belt slipping on pulley.
• Worse under high load (quick turns, cold fluid).
• Check belt tension, condition, and pulley alignment.

Memory trick: Belt Squeals Quickly, especially when cold.

Camber is the inward or outward tilt of the wheel when viewed from the front of the vehicle. It is adjusted to ensure proper tire contact and handling.

• Positive camber: top of wheel tilts outward.
• Negative camber: top of wheel tilts inward.
• Adjustment methods vary by suspension design (e.g., eccentric cams, shims, slotted mounts).

Memory trick: Camber's tilt, adjust it right, for tire's perfect bite.

An electronic power steering (EPS) control module fault indicates an internal malfunction within the module, often requiring replacement of the module or the component it's integrated with.

• Typically results in a warning light and loss of assist.
• Specific DTCs (e.g., C0550) point to internal module issues.
• Module replacement is the common repair, sometimes as part of a larger assembly.

Memory trick: Module faults mean module replacement.

On MacPherson strut suspensions, camber is often adjusted by loosening the lower strut-to-knuckle bolts and pivoting the strut assembly.

• Common factory adjustment method.
• Uses slotted holes or eccentric bolts.
• Allows for precise camber angle changes.

Memory trick: Slotted holes mean a pivot, not a bolt swap.

Insufficient positive caster reduces directional stability, steering wheel returnability, and can cause a 'wandering' sensation at highway speeds.

• Reduces self-centering action.
• Increases steering effort at low speeds.
• Common cause of 'wandering' or 'nervous' steering.

Memory trick: Low caster makes cars wander like lost sheep.

To center an off-center steering wheel when vehicle toe is already correct, both tie rod ends must be adjusted an equal amount in opposite directions to rotate the steering rack/gear without altering the overall toe.

• Applies when vehicle tracks straight with no tire wear.
• Requires careful, simultaneous adjustment of both tie rods.
• Ensures steering wheel is straight when wheels are straight.

Memory trick: Equal opposite tie rod twists, straight wheel.

Included angle is the sum of SAI and camber. A difference in included angle between sides, especially when camber is set correctly, indicates a bent steering knuckle or strut affecting SAI.

• Included Angle = SAI + Camber.
• SAI is fixed by design, camber is adjustable.
• Split IA often means bent knuckle/strut affecting SAI.
• Useful for diagnosing damage post-impact.

Memory trick: Included Angle's sum, if split, means the knuckle took a hit.

When an Electric Power Steering system has a 'notchy' or 'binding' feel in the steering wheel, particularly at low speeds and without DTCs, it often indicates mechanical friction or wear within the steering column bearings or universal joints, not an electrical EPS fault.

• Sensation felt directly through the wheel.
• No DTCs suggests mechanical resistance.
• Inspect steering column U-joints and bearings.

Memory trick: Notchy steering with no codes? Check the column's joints and bearings.

Caster angle influences steering stability, effort, and returnability. Positive caster provides directional stability and self-centering.

• Positive caster improves straight-line stability.
• Insufficient positive caster can cause wandering and poor returnability.
• Excessive positive caster can lead to heavy steering.

Memory trick: Caster's angle, steering's feel; too little, it wanders; just right, it's real.

Symptoms of a worn ball joint include creaking or popping noises during turns or over bumps, and excessive play when inspecting the wheel.

• Torn boot allows contamination and lubricant loss.
• Causes friction and excessive movement.
• Can lead to steering instability and uneven tire wear.

Memory trick: Noisy joints make the ride rough, check for play and torn cuffs.

The upper strut mount bearing allows the MacPherson strut to rotate with the steering knuckle. Failure results in binding, popping, or groaning noises during steering.

• Enables strut rotation for steering
• Wear causes popping/groaning noise
• Affects steering feel and noise

Memory trick: Turning and popping, a strut mount's plea, the bearing's seized, it's plain to see!

A short to ground in the electrical circuit of an active damper's control valve prevents the valve from receiving proper commands, leading to loss of damping control, a default stiff setting, and a diagnostic trouble code.

• Causes loss of damping adjustment.
• Often results in a default stiff ride (fail-safe).
• Triggers a specific electrical DTC.
• Requires electrical circuit diagnosis and repair.

Memory trick: A 'short' in the 'circuit' means the 'control' is gone.