ASE H5 Suspension & Steering (Transit Bus) flashcards

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

Steering wheel free play

Measured at the rim with wheels straight ahead and engine running on power steering; excessive play indicates worn gear, linkage, or column components.

Hard steering at idle

Usually caused by low power steering pump flow at low engine speed, a restricted hose, or a slipping belt rather than the steering gear itself.

Shimmy diagnosis

Vibration that occurs at a specific road speed points to wheel or tire imbalance or runout; vibration at all speeds suggests worn linkage or gear.

Steering pull causes

Pull on a level road can come from misalignment, tire conicity, a dragging brake, or a binding steering component; road crown pull is normal.

Power steering relief pressure

Pump relief pressure is typically 1,000 to 1,500 psi; a pressure and flow test confirms whether the pump or the gear is at fault.

Steering gear high point

The recirculating-ball gear is tightest at center; the gear must be centered before setting toe to avoid unequal turning radius and gear wear.

Tilt column free play

Vertical movement of the steering wheel often comes from a worn tilt pivot or loose locking pawl rather than the steering gear.

Collapsible steering shaft

A shaft section designed to collapse in a collision to absorb impact energy; once collapsed it must be replaced, never straightened.

Tie rod end inspection

Check for axial and radial play at the ball stud with the suspension loaded; any detectable play requires replacement of the tie rod end.

Adjusting sleeve threads

Tie rod and drag link sleeves use opposite-hand threads; counting turns during adjustment preserves the existing toe setting.

Idler arm wear

Worn idler arm bushings allow the linkage to move vertically, causing wander and uneven front tire wear; check play at the joint.

Power steering hose restriction

A collapsed or restricted hose causes whine and hard steering; a pressure and return flow test isolates the hose from the pump.

Loaded ball joint play

Axial play limit for a loaded ball joint is typically 0.5 mm (0.020 in); measure with the suspension at ride height under load.

Torsion bar ride height

Ride height is set with the anchor arm adjusting bolt; changing it alters camber and toe on short-long arm front suspensions.

Coil spring sag check

Compare curb height at the specified measuring points to specification; visual inspection alone cannot confirm a sagged spring.

Control arm bushing wear

Cracked or separated bushings allow camber change and cause wander and clunking; inspect with the suspension at ride height.

Front air bag leak test

Apply soap solution to the top seal and airline fitting; air suspension leaks often occur where a static height check cannot detect them.

Shock absorber replacement

A leaking or worn shock is replaced in axle pairs; a single replacement can cause uneven damping and handling imbalance.

Included angle meaning

Included angle is camber plus steering axis inclination; it is not adjustable, so an out-of-spec value indicates a bent spindle or knuckle.

Track bar function

On coil-spring rear suspensions the track bar or Panhard rod controls lateral axle location; worn bushings cause body shift and dog-tracking.

Leaf spring inspection

Check for broken leaves, a sheared center bolt, and worn shackle bushings; broken leaves change ride height and pinion angle.

Rear height sensor fault

A faulty rear height sensor causes the air suspension to over-inflate or fail to inflate; scan tool data confirms before replacement.

Rear wheel bearing play

Rock the wheel at 12 and 6 o'clock with the brake applied to isolate bearing play from brake component movement.

Pinion angle vibration

Incorrect pinion angle from ride height change causes driveline vibration often misdiagnosed as a tire or wheel imbalance problem.

Dog-tracking cause

A rear axle that is not centered or a bent frame causes the vehicle to track offset from the front wheels; measure frame to axle.

Camber definition

The inward or outward tilt of the wheel viewed from the front; positive tilts the top outward, negative tilts the top inward.

Caster definition

The forward or rearward tilt of the steering axis; positive caster improves straight-line stability and increases steering effort.

Toe definition

The difference in distance between the front and rear of the tires at hub height; toe-in means the fronts are closer together.

Thrust angle

The angle between the vehicle centerline and the rear axle; a non-zero thrust angle causes an off-center steering wheel.

Alignment adjustment order

Set camber and caster first, then center the steering wheel and set toe last, because toe changes affect steering wheel position.

Tire placard pressure

The cold inflation pressure specified for the vehicle; the maximum pressure molded on the sidewall is not the operating pressure.

Tire conicity

A manufacturing characteristic that produces a steady pull which changes direction when the tire is rotated side to side.