ASE H5 Suspension & Steering (Transit Bus)

A transit bus has excessive steering wheel free play and wandering on the highway. Which component should be inspected FIRST?

• ASteering gear sector shaft adjustment and linkage joints for wear
• BThe kneeling system air bag
• CThe radius rod bushings on the rear axle
• DThe windshield wiper linkage

Tech A says an integral hydraulic power steering gear uses a torsion bar to sense steering effort. Tech B says the rotary valve directs pump pressure to either side of the gear piston. Who is correct?

• ATech B only
• BBoth Tech A and Tech B
• CNeither Tech A nor Tech B
• DTech A only

A transit bus power steering pump is noisy and produces foamy fluid. The MOST likely cause is:

• AExcessive caster on the steered axle
• BA seized tie-rod end
• CAir being drawn into the system through a low reservoir or loose suction hose
• DA worn pitman arm

During a steering linkage inspection on a transit bus, a technician finds a drag link end with detectable axial play. The correct action is to:

• ATighten the steering gear sector lash
• BIncrease power steering pump pressure
• CAdd grease until the play disappears
• DReplace the drag link or worn end

A transit bus has hard steering only during low-speed parking maneuvers but steers normally at road speed. The MOST likely cause is:

• ALow power steering pump output at low engine rpm or a failing pump
• BExcessive toe-out on turns
• CA leaking kneeling valve
• DA worn rear shock absorber

Which inspection BEST evaluates kingpin wear on a transit bus front axle?

• AMeasuring tire tread depth
• BRaising the wheel and checking vertical and lateral movement at the knuckle with a dial i…
• CChecking power steering fluid color
• DMeasuring steering wheel diameter

A transit bus pulls steadily to the right with no braking applied and tires are properly inflated. Which is the MOST likely steering/alignment cause?

• ACorrect thrust angle
• BEqual caster on both sides
• CUnequal caster or camber between the left and right steered wheels
• DA worn rear sway bar link

On a transit bus air suspension, the height control valve's primary function is to:

• AControl the power steering assist level
• BEngage the kneeling feature automatically while driving
• CRegulate brake application pressure
• DMaintain a constant chassis ride height by adding or exhausting air from the air springs

A transit bus sits low at one rear corner overnight but rises to correct height shortly after the engine starts. The MOST likely cause is:

• AAn air leak at the air spring or fitting that bleeds down when the system is not pressuri…
• BExcessive positive caster
• CA worn tie-rod end
• DA normal condition requiring no repair

Tech A says a hub-piloted wheel system centers the wheel on the hub pilot, not on the lug studs. Tech B says hub-piloted wheel fasteners must be tightened to the specified torque in the correct sequence. Who is correct?

• ATech B only
• BBoth Tech A and Tech B
• CNeither Tech A nor Tech B
• DTech A only

A transit bus exhibits feathered tire wear across the front tires. This wear pattern is MOST commonly caused by:

• AA leaking shock absorber
• BOver-inflation only
• CIncorrect toe setting
• DExcessive caster

When measuring caster on a transit bus steered axle, caster is defined as the:

• ADifference in toe between left and right turns
• BAngle between the wheel centerline and vehicle centerline
• CInward or outward tilt of the wheel viewed from the front
• DForward or rearward tilt of the steering axis viewed from the side

A transit bus rides harshly and the air pressure gauge reads normal. The technician finds the air springs are fully collapsed. The MOST likely cause is:

• AA height control valve stuck in the exhaust position
• BToo much power steering fluid
• CExcessive negative camber
• DA worn steering shaft U-joint

The kneeling system on a transit bus is designed to:

• ARaise the rear of the bus for better ground clearance off-road
• BLower the entrance side of the bus to ease passenger boarding at a stop
• CIncrease steering assist during turns
• DLock out the suspension at highway speed

A transit bus steering column has a tilt and telescoping feature that will not lock in position. Tech A says a worn or broken lock mechanism could be the cause. Tech B says low power steering fluid causes the column lock to release. Who is correct?

• ABoth Tech A and Tech B
• BNeither Tech A nor Tech B
• CTech A only
• DTech B only

During a wheel alignment on a transit bus, the thrust angle is found to be significantly off. Thrust angle is MOST directly affected by:

• APower steering pump pressure
• BTire brand selection
• CFront toe only
• DRear axle alignment relative to the vehicle centerline

A transit bus has a steering wheel that does not return to center smoothly after a turn. The MOST likely mechanical cause is:

• AInsufficient positive caster or a binding kingpin/steering joint
• BExcessive rear ride height
• CAn over-inflated rear tire
• DA loose seat track

A radius rod (torque rod) on a transit bus rear suspension has a worn bushing. The MOST likely symptom is:

• AA collapsed front air spring
• BAxle misalignment and a clunk or shifting under acceleration and braking
• CAerated power steering fluid
• DExcessive steering wheel free play only

A transit bus tire shows wear on both outer edges with the center relatively unworn. The MOST likely cause is:

• AExcessive positive caster
• BA bent pitman arm
• CChronic under-inflation
• DChronic over-inflation

When servicing an integral power steering gear on a transit bus, the over-center (sector lash) adjustment should be performed:

• AOnly while the engine is running at full throttle
• BAfter removing the torsion bar
• CWith the gear at the extreme end of its travel
• DWith the gear centered on its high point, off the vehicle or with linkage disconnected

A transit bus leans excessively in turns but ride height is correct on a level surface. The MOST likely cause is:

• AA worn or disconnected sway bar (anti-roll bar) or its links
• BAn overfilled power steering reservoir
• CExcessive front toe-in
• DA stuck-open kneeling valve

A transit bus front shock absorber is suspected of being worn. The BEST functional check is to:

• AMeasure tire pressure
• BPerform a bounce test and inspect for fluid leakage and mounting bushing condition
• CCheck power steering fluid level
• DMeasure steering wheel free play

On a transit bus, a tubeless radial truck tire is losing air slowly with no visible puncture. The technician should FIRST:

• AAdjust the height control valve
• BReplace the wheel hub
• CCheck the valve stem and the tire bead seat seal with a soap solution
• DReplace the steering gear

Tech A says camber is adjusted on most transit bus solid front axles by replacing or correcting the bent axle or knuckle, not by an eccentric. Tech B says caster on a solid-axle transit bus is typically adjusted with tapered shims or by rotating the axle. Who is correct?

• ANeither Tech A nor Tech B
• BTech A only
• CTech B only
• DBoth Tech A and Tech B

A transit bus has a vibration felt in the steering wheel that increases with road speed. The MOST likely cause is:

• AFront tire/wheel imbalance or radial runout
• BA stuck kneeling valve
• CLow engine coolant
• DAn incorrect thrust angle only at low speed

The drag link on a transit bus connects the:

• APower steering pump to the reservoir
• BPitman arm to the steering arm/knuckle
• CTwo front tie-rod ends together
• DRear axle to the frame

A transit bus air spring (bellows) shows a bulge on one side. The correct action is to:

• AIncrease ride height to relieve the bulge
• BReduce system air pressure permanently
• CReplace the air spring
• DAdd lubricant to the bellows surface

A transit bus power steering system has slow steering response and a momentary lag when the wheel is turned quickly. With the pump and belt good, the MOST likely cause is:

• AExcessive positive caster
• BA loose lug nut
• CWorn rear shock bushings
• DA worn rotary control valve or internal gear leakage

During a total-bus (four-wheel) alignment, why must rear axle thrust angle be checked before setting front toe?

• AFront toe should be set relative to the thrust line so the steering wheel is centered whe…
• BThrust angle changes power steering pressure
• CToe cannot be measured until tires are replaced
• DIt is not necessary; front toe is independent

A transit bus rear suspension uses leveling valves. If a leveling valve linkage is bent so the valve senses a higher-than-actual ride height, the result will be:

• AThe bus rides too low at that location
• BThe bus rides too high at that location
• CSteering effort increases
• DFront camber becomes negative

A transit bus exhibits bump steer (the front wheels steer slightly when hitting a bump) with no driver input. The MOST likely cause is:

• AA clogged cabin air filter
• BExcessive power steering fluid
• CIncorrect steering linkage geometry or worn linkage joints
• DOver-inflated rear tires

A transit bus uses a hub-piloted disc wheel. After a wheel-off service, the wheels should be re-torqued:

• AOnly at the next annual inspection
• BOnly if a noise is heard
• CNever; initial torque is sufficient
• DAfter a short break-in distance per the manufacturer's specification

A transit bus power steering pump uses an integral flow-control and pressure-relief valve. The pressure-relief portion functions to:

• ALimit maximum system pressure to protect components during steering against a stop
• BSet the engine idle speed
• CControl the kneeling air pressure
• DAdjust caster automatically

A transit bus dog-tracks (rear of the bus does not follow the front) on a straight road. The MOST likely cause is:

• AAn over-inflated spare tire
• BA misaligned rear axle creating an incorrect thrust angle
• CA worn power steering belt
• DLow brake fluid

Before adjusting front toe on a transit bus, the technician should FIRST:

• ABleed the power steering system
• BDisconnect the battery
• CVerify and correct worn steering/suspension components and proper ride height
• DReplace all four tires

A transit bus air suspension has one front air spring that fills slowly compared to the other side. The MOST likely cause is:

• AExcessive positive caster
• BA worn pitman arm
• CA leaking front shock absorber
• DA restricted air line or partially blocked port to that air spring

Tech A says worn kingpins can cause shimmy and wander on a transit bus. Tech B says worn kingpins have no effect on tire wear. Who is correct?

• ATech A only
• BTech B only
• CBoth Tech A and Tech B
• DNeither Tech A nor Tech B

A transit bus tire shows one-sided (inner edge) wear on a front tire. With toe correct, the MOST likely cause is:

• AA clogged power steering filter
• BExcessive negative camber on that wheel
• COver-inflation
• DA worn rear sway bar bushing

On a transit bus, the steering gear input shaft connects to the steering column through universal joint(s). A worn steering shaft U-joint will MOST likely cause:

• ARear axle dog-tracking
• BA collapsed kneeling bellows
• CSteering free play, notchiness, or a clunk felt in the steering wheel
• DIncreased air spring pressure

A transit bus exhibits a harsh ride and frequent bottoming over bumps even though ride height is correct and air springs hold pressure. The MOST likely cause is:

• AExcessive positive caster
• BA loose tie-rod clamp
• CAn over-tightened lug nut
• DWorn or ineffective shock absorbers

A transit bus power steering hose is weeping fluid at a crimped fitting. The correct repair is to:

• AReplace the hose assembly
• BAdd stop-leak additive to the reservoir
• CTighten the crimp with pliers
• DApply thread sealant over the crimp

During a transit bus alignment, included angle is calculated as the sum of:

• ACaster and camber
• BCamber and steering axis inclination (SAI)
• CCaster and toe
• DToe and thrust angle

A transit bus kneeling system will lower the bus but will not return to normal ride height. The MOST likely cause is:

• AA worn drag link end
• BAn over-inflated front tire
• CA failed kneeling/leveling valve or restricted air supply preventing refill
• DExcessive negative camber

A transit bus has a steering wheel that is off-center when driving straight, but the bus tracks straight and tires wear evenly. The MOST appropriate correction is to:

• AReplace both front tires
• BIncrease power steering pressure
• CReplace the steering column
• DRe-center the steering wheel by adjusting toe equally on both tie rods (split toe)

A transit bus air suspension dumps air at the height control valve continuously even at correct ride height. Tech A says a damaged or sticking height control valve could cause this. Tech B says a bent valve linkage could cause this. Who is correct?

• ABoth Tech A and Tech B
• BNeither Tech A nor Tech B
• CTech A only
• DTech B only

A transit bus front wheel bearing is being adjusted. After seating the bearing, the correct final adjustment generally results in:

• ASignificant preload with the nut fully torqued tight
• BA slight end play or a light preload per the manufacturer's procedure
• CZero clearance achieved by maximum tightening
• DNo adjustment; bearings are non-adjustable in all cases

A transit bus has excessive steering effort in both directions equally with the engine running. The MOST likely cause is:

• AA single worn tie-rod end
• BAn incorrect thrust angle
• CLow power steering pump pressure/flow or a slipping drive belt
• DUnequal caster side to side