ASE T5 Suspension & Steering (Medium/Heavy Truck) 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 the front wheels straight ahead and the engine running; compare the reading to the OEM specification, which is usually given in degrees or inches of rim travel.

Power steering relief pressure

Pump output pressure measured at full lock with a gauge and compared to OEM specification; low relief pressure causes hard steering and slow assist, especially with hot oil.

Bleeding a power steering system

With the front wheels off the ground, run the engine and turn the steering lock to lock several times while keeping the reservoir full, until foam and whine disappear.

Worm bearing preload adjustment

Set before sector shaft mesh on an integral steering gear; too little preload causes wander, while too much causes bearing wear and a stiff spot at steering center.

Dry kingpin symptom

Lack of lubrication at the kingpin bushings produces hard steering, poor return to center and front-end shimmy; grease until fresh lubricant appears at the seals.

Steering damper purpose

A hydraulic shock on the steering linkage that controls kickback and shimmy from road inputs and wheel imbalance; a leaking or seized damper is replaced, not adjusted.

Drag link inspection

Check ball sockets and tapered stud seats for looseness and torn boots; replace worn ends rather than adjusting, because a loose drag link causes wander and irregular tire wear.

Leaf spring center bolt

Clamps the leaf pack together and locates the axle; a sheared center bolt lets the axle shift, causing dog tracking and rapid wear of spring seats and U-bolts.

Air ride height valve

Senses axle-to-frame distance through a link and adds or exhausts air to hold design ride height; a misadjusted link changes driveline angles and alignment angles.

Hendrickson equalizer bushing

Worn bushings in the walking beam allow axle misalignment, causing dog tracking, irregular tire wear and excessive tire scrub as the beam moves during turns.

Torque rod bushing wear

Worn track bar or torque rod bushings let the axle move sideways under load, producing wander, constant steering correction and uneven front tire wear.

Shock absorber heat test

After a road test all shocks should feel similarly warm; a cold shock on one side shows it is not valving and can cause tire cupping.

U-bolt retorque rule

New or replaced spring U-bolts must be re-torqued to OEM specification after the first 100 to 500 miles, because seating of the components relaxes clamp load.

Caster pull direction

A vehicle pulls toward the side with the least positive caster; a side-to-side caster difference is the usual cause of a steady directional pull on a level road.

Camber wear pattern

Excessive positive camber wears the outer shoulder of the tire, excessive negative camber wears the inner shoulder, and the vehicle pulls toward the more positive side.

Thrust angle definition

The angle between the vehicle geometric centerline and the perpendicular to the rear axle; a nonzero thrust angle makes the truck dog track and the steering wheel off center.

SAI diagnostic use

Steering axis inclination is a fixed knuckle angle; if camber reads correct but SAI is out of specification, a bent steering knuckle or spindle is indicated.

Set toe adjustment last

Toe is adjusted after ride height, caster and camber are correct and the steering gear is centered, using the tie rod to split total toe equally.

Dual tire diameter match

Mismatched duals make the larger tire carry more load while the smaller one drags; keep diameters within about 1/4 inch (6 mm) on the same axle.

Center tread wear cause

Worn tread in the center of the tire with good shoulders indicates overinflation; the casing bulges and contact pressure concentrates in the middle of the tread.

Feathered tire wear

A feathered or saw-toothed pattern across the rib edges indicates incorrect toe; the ribs scrub sideways and wear one edge of each rib sharply.

Hub-piloted wheel nuts

Hub-piloted wheels use two-piece flange nuts that center the wheel on the hub, while stud-piloted wheels use ball-seat nuts; the two systems cannot be mixed.

Loose wheel nut evidence

Rust streaks, shiny threads, cracked paint around the nut or a polished stud indicate a loose or fretting wheel nut; retorque and inspect the wheel.

Cupped tread wear

Scalloped or cupped tread indicates wheel imbalance, worn shock absorbers or loose wheel bearings; the tire skips along the road instead of rolling smoothly.

Fifth wheel jaw adjustment

The locking jaws must close fully on the kingpin; adjust with the OEM gauge until no fore-aft slack remains, or the trailer will chuck and wear the kingpin.

Kingpin wear measurement

Measure the kingpin diameter with a gauge at the worn area and replace the pin when it is below the OEM wear limit, usually a few thousandths under two inches.

Frame crack stop drilling

Cracks in a frame rail must be stop-drilled at each end before repair; welding across a flange without approved reinforcement usually allows the crack to restart.

Fifth wheel lubrication

The top plate and jaw area require regular OEM-approved grease; a dry fifth wheel transfers steering resistance to the trailer and accelerates kingpin and plate wear.

Cab air bag leak symptom

A leaking cab air bag or fitting makes the cab lean, the leveling valve hunt, and the compressor cycle frequently; locate the leak with soap solution.

Cab mount isolator wear

Worn rubber cab mounts let the cab move on the frame, producing clunks, vibration and cracked mount brackets; replace crushed or separated isolators.

Cab leveling valve link

The link sets cab ride height; bending or misadjusting it changes the valve neutral position and makes the suspension overinflate or exhaust continuously.

Cab latch safety check

Before tilting or working under a raised cab, confirm the latch engages fully and the safety prop is in place, because hydraulic lines can fail without warning.