Wheels, Tires, Hub Diagnosis and Repair Flashcards
What should the technician do to determine if repairs are needed due to premature the wear/damage?
The technician must first decide if the wear/damage was a result of external factors or vehicle component issues.
_irregular tread wear is generally a result of under/over tire inflation, component wear or alignment, and/or tire imbalance.
_To pinpoint the cause(s) of uneven, premature, feathering/cupping wear patterns, or internal/external damage, a visual inspection of the vehicle suspension/steering components should be performed.
_Next, determine if air pressure corresponds to proper tire/wheel, suspension type, and load rating.
_Then determine load type (weight and center of gravity) and load placement on the vehicle.
_this may lead to bent/broken frame and cross members, resulting in unstable/incorrect alignment.
_Inside or outside edge tire wear may be contributed to improper camber angle adjustment.
_Featheredge wear may be contributed to improper toe settings.
_Cupping around the inside edge of the tire may indicate worn shocks or worn shackle bushings.
_Underinflated tires will wear both edges and not the center of the tire.
Overinflation wears the center of the tire tread and not the edges.
What must the technician do to assist in the tire analysis?
A technician may refer to the TMC Radial Tire Conditions Analysis Guide for a more detailed description of tire wear patterns and component diagnosis.
_Determine if trailer load is a factor in alignment conditions.
_Return all components to manufacturer’s specifications.
Perform alignment measurements and set adjustments to manufacturer’s specifications,
What should you do while performing a visual inspection of all vehicle tires?
Check for correct air pressure and tire/wheel suspension ratings.
_Inspect tires/wheels for damage (i.e. bent wheels, impact bruises, out-of alignment wear patterns).
_Road test to confirm customer complaint.
_Determine if vehicle load (weight), load placement, or road condition/lane type was a factor in the complaint.
Note: All of these conditions (i.e., shimmy, hop) could be caused by alignment change due to improper loading of the vehicle.
What causes vibration of vehicle tires?
Vibration is usually caused by out-of-balance or a broken tire belt.
What causes shimmy of vehicle tires?
Shimmy is usually caused by a broken tire belt or worn steering component.
What causes Hop, tramp, or pounding of vehicle tires?
Hop, tramp, or pounding is usually related to improper wheel balance or worn components (i.e., shock absorbers, springs/bushings, torque rods, or broken or loose frame components).
Note: All of these components and conditions can combine to create interrelated symptoms.
What should you do to determine damage or serviceability due to wear, climatic or environmental elements, or road/driver damage of wheels/rims?
Perform a visual inspection of the wheel/rim and mounting hardware including clamps, studs, and wheel nuts.
_Check for proper fastener grade markings.
_Observe for signs of overload (i.e., stretched wheel studs [perform length measurement], shifted spacers, loose nuts, or shifted rime clamps).
_If equipped, check if locking rings are evenly seated and secure.
_Locate and verify vehicle load rating and compare to actual load.
_Determine and follow manufacturer’s installation of proper components as per manufacturer’s specifications.
What would you use a dial indicator with rotating wheel end to do?
Perform run out measurements (radial and lateral) of mounted (in position) on the vehicle tire/wheel.
_Confirm actual measurements in comparison to manufacturer’s specifications.
_If measurements of tire runout exceed specifications, visually inspect tire/rim contact area to ascertain proper bead/rim seating.
_Tires/wheels not conforming to specifications should be replaced.
When inspecting tires what should you check for?
_Environmental damage, that is, weather checking.
_Per specifications, correct air pressure for load, suspension, tire, and rim size.
_Indicators of irregular alignment factors such as inside or outside tire tread wear or feather edging.
_Indicators of worn steering or suspension components such as tread cupping around the inner circumference of the tire or irregular wear patterns.
_Tread separation.
Impact damage to tread, belts, sidewall, or exposed belts and cords.
_Zipper, rupture, which is a fatigue failure that occurs in the upper sidewall area, beginning with the fracture of one or more ply cords, then progressing circumferentially. This is generally seen as ripples in the sidewall of the tire.
_Mismatched tire, that is size, construction, and correct as necessary.
_Equal tire bead seating around the circumference of the rim.
What is wheel balance?
The equal distribution of weight in the wheel assembly with the tire mounted.
_This is an important factor that affects tire wear and vehicle control.
If the tire wheel unit is within balance statically, what should happen?
With the tire/wheel unit mounted on the vehicle (brakes not applied) or balance machine, the wheel should not move from a rest position anywhere it is rotated.
What does the static balance test indicate?
A heavy area in the tire or wheel.
What are wheel hop and a vibration felt in the vehicle a symptom of?
Of static imbalance.
What should you look for when performing a visual inspection of wheel and tire assembly?
_Determine that deposits of rust, rucks, ice, snow, and so on, have not become attached in any manner to the tire/wheel unit, thus causing an out-of-balance condition.
-Remove as necessary.
_Also check for proper bead seating as a mismounted tire may contribute to a static impalance issue.
How can static imbalance be corrected?
By adding an offsetting amount of weight directly across (180 degrees) from the heavy area.
_The most common method of curing an imbalance condition is the addition of lead weights attached to the rim.
What is dynamic imbalance?
Exhibits itself as the wheel is in motion (rotating).
_Usually this is a result of the tire/wheel having the weight distributed unevenly from side to side.
What may be the cause of front-end shimmy and cupping of the tire in random patterns?
May be caused by wheel assemblies that are either out of balance or out of round.
Before performing a dynamic balance test, what should be inspected?
_Visually inspect the tire for signs of damage (i.e., broken belt or tire not seated properly onto rim.
_Measure and connect air pressure.
_Check for proper wheel bearing endplay and correct if necessary.
_Inspect all steering and suspension components to determine if they conform to manufacturer’s specifications.
What are the benefits of off-track wheel balancing and on-truck wheel balancing?
A complementary combination for fine-tuning wheel balance.
What should you do if a wheel vibration problem still exist after an off-truck balance procedure?
The on-truck balancer may be used to correct the problem.
What purpose is a drum driven by an electric motor on on-truck wheel balancers
The drum is positioned against the tire on the vehicle, which allows the electric motor to rotate the wheel.
_Many on-truck balancers have a strobe light with a meter and electronic vibrations sensor.
What problems do the on-truck balance procedure correct?
Corrects imbalance problems in all rotating components, including brake drums or rotors.
What precautions should you take concerning spinning the wheel.
_Do not spin the wheel at excessive speeds.
_Spin the wheel only until the vibration occurs.
_Spinning the wheel at excessive speed may cause equipment or component damage or personal injury.
How should you measure tire diameter and matching tires?
The most accurate method is to use an endless tape to measure the circumference of the tire/wheel assembly.
_This should be done with the tire already inflated to the proper inflation pressure and before the tire is mounted on the vehicle.
