Wheel-Bearing Service

Custom Search

Wheel Balancing

Construction Mechanic Basic Volume 2

Tire Inflation Problems

Wheel-Bearing Service
Wheel bearings are normally filled with grease. If this grease dries out, the bearing will fail. Some wheel bearings can be disassembled and packed (filled) with grease, while others are sealed units that require replacement when worn. When performing tire-related service, check the wheel bearings for play and wear.

NOTE
For procedures on checking, removing, and replacing wheel bearings, refer to the manufacturer's service manual.

TROUBLESHOOTING
Tire problems usually show up as vibrations, abnormal wear patterns, abnormal noises, steering wheel pull, and other similar symptoms. In some cases, you may need to operate the vehicle to verify the problem. Make sure that symptoms are NOT being caused by steering, suspension, or front-wheel alignment problems.

Figure 8-46.- On-the-vehicle balancer.

When inspecting tires, you should look closely at the outer sidewall, tread area, and inner sidewall for bulges, splits, cracks, chunking, cupping, and other abnormal wear or damage. If problems are found before repairing or replacing the tire, determine what caused the failure.

Tire Impact Damage
Tire impact damage or road damage includes tears, punctures, cuts, and other physical injuries. Depending upon the severity of the damage, the tire must either be repaired or replaced.

Tire Wear Patterns
Tire wear patterns can be studied to determine the cause of abnormal tread wear. By inspecting the tread wear, you can determine what parts should be serviced, repaired, or replaced. Common tread wear patterns are as follows (fig. 8-47):

FEATHERING (A) is caused by erratic scrubbing against the surface of the road when the tire is in need of toe-in or toe-out alignment correction.

OVERINFLATION (B) causes fast center line wear in bias and bias belted tires. In this case, the center of the tread has more contact with the road and wears faster than the outer area of the tread.

UNDERINFLATION (C) causes the outer tread areas (shoulders) of the tire to have more contact with the road; therefore, they wear faster than the center area of the tread.

ONE-SIDE WEAR (D) is caused by excessive camber, which means that the tire is leaning too much to the inside or outside. This places all the work on one side of the tire, resulting in excessive wear.

CUPPING (E) is caused by several problems, such as imbalanced wheels. faulty shock absorbers, faulty ball joints. or a combination of these troubles.