Wheel Bearing Wear - Rear Axle

Tapered Roller Bearing Diagnosis
Consider the following factors when diagnosing a bearing condition:
^ The general condition of all the parts during disassembly and inspection.
^ Classify the failure with the aid of the illustrations.
^ Determine the cause.
^ Make all repairs following the recommended procedures.


Abrasive Roller Wear





The pattern on the races and the rollers is caused by fine abrasives.
1. Clean all of the parts and the housings.
2. Inspect the seals and the bearings.
3. Replace any leaky, rough, or noisy bearings.



Abrasive Step Wear





The pattern on the roller ends is caused by fine abrasives.
1. Clean all of the parts and the housings.
2. Inspect the seals and the bearings.
3. Replace any leaky, rough, or noisy bearings.


Galling





The metal smears on the roller ends are due to overheating, lubricant failure, or lubricant overload.
1. Replace the bearing.
2. Inspect the seals.
3. Inspect for proper lubrication.

Etching





The bearing surfaces appear gray or grayish black in color, with related etching away of material usually at roller spacing.
1. Replace the bearings.
2. Inspect the seals.
3. Inspect for proper lubrication.

Bent Cage





When a cage is damaged due to improper handling or improper too[ usage, replace the bearing.

Cage Wear





The wear around the outside diameter of the cage and the roller pockets is caused by abrasive material or inefficient lubrication.
1. Clean the related parts and the housings.
2. Inspect the seals.
3. Replace the bearings.


Indentations





The surface depressions on the race and the rollers are caused by hard particles of foreign matter.
1. Clean all the parts and the housings.
2. Inspect the seals.
3. Replace rough or noisy bearings.

Frettage





The corrosion is caused by small relative movement of parts with no lubrication.
1. Replace the bearing.
2. Clean the related parts.
3. Inspect the seals.
4. Inspect for proper lubrication.

Smears





The smearing of the metal is due to slippage. Slippage can be caused by the following factors:
^ Poor fits
^ Lubrication
^ Overheating
^ Overloads
^ Handling damage
If this condition occurs, perform the following:
1. Replace the bearings.
2. Clean the related parts.
3. Check for proper fit and lubrication.


Stain Discoloration





The discoloration on the bearings is caused by incorrect lubrication or moisture. The discoloration ranges in color from light brown to black. Reuse the bearing if you can remove the stains with a light polishing and there is no evidence of overheating. Inspect the seals and the related parts for damage.

Heat Discoloration





The discoloration on the bearings ranges from faint yellow to dark blue. The discoloration results from an overload or an incorrect lubricant. Excessive heat causes softening of the races or the rollers. In order to inspect for the loss of temper on the races and the rollers, perform a file test. A file drawn over a tempered part will grab and cut the metal and fail the file test. A file drawn over a hard part will glide readily with no metal cutting.
If overheating damage is indicated, perform the following procedure:
1. Replace the bearings.
2. Inspect the seals and the other related parts.

Misalignment





The outer race is misaligned due to a foreign object.
1. Clean the related parts.
2. Replace the bearing.
3. Ensure the races are properly sealed.

Cracked Inner Race





The race is cracked due to improper fit, cocking, or poor bearing seats.
1. Replace the bearing.
2. Correct the bearing seats.


Fatigue Spalling





The surface is flaked with metal due to bearing fatigue.
1. Replace the bearing.
2. Clean all related parts.

Brinelling





The surface indentations in the race way are caused by the rollers under impact loading or from vibration while the bearing is not rotating. Replace a rough or noisy bearing.