Wheel Bearing Inspection and Repacking

WHEEL BEARING INSPECTION
Inspect the wheel bearing closely for the following:

Fatigue Spalding
Look for small flakes of shiny metal (babbit) embedded in the grease. This can easily be done by dragging the bearing across a clean shop towel. Any metal flakes will be readily visible in the grease deposited on the shop towel. If any flakes are found the wheel bearing should be replaced.




Brinelling
Look for a series of vertical indentations on the races. This is caused by impact loading or vibration while the bearing is not rotating. Replace the bearing if the indentations are severe or the bearing is noisy.

Heat Discoloration
Heat discoloration can range from faint yellow to dark blue. This results from the bearing being adjusted too tightly or an insufficient amount of lubricant/grease.

Excessive heat can cause the races and rollers to soften. To check for a loss of temper on the races or rollers a simple file test may be performed. A file drawn lightly over a race or roller which has lost its case hardening will grab and cut metal, whereas a file drawn lightly over a hardened part will glide readily without scratching the metal.

Replace the bearing and race if softening is indicated.

Cracked Outer Race
Cracked races often result from the race being driven in cocked or at an angle. Replace the bearing and race and be careful to drive the new race in evenly.

Loose Outer Race
Check to see that the race is tight and secure in the hub. If there is any evidence of movement or slippage, replace both the hub assembly and the bearing.




Bent or Damaged Cage
Verify that the cage has not been bent or distorted. Bent or damaged cages are often the result of improper bearing and grease seal removal techniques.

When removing the inner wheel bearing use a seal puller to remove the grease seal. The inner bearing should then just slide out of the hub.

Do not re-install the spindle nut and attempt to slide-hammer the grease seal from the hub.

WHEEL BEARING REPACKING
- The hub and spindle should be thoroughly cleaned of all old grease.
- The bearings should be cleaned in solvent and allowed to dry completely.

WARNING: Do not spin dry the bearings with compressed air, this practice can rapidly damage bearings.

- If possible use a commercial wheel bearing packer, otherwise repack the bearings by hand.

Hand Repacking
- Place a quantity of high-temperature, multi purpose wheel bearing grease in the palm of your hand.
- Cup the bottom of the bearing cage (the wider end) into the palm of your hand forcing grease up through the cage. Repeat the procedure until the new grease is pushed out of the top of the cage.
- Repeat this around the entire circumference of the bearing.





- Apply a coating of new wheel bearing grease to the spindle and the inside of the hub.

NOTE: The hub should not be completely packed with new grease. As the brakes are applied the hub will heat up and the grease will expand. If an excessive amount of grease is prepacked into the hub, upon heating it will force its way past the grease seals and contaminate the brake system.

- Also apply a thin coating of grease to the inside lip of the new grease seals.

NOTE: The side of the grease seal from which the spring is visible should point towards the bearing.