Wheel Bearing Wear - Front Drive Axle (Differential Case/Pinion Bearings)

Wheel Bearing Wear - Front Drive Axle (Differential Case/Pinion Bearings)

Tapered Roller Bearing Diagnosis

Consider the following factors when diagnosing a bearing condition:

* Note the general condition of all parts during disassembly and inspection.
* Classify the failure with the aid of the illustrations.
* Determine the cause.
* Make all repairs following recommended procedures.

Abrasive Roller Wear

Abrasive Roller Wear:

Pattern on the races and the rollers can be caused by fine abrasives. Clean all of the parts and the housings. Inspect the seals and the bearings. Replace any leaky, rough, or noisy bearings.

Abrasive Step Wear

Abrasive Step Wear:

Pattern on the roller ends can be caused by fine abrasives. Clean all of the parts and the housings. Inspect the seals and the bearings. Replace any leaky, rough, or noisy bearings.

Galling

Galling:

Metal smears on the roller ends can be due to overheating, lubricant failure, or lubricant overload. Replace the bearing. Inspect the seals. Inspect for proper lubrication.

Etching

Etching:

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

Bent Cage

Bent Cage:

A damaged cage can be due to improper handling or improper tool usage. Replace the bearing.

Cage Wear

Cage Wear:

Wear around the outside diameter of the cage and the roller pockets can be caused by abrasive material. Wear can be caused from inefficient lubrication. Clean the related parts and the housings. Inspect the seals. Replace the bearings.

Indentations

Indentations:

Surface depressions on the race and the rollers can be caused by hard particles of foreign matter. Clean all the parts and the housings. Inspect the seals. Replace rough or noisy bearings.

Frettage

Frettage:

Corrosion can be caused by small relative movement of parts with no lubrication. Replace the bearing. Clean the related parts. Inspect the seals. Inspect for proper lubrication.

Smears

Smears:

Smearing of the metal can be due to slippage. Slippage can be caused by the following factors:

* Poor fits
* Lubrication
* Overheating
* Overloads
* Handling damage

Replace the bearings. Clean the related parts. Inspect for proper fit and lubrication.

Stain Discoloration

Stain Discoloration:

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

Heat Discoloration

Heat Discoloration:

Heat discoloration ranges from faint yellow to dark blue. This discoloration results from overload or an incorrect lubricant. Excessive heat causes softening of the races or the rollers. In order to inspect for 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. A file drawn over a hard part will glide readily with no metal cutting. Replace the bearings if overheating damage is indicated. The tempered part will fail the file test. Inspect the seals and the other related parts.

Misalignment

Misalignment:

A misaligned outer race can be due to a foreign object. Clean the related parts. Replace the bearing. Ensure the races are properly sealed.

Cracked Inner Race

Cracked Inner Race:

Cracked race can be due to improper fit, cocking, or poor bearing seats. Replace the bearing. Correct the bearing seats.

Fatigue Spalling

Fatique Spalling:

Flaking of surface metal results from fatigue. Replace the bearing. Clean all related parts.

Brinelling

Brinelling:

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