GM Service Manual Online
For 1990-2009 cars only

Front Drive Axle Bearing Wear 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


Object Number: 1452  Size: SH

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


Object Number: 1453  Size: SH

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


Object Number: 1454  Size: SH

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


Object Number: 1455  Size: SH

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


Object Number: 1648  Size: SH

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

Cage Wear


Object Number: 1457  Size: SH

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


Object Number: 1458  Size: SH

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


Object Number: 1459  Size: SH

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


Object Number: 1460  Size: SH

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


Object Number: 1461  Size: SH

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


Object Number: 1462  Size: SH

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


Object Number: 1463  Size: SH

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


Object Number: 1464  Size: SH

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

Fatigue Spalling


Object Number: 1465  Size: SH

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

Brinelling


Object Number: 1466  Size: SH

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.