Signs of a worn wheel hub bearing can be hard to spot, but failure to identify and correct the problem can cause damage before a driver even knows there is a problem. When damage that occurred can be attributed to driving conditions and/or installation procedures. Noise is a classic sign of a bad wheel bearing or wheel hub bearing but determines exactly Why damage that has occurred may require investigation.
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To diagnose the cause of bearing damage, carefully examine damaged hubs and compare customer hubs with accompanying photos.
LOSS OF BEARING RETENTION (Figure 1)
Symptoms: Wheel vibration and/or excessive noise.
Diagnostic: Rough or worn axle retainer nuts indicate movement due to loss of bearing retention. Refer to the original equipment manufacturer’s instructions or visit timkeninfo.com to identify the proper torque for the axle retainer nut.
Cause: Loss of bearing retention is the number one cause of hub bearing damage, resulting in wheel vibration and/or noise. The axle retaining nut backs off when the bearings are incorrectly torqued or have lost their self-retaining characteristics. This changes the setting of the bearings inside the hub, causing misalignment and accelerating wear.
Solution: Always use a new axle retainer nut and tighten it to the correct torque to avoid a rough, worn surface under the nut. Tighten the axle lock nut to the correct torque to help avoid a rough, worn surface under the nut.
EXCESSIVE WEAR ON CONE BORE (Figure 2)
Symptoms: Accelerated bearing wear or multiple returns for the same wheel end application.
Diagnostic: Inspect the hub barrel when replacing a wheel bearing with a separate hub. Check the hub body outside diameter (OD) for signs of damage. Look for ridges or discoloration on the surface of the barrel due to heat damage from cone rotation. Replace the hub if you find any signs of damage.
Cause: Loss of axle retention or reinstallation of a worn hub can allow the cone or inner race to rotate on the hub, accelerating wear of the cone bore and hub body. This rotation of the cone may indicate a loss of bearing retention or a poor fit between the bore of the cone and the diameter of the hub body.
Solution: If you see damage to the hub barrel, replace it.
ABS MALFUNCTION (Figure 3)
Symptoms: A damaged sensor cable or a broken wheel speed sensor has illuminated the Anti-lock Braking System (ABS) warning light.
Diagnostic: Look for damage from sharp objects or evidence that the cable has been caught in a pinch point. Make sure the cable is routed through the sensor cable retention clip assembly. If the sensor cable is not damaged, examine the external sensor for cracks in the sensor body or a loose cable in the sensor head.
Cause: Sharp objects may have damaged, pinched or bent the sensor cable. Damage to the sensor cable is a common cause of ABS malfunctions. The installation may have damaged the wheel speed sensor.
Solution: Route the sensor cable through all retaining clips. Use hubs in good condition to reduce wear. Avoid pinched cables by using retaining clips.
Courtesy of Timken.