Monitoring Wheel End Setting In Adjustable Wheel Bearing Systems

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Skill Level: Difficult | Special Tools: Endplay Gauge

Fig. 1 – Outer race (cup) scalloping; uneven localized wear resulting from excessive end play.

Maintain proper wheel end setting to maximize bearing, seal and tire life. For adjustable wheel bearing systems, Timken recommends following the Technology & Maintenance Council (TMC) Recommended Practice (RP) 618.

When adjusted properly, wheel end setting should not change significantly during early operation. Over time, wear causes small changes, which worsen with poor cleanliness and improper maintenance practices. For proper wheel end cleaning and maintenance procedures, refer to TMC RP 622. Follow the axle
manufacturer’s guidelines for wheel bearing service intervals.

Timken Recommends Performing Step 8 of TMC RP 618 (Verifying Wheel Endplay Setting) When Any Wheel End:

• Maintenance is performed
• Component appears worn or stained
• Component is inspected or replaced

Fig. 2 – Cage pocket wear: heavy contact between the rollers and cage pocket surfaces caused by bearing operating too loosely.

This Includes (But is Not Limited to):
• Brake jobs
• Tire changes
• Lubrication changes or checks
• Removal of the hub cap or end cap
• Maintenance or replacement of S-cams or bushings
• When abnormal tire wear occurs
• When wheel seal leakage occurs

If there is a questionable increase in mounted end play (internal axial clearance), conduct a thorough investigation of the wheel end system. Figures 1 and 2 show damage caused by excessive end play on bearing components.

Fig. 3 – A typical end play gauge.

After completing the adjustment procedure, use a dial indicator (Fig. 3) to verify wheel bearing setting. A dial indicator measures wheel bearing end play after the adjustment procedure is complete. The correct end play range is 0.001 in. to 0.005 in. per “TMC RP 618”.

Note: The two other main types of wheel bearing systems are pre-adjusted
and unitized. Unitized systems are non-serviceable. A pre-adjusted wheel end assembly can be serviced. Always refer to the manufacturer’s service recommendations for specific service instructions.

Safety Check
For your safety and the safety of everyone on the road. Always follow recommended wheel-end inspection and maintenance guidelines.

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WARNING Failure to observe the following warnings could create a risk of death or serious injury.

Do not attempt to disassemble and reassemble unitized wheel end hubs and bearing assemblies. Improper reassembly could lead to failure.

Proper maintenance and handling practices are critical. Always follow installation instructions and maintain proper lubrication.

Tensile stresses can be very high in tightly fitted bearing components. Attempting to remove such components by cutting the cone (inner race) may result in a sudden shattering of the component causing fragments of metal to be forcefully expelled. Always use properly guarded presses or bearing pullers to remove bearings from shafts, and always use suitable personal protective equipment, including safety glasses.

CAUTION Failure to follow these cautions may result in property damage.

The products cataloged are application specific. Any use in applications other than those intended could lead to equipment failure or to reduced equipment life.

Use of improper bearing fits may cause damage to equipment.

Do not use damaged bearings. The use of a damaged bearing can result in equipment damage.

TechTips is not intended to substitute for the specific recommendations of your equipment suppliers. Every reasonable effort has been made to ensure the accuracy of the information contained in this writing, but no liability is accepted for errors, omissions or for any other reason.

Monitoring Wheel End Setting In Adjustable Wheel Bearing Systems

Related Information

Checking A Hub Bearing Assembly

Bearing Adjustment Basics