SB-10043806-1630

35-8

Lubricating the Wheel Bearings, Rear Drive Axles
Recreational Vehicle
School Bus
Shuttle Bus

Freightliner Custom Chassis
Service Bulletin

Walk-In Van
> S2

Description of Revision: This bulletin replaces the version dated

May 2011. Information is added about ConMet hubs with a fill port.

General Information
Proper wheel bearing lubrication is critical to sound wheel end health and safe vehicle operation. Insufficient
lubrication can lead to catastrophic consequences that could have been avoided.
The procedure for lubricating wheel bearings (after a maintenance inspection, for example) depends on whether
or not the hub has an oil fill port. This bulletin provides instructions for ConMet hubs with and without a fill port.

Lubricating the Wheel Bearings
ConMet Hub with an Oil Fill Port
For ConMet hubs with an oil fill port, lubricant is added through the fill port; see Fig. 1 and use the following
instructions.
2
3

1

01/05/2012

f350549

1. Hub
2. Fill Port Plug
3. O-Ring
Fig. 1, ConMet Hub with Oil Fill Port

1. Park the vehicle on a level surface, shut down the engine, and set the parking brake. Chock the tires.

IMPORTANT: When removing the fill port plug, make sure the rubber O-ring is attached to it and not
stuck inside the fill port.
2. Clean the area surrounding the oil fill port plug, then remove the plug and O-ring.

Freightliner Custom Chassis Service Bulletin, February 2012

Page 1

35-8

Lubricating the Wheel Bearings, Rear Drive Axles

Freightliner Custom Chassis
Service Bulletin

Recreational Vehicle
School Bus
Shuttle Bus

Walk-In Van
> S2

NOTE: The fill port plug is magnetic. On drive axles, it is normal to find a small amount of very fine
metallic particles from the carrier housing on the magnetic fill plug. These particles should be removed from the magnet anytime the plug is removed for inspection.
3. Inspect the plug for metallic particles picked up by the magnet. If very fine metallic particles are found, remove them from the magnet. If larger particles or chunks of metal are found, remove the hub from the
spindle and inspect the bearings and other wheel end and axle components for signs of damage or excessive wear, and make the necessary repairs.

WARNING
Failure to adequately lubricate wheel bearings can cause them to seize during vehicle operation. Seized
wheel bearings can cause sudden, catastrophic damage to the wheel end and axle, possibly resulting in
severe personal injury or death.
4. Using a clean funnel, add 1.0 quart (0.95 liter) of the recommended drive axle lubricant through the oil fill
port. For recommended lubricants, see the vehicle maintenance manual.
5. Install the fill port plug, and tighten it 20 to 25 lbf·ft (27 to 34 N·m).

ConMet Hub without an Oil Fill Port
For ConMet hubs without an oil fill port, lubricant must be transferred from the axle carrier housing to the hubs.
To ensure each bearing is adequately lubricated, the axle must be filled with lubricant and tilted three times.
See Fig. 2 and use the following instructions to lubricate the wheel bearings on a rear drive axle.
1

2

3

A

4

B
5
6

04/25/2011

f350536

For an axle equipped with hubs without fill ports, when side A is raised first, bearing 4 is lubricated. Side B is raised next to
lubricate bearings 3 and 1. Side A is raised again to lubricate bearing 2. The carrier housing must be refilled before and after
each time the axle is lifted to ensure there is enough lubricant to reach the bearings.
A.
1.
2.
3.

Driver Side
Outer Wheel Bearing, Driver Side
Inner Wheel Bearing, Driver Side
Inner Wheel Bearing, Passenger Side

B.
4.
5.
6.

Passenger Side
Outer Wheel Bearing, Passenger Side
Carrier Housing
Lubricant (full)

Fig. 2, Rear Drive Axle and Wheel Bearings

1. Park the vehicle on level ground, apply the parking brakes, and chock the front wheels.

NOTE: Some Freightliner and Meritor axles have a small tapped and plugged hole located below the
housing oil fill hole. This smaller hole is for the lubricant temperature sensor only and must not be
used as a fill hole.

Page 2

Freightliner Custom Chassis Service Bulletin, February 2012

35-8

Lubricating the Wheel Bearings, Rear Drive Axles
Recreational Vehicle
School Bus
Shuttle Bus

Freightliner Custom Chassis
Service Bulletin

Walk-In Van
> S2

2. With the axle level and all wheels on the ground, clean the oil fill hole plug and the area surrounding it, then
remove the fill plug. For Freightliner axles, see Fig. 3; for Meritor axles, see Fig. 4; for Dana Spicer axles,
see Fig. 5.
1

2

1

2

3

3

06/07/94
04/21/2011

f350509b

1. Oil Fill Plug
2. Breather Hose
3. Temperature Sensor Port

f350062a

1. Axle Housing Breathers
2. Carrier Oil Fill Plugs
3. Interaxle Differential
Fig. 4, Fill Hole Plug Locations, Meritor Axles

Fig. 3, Fill Hole Plug Location, Freightliner Tandem
Axle (forward axle shown)

WARNING
Failure to adequately lubricate wheel bearings can cause them to seize during vehicle operation. Seized
wheel bearings can cause sudden, catastrophic damage to the wheel end and axle, possibly resulting in
severe personal injury or death.

IMPORTANT: A lubricant level close enough to be seen or touched is not sufficient; it must be level
with the bottom of the fill hole. See Fig. 6.
3. Use a clean funnel to add lubricant until it reaches the fill hole, then insert the fill plug. For recommended
lubricants, see the vehicle maintenance manual.
4. To tilt the axle, position a suitable jack at a leaf spring U-bolt, and raise it until the bottom of the outside part
of the outside tire is 8 inches (20 cm) above the ground. See Fig. 7 and Fig. 8.

IMPORTANT: The axle must be tilted three times and the tilted position must be held for two minutes
each time to allow enough lubricant to reach the hub and wheel bearings.
5. After two minutes, lower the axle, and add lubricant as described earlier in this procedure.
6. At a leaf spring U-bolt on the other end of the axle, tilt the axle as described earlier in this procedure.
7. After two minutes, lower the axle, and add lubricant as described earlier in this procedure.
8. At the U-bolt where the axle was first lifted, tilt the axle as described earlier in this procedure.

Freightliner Custom Chassis Service Bulletin, February 2012

Page 3

35-8

Lubricating the Wheel Bearings, Rear Drive Axles

Freightliner Custom Chassis
Service Bulletin

Recreational Vehicle
School Bus
Shuttle Bus

Walk-In Van
> S2

3
A

B

f350061a

08/17/2009

A. Correct (lube level at bottom of fill hole)
B. Incorrect (lube level below fill hole)

1

Fig. 6, Axle Lubricant Level Check

2
12/09/2010

1. Oil Fill Plug
2. Oil Drain Plug

f350531

3. Axle Breather

Fig. 5, Fill Hole Plug Location, Dana Spicer Axles

1

2

04/20/2011

f350535

1. Jack
2. U-bolt
Fig. 7, Axle Lifted at Leaf Spring U-bolt

9. After two minutes, lower the axle, and add lubricant as described earlier in this procedure.

Warranty
This bulletin is informational only. Warranty does not apply.

Page 4

Freightliner Custom Chassis Service Bulletin, February 2012

35-8

Lubricating the Wheel Bearings, Rear Drive Axles
Recreational Vehicle
School Bus
Shuttle Bus

Freightliner Custom Chassis
Service Bulletin

Walk-In Van
> S2

A

1

04/20/2011

2

f350534

Each time you lift a side of the axle to distribute lubricant, raise it until the bottom of the outside part of the outside tire is 8
inches (20 cm) above the ground.
A. 8 inches (20 cm)
1. Ruler
2. Jack
Fig. 8, Distributing Lubricant from Carrier Housing to Wheel Bearings for ConMet Hubs without Oil Fill Ports

Freightliner Custom Chassis Service Bulletin, February 2012

Page 5