SECTION 13: WHEELS, HUBS AND TIRES
PA1621 Maintenance Manual All Series | January 2017
13
9.1 TAG AXLE HUB BEARING INSPECTION
MAINTENANCE
Tag axle unitized bearing
Unitized bearing inspection should be made
at the intervals specified by the Lubrication
And Servicing Schedule in Section 24:
LUBRICATION & SERVICING..
1. Apply parking brake, raise wheels off the
ground and support axle on stands.
2. When the wheels are raised, they should
revolve quite freely without roughness.
3. Place magnetic base of a dial indicator on
brake caliper and position dial indicator stem
against a convenient marked spot on face of
hub flange.
4. With dial indicator in position pull hard but
steadily on hub flange and oscillate at same
time until a steady reading is achieved.
5. Without releasing the pressure, turn bearing
so that dial indicator stem contacts marked
spot and note reading on indicator.
6. Push bearing flange hard and oscillate as
before until a steady reading is achieved.
7. Without releasing the pressure, turn bearing
so that indicator stem again contacts the
marked spot and note new reading on
indicator.
8. The difference between readings is the
amount of mounted end play in bearing unit.
9. Refer to the following table for allowed end
plays:
New Tag Axle Unitized Hub Bearing Axial
Endplay
Maximum axial
clearance/end
play
0.0024 inch (0.061mm) based
on clamp load of 20000 lbf
(90kN).
Tag Axle Unitized Hub Bearing Axial
Endplay In Service
 If the endplay is between 0 – 0.002 in (0 –
0.05 mm), the inspection is complete.
ï‚· If the endplay is greater than 0.002 in (0.05
mm), but less than 0.008 in (0.20mm),
check and retighten the wheel bearing
adjusting nut. Again check endplay to make
sure that the clamping process is done
properly.
ï‚· If the endplay is equal to or greater than
0.008 in (0.20mm), replace the unitized hub
bearing as soon as possible since the hub
assembly may not be safe to operate.
9.2 TAG AXLE HUB BEARING REMOVAL
1. Stop engine and apply parking brake.
2. Loosen wheel nuts about one turn (do not
remove the nuts). This is not necessary if
equipped with hydraulic powered gun.
3. Raise the vehicle by its jacking points on the
body. See Section 18, "Body", under
heading "Vehicle Jacking Points".
4. Unscrew 10 wheel hex stud nuts and
remove the wheel.
5. Unscrew 14 hub flange hex cap screws.
Discard hub flange cap screws (single-
use only).
6. Remove hub flange and rotor.
7. Unscrew hub nut.
8. Remove hub nut and thrust washer.
9.3 TAG AXLE HUB BEARING INSTALLATION
1. Clean spindle using EFX degreaser (Prevost
#685313)
2. Screw insertion tool onto spindle (FIGURE
9).
FIGURE 9: INSERTION TOOL PREVOST P/N 491115
3. Apply a thin layer of antifriction/antifretting
lubricant on spindle where bearing will be
located (use Gleitmo 805 grease, Prevost
#685274).
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