Mi21-07A Service Bulletin/Repair Instructions

MAINTENANCE

INFORMATION
Revision: A
MI21-07A
DATE :
September 2021
SECTION : 13 WHEEL, HUB &

TIRES
SUBJECT :
FRONT & TAG AXLE – UNITIZED HUB

BEARING END PLAY VERIFICATION AND

REPLACEMENT
Step added about spindle thread repair
September 2021
APPLICATION
FROM
Writer:
EL
H3 SERIES
X SERIES
2010
2009
A-1656
9-9952
Table of contents
MATERIAL .............................................................................................................................................................. 3

REQUIRED TOOLS ................................................................................................................................................... 3

PROCEDURE ........................................................................................................................................................... 4

UNITIZED BEARING END PLAY VERIFICATION ........................................................................................................................ 7

UNITIZED HUB BEARING REMOVAL .................................................................................................................................... 9

UNITIZED HUB BEARING INSTALLATION ............................................................................................................................. 14

PARTS / WASTE DISPOSAL .....................................................................................................................................22
Writer:
EL
MATERIAL

NOTE

Parts can be obtained through regular channels. Please, refer to your vehicle Parts Manual

Other material required:

Part No.
Description
685274
GLEITMO 805 GREASE
685325
FUCHS RENOLITE LX PEP 2
REQUIRED TOOLS

METRIC OPEN END WRENCH SET
SOFT FACED HAMMER
IMPACT WRENCH & APPROPRIATE HEX

SOCKETS
RATCHET AND SOCKET SET
UNITIZED BEARING INSERTION TOOL

FRONT & TAG AXLE Ø 70 mm SPINDLE
TRUCK LUG NUT TORQUE WRENCH AND

APPLICABLE HEX SOCKETS
# 491115
UNITIZED BEARING INSERTION TOOL

TAG AXLE Ø 82 mm SPINDLE
SHOP TOWELS
# G32950
#682384 CHIX CLOTH
Writer:
EL
PROCEDURE

DANGER

Park vehicle safely, apply parking brake, stop the engine. Prior to working on the vehicle, set the ignition

switch to the OFF position and trip the main circuit breakers equipped with a trip button. On Commuter

type vehicles, set the battery master switch (master cut-out) to the OFF position.

Lockout & Tag out (LOTO) must be performed during set-up, maintenance or repair activities. Refer to

your local procedure for detailed information regarding the control of hazardous energy.
The unitized hub bearings used on the tag axle and front axle are non-serviceable items. Bearings

are pre-adjusted, lubricated and have seals fitted as part of the manufacturing process. The

bearings are greased for life and there is no need or facility for re-lubrication.
Figure 1: TYPICAL Ø82 mm SPINDLE TAG AXLE HUB AND ROTOR ASSEMBLY
Writer:
EL
Figure 2: TYPICAL Ø82 mm SPINDLE TAG AXLE UNITIZED BEARING & WHEEL HUB. HUB FLANGE CAP

SCREW SINGLE USE ONLY, DO NOT REUSE APPLICABLE TO TAG AXLE ONLY
Writer:
EL
Figure 3: TYPICAL Ø70 mm SPINDLE FRONT AXLE HUB AND ROTOR ASSEMBLY
Writer:
EL
Unitized Bearing End Play Verification

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. Remove the wheels.

4. Place magnetic base of a dial indicator on the brake caliper and position dial indicator stem

against a convenient marked spot on the face of the hub flange.
Figure 4
5. With dial indicator in position pull hard but steadily on hub flange and oscillate at same time

until a steady reading is achieved.

6. Without releasing the pressure, turn bearing so that dial indicator stem contacts marked spot

and note reading on indicator.

7. Push bearing flange hard and oscillate as before until a steady reading is achieved.

8. Without releasing the pressure, turn bearing so that indicator stem again contacts the marked

spot and note new reading on indicator.

9. The difference between readings is the amount of mounted end play in bearing unit.

10. Refer to the following table for allowed end play:
Writer:
EL
New Tag Axle Unitized Hub Bearing Axial End play

Maximum axial play
0.0024 inch (0.061mm) based on clamp load of 20000 lbf (90 kN).
Tag Axle Unitized Hub Bearing Axial Endplay in Service

•
If the end play is between 0 – 0.002 in (0 – 0.05 mm), the inspection is complete.
•
If the end play is greater than 0.002 in (0.05 mm), but less than 0.008 in (0.20 mm), check

and retighten the wheel bearing adjusting nut. Again, check end play to make sure that the

clamping process is done properly.
•
If the end play is equal to or greater than 0.008 in (0.20 mm), replace the unitized hub

bearing as soon as possible since the hub assembly may not be safe to operate.

New Front Axle Unitized Hub Bearing Axial Endplay
Maximum axial play
0.002 inch (0.05 mm)
Front Axle Unitized Hub Bearing Axial Endplay in Service

Maximum axial play
Writer:
EL
0.008 inch (0.2 mm)
Unitized Hub Bearing Removal
NOTE FOR FRONT AXLE: You can find detailed information on the front axle wheel hub bearing

removal, refer to the following manual included on your vehicle Technical Publications USB flash

drive in PDF format:

Dana Parts & Service Instructions S84U Steer Axle HUB BEARING REWORK_ Manual NO

1963 A+B iss A.

See OVERHAUL PROCEDURES, HUB END DISASSEMBLY, pages No. B3, B4, B5 & B6.

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.
Figure 5
3. Raise the vehicle by its jacking points on the axles.

4. Unscrew 10 wheel hex stud nuts and remove the wheel.
Figure 6
Figure 7
5. Remove the brake caliper/carrier assembly. Refer to Knorr-Bremse Pneumatic Disc Brake

Y006471 Service Manual included on the Technical Publications USB flash drive and also

available on Prevost Technical Publications site.
Writer:
EL
Figure 8
6. Loosen but do not remove the hub flange cap screws (Figure 9).

7. Remove 2 diametrically opposed hub flange cap screws (Figure 10).
Figure 9
Figure 10
8. Replace the two diametrically opposed hub flange cap screws with 2 loosely fitted studs.

NOTE: Replacement studs should protrude beyond the front face of the hub flange to aid removal.
Writer:
EL
9. Unscrew 12 hub flange cap screws.

Applicable to the tag axle: discard hub flange serrated cap screws (single use only).

NOTE: The following images are generic images and do not show the actual tag or front axle hub

but they remain representative of the following steps.

10. Gently tap hub flange outwards using a hide faced hammer.
Figure 11
11. Support weight of hub flange. Remove the hub flange and place on a suitable workbench.
Figure 12
12. Inspect wheel stud and replace the ones that are found defective.

13. Once the hub flange has been removed, insert two guide studs.
Writer:
EL
Figure 13
14. Insert two bolts into brake disc extraction holes.

15. Tighten to free brake disc from hub bearing.
Figure 14
16. Support weight of brake disc and carefully slide along guide studs to remove.
Figure 15
17. Using a small ended chisel, pry off the staking on the hub nut.
Writer:
EL
Figure 16
Figure 17
18. Unscrew hub nut and discard (Figure 18).

19. Remove the thrust washer (Figure 19).
Figure 18
Figure 19
20. Screw insertion tool onto spindle (Figure 20) (front axle: 491115; tag axle G32950).
Figure 20
21. Carefully pull unitized bearing assembly and remove.
Writer:
EL
MI21-07A

Page 14 / 15
Unitized Hub Bearing Installation

1. If required, repair the first spindle threads using appropriate thread cutting die.

Front & Tag axle spindle thread: 1 ¾-8 UNR 3A

Independent Front Suspension spindle thread: M42-2.0
Figure 21
Figure 22
2. Thoroughly clean threads and spindle using EFX degreaser (Prevost #685313) or brake

cleaner.
Figure 23
3. Screw insertion tool onto spindle (front axle: 491115; tag axle G32950).
Writer:
EL
MI21-07A

Page 15 / 16
Figure 24
4. Apply a thin layer of antifriction/antifretting lubricant on the spindle where bearing will be

located (use Gleitmo 805 grease, Prevost #685274).
Figure 25: APPLY GLEITMO 805 GREASE
5. Slip unitized hub bearing over spindle.

6. Make sure the O-ring is present, see Figure 2.
Figure 26: SLIP UNITIZED HUB BEARING OVER

SPINDLE
Writer:
EL
MI21-07A

Page 16 / 17
NOTE

If the inner rings are not properly guided (i.e. not in line to the spindle) there may occur seizing

between inner ring and spindle before the assembly be completed. By pushing abruptly the

hub unit back, there is a risk of separation of inner rings. The clip can be dislodged as per the

two pictures below.

Always use an insertion tool
NOTE

If original bearing unit is refitted, and end float is measured at 1 mm, with hub not fully tightened

to specified torque, then the retaining clip within the unit is damaged and a new unit must be

fitted.

7. Remove the insertion tool.

8. Clean thrust washer both sides and hub nut using a good quality degreaser or brake cleaner.

9. Install thrust washer, hub nut then torque hub nut (Figure 27).

tag axle torque: 563-687 lb-ft (763-931 Nm)

front axle torque: 575-625 lb-ft (780-847 Nm)
NOTE: Rotate bearing, minimum 10 revolutions necessary (simultaneous rotation till final clamp

torque is achieved).
Writer:
EL
MI21-07A

Page 17 / 18
10. Make sure there is no play between the bearing and the spindle shoulder (Figure 28).
Figure 27: INSTALL THRUST WASHER AND HUB NUT
Figure 28: NO PLAY BETWEEN THE BEARING AND

THE SPINDLE SHOULDER
11. Check the unitized bearing end play. Refer to Unitized Bearing End Play Verification in this

document.

12. Stake the hub nut by deforming with a round nosed chisel.
Figure 29
Writer:
EL
Figure 30: CORRECT - PREVENTS THE NUT FROM

GETTING LOOSE
MI21-07A

Page 18 / 19
Figure 31: CORRECT – 2 to 3 mm / 0.078 to 0.118 in

MAX GAP
Figure 32: BROCKEN OR TORN LIP – REJECTED
Figure 33: LIP INADEQUATELY PRESSED IN – REJECTED
13. Clean hub bearing, rotor and hub flange clamping surfaces using a good quality degreaser or

brake cleaner.
Figure 34: CLEANING HUB BEARING, ROTOR AND HUB FLANGE CLAMPING SURFACES
14. Install two guide studs on the unitized bearing (Figure 35).
Writer:
EL
MI21-07A

Page 19 / 20
15. Install rotor onto hub bearing (Figure 36).
Figure 35
Figure 36
16. Add some grease (25-50 ml) (Fuchs Renolite LX PEP-2) (Prevost #685325) into the bottom of

the hub flange cap. Mount hub flange onto rotor.
Figure 37
17. Secure hub flange and rotor to unitized hub bearing (Figure 38).

•
Tag axle: use 14 new cap screws (single-use only).
•
Front axle: discard cap screws showing signs of deformation in the threads area

and beneath the head of the bolt.
Writer:
EL
MI21-07A

Page 20 / 21
Refer to Figure 39 for tightening sequence.

front axle torque: 174-192 lb-ft (236-260 Nm)

tag axle torque: 161-197 lb-ft (218-267 Nm)
Figure 38: HUB FLANGE HEX CAP SCREWS
Figure 39: HUB FLANGE HEX CAP SCREW

TIGHTENING SEQUENCE
18. Once the hub flange has been correctly fitted; it is necessary to check the axial run out of the

brake disc.

19. Position a dial test indicator onto the axle in a suitable position.
Figure 40
20. Position the stylus of dial test indicator onto brake disc as shown.
Writer:
EL
MI21-07A

Page 21 / 22
Figure 41
21. Rotate the hub through 360° and note any movement of the dial test indicator.

THE MAXIMUM RUNOUT IS 0.1 mm / 0.004 in

22. Remove and check out of specification disc to ensure no damage has occurred to the mounting

faces, or that no dirt is present.

23. Remove any dirt found on the mounting faces and refit and recheck disc.

24. Should it be found that a cleaned and refitted disc is still out of specification; it must be

replaced.

25. Mount the brake caliper. Refer to Knorr Bremse manual.

CALIPER MOUNTING BOLTS TORQUE

Tag Axle: 405-495 lbf-ft (549-671 N-m)

Front axle : 433-479 lb-ft (587-649 Nm)

26. Mount the wheel over wheel studs, being careful not to damage stud threads.

27. Screw in the hex stud nuts (refer to Figure 43 for sequence) so that the wheel will position

itself concentrically with hub. This is important, otherwise wheel may be eccentric with hub and

will not run straight. In this initial step, slightly tighten the nuts to correctly position the wheel.
Writer:
EL
MI21-07A

Page 22 / 22
Figure 42
Figure 43
28. Tighten stud nuts progressively as shown in Figure 43. The final tightening should be done

with a torque wrench. Tighten stud nuts.
TORQUE: 450-500 lb-ft (610-678 Nm)
PARTS / WASTE DISPOSAL

Discard according to applicable environmental regulations (Municipal/State[Prov.]/ Federal)
Access all our Service Bulletins on http://techpub.prevostcar.com/en/

Or scan the QR-Code with your smart phone

.

Are you a Vehicle owner?

E-mail us at technicalpublications_prev@volvo.com and type “ADD” in the subject to

receive warranty bulletins applicable to your vehicle(s) by e-mail.
Writer:
EL

Bestseller No. 1

iCarsoft Bidirectional Scan Tool, CR Max OBD2 Diagnostic Scanner for All Vehicles, Full System 49 Resets+46 Extra Services, 40000+Active Tests,ECU Coding, Battery Registration, Oil Reset/ABS,CAN FD

WHY CHOOSE THE 2025 CR MAX -Upgrade the latest diagnostic capabilities for all vehicles after 1996: upgrade to 49+maintenance services; 46 extra specific functions; real all systems/all control modules diagnose; over 40K+ bidirectional actuation tests for diagnosing all control moduels of cars; Powerful full OBD2 Functions; built-in ECU Coding for BMW/ Audi/ VW/ RollsRoyce; Fr ee V.A.G Guide Function; Battery retistration for new battery adaptation and more. It covers all vehicle diagnostic services and some special professional vehicle maintenance servces, assists you to do home DIY vehicle maintenance or car repair as a pro technician.
NEWEST IN INNOVATION FULL OBD2 SERVICES- iCarsoft auto car diagnostic scanner compatible with CAN-FD, CR MAX can do it all-reads and clears trouble codes, ALL SYSTEM DIAGNOSIS such as engine, transmission, ABS and airbag etc. CR MAX code reader for all cars can perform I/M Readiness, Live Data, Freeze Frame, Vehicle Information, Monitor Test, On-Board Monitor, E vap System Test,O2 Sensor Test,DTC Library Lookup,etc. (Warm Tips: If you car is after 2023,please contact us for compatibility; 3. It comes with 16PIN OBD2 diagnostic adapter, please check your car diagnostic socket if it is 16pin socket, if your car is 14pin diagnostic socket please contact us for the solution.)
49 RESET+ 46 SERVICES- Performs: Oil Reset, EPB,SAS,Throttle, D-P - F, Battery, ABS, Injector, TPMS, Suspension, AC, Head Lamp, Body Stablity, Engine, Tramsmission, Airbag, Seat, Door-Win-Roof, Fuel Pump, Door, E-G- R.+21 NEWEST SERVICES( Need update scanner)-AdBlue, Clutch, Crankshaft, High Voltage Battery, Cruise Control, NO xSensor, Rain Sensor, Stop And Start, Turbocharger, Head Up Display, Radar Camera, Vehicle Setup, Cyliner Misfire Check,Speedlimitassist, ControlUnitReset,OxygenSensor, Seatbelt. Extra 46+ extra services based on car brand.(Tips: Quantity of reset/ calibration fucitons are based on car system that your vehicle model has)
REVOLUTIONARY 40000+BIDIRECTIONAL ACTIVE TESTS: Upgraded CR Max scanner equip with numberous of actuational test items for covering all available vehicle control modules, no longer only do simple light test or window test like other scanners, performs hardware modules test and software control modules test for checking car units or new updated control moduels work well or not after maintenance/ repair/ re-installation/ control system updated (Example for Benz- Roller Sun Blind test; Backup Camera test ;Self-test; EPB test; Transport Mode test;Boost Pressure Positioner test; Fuel Pump test; AND MORE!!).(Warm tip: The available test items are based on control modules your car has)
ECU CODING+ BATTERY REGISTRATION- Powerful ECU Coding service for BMW/MINI/RollsRoyce / Audi/VW/Seat/Skoda/Bentley/Bugatti/Lamborghini, Improves Engine Power Performance and Optimizes Fuel Efficiency and Match New Hardware Unit to car and Customized a comfortable Driving Modes and Fixes & Updates Original Software Bug. The battery test function for checking car battery health, perform battery reset (BMS ) for replacing a damaged or aging car battery with a new one and register new battery to car ECU

SaleBestseller No. 2

iCarsoft Auto Diagnostic Scanner POR V2.0

Scanner POR V2.0 with all obd2 services
Do the scanning for engine
Support OBDII/EOBD Ten Modes of Operation

SaleBestseller No. 3

iCarsoft Bidirectional Diagnostic Tool for Most Mercedes-Benz/Sprinter/Smart from 1996-2023 MB V3.0 2026 Version Up to 38 Service Full System OBD2 Scanner All Test AutoVIN Battery Test Free Update

【Designed for Most Mercedes-Benz, Sprinter and Smart from 1996-2023】As every car model of Benz has its-owned specific car system and ECUs, not all models are equipped with a complete vehicle ECU, which may cause the scanner to be unable to perform all listed reset services on some models, or even completely incompatible. Like For Sprinter's newer models, it support diagnostic functions only, lacking support for specialized service functions.. So please tell us the car's VIN and required service before purchase for compatibility check. You may also refer to the instructions in the eighth image of the main product photos to perform your inquiry.
【Up to 38 Reset Services】MB V3.0 2026 Version diagnostic tool performs Up to 38 maintenance services - Oil Rest , SAS, EPB, ETC, D-P-F, TPMS, ABS, Suspension, Air Conditioner, Head Lamp, Body Stability, Engine Control, Seat, Fuel Pump, Air-Filter, Engine Idle, Door, Im-mo-bilizer, Injector Coding, Transmission Control, Miscellaneous, Adblue, BMS, Cluth, Water Pump, NOxSensor, Rain/Light Sensor, Start/Stop, Radar/Camera, Cylinder Shutoff Test, Speed Limit Assist, Control Unit Reset, Oxygen Sensor, Seat Belt, Cruise Control System, Turbocharger, Crankshaft, Language Setting and etc. (Tips: Please update the software after receiving the product to obtain new service functions)
【OE-Level All System OBD2 Scanner】iCarsoft MB V3.0 (2026 Version) diagnostic scanner offers comprehensive OBDII services, allowing you to quickly scan all systems, including the Engine, ABS, SAS, SRS, TPMS, TCM, Fuel Pump System, ESP, EPB, EPS, Suspension, SCM, Adaptive Systems, and more. It supports functions such as reading and erasing codes, checking I/M readiness, viewing freeze frame data, performing O2 sensor tests, conducting on-board monitoring, testing the evap system, auto VIN retrieval, and reading both generic and specific codes, as well as DTCs and battery tests.
【Bidirectional Scan Tool】iCarsoft MB V3.0 (2026 Version) Bidirectional scanner supports activate or control a vehicle system or component, allows commanding cars’ modules and receiving info from the ECU to perform active tests on individual components, including EVAP/ABS Motor Pump/Windows/Sunroof and more, to pinpoint fault causes & resolve issues,and allows you to re-learn certain components after making repairs or replacement.
【Real Time Record & Graph View】iCarsoft MB V3.0 (2026 Version) can automatically record vehicle text history and identify vehicle information. Preserve real-time data information. View & Graph Live Data. Support Data Review and Print. Multi-language: English, German, Dutch, Spanish, French and so on. We promise to offer Lifetime updates (Lifetime free Update via PC), and confidence in products. We also provide 1 year warranty + extra lifetime hardware free repair if you need it in the future. We prioritize user experience & strive to meet your expectations. Please do feel free to reach out to us if you have any question or problem about the usage, our tech team will service you in time.

This product presentation was made with AAWP plugin.

Last update on 2026-05-12 / Affiliate links / Images from Amazon Product Advertising API

Buffer Email Facebook Flipboard Hacker News LinkedIn Messenger Mix Pinterest Print Reddit SMS Telegram Tumblr X VK WhatsApp Line Xing Threads Bluesky Copy Mastodon Nextdoor