Auto Locking Hubs - Diagnosing Noise Concerns
Bulletin No. 002/95Issued 12/07/95
Revised
Category
M
Applicable Model/s
1991-94 Navajo
1994 B-Series
Subject
AUTO-LOCKING HUBS DIAGNOSTIC PROCEDURE
APPLICABLE MODELS
All 1991 - 94 Navajo vehicles with 4WD
All 1994 B-Series vehicles with 4WD
DESCRIPTION
The information in this bulletin addresses the most common noise related customer concerns when operating the auto-locking features of the vehicle. Use this information to diagnose and repair the following:
^ Contamination In The Hubs
^ Buzzing Noise In 2WD After 4WD Engagement
^ Ratcheting Noise In 2WD
^ Buzzing Noise when Engaging 4WD (Electric Shift)
^ Popping Noise From Front Axle In 4WD Also included in this bulletin are the auto-locking hub removal and installation procedures.
CONTAMINATION IN THE HUBS
An o-ring is installed in the hub assembly to guard against contamination. When the hubs are serviced, inspect this 0-ring for damage and replace if necessary.
1. If contamination is found in the hub assembly, determine the path of entry.
^ O-ring
^ Wheel Bearing Seals
^ Axle Pinion Seals
2. Repair as necessary.
BUZZING NOISE IN 2WD AFTER 4WD ENGAGEMENT
If noise is heard in 2WD shortly after shifting from 4WD, it may be caused by one of the hubs not disengaging.
1. The hub which did not disengage:
^ will rotate its axle shaft through the differential and,
^ attempt to rotate the nonengaged axle shaft in the opposite direction (differential motoring torque)
2. The differential motoring torque will cause the disengaged hub to attempt engagement resulting in a "ratcheting or buzzing" noise.
^ This type of noise is usually found on vehicles with the wrong differential axle lubricant (1991 Navajo Only).
^ This type of noise will occur on 4WD vehicles with very low mileage.
Repair
1. 1991 Navajo - Verify that the lubricant has been replaced with ZZL0 26 001 (part number of lubricant).
^ If the lubricant can not be verified, extract the existing lubricant from the differential with a suction gun.
NOTE:
Breaking the carrier seal is not a recommended method for extracting lubricant.
^ Refill the front axle with 56 ounces of lubricant (ZZL0 26 001).
2. Front Axle Break-In - As the vehicle accumulates 100 - 200 miles (with hub engaged), differential motoring torque reduces significantly. Front axle break-in instructions are listed below.
^ Engage 4WD
^ Shift out of 4WD without disengaging the hubs.
^ Drive the vehicle with the hubs engaged until 100 - 200 miles are accumulated.
NOTE:
If the vehicle is operated in reverse (backed up) the hubs will disengage and require engagement again.
After Break-In and/or Lubrication (ZZL0 26 001) Change
If the "ratcheting or "buzzing" noise is still heard in 2WD (shortly after 4WD disengagement) replace the hub that is not ratcheting.
NOTE:
Replace both hubs if the vehicle is a 1991 Navajo built after 2/91 1992-93 Navajo or 1994 B-Series built before 9/20/93. Refer to the yellow stamp on the upper radiator support for the applicable build date.
RATCHETING NOISE IN 2WD
This noise occurs during turns or when the suspension travels through its normal range of motion (stroke). The noise is more noticeable in cold weather with new front axles.
Repair
Refer to the instructions listed under "Buzzing Noise In 2WD After 4WD Engagement."
BUZZING NOISE WHEN ENGAGING 4WD (Electric Shift)
This noise occurs from delayed 4WD engagement or no engagement. This may be caused by damaged auto-locking hubs. Modifications to the auto-locking hubs and transfer case assemblies since March 31, 1991 prevent hub damage and provide unrestricted engagement.
Repair
Refer to Service Bulletin R, 002/93 for transfer case modification procedure.
POPPING NOISE FROM FRONT AXLE IN 4WD
Confirm that the noise is coming from the hubs by steering the vehicle in a tight turn on dry pavement. Repair.
Replace the hub assembly that is creating the noise.
NOTE:
Replace both hubs if the vehicle is a 1991 Navajo built after 2/91, 1992-93 Navajo or 1994 B-Series built before 9/20/93.
Refer to the yellow stamp on the upper radiator support for the applicable build date.
HUB ASSEMBLY REMOVAL AND INSTALLATION PROCEDURE
1. Remove the old hub. Refer to the instructions in the workshop manual.
2. Remove the new wheel bearing retaining nut from the cam assembly and install it on the threaded spindle.
3. Rotate the wheel and tighten the wheel bearing retaining nut using SST 49 Un01 037.
Tightening Torque: 47Nm (35 ft-lbs) while rotating the wheel.
4. Back the nut off 1/4 turn and retighten. Tightening Torque: 1.8Nm (16 in-lbs).
5. Advance the nut (clockwise) until the scallop of the wheel bearing nut is aligned with the center of the spindle keyway.
6. Install the retaining key into the spindle keyway.
7. With the garter spring inboard, align the key on the cam assembly with the keyway on the spindle.
8. Press the cam assembly on the wheel bearing retaining nut firmly.
NOTE:
DO NOT install the shims from the old hub assembly on the bearing retaining nut.
CAUTION:
DO NOT pack the hubs with grease. Too much grease may cause improper hub operation and may damage the hub.
9. Install:
^ One piece spline washer
^ "C" clip into axle groove - It may be necessary to push the axle outboard from the inboard side of the knuckle.
CAUTION:
Check that the "C" clip is seated properly in the groove.
10. Check the 0-ring seal on the flange face for:
^ Damage
^ Proper seating in groove
11. Install hub body assembly onto the vehicle hub and rotor assembly.
NOTE:
If necessary, rotate the hub assembly to align the three (3) prongs of the cam follower (inside the hub) with the cam assembly.
DO NOT force fit the hub to the vehicle hub. If installation is not smooth, check the alignment of all components.
12. Install the speed nut to retain the assembly in place.
13. Install wheels and tighten. Tightening Torque: 135 Nm (100 ft-lbs.)
PARTS INFORMATION
WARRANTY INFORMATION
(Applies To Verified Customer Complaints On Vehicles Covered Under Normal Warranty Refer To The SRT Microfiche For Warranty Term Information.)
Warranty Type: A
Symptom Code: 80
Damage Code: 9C
Part Number Main Cause: ZZM1 33 2XY
Quantity: 1 or 2 (if replacement is required)