Lincoln Aviator: Rear Drive Axle/Differential / Diagnosis and Testing - Rear Drive Axle and Differential
Preliminary Inspection
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Visually inspect the housing, seals, drive pinion stem for obvious signs of mechanical damage.
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If an obvious cause for an observed or reported concern is
found, correct the cause (if possible) before proceeding to the next
step
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If the cause is not visually evident, verify the symptom and REFER to Symptom Chart: NVH.
Symptom Chart(s)
Diagnostics in this manual assume a certain skill level and knowledge of Ford-specific diagnostic practices.
REFER to: Diagnostic Methods (100-00 General Information, Description and Operation).
Symptom Chart - Differential
Symptom Chart - Differential
Condition
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Possible Sources
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Actions
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Axle overheating
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|
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CHECK the lubricant level. FILL the axle to specification.
REFER to: Differential Fluid Level Check (205-02 Rear Drive Axle/Differential, General Procedures).
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Incorrect or contaminated lubrication type
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INSPECT the axle for damage.
REPAIR as necessary or INSTALL a new axle assembly as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation). CLEAN and REFILL the axle to specification as necessary. REFER to: Specifications (205-02 Rear Drive Axle/Differential, Specifications).
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INSPECT all the axle gears for
wear or damaged. INSTALL a new axle assembly as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Incorrect ring gear backlash
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INSPECT the ring gear for
scoring. INSPECT the ring and pinion wear pattern. ADJUST the ring gear
backlash as necessary.
REFER to: Ring Gear Backlash Adjustment (205-02 Rear Drive Axle/Differential, General Procedures).
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Broken gear teeth on the ring gear or pinion
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INSPECT all the axle gears for
wear or damaged. INSTALL a new axle assembly as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Differential side gears/pinion gears are scored
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FILL the axle to specification.
REFER to: Specifications (205-02 Rear Drive Axle/Differential, Specifications). or INSPECT all the axle gears for wear or damaged. INSTALL a new axle assembly as necessary. REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Incorrect or contaminated lubricant type
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CHECK and REFILL the axle to specification as necessary.
REFER to: Specifications (205-02 Rear Drive Axle/Differential, Specifications).
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Gray or milky axle lubricant in low mileage vehicles
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Marking compound in axle fluid
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Inspect axle housing and vent
for damage or leaks. Refer to Axle Fluid Analysis in this section.
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Lubricant leaking from the pinion seal, axle shaft oil seals or support arm to the housing
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CLEAN the axle housing vent.
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Damage in the seal contact area
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INSTALL a new driveshaft and the drive pinion seal if damage is found.
REFER to: Rear Driveshaft (205-01 Driveshaft, Removal and Installation).
REFER to: Drive Pinion Seal (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Symptom Chart: NVH
Symptom Chart
Condition
|
Possible Sources
|
Actions
|
Axle howling or whine
|
|
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CHECK the lubricant level. FILL the axle to specification.
REFER to: Differential Fluid Level Check (205-02 Rear Drive Axle/Differential, General Procedures).
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INSPECT and INSTALL a new axle assembly as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Damaged, worn or incorrect ring and pinion gear contact
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INSPECT and INSTALL a new axle assembly as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Driveline clunk - loud clunk when shifting from REVERSE to DRIVE
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Incorrect axle lubricant level
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CHECK the lubricant level. FILL the axle to specification.
REFER to: Differential Fluid Level Check (205-02 Rear Drive Axle/Differential, General Procedures).
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Excessive backlash in the axle
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CHECK for excessive axle backlash. ADJUST backlash as necessary.
REFER to: Ring Gear Backlash Adjustment (205-02 Rear Drive Axle/Differential, General Procedures).
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Driveline clunk — occurs as the vehicle starts to move forward following a stop
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INSPECT and INSTALL a new axle assembly as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Grinding, popping or chattering – noise from the rear axle when the vehicle is turning
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Damaged or worn differential (differential side gears and pinion gears)
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INSPECT the differential carrier
and the components of the differential carrier. INSTALL a new axle
assembly as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Grunting — normally associated with a
shudder experienced during acceleration from a complete stop
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Loose rear axle mount bolts or suspension fasteners
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CHECK for loose bolts. TIGHTEN to specifications.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Howl – can occur at various speeds and
driving conditions. Affected by acceleration and deceleration
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Incorrect ring and pinion contact, incorrect bearing preload or gear damage
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INSPECT and ADJUST as necessary.
Refer to, Contact Pattern of this procedure, or
REFER to: Ring Gear Backlash Adjustment (205-02 Rear Drive Axle/Differential, General Procedures). or INSTALL a new axle assembly as necessary. REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Chuckle – heard at coast/ deceleration. Also described as knock
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Incorrect ring and pinion
contact or damaged teeth on the coast side of the ring and pinion
|
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INSPECT and INSTALL a new axle
assembly as necessary. Refer to, Contact Pattern of this procedure, or
REFER to: Ring Gear Backlash Adjustment (205-02 Rear Drive Axle/Differential, General Procedures). or INSTALL a new axle assembly as necessary.REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Knock – noise occurs at various speeds. Not affected by acceleration or deceleration
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Gear tooth damage to the driver side of the ring and pinion
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INSPECT and INSTALL a new axle assembly as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Scraping noise – a continuous low pitched noise starting at low speed
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Worn or damaged pinion bearings
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INSPECT and INSTALL a new axle assembly as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Driveline shudder – occurs during acceleration from a slow speed or stop
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Rear drive axle assembly mispositioned
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CHECK the axle mounts and the
rear suspension for damage or wear. REPLACE as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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CHECK the rear axle for loose bolts. TIGHTEN the bolts as necessary.
REFER to: Axle Assembly (205-02 Rear Drive Axle/Differential, Removal and Installation).
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Driveline angles out of specification
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CHECK for correct driveline angles.
REFER to: Driveshaft Angle Measurement (205-01 Driveshaft, General Procedures).
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Axle Fluid Analysis
The
appearance of milky or gray axle fluid in early mileage axles is a
result of white marking compound used at the assembly plant to verify
gear mesh contact pattern. The marking compound within the fluid will
darken some over time. The milky fluid appearance will diminish and
cause no harm and does not require a fluid change.
Analysis of Leakage
Clean up the leaking area enough to identify the exact source.
A plugged Rear axle housing vent can cause excessive pinion seal lip wear due to internal pressure buildup.
Verify the differential lubricant level is at the correct level.
REFER to: Differential Fluid Level Check (205-02 Rear Drive Axle/Differential, General Procedures).
Axle Vent
A
plugged vent will cause excessive seal lip wear due to internal
pressure buildup. If a leak occurs, check the vent. If the vent cannot
be cleared, install a new vent.
Drive Pinion Seal
Leaks at the drive pinion seal originate from the following causes:
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Damaged seal
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Worn seal journal surface
A new drive pinion flange must be installed if any of these conditions exist.
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Any damage to the seal bore (dings, dents, gouges or
other imperfections) distorts the seal casing and allows leakage past
the outer edge of the drive pinion seal.
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The drive pinion seal can be torn, cut or gouged if it
is not installed correctly. The spring that holds the drive pinion seal
against the pinion flange may be knocked out and allow fluid to pass the
lip.
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Metal chips trapped at the sealing lip can cause oil
leaks. These can cause a wear groove on the drive pinion flange and
result in pinion seal wear.
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When a seal leak occurs, install a new drive pinion seal
and check the vent to make sure it is clean and free of foreign
material.
Contact Pattern
In general, desirable ring gear tooth patterns must have the following characteristics:
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Drive pattern on the drive side ring gear well centered on the tooth.
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Coast pattern on the coast side ring gear well centered on the tooth.
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Clearance between the pattern and the top of the tooth.
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No hard lines where the pressure is high.
Acceptable ring gear tooth patterns for all axles.
Correct backlash with a thinner pinion position shim required.
Correct backlash with a thicker pinion position shim required.
Correct pinion position shim that requires a decrease in backlash.
Correct pinion position shim that requires an increase in backlash.
The 8.8-inch ring gear open rear differential axle has 3.31 gear ratio versions.
Rear Drive Axle and Differential
The rear axle assembly consists of the following:
Integral-type housing hypoid gear design (center of the pinion set below the centerline of the ring gear)
Hypoid differential ring gear and pinion consisting of a
8...
Materials
Name
Specification
Motorcraft® SAE 75W-85 Premium Synthetic Hypoid Gear LubricantXY-75W85-QL
WSS-M2C942-A
Draining
With the vehicle in NEUTRAL, position it on a hoist...
Other information:
Special Tool(s) /
General Equipment
Three Leg Puller
Punch
Copper Hammer
Vise
Materials
Name
Specification
Motorcraft® Premium Long-Life GreaseXG-1-E1
ESA-M1C75-B
DISASSEMBLY
Remove the rear driveshaft...
When the system detects an
approaching vehicle, a tone
sounds, a warning lamp illuminates
in the relevant exterior mirror and arrows
appear in the information display to show
which side the approaching vehicle is coming
from.
Note: If arrows do not display, a message
appears in the information display...