Inspect the rear axle before disassembly.
This will aid in determining the type of repairs or adjustments that are necessary.
The following conditions may cause rear axle noise:
| • | The inner bearing preload of the differential drive pinion gear |
| • | The outer bearing preload of the differential drive pinion gear |
| • | The differential side bearing preload |
| • | Any combination of the above items |
Measure the following items before removing the differential case from
the housing:
| • | The total differential preload |
| • | The tooth contact pattern |
Record and analyze these measurements before you remove the differential
case from the housing.
Do not allow foreign matter (such as dirt or sand) near the rear axle.
The presence of foreign matter in the rear axle may cause rear axle failure.
Differential Ring Gear Tooth Nomenclature
The drive side (5)
of the differential ring gear tooth curves outward (convex).
The tooth contact (4) of the differential ring gear is the center
area of the drive side (5) that makes the most physical contact with
the pinion gear. Refer to Effects Of Increasing Load On Tooth Contact Pattern.
The coast side (3) of the differential ring gear tooth curves
inward (concave).
The toe end (2) of the differential ring gear tooth is the end
that is nearest to the center of the differential ring gear.
The heel end (1) of the differential ring gear tooth is the end
that is farthest away from the center of the differential ring gear. The toe
end of the tooth is smaller than the heel end.
Effects Of Increasing Load On Tooth Contact Pattern
The load on the differential ring and on the drive pinion
gear is increased during vehicle acceleration.
An increased load on the differential ring and on the drive pinion gear
may cause the tooth contact (4) to spread out. Under a
very heavy load, the tooth contact may extend from the near toe to the near
heel on the drive side.
Increasingly heavier loads cause the following changes in tooth contact:
| • | The entire contact tends to shift toward the heel |
| • | The entire contact becomes broader with respect to the tops and
the bottoms of the teeth |
The following tooth contact pattern test recreates the effects of a
light load. For this reason, the patterns that will be obtained by the following
test will only extend to about half of their potential expansion.
Important: The contact pattern is centrally located up and down on the face of
the differential ring gear teeth.
The following conditions may cause a change in the tooth contact pattern
under a load:
| • | A drive pinon gear is insufficiently preloaded |
| • | The differential bearings are insufficiently preloaded |
Adjustments Affecting Tooth Contact
The following two adjustments
will affect the
tooth contact pattern:
| • | An adjustment to the backlash |
| • | An adjustment to the position of the drive pinion gear (7)
in the rear axle housing |
The effects of bearing preloads are not readily apparent on hand-loaded
tooth contact pattern tests.
Use differential bearing shims (6) in order to adjust the backlash.
The shims (6) move the entire differential (5) closer to or
farther from the drive pinion gear (7).
You can also use bearing shims (2) can in order to set both the
differential bearing preload and the pinion depth (1).
| • | Make the following changes in order to increase the backlash: |
| - | Increase the thickness of the right bearings shim (6) |
| - | Decrease the thickness of the left bearing shim (3) |
| • | Make the following changes in order to decrease the backlash: |
| - | Decrease the thickness of the right bearings shim (6) |
| - | Increase the thickness of the left bearing shim (3) |
You can adjust the position of the drive pinion gear (1) by changing
the thickness of the shims (2) between the following components:
| • | The drive pinion gear head (7) |
| • | The race of the differential drive pinion gear inner bearing |
The drive pinion gear shim (2) is used in the rear axle in order
to compensate for manufacturing tolerances.
| • | Increasing the shim thickness moves the drive pinion gear (7)
closer to the centerline of the differential ring gear (4). |
| • | Decreasing shim thickness moves the drive pinion gear (7)
farther away from the centerline of the differential ring gear (4). |
Effects Of Differential Drive Pinion Gear Position On Tooth Pattern
The following tooth contact
pattern exists when the differential drive pinion gear is too far away from
the centerline of the differential ring gear:
| • | High heel (2) contact on the drive side (4) |
| • | High toe (1) contact on the coast side (3) |
Decrease the backlash
in order to move the differential drive pinion gear closer to the centerline
of the differential ring gear. This will cause the following tooth contact
pattern:
| • | High heel (2) contact on the drive side (4) moves
down and toward the toe (1). |
| • | High toe (1) contact on the coast side (3) moves
down and toward the heel (2). |
The following tooth contact
pattern exists when the differential drive pinion gear is too close to the
centerline of the differential ring gear:
| • | Low toe (1) contact on the drive side (4) |
| • | Low heel (2) contact on the coast side (3) |
Increase the backlash
in order to move the differential drive pinion gear further away from the
centerline of the differential ring gear. This will cause the following tooth
contact pattern to exist:
| • | Low toe contact on the drive side (4) moves up and toward
the heel (2). |
| • | Low heel contact on the coast side (3) moves up and toward
the toe (1). |
