Subaru Legacy 2005 Service Manual page 2789

2. DIFFERENTIAL
Symptom
1. Broken differential (case, gear, bear-
ing, etc.)
NOTE:
Noise will be developed and finally it will
become impossible to continue to run due
to broken pieces obstructing the gear rev-
olution.
2. Differential and hypoid gear noises
Troubles of the differential and hypoid
gear always appear as noise problems.
Therefore noise is the first indication of
trouble. However noises from the engine,
muffler, tire, exhaust gas, bearing, body,
etc. are easily mistaken for the differential
noise. Pay special attention to the hypoid
gear noise because it is easily confused
with other gear noises. There are the fol-
lowing four kinds of noises.
• Gear noise when driving:
If noise increases as the vehicle speed
increases it may be due to insufficient
gear oil, incorrect gear engagement,
damaged gears, etc.
• Gear noise when coasting:
Damaged gears due to maladjusted bear-
ings and incorrect shim adjustment.
• Bearing noise when driving or coast-
ing:
Cracked, broken or rusty bearings
• Noise mainly when turning:
Noise occurs form differential side gear,
differential pinion or differential pinion
shaft, etc.
General Diagnostic Table
Possible cause
(a) Insufficient or improper oil
(b) Use of vehicle under severe condi-
tions such as excessive load and
improper use of clutch
(c) Improper adjustment of taper roller
bearing
(d) Improper adjustment of drive pinion
and hypoid driven gear
(e) Loose hypoid driven gear tightening
bolts
(a) Insufficient oil
(b) Improper adjustment of hypoid driven
gear and drive pinion
(c) Worn teeth of hypoid driven gear and
drive pinion
(d) Loose roller bearing
(e) Distorted hypoid driven gear or differ-
ential case
6MT-127
MANUAL TRANSMISSION AND DIFFERENTIAL
Corrective action
Disassemble differential and replace bro-
ken components. At the same time check
other components for any trouble, and
replace if necessary.
Readjust bearing preload and backlash
and face contact of gears.
Adjust.
Adjust.
Tighten.
Lubricate.
Check tooth contact.
Replace as a set.
Readjust bearing preload.
Readjust hypoid driven gear to drive pin-
ion backlash and check tooth contact.
Replace.