Subaru Legacy 2002 Service Manual page 1733

Manual Transmission and Differential
2. DIFFERENTIAL
S503278A1002
Symptom
1. Broken differential (case, gear,
bearing, etc.)
NOTE:
Abnormal noise will develop and finally it
will become impossible to continue to
run due to broken pieces obstructing the
gear revolution.
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
the 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 following four
kinds of noises.
¼ Gear noise when driving: If noise
increases as vehicle speed increases it
may be due to insufficient gear oil, incor-
rect gear engagement, damaged gears,
etc.
¼ Gear noise when coasting: Damaged
gears due to maladjusted bearings and
incorrect shim adjustment
¼ Bearing noise when driving or when
coasting: Cracked, broken or damaged
bearings
¼ Noise which mainly occurs when turn-
ing: Unusual noise from differential side
gear, differential pinion, differential pinion
shaft, etc.
GENERAL DIAGNOSTIC
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) Excessive backlash due to worn dif-
ferential side gear, washer or differential
pinion vehicle under severe operating
conditions.
(f) Loose hypoid driven gear clamping
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
(f) Worn washer and differential pinion
shaft
MT-108
Remedy
Disassemble differential and replace bro-
ken components and 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.
Add recommended oil to specified level.
Do not use vehicle under severe operat-
ing conditions.
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.
Replace.