5MT-112
MANUAL TRANSMISSION AND DIFFERENTIAL
General Diagnostic
2. DIFFERENTIAL
Symptom Possible cause Remedy
1. Broken differential (case, gear, bear-
ing, etc.)
N
OTE:
Noise will develop and finally it will be-
come impossible to continue to run due to
broken pieces obstructing the gear revo-
lution. (a) Insufficient or improper oil Disassemble the differential and replace
broken components and at the same time
check other components for any trouble,
and replace if necessary.
(b) Use of vehicle under severe condi-
tions such as excessive load and
improper use of clutch Readjust the bearing preload and back-
lash and face contact of gears.
(c) Improper adjustment of taper roller
bearingAdjust.
(d) Improper adjustment of drive pinion
and hypoid driven gear Adjust.
(e) Excessive backlash due to worn dif-
ferential side gear, washer or differential
pinion vehicle under severe operating
conditions. Add recommended oil to specified level.
Do not use the vehicle under severe oper-
ating conditions.
(f) Loose hypoid driven gear clamping
boltsTighten.
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, bear-
ing, 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.
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.
Gear noise when coasting: Damaged
gears due to maladjusted bearings and
incorrect shim adjustment
Bearing noise when driving or when
coasting: Cracked, broken or damaged
bearings
Noise which mainly occurs when turn-
ing: Unusual noise from differential side
gear, differential pinion, differential pinion
shaft, etc. (a) Insufficient oil Lubricate.
(b) Improper adjustment of hypoid driven
gear and drive pinionCheck tooth contact.
(c) Worn teeth of hypoid driven gear and
drive pinionReplace as a set.
Readjust the bearing preload.
(d) Loose roller bearing Readjust the hypoid driven gear to drive
pinion backlash and check tooth contact.
(e) Distorted hypoid driven gear or differ-
ential caseReplace.
(f) Worn washer and differential pinion
shaftReplace.
