Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 504

DI-61

Rear Differential Mount Bushing

DIFFERENTIALS

11) Insert the ST set in the step 9) through the sub

frame from the front side of vehicle, and screw in

the ST1 by hand till the front end of ST1 comes out

slightly from the rear end of ST2.
CAUTION:

Set the rear differential mount bushing with its

mark facing the bottom end direction.

ST1 41399FG091 SPECIAL TOOL SHAFT

ST2 41399FG061 SPECIAL TOOL RING

12) Hold the ST1 to prevent it from rotating, and

screw in the ST2 by hand till there is no loose fit on

the ST and the rear differential mount bushing.
CAUTION:

Make sure that the ST and rear differential

mount bushing are not tilted.

ST1 41399FG091 SPECIAL TOOL SHAFT

ST2 41399FG070 SPECIAL TOOL NUT

13) Screw in the ST2 while holding the ST1 with a

tool to prevent it from rotating, and press-fit the rear

differential mount bushing to the front end of sub

frame cylinder.

ST1 41399FG091 SPECIAL TOOL SHAFT

ST2 41399FG070 SPECIAL TOOL NUT

14) Make sure that the rear differential mount bush-

ing is inserted to the front end of sub frame cylinder.

15) Install the rear differential. <Ref. to DI-24, IN-

STALLATION, Rear Differential (T-type).>

(A) Mark

DI-00977

( A)

ST2

ST1

ST1

DI-00664

ST2

ST1

(A) Front side of vehicle

DI-00665

ST2

ST1

DI-00666

(A)

DI-62

General Diagnostic Table

DIFFERENTIALS

9. General Diagnostic Table

A: INSPECTION

Symptom or trouble

Possible cause

Remedy

1. Oil leakage

(1) Worn, scratched, or incorrectly seated
front or side oil seal. Scored, battered or
excessively worn sliding surface of com-
panion flange.

Repair or replace.

(2) Clogged or damaged air breather cap. Clean, repair or replace.
(3) Loose bolts on the side retainer, or
incorrectly fitted O-ring.

Tighten the bolts to specified torque.
Replace the O-ring.

(4) Loose rear cover attachment bolts or
damaged gasket.

Replace the gasket, and tighten the bolts
to specified torque.

(5) Loose filler plug or drain plug.

• Apply liquid gasket, and tighten to the
specified torque. (T-type (B2))
• Replace the gasket, and tighten to the
specified torque. (T-type (H3))

(6) Wear, damage or incorrect fitting of
drive shaft, side retainer or oil seal.

Repair or replace.

2. Seizure
NOTE:

Seized or damaged parts should be re-
placed, and also other parts should be
thoroughly checked for any defect and
should be repaired or replaced as re-
quired.

(1) Insufficient backlash for hypoid gear.

Readjust or replace.

(2) Excessive preload for side, rear or
front bearing.

Readjust or replace.

(3) Insufficient or improper oil used.

Add recommended differential oil to the
specified level.

3. Damage
NOTE:

Damaged parts should be replaced, and
also other parts should be thoroughly
checked for any defect and should be re-
paired or replaced as required.

(1) Improper backlash for hypoid gear.

Readjust or replace.

(2) Insufficient or excessive preload for
side, rear or front bearing.

Readjust or replace.

(3) Excessive backlash for side gear.

• Replace gear or thrust washer. (T-type
(B2))
• Replace the differential case assembly.
(T-type (H3))

(4) Loose bolts and nuts such as hypoid
driven gear bolt.

Retighten.

(5) Damage due to overloading.

Replace.

4. Noises when starting or shifting
gears
NOTE:

Noises may be caused by differential as-
sembly, universal joint, wheel bearing,
etc. Find out what is actually making noise
before disassembling.

(1) Improper tooth contact of hypoid
driven gear and drive pinion

Readjust. (Drive pinion shim adjustment,
backlash adjustment)

(2) Excessive backlash for hypoid driven
gear

Replace the gear or the pinion height
adjusting washer.

(3) Excessive backlash for side gear.

• Replace gear or thrust washer. (T-type
(B2))
• Replace the differential case assembly.
(T-type (H3))

(4) Insufficient preload for front or rear
bearing.

Readjust.

(5) Loose drive pinion nut.

Tighten to the specified torque.

(6) Loose bolts and nuts such as side
retainer attachment bolt.

Tighten to the specified torque.

DI-63

General Diagnostic Table

DIFFERENTIALS

5. Noises when cornering

(1) Damaged differential gear.

• Replace the differential gear. (T-type
(B2))
• Replace the differential case assembly.
(T-type (H3))

(2) Excessive wear or damage of thrust
washer.

Replace the thrust washer. (T-type (B2))

(3) Broken pinion mate shaft.

Replace the pinion mate shaft. (T-type
(B2))

(4) Stuck or damaged side bearing

Replace.

6. Gear noise
NOTE:

Since noises from engine, muffler, trans-
mission, propeller shaft, wheel bearings,
tires, and body are sometimes mistaken
for noises from differential assembly, be
careful in checking them. Inspection
methods to locate noises include coast-
ing, accelerating, cruising, and lifting-up
all four wheels. Perform these inspections
according to the condition of trouble.
When listening to noises, shift the gear
into four-wheel drive and fourth speed po-
sition, trying to pick up only differential
noise.

(1) Improper tooth contact of hypoid
driven gear and drive pinion

Readjust or replace the hypoid gear set.

(2) Improper backlash of the hypoid
driven gear

Readjust.

(3) Scored or chipped teeth of hypoid
gear.

Replace hypoid gear set.

(4) Scuffed hypoid gear

Replace hypoid gear set.

(5) Improper preload for front or rear
bearings.

Readjust.

(6) Stuck, scored or chipped teeth of front
or rear bearing

Replace.

(7) Stuck, scored or chipped teeth of side
bearing

Replace.

(8) Vibrating differential gear.

Replace the differential gear.

Symptom or trouble

Possible cause

Remedy

DI-64

General Diagnostic Table

DIFFERENTIALS