Subaru Legacy IV (2008 year). Manual - part 828

6MT-125

Clutch Housing

MANUAL TRANSMISSION AND DIFFERENTIAL

D: ASSEMBLY

1) Attach the oil seal to the clutch housing, being
careful not to damage the seal.

NOTE:
Use a new oil seal.
ST

18657AA020

OIL SEAL INSTALLER

2) Install the clutch release bearing guide.

Tightening torque:

6.4 N·m (0.7 kgf-m, 4.7 ft-lb)

E: INSPECTION

1) Check to make sure there is no damage or
cracks on the clutch housing. If there is excessive
damage, replace the clutch housing.
2) Inspect the clutch housing for transmission gear
oil leakage. If any oil leaks are found, repair or re-
place the applicable part.

MT-01382

ST

MT-01383

6MT-126

General Diagnostic Table

MANUAL TRANSMISSION AND DIFFERENTIAL

24.General Diagnostic Table

A: INSPECTION

1. MANUAL TRANSMISSION

Symptom

Possible cause

Corrective action

1. Gears are difficult to engage

NOTE:
If it is difficult to shift, there are 2 possible 
causes. One is a defective gear shift sys-
tem and the other is defective transmis-
sion. However, if the operation is heavy 
and engagement of the gears is difficult, a 
defective clutch function may also be re-
sponsible. Check whether the clutch is 
correctly functioning, before checking the 
gear shift system and transmission.

(a) Worn, damaged or burred chamfer at 
internal spline of the sleeve

Replace.

(b) Gear spline wear, damage, dents

Replace.

(c) Worn or scratched bushings

Replace.

(d) Incorrect contact or wear between 
synchronizer ring and gear cone

Repair or replace.

2. Gear slip-out
• Gear slips out when coasting on rough 
road.
• Gear slips out during acceleration.

(a) Defective pitching stopper

Adjust.

(b) Loose engine mounting bolts

Tighten or replace.

(c) Worn fork shifter, broken shifter fork 
rail spring

Replace.

(d) Worn or damaged ball bearing

Replace.

(e) Large clearance between splines of 
synchronizer hub and synchronizer 
sleeve

Replace.

(f) Worn in the synchronizer hub chamfer 
angle

Replace.

(g) Worn 1st driven gear, needle bearing 
and race

Replace.

(h) Worn 2nd driven gear, needle bearing 
and race

Replace.

(i) Worn 3rd drive gear and bushing

Replace.

(j) Worn 4th drive gear and bushing

Replace.

(k) Worn 5th drive gear and bushing

Replace.

(l) Worn 6th drive gear and bushing

Replace.

(m) Worn reverse idler gear and bushing

Replace.

3. Noise emitted from transmission

NOTE:
If a noise is heard when the vehicle is 
parked with its engine idling and ceases 
when the clutch is disengaged, it may be 
considered that the noise is coming from 
the transmission.

(a) Insufficient or improper lubrication

Replenish the specified amount of desig-
nated oil or replace.

(b) Worn or damaged gears and bearings

NOTE:
If the trouble is only wear of the gear teeth 
surfaces, only a high whirring noise will 
occur at high speeds, but if any part is bro-
ken, rhythmical clicking sounds will be 
heard even at low speeds.

Replace.

6MT-127

General Diagnostic Table

MANUAL TRANSMISSION AND DIFFERENTIAL

2. DIFFERENTIAL

Symptom

Possible cause

Corrective action

1. Broken differential (case, gear, bear-
ing, etc.)

NOTE:
Noise will occur, and eventually the differ-
ential will not be able to operate due to 
broken pieces obstructing the gear revo-
lution.

(a) Insufficient or improper oil

Disassemble the differential and replace 
broken components. 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 the clutch

Readjust the preload and backlash of the 
bearing, and the contact surface of gear.

(c) Improper adjustment of taper roller 
bearing

Adjust.

(d) Improper adjustment of the drive pin-
ion and the hypoid driven gear

Adjust.

(e) Loose hypoid driven gear clamp bolts

Tighten.

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 misadjusted bearings and 
incorrect shim adjustment
• Bearing noise when driving or coasting: 
Cracked, broken or damaged bearings.

(a) Insufficient oil

Replenish the specified amount of desig-
nated oil or replace.

(b) Improper adjustment of hypoid driven 
gear and drive pinion

Check the tooth contact.

(c) Worn teeth of hypoid driven gear and 
drive pinion

Replace as a set.
Readjust the bearing preload.

(d) Loose roller bearing

Readjust the backlash of the hypoid 
driven gear to drive pinion, and check the 
tooth contact.

(e) Distorted hypoid driven gear or differ-
ential case

Replace.

6MT-128

General Diagnostic Table

MANUAL TRANSMISSION AND DIFFERENTIAL