Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 501

DI-49

Rear Differential (T-type)

DIFFERENTIALS

• Face contact

Check item: Backlash is too large.

Contact pattern

Corrective action: Increase thickness of pinion

height adjusting washer according to the proce-

dure for bringing drive pinion close to hypoid

driven gear side.

• Flank contact

Check item: Backlash is too small.

Contact pattern

Corrective action: Reduce the thickness of pin-

ion height adjusting washer according to the

procedure for bringing drive pinion away from

hypoid driven gear.

AT-00208

AT-00212

AT-00209

AT-00213

DI-50

Rear Differential (T-type)

DIFFERENTIALS

• Toe contact (inside contact)

Check item: Teeth contact area is too small.

Contact pattern

Corrective action: Reduce the thickness of pin-

ion height adjusting washer according to the

procedure for bringing drive pinion away from

hypoid driven gear.

• Heel contact (outside end contact)

Check item: Teeth contact area is too small.

Contact pattern

Corrective action: Increase thickness of pinion

height adjusting washer according to the proce-

dure for bringing drive pinion close to hypoid

driven gear side.

27) If proper tooth contact is not obtained, readjust

the drive pinion height by changing the RH and LH

side retainer shims and the hypoid gear backlash.

28) Remove the RH and LH side retainers.

29) Install the O-ring to left and right side retainers.
NOTE:

Use new O-rings.

30) Install the oil seal to the side retainers on both

sides. <Ref. to DI-56, REPLACEMENT, Rear Dif-

ferential Side Oil Seal.>

31) Align the arrow mark on the differential carrier

with the arrow mark on the side retainer during in-

stallation.

AT-00210

AT-00213

(A) Arrow mark (on the side retainer)
(B) Arrow mark (on the differential carrier)

AT-00211

AT-00212

DI-00543

(B)

(A)

DI-51

Rear Differential (T-type)

DIFFERENTIALS

32) Apply liquid gasket to the bolts indicated by ar-

rows, and tighten the side retainer bolt.
Liquid gasket:

THREE BOND 1110F (Part No. K0879Y0021),

THREE BOND 1110B or equivalent

Tightening torque:

10.5 N·m (1.1 kgf-m, 7.7 ft-lb)

33) Install the gasket and rear cover, and tighten

the bolts to specified torque.
NOTE:

Use a new gasket.
Tightening torque:

44 N·m (4.5 kgf-m, 32.5 ft-lb)

34) Install the air breather cap.
NOTE:

When installing the air breather cap, do not tap sec-

tion (A). Be sure to tap section (B) to install.

35) Install the drain plug.
NOTE:

Use a new gasket.
Tightening torque:

60 N·m (6.1 kg-m, 44.3 ft-lb)

36) Install the oil temperature switch.
NOTE:

• Install the oil temperature switch and adapter as

a unit.

• After installing the rear differential assembly to

the vehicle, fill the gear oil, then use a new gasket,

and tighten to the specified torque. <Ref. to DI-19,

REPLACEMENT, Differential Gear Oil.>

E: INSPECTION

Wash all the disassembled parts clean, and exam-

ine them for wear, damage and other defects. Re-

pair or replace the defective parts as necessary.

1) Hypoid driven gear and drive pinion

• If there is evidently an abnormal tooth contact,

find out the cause and adjust until the teeth contact

correctly. Replace the gear if there is an excessive

worn or an incapable adjustment.

• If crack, cutout or seizure is found, replace the

parts as a set. Slight damage of some teeth can be

corrected by oil stone or the like.

2) Side gear and pinion mate gear (T-type (B2))

• Replace if cracks, scoring or other defects are

evident on the tooth surface.

• Replace if thrust washer contact surface is worn

or seized. Slight damages of the surface can be

corrected by oil stones or equivalent.

3) Bearing

Replace if seizure, peeling, wear, rust, dragging

during rotation, noise or other defect is evident.

4) Thrust washer of side gear and pinion mate gear

(T-type (B2))

Replace if seized, flawed, abnormally worn or hav-

ing other defects.

5) Oil seal

Replace if deformed or damaged, and at every dis-

assembling.

6) Differential carrier

Replace if the bearing bores are worn or damaged.

7) Differential case

Replace if sliding surfaces are abnormally worn,

burned, or cracked.

8) Companion flange

Replace if the oil seal lip contact surface shows

cracking.

DI-00461

DI-00679

(A)

(B)

DI-52

Rear Differential (T-type)

DIFFERENTIALS

9) Rear differential oil temperature switch (T-type

(H3))

Check the rear differential oil temperature switch

for continuity.

1. SIDE GEAR BACKLASH (T-TYPE (B2))

Using a dial gauge, check the backlash of side

gear.
Side gear backlash:

0.10 — 0.20 mm (0.004 — 0.008 in)

If the side gear backlash is not within the specifica-

tion, select the side gear thrust washer and adjust

the side gear backlash to the specification.

2. HYPOID DRIVEN GEAR BACKLASH

Using a dial gauge, check the backlash of hypoid

driven gear.
Hypoid driven gear backlash:

0.10 — 0.20 mm (0.004 — 0.008 in)

If the hypoid driven gear backlash is not within the

specification, adjust the side bearing preload or re-

pair if necessary.

3. HYPOID DRIVEN GEAR RUNOUT ON ITS

BACK SURFACE

Using a dial gauge, check the hypoid driven gear

back surface runout.
Hypoid driven gear back surface runout:

0.05 mm (0.002 in)

If the hypoid driven gear runout exceeds specifica-

tion, replace the hypoid driven gear.

4. TOOTH CONTACT BETWEEN HYPOID

DRIVEN GEAR AND DRIVE PINION

Inspect the tooth contact between the hypoid driv-

en gear and drive pinion. <Ref. to DI-31, ASSEM-

BLY, Rear Differential (T-type).>

Resistance

Criteria

Less than 1 Ω

Normal

1 MΩ or more

REPLACEMENT

DI-00534

DI-00315

DI-00099

DI-00101