Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 498

DI-37

Rear Differential (T-type)

DIFFERENTIALS

(4) Align the arrow mark on the differential car-

rier with the arrow mark on the side retainer

when installing the side retainer.

NOTE:

Be careful that the side bearing outer race is not

damaged by the bearing roller.

(5) Tighten the side retainer bolts.

Tightening torque:

10.5 N·m (1.1 kgf-m, 7.7 ft-lb)

(6) Measure the hypoid driven gear to drive pin-

ion backlash. Set the magnet base on differen-

tial carrier. Align the contact point of dial gauge

with tooth face of hypoid driven gear, and move

hypoid driven gear while holding drive pinion

still. Read the value indicated on dial gauge. If

the backlash is outside the standard range, ad-

just the side retainer shim by the following

method.

• When backlash is less than 0.1 mm (0.004

in):

Reduce the thickness of shim on the back side

of the hypoid driven gear and increase the

thickness of shims on the teeth side of the hy-

poid driven gear.

• When backlash exceeds 0.2 mm (0.008 in):

Increase the thickness of shim on the back side

of the hypoid driven gear and reduce the thick-

ness of shims on the teeth side of the hypoid

driven gear.

Backlash:

0.10 — 0.20 mm (0.004 — 0.008 in)

(7) Measure the total preload of the drive pin-

ion. If the total preload is not within specifica-

tion, adjust the thickness of side retainer shims,

increasing/reducing both shims by an even

amount at a time.

Total preload:

20.7 — 54.4 N (2.1 — 5.5 kgf, 4.7 — 12.2 lbf)

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

DI-00543

(B)

(A)

DI-00487

DI-00099

DI-38

Rear Differential (T-type)

DIFFERENTIALS

17) Recheck the hypoid driven gear to drive pinion

backlash.
Backlash:

0.10 — 0.20 mm (0.004 — 0.008 in)

18) Check pinion and hypoid driven gears rotate

smoothly and make sure of the hypoid driven gear

runout on its back surface. If the hypoid driven gear

runout on its back surface exceeds the specifica-

tion, check for any foreign objects between the hy-

poid driven gear and differential case, and for any

deformation of the case or gear.
Hypoid driven gear back surface runout:

0.05 mm (0.002 in)

19) Check and adjustment of the tooth contact of

hypoid driven gear and drive pinion

(1) Apply lead-free red dye evenly on the both

sides of three to four teeth of the hypoid driven

gear. Check the contact pattern after rotating

the hypoid driven gear several revolutions back

and forth until a definite contact pattern appears

on the hypoid driven gear.

(2) When the contact pattern is not correct, re-

adjust.

NOTE:

Be sure to wipe off the lead-free red dye completely

after the adjustment is completed.

• Correct tooth contact

Check item: Tooth contact pattern is slightly

shifted toward toe side under no-load rota-

tion. (When driving, it moves towards the

heel side.)

• 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.

DI-00099

DI-00101

(A) Toe side
(B) Heel side

(A)

(B)

MT-01401

AT-00208

AT-00212

DI-39

Rear Differential (T-type)

DIFFERENTIALS

• 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.

• 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.

AT-00209

AT-00213

AT-00210

AT-00213

DI-40

Rear Differential (T-type)

DIFFERENTIALS

• 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.

20) 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.

(1) Drive pinion height

ST1 398507702

DUMMY SHAFT

ST2 398507701

DIFFERENTIAL CARRIER

GAUGE

T = To + N – (H × 0.01) – 0.20 mm (0.008 in)

(2) Hypoid gear backlash

Backlash:

0.10 — 0.20 mm (0.004 — 0.008 in)

21) Remove the RH and LH side retainers.

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

Use new O-rings.

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

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

ferential Side Oil Seal.>

24) Align the arrow mark on the differential carrier

with the arrow mark on the side retainer when in-

stalling the side retainer.

T

Thickness of pinion height adjusting washer mm (in)

To

Thickness of washer temporarily inserted mm (in)

N

Clearance of thickness gauge mm (in)

H

Figure marked on drive pinion head

Memo:

AT-00211

AT-00212

DI-00084

ST2

ST1

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

DI-00099

DI-00543

(B)

(A)