Rear Differential: Assembly

1. Install the rear bearing race into the differential carrier using ST1 and ST2.

   ST1 398477701 HANDLE

   ST2 398477703 DRIFT 2

   Fig 2: Identifying Special Tools

   Courtesy of SUBARU OF AMERICA, INC.
2. Install the front bearing race to the differential carrier using ST1 and ST2.

   ST1 398477701 HANDLE

   ST2 398477702 DRIFT

3. Insert the ST1 into carrier with the pinion height adjusting washer and rear bearing cone fitted onto it.
   NOTE:

   • If tooth contact (drive pinion, hypoid driven gear) is normal in the inspection before disassembling, verify that the washer is not deformed, and then reuse the used washer.
   • Use new rear bearing cone.
4. Install the preload adjusting spacer & washer, front bearing cone, ST2, companion flange, and washer & self-locking nut.

   ST1 398507702 DUMMY SHAFT

   ST2 398507703 DUMMY COLLAR

   Fig 3: Identifying Pinion Height Adjusting Washer And Preload Adjuster Spacer

   Courtesy of SUBARU OF AMERICA, INC.
5. Turn the ST1 by hand to smooth the bearing, and tighten the self-locking nut while measuring the initial load or initial torque with a spring scale or torque wrench. Select the preload adjusting washer and spacer so that the specified preload is obtained when nut is tightened to the specified torque.

ST1 398507702 DUMMY SHAFT

ST2 398507704 BLOCK

Tightening torque: 

181.5 N.m (18.5 kgf-m, 134.0 ft-lb) 

Fig 4: Identifying Special Tools

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Initial load: 

17.7 - 38.8 N (1.8 - 4.0 kgf, 4.0 - 8.7 lb) 

Fig 5: Measuring Initial Load

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Initial torque: 

0.67 - 1.47 N.m 

(0.07 - 0.15 kgf-m, 0.49 - 1.08 ft-lb) 

Fig 6: Measuring Initial Torque

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Adjust the drive pinion height with washer installed between the rear bearing cone and the back of pinion gear.

1. Attach the ST2.
   NOTE: At this time, install a pinion height adjusting washer, temporarily selected, or the same as that used before. Measure and record the thickness.

   ST1 398507702 DUMMY SHAFT

   ST2 398507701 DIFFERENTIAL CARRIER GAUGE

   ST3 398507703 DUMMY COLLAR

   Fig 7: Identifying Pinion Height Adjuster Washer

   Courtesy of SUBARU OF AMERICA, INC.
2. Measure the clearance N between the end of ST2 and the end surface of ST1 by using a thickness gauge.
   NOTE: Make sure there is no clearance between the case and ST2.

   ST1 398507702 DUMMY SHAFT

   ST2 398507701 DIFFERENTIAL CARRIER GAUGE

   Fig 8: Identifying Special Tools

   Courtesy of SUBARU OF AMERICA, INC.
3. Obtain the thickness of pinion height adjusting washer to be inserted from the following formula, and replace the temporarily installed washer with this one.

T = To + N - (H x 0.01) - 0.20 mm (0.0079 in)

(Example of calculation)

To = 2.20 mm (0.0866 in) + 1.20 mm (0.0472 in)

= 3.40 mm (0.1339 in)

N = 0.23 mm (0.0091 in)

H = + 1

T = 3.40 mm (0.1339 in) + 0.23 mm (0.0091 in)

- 0.01 mm (0.0004 in) - 0.20 mm (0.0079 in) =

3.42 mm (0.1346 in)

Thickness = 3.42 mm (0.1346 in)

Therefore use washer 383605200.

ST 398177700 INSTALLER

Fig 9: Pressing Rear Bearing Cone

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ST1 398507703 DUMMY COLLAR

ST2 399780104 WEIGHT

ST3 899580100 INSTALLER

Fig 11: Pressing Front Bearing Cone Into Case

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ST1 399780104 WEIGHT

ST2 899580100 INSTALLER

Fig 12: Pressing Pilot Bearing

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ST 498447120 INSTALLER

Fig 13: Pressing Oil Seal

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ST1 899874100 INSTALLER

ST2 399780104 WEIGHT

Fig 14: Pressing Companion Flange

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SEAL MATERIAL 

THREE BOND 1324 (Part No. 004403042) or equivalent 

ST 498427200 FLANGE WRENCH

Tightening torque: 

181.5 N.m (18.5 kgf-m, 134.0 ft-lb) 

Fig 15: Tightening Self-Locking Nut

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Install the side gears and pinion mate gears, with their thrust washers and pinion mate shaft, into the differential case.

Fig 16: Identifying Differential Gears

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1. Measure the side gear backlash.

   Side gear backlash: 

   0.10 - 0.20 mm (0.004 - 0.008 in) 

   Fig 17: Measuring Side Gear Backlash

   Courtesy of SUBARU OF AMERICA, INC.
2. Adjust the backlash as specified by selecting side gear thrust washer.
   SIDE GEAR THRUST WASHER THICKNESS
   
   

   Side gear thrust washer
   Part No.	Thickness mm (in)
   383445201	0.75 - 0.80 (0.0295 - 0.0315)
   383445202	0.80 - 0.85 (0.0315 - 0.0335)
   383445203	0.85 - 0.90 (0.0335 - 0.0354)

3. Check the condition of rotation after applying oil to the gear tooth surfaces and thrust washer surfaces.
4. After inserting the pinion shaft lock pin into differential case, stake the both sides of the hole to prevent pin from falling off.

SEAL MATERIAL 

THREE BOND 1324 (Part No. 004403042) or equivalent 

Tightening torque: 

103 N.m (10.5 kgf-m, 76.0 ft-lb) 

Fig 18: Tightening Differential Case Bolts

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ST 398487700 DRIFT

Fig 19: Pressing Side Bearing Into Differential Case

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ST 398417700 DRIFT

Fig 20: Pressing Side Bearing Outer Race Into Side Bearing Retainer

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1. The hypoid driven gear backlash and side bearing preload can be adjusted by the side bearing retainer shim thickness.
2. Install the differential case assembly into differential carrier in the reverse order of disassembly.
   NOTE: Be careful so that the teeth do not hit against the case.
   Fig 21: Installing Differential Case Assembly Into Differential Carrier

   Courtesy of SUBARU OF AMERICA, INC.
3. Install the side bearing retainer shims and O-ring to retainers RH and LH on which they were installed.
   NOTE:

   • Replace the broken or cracked O-ring with a new part.
   • Replace broken or corroded side retainer shims with a new part of the same thickness.
   SIDE BEARING RETAINER SHIM THICKNESS
   
   

   Side bearing retainer shim
   Part No.	Thickness mm (in)
   383475201	0.20 (0.0079)
   383475202	0.25 (0.0098)
   383475203	0.30(0.0118)
   383475204	0.40(0.0157)
   383475205	0.50(0.0197)

4. Align the arrow mark on differential carrier with the mark on side retainer during installation.
   NOTE: Be careful that side bearing outer race is not damaged by the bearing roller.
   Fig 22: Aligning Arrow Mark On Differential Carrier

   Courtesy of SUBARU OF AMERICA, INC.
5. Tighten the side bearing retainer bolts.

   Tightening torque: 

   10.5 N.m (1.1 kgf-m, 7.7 It-lb) 

   Fig 23: Locating Side Bearing Retainer Bolts

   Courtesy of SUBARU OF AMERICA, INC.
6. Measure the backlash between the hypoid driven gear and drive pinion. Set the magnet base on differential carrier. Align the contact point of dial gauge with the tooth surface of hypoid driven gear, and move the hypoid driven gear while securing the drive pinion. Read the value indicated on dial gauge. If the backlash is not within the range of specifications, adjust the side bearing retainer shim using the following procedures.
   • When backlash is less than 0.1 mm (0.004 in): 

     Reduce the hypoid driven gear rear face shim thickness and increase the hypoid driven gear tooth surface side shim thickness.

   • When backlash exceeds 0.2 mm (0.008 in): 

   Increase the hypoid driven gear rear face shim thickness and reduce the tooth surface side shim thickness.

   Backlash: 

   0.10 - 0.20 mm (0.004 - 0.008 in) 

   Fig 24: Measuring Backlash Between Hypoid Driven Gear And Drive Pinion

   Courtesy of SUBARU OF AMERICA, INC.
7. At the same time, measure the total preload of the drive pinion. Compared with the resistance when differential case is not installed, if the total preload is not within specification, adjust the thickness of side bearing 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) 

Backlash: 

0.10 - 0.20 mm (0.004 - 0.008 in) 

Fig 25: Measuring Backlash Between Hypoid Driven Gear And Drive Pinion

Courtesy of SUBARU OF AMERICA, INC.

If the hypoid driven gear runout on its back surface exceeds the specification, check for any foreign objects between the hypoid 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) 

Fig 26: Measuring Hypoid Driven Gear Back Surface Runout

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1. Apply red lead evenly to the both side of three or four teeth on 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, readjust.

• Correct tooth contact

Check item: Tooth contact pattern is slightly shifted toward toe side under no-load rotation. (When driving, it moves towards the heel side.) 

Fig 27: Identifying Toe And Heel Side

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• Face contact

Check item: Backlash is too large. 

Contact pattern

Fig 28: Identifying Contact Pattern - Face

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Corrective action: Increase thickness of drive pinion height adjusting washer in order to bring drive pinion close to hypoid driven gear.

Fig 29: Increasing Thickness Of Drive Pinion Height Adjusting Washer

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• Flank contact

Check item: Backlash is too small. 

Contact pattern

Fig 30: Identifying Contact Pattern - Flank

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Adjustment: Reduce the thickness of pinion height adjusting washer according to the procedure for bringing the drive pinion away from hypoid driven gear.

Fig 31: Reducing Thickness Of Pinion Height Adjusting Washer

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• Toe contact (inner side contact)

Check item: Contact area is too small. 

Contact pattern

Fig 32: Identifying Contact Pattern - Toe Contact

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Adjustment: Reduce the thickness of pinion height adjusting washer according to the procedure for bringing the drive pinion away from hypoid driven gear.

Fig 33: Reducing Thickness Of Pinion Height Adjusting Washer

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• Heel contact (outside end contact)

Check item: Contact area is too small. 

Contact pattern

Fig 34: Identifying Contact Pattern - Heel Contact

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Corrective action: Increase thickness of drive pinion height adjusting washer in order to bring drive pinion close to hypoid driven gear.

Fig 35: Increasing Thickness Of Drive Pinion Height Adjusting Washer

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1. Drive pinion height

ST1 398507702 DUMMY SHAFT

ST2 398507701 DIFFERENTIAL CARRIER GAUGE

Fig 36: Identifying Special Tools

Courtesy of SUBARU OF AMERICA, INC.

T = To + N - (H x 0.01) - 0.20 (mm)

Place:

T = Thickness of pinion height adjusting washer (mm)

To = Thickness of washer temporally inserted (mm)

N = Clearance of thickness gauge (mm)

H = Figure marked on drive pinion head

(2) Hypoid gear backlash

Backlash: 

0.10 - 0.20 mm (0.004 - 0.008 in) 

Fig 37: Measuring Hypoid Gear Backlash

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Liquid gasket: 

THREE BOND 1105 (Part No. 004403010) or equivalent 

Tightening torque: 

10.5 N.m (1.1 kgf-m, 7.7 ft-lb) 

Fig 39: Locating Side Bearing Retainer Bolts

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Tightening torque: 

29.5 N.m (3.0 kgf-m, 21.8 ft-lb) 

Fig 40: Identifying Rear Cover Gasket

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Tightening torque: 

49 N.m (5.0 kgf-m, 36.2 ft-lb)