Differentials: Overhaul Subaru Forester SG

DISASSEMBLY

To detect the real cause of trouble, inspect the following items before disassembling.

1. Tooth contact of crown gear and pinion, and backlash
2. Runout of crown gear at its back surface
3. Turning resistance of drive pinion

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1. Set the ST on vise and install the differential assembly to ST. ST 398217700 ATTACHMENT
2. Drain the gear oil by removing the plug.
3. Remove the air breather cap. NOTE: Do not attempt to remove the air breather cap unless necessary. When removing the air breather cap, replace the air breather cap with a new one.
4. Remove the rear cover by loosening the retaining bolts.
5. Make right and left side bearing retainers in order to identify them at reassembly. Remove the side bearing retainer attaching bolts, set the ST to differential case, and extract right and left side bearing retainers with a puller. NOTE: Each shim, which is installed to adjust the side bearing preload, should be kept together with its mating retainer. ST 398457700 ATTACHMENT
6. Pull out the differential case assembly from differential carrier. NOTE: Be careful not to hit the teeth against the case.
7. Remove the O-ring from side bearing retainer.
8. Remove the oil seal from side bearing retainer. Refer to «REPLACEMENT»(ref-200799-S37428741292005102300000) , Rear Differential Side Oil Seal.
9. Pull the bearing cup from side bearing retainer using ST. ST 398527700 PULLER ASSY
10. Extract the bearing cone with ST. NOTE: Set the puller so that its claws catch the edge of bearing cone. Never mix up the right and left hand bearing races and cones. ST 399527700 PULLER SET
11. Remove the crown gear by loosening the crown gear bolts.
12. Drive out the pinion shaft lock pin from crown gear side. (Without LSD) NOTE: The lock pin is staked at the pin hole end on the differential carrier; do not drive it out forcibly before unstaking it. ST 899904100 STRAIGHT PIN REMOVER
13. Draw out the pinion mate shaft and remove the pinion mate gears, side gears and thrust washers. (Without LSD) NOTE: The gears as well as thrust washers should be marked or kept separated right and left, front and rear.
14. Hold the companion flange with ST and remove the drive pinion nut. ST 498427200 FLANGE WRENCH
15. Extract the companion flange with a puller.
16. Press the end of drive pinion shaft and extract it together with the rear bearing cone, preload adjusting spacer and washer. NOTE: Hold the drive pinion so as not to drop it. ST 398467700 DRIFT
17. Remove the rear bearing cone from drive pinion by supporting the cone with ST. NOTE: Place the replacer so that its center-recessed side faces the pinion gear. ST 398517700 REPLACER
18. Remove the front oil seal from differential carrier using ST. ST 398527700 PULLER ASSY
19. Remove the pilot bearing together with front bearing cone using ST. ST 398467700 DRIFT
20. When replacing the bearings, hit out the front bearing cup and rear bearing cup in this order out of case by using a brass bar.

ASSEMBLY

Note. Assemble in the reverse order of disassembling. Check and adjust each part during assembly. Keep the shims and washers in order, so that they are not improperly installed. Thoroughly clean the surfaces on which the shims, washers and bearings are to be installed. Apply gear oil when installing the bearings and thrust washers. Be careful not to mix up the right and left hand races of the bearings. Use a new O-ring and gasket. Replace the oil seal with a new one at every disassembly. Apply chassis grease between the lips when installing the oil seal.

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1. Adjusting preload for front and rear bearings Adjust the bearing preload with spacer and washer between front and rear bearings. Pinion height adjusting washer are not affected by this adjustment. The adjustment must be carried out without oil seal inserted. Press the rear bearing race (rear) into differential carrier using ST1 and ST2. ST1 398477701 HANDLE ST2 398477703 DRIFT 2 Using ST1 and ST2, install the rear bearing race (front) to differential carrier. ST1 398477701 HANDLE ST2 398477702 DRIFT Insert the ST1 into carrier with pinion height adjusting washer and rear bearing cone fitted onto it. NOTE: Re-use the used washer if not deformed. Use a new rear bearing cone. Then install the preload adjusting spacer and washer, front bearing cone, ST2, companion flange, and washer and drive pinion nut. ST1 398507702 DUMMY SHAFT ST2 398507703 DUMMY COLLAR Turn the ST1 with hand to make it seated, and tighten the drive pinion nut while measuring the preload with spring balance. Select the preload adjusting washer and spacer so that the specified preload is obtained when nut is tightened to the specified torque. NOTE: Use a new lock nut. Be careful not to give excessive preload. When tightening the drive pinion nut, lock ST2 with ST1 as shown in the figure. ST1 398507704 BLOCK ST2 398507702 DUMMY SHAFT Tightening torque: 181 N.m (18.5 kgf-m, 134 ft-lb)
2. Adjusting drive pinion height Adjust the drive pinion height with shim installed between the rear bearing cone and back of pinion gear. Do not remove the ST1, ST2 and ST3 out of position after adjusting pinion bearing preload in previous step. NOTE: At this time, install a pinion height adjusting shim which is 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 Measure the clearance N between the end of ST2 and 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 Obtain the thickness of pinion height adjusting shim to be inserted from the following formula, and replace the temporarily installed shim with this one. T = To + N - (H x 0.01) - 0.20 mm (0.0079 in) NOTE: Use copies of this page. (Example of calculation) To = 2.20 + 1.20 = 3.40 mm N = 0.23 mm H = +1 T = 3.40 + 0.23 - 0.01 - 0.20 = 3.42 Result: Thickness = 3.42 mm Therefore use the shim 383605200.
3. Install the selected pinion height adjusting shim on drive pinion, and press the rear bearing cone into position with ST. ST 398177700 INSTALLER
4. Insert the drive pinion into differential carrier, install the previously selected bearing preload adjusting spacer and washer.
5. Press-fit the front bearing cone into case with ST1, ST2 and ST3. ST1 398507703 DUMMY COLLAR ST2 399780104 WEIGHT ST3 899580100 INSTALLER
6. Insert the spacer, then press-fit the pilot bearing with ST1 and ST2. ST1 399780104 WEIGHT ST2 899580100 INSTALLER
7. Fit a new oil seal with ST. NOTE: Press-fit until the end of oil seal is 1 mm (0.04 in) inward from end of carrier. Apply grease between the oil seal lips. ST 498447120 DRIFT
8. Press-fit the companion flange with ST1 and ST2. NOTE: Be careful not to damage the bearing. ST1 899874100 INSTALLER ST2 399780104 WEIGHT
9. Install the self-locking nut. Then tighten it with the ST. ST 498427200 FLANGE WRENCH Tightening torque: 181.5 N.m (18.5 kgf-m, 133.8 ft-lb)
10. Assembling differential case Install the side gears and pinion mate gears, with their thrust washers and pinion mate shaft, into differential case. (Without LSD) NOTE: Apply gear oil on both sides of the washer and on the side gear shaft before installing. Insert the pinion mate shaft into the differential case by aligning the lock pin holes. Measure the side gear backlash. Side gear back clearance: 0.10 - 0.20 mm (0.0039 - 0.0079 in) Adjust the backlash as specified by selecting the side gear thrust washer. Check the condition of rotation after applying oil to the gear tooth surfaces and thrust surfaces. After inserting the pinion shaft lock pin into differential case, stake both sides of the hole to prevent pin from falling off.
11. Install the crown gear on differential case. NOTE: Before installing the bolts, apply Lock Tite to bolt threads. Lock Tite: THREE BOND 1324 (Part number: 004403042) or equivalent NOTE: Tighten diagonally while tapping the bolt heads. Tightening torque: 103 N.m (10.5 kgf-m, 75.9 ft-lb)
12. Press the side bearing onto differential case with ST. ST 398237700 DRIFT
13. Press the side bearing cone into side bearing retainer using ST. ST 398487700 DRIFT
14. Adjusting side bearing retainer shims The driven gear backlash and side bearing preload can be determined by the side bearing retainer shim thickness. Install the differential case assembly into differential carrier in the reverse order of disassembly. Install the side retainer shims to the right and left retainers from which they were removed. NOTE: Replace the broken or corroded side retainer shim with a new one of same thickness. Align the arrow mark on differential carrier with the mark on side retainer during installation. Tighten the side bearing retainer bolts. Lock Tite: THREE BOND 1105 (Part No. 004403010) or equivalent Tightening torque: 10.3 N.m (1.05 kgf-m, 7.6 ft-lb) Measure the crown gear-to-drive pinion backlash. Set the magnet base on differential carrier. Align the contact point of dial gauge with tooth face of crown gear, and move the crown gear while holding drive pinion still. Read the value indicated on dial gauge. If the backlash is not within specification, adjust the side bearing retainer shim as follows. When backlash is more than 0.2 mm (0.0079 in): Reduce shim thickness of behind crown gear, and increase shim thickness of crown gear side. When backlash is less than 0.1 mm (0.0039 in): Increase shim thickness of behind crown gear, and reduce shim thickness of crown gear side. Backlash: 0.10 - 0.20 mm (0.0039 - 0.0079 in) If the total preload is not within specification, adjust the thickness of side bearing retainer shims, increasing/reducing by an even amount at a time. Turning resistance increase: 2.9 - 10.8 N (0.3 - 1.1 kgf, 0.7 - 2.4 lb)
15. Re-check the crown gear-to-pinion backlash. Backlash: 0.10 - 0.20 mm (0.0039 - 0.0079 in)
16. Check the crown gear runout on its back surface, and make sure that pinion and crown gear rotate smoothly. Limit of runout: Less than 0.05 mm (0.0020 in)
17. Checking and adjusting tooth contact of crown gear Apply an even coat of red lead on both sides of three or four teeth on the crown gear. Check the contact pattern after rotating the crown gear several revolutions back and forth until a definite contact pattern appears on the crown gear. When the contact pattern is incorrect, readjust according to the instructions given in "TOOTH CONTACT PATTERN". NOTE: Be sure to wipe off red lead completely after adjustment is completed. Correct tooth contact Checking item: Tooth contact pattern is slightly shifted toward to toe side under no-load rotation. (When loaded, contact pattern moves toward heel) Face contact Checking item: Backlash is too large. Contact pattern Corrective action: Increase thickness of drive pinion height adjusting shim in order to bring drive pinion close to crown gear. Flank contact Checking item: Backlash is too small. Contact pattern Corrective action: Reduce thickness of drive pinion height adjusting shim in order to move drive pinion away from crown gear. Toe contact (Inside end contact) Checking item: Contact area is small. Contact pattern Corrective action: Reduce thickness of drive pinion height adjusting shim in order to move drive pinion away from crown gear. Heel contact (Outside end contact) Checking item: Contact area is small. Contact pattern Corrective action: Increase thickness of drive pinion height adjusting shim in order to bring drive pinion close to crown gear.
18. If proper tooth contact is not obtained, once again adjust the drive pinion height by changing RH and LH side bearing retainer shims and the hypoid gear backlash. Drive pinion height ST1 398507702 DUMMY SHAFT ST2 398507701 DIFFERENTIAL CARRIER GAUGE T = To + N - (H x 0.01) - 0.20 (mm) Where: T = Thickness of pinion height adjusting shim (mm) To = Thickness of shim temporarily inserted (mm) N = Reading of thickness gauge (mm) H = Figure marked on drive pinion head Hypoid gear backlash Backlash: 0.10 - 0.20 mm (0.0039 - 0.0079 in)
19. Remove the right and left side bearing retainers.
20. Install the right and left side bearing retainer, O-rings and side bearing retainer shims.
21. Install the oil seals to the right and left side bearing retainers.
22. Align the arrow mark on differential carrier with the mark on side retainer during installation.
23. Tighten the side bearing retainer bolts. Lock Tite: THREE BOND 1105 (Part No. 004403010) or equivalent Tightening torque: 10.3 N.m (1.05 kgf-m, 7.6 ft-lb)
24. Install the new gasket and rear cover and tighten the bolts to specified torque.

1. Tightening torque: 29 N.m (3.0 kgf-m, 21.7 ft-lb)

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Note. Clean the rear differential member before disassembly.

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1. Remove the bolt (A) and (B) which connect front differential member and differential mounting bracket.
2. Remove the dynamic damper from front differential member.

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1. Install the dynamic damper to front differential member. Tightening torque: 20 N.m (2.0 kgf-m, 14.5 ft-lb)
2. Temporarily tighten the connecting bolt (A) which secures front differential to differential mount.
3. Tighten the nut of connecting bolt (B). Tightening torque: 125 N.m (12.7 kgf-m, 92.2 ft-lb)
4. Tighten the nut of connecting bolt (A). Tightening torque: 70 N.m (7.1 kgf-m, 51.6 ft-lb)