Differentials: Overhaul — Subaru Outback BP (2003-2006)

DISASSEMBLY

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

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

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Set ST on vise and install the differential assembly to ST. ST 398217700 ATTACHMENT
Drain gear oil by removing plug.
Remove the air breather cap. NOTE: Do not attempt to remove the air breather cap unless necessary. When the air breather cap is removed, replace it with a new one.
Remove rear cover by loosening bolts. NOTE: Remove rear cover while tapping it lightly with plastic hammer, if it is hard to remove.
Make right and left side bearing retainers in order to identify them at reassembly. Remove side bearing retainer attaching bolts, set 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
Pull out differential case assembly from differential carrier. CAUTION: Be careful not to hit the teeth against the case.
Remove O-ring from side bearing retainer.
Remove oil seal from side bearing retainer.
Remove bearing cup from side bearing retainer using ST. ST 398527700 PULLER ASSY
Extract bearing cone with ST. NOTE: Do not attempt to disassemble the parts unless necessary. Set puller so that its claws catch the edge of the bearing cone. Never mix up the right and left hand bearing races and cones. ST 399527700 PULLER SET
Remove crown gear by loosening crown gear bolts. NOTE: Further disassembling is not allowed.
Drive out 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
Draw out pinion mate shaft and remove pinion mate gears, side gears and thrust washers. (Without LSD) NOTE: The gears as well as thrust washers should be marked or kept separated left and right, and front and rear.
Hold companion flange with ST and remove drive pinion nut. ST 498427200 FLANGE WRENCH
Extract the companion flange with a puller.
Press the end of drive pinion shaft and extract it together with rear bearing cone, preload adjusting spacer and washer. NOTE: Hold the drive pinion so as not to drop it. ST 398467700 DRIFT
Remove rear bearing cone from drive pinion by supporting cone with ST. NOTE: Place the replacer so that its center-recessed side faces the pinion gear. ST 398517700 REPLACER
Remove front oil seal from differential carrier using ST. ST 398527700 PULLER ASSY
Remove pilot bearing together with front bearing cone using ST. ST 398467700 DRIFT
When replacing bearings, tap 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 misinstalled. 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. Replace the oil seal with new one at every disassembly. Apply chassis grease between the lips when installing the oil seal. Use new O-ring and gasket.

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Scheme 32: ASSEMBLY

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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 rear bearing race rear into differential carrier with ST1 and ST2. ST1 398477701 HANDLE ST2 398477703 DRIFT 2 Install rear bearing race (front) in differential carrier using ST1 and ST2. ST1 398477701 HANDLE ST2 398477702 DRIFT Measure and record the thickness of pinion height adjusting washer. NOTE: The used washer can be used after checking that it is not deformed when the tooth contact of drive gear and driven gear is correct during pre-disassembly. Insert ST1 into carrier with pinion height adjusting washer and new rear bearing cone fitted onto it. Then install 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 ST1 with hand to make it seated, and tighten drive pinion nut while measuring the preload with spring balance. Select 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)
Adjusting drive pinion height Adjust drive pinion height with shim installed between rear bearing cone and the back of pinion gear. Set ST2. ST1 398507702 DUMMY SHAFT ST2 398507701 DIFFERENTIAL CARRIER GAUGE ST3 398507703 DUMMY COLLAR 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 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.
Install the selected pinion height adjusting shim on drive pinion, and press the rear bearing cone into position with ST. ST 398177700 INSTALLER
Insert drive pinion into differential carrier, install the previously selected bearing preload adjusting spacer and washer.
Press-fit front bearing cone into case with ST1, ST2 and ST3. ST1 398507703 DUMMY COLLAR ST2 399780104 WEIGHT ST3 899580100 INSTALLER
Insert spacer, then press-fit pilot bearing with ST1 and ST2. ST1 399780104 WEIGHT ST2 899580100 INSTALLER
Fit a new oil seal with ST. NOTE: Press-fit until end of oil seal is 1 mm (0.04 in) inward from end of carrier. Apply grease between the oil seal lips. ST 498447120 OIL SEAL INSTALLER
Press-fit companion flange with ST1 and ST2. NOTE: Be careful not to damage bearing. ST1 899874100 INSTALLER ST2 399780104 WEIGHT
Install new self-locking nut. Then fix and tighten companion flange with ST. ST 498427200 FLANGE WRENCH Tightening torque: 181 N.m (18.5 kgf-m, 134 ft-lb)
Assembling differential case (Without LSD) Install side gears and pinion mate gears, with their thrust washers and pinion mate shaft, into differential case. 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 side gear thrust washer. Check the condition of rotation after applying oil to the gear tooth surfaces and thrust surfaces. After inserting pinion shaft lock pin into differential case, stake the both sides of the hole to prevent pin from falling off.
Install crown gear on differential case. NOTE: Before installing bolts, apply Lock Tite to bolt threads. Lock Tite: THREE BOND 1324 (Part No. 004403042) or equivalent Tighten diagonally while tapping the bolt heads. Tightening torque: 105 N.m (10.7 kgf-m, 77.4 ft-lb)
Press side bearing onto differential case with ST. ST 398237700 DRIFT NOTE: When replacing bearing cone, replace it with bearing cap as a set.
Install bearing cup to side bearing retainer. NOTE: Press in while be careful not to scratch bearing cup and side bearing retainer. When replacing bearing cup, replace it with bearing cone as a set.
Using ST, press in new oil seal to side bearing retainer. ST 398437700 DRIFT NOTE: Apply thin oil gear oil on the mating surface of side bearing retainer and oil seal.
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 side retainer shims to the left and right retainers from which they were removed. NOTE: Replace broken or corroded side retainer shim with new one of same thickness. Align arrow marked on differential carrier with that marked on side retainer during installation. NOTE: Be careful that side bearing outer race is not damaged by bearing roller. Tighten side bearing retainer bolts. Tightening torque: 10.3 N.m (1.05 kgf-m, 7.6 ft-lb) Measure the crown gear-to-drive pinion backlash. Set magnet base on differential carrier. Align contact point of dial gauge with tooth face of crown gear, and move crown gear while holding drive pinion still. Read value indicated on dial gauge. If the measured backlash is not within the specified range, adjust side bearing retainer shims as follows: Backlash is over 0.2 mm (0.008 in): Reduce the shim thickness of crown gear backside and increase crown gear tooth-side. Backlash is less than 0.1 mm (0.004 in): Increase the shim thickness of crown gear backside and reduce crown gear tooth-side. Backlash: 0.10 - 0.20 mm (0.0039 - 0.0079 in) At the same time, measure the turning resistance of drive pinion. Compare with the resistance when differential case is not installed, if the increase of the resistance is not within the specified range, adjust thickness of side bearing retainer shims so that the back- and tooth-sides are the same thickness. Turning resistance increase: 20.7 - 54.4 N (2.1 - 5.5 kgf, 4.7 - 12.2 lb)
Re-check crown gear-to-pinion backlash. Backlash: 0.10 - 0.20 mm (0.0039 - 0.0079 in)
Check the crown gear runout on its back surface, and make sure pinion and crown gear rotate smoothly. Limit of runout: Less than 0.05 mm (0.0020 in)
Checking and adjusting tooth contact of crown gear Apply an even coat of red lead on both sides of three of four teeth on the crown gear. Check the contact pattern after rotating crown gear several revolutions back and forth until a definite contact pattern appears on the crown gear. When the contact pattern is incorrect, re-adjust 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.
If proper tooth contact is not obtained, once again adjust the drive pinion height changing RH and LH side bearing retainer shims and the hypoid gear backlash.
Remove left and right side retainer.
Install left and right side bearing retainer, new O-rings and side retainer shims.
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)
Install new gasket and rear cover, and tighten bolts to specified torque. Tightening torque: 29 N.m (3.0 kgf-m, 21.7 ft-lb)

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

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

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Set ST on vise and install the differential assembly to ST. ST 398217700 ATTACHMENT
Drain gear oil by removing plug.
Remove rear cover by loosening retaining bolts.
Replace air breather cap. NOTE: Do not attempt to replace the air breather cap unless necessary.
Remove right and left lock plates.
Remove right and left holders with ST. ST 499785500 WRENCHD
Pull out differential assembly from differential case. NOTE: Be careful not to hit the teeth against the case.
Remove bearing race from right and left holders with ST1 and ST2. ST1 499705401 PULLER ASSY ST2 499705404 SEAT
Remove oil seal from right and left holders with screwdriver.
Extract bearing cone with ST1 and ST2. NOTE: Do not attempt to disassemble the parts unless necessary. Set puller so that its claws catch the edge of the bearing cone. Never mix up the right and left hand bearing races and cones. ST1 899524100 PULLER SET ST2 399520105 SEAT
Remove crown gear by loosening crown gear bolts.
Drive out pinion shaft lock pin from crown gear side. (Without LSD) NOTE: The lock pin is staked at the pin hole end on the differential case; do not drive it out forcibly before unstaking it. ST 899904100 STRAIGHT PIN REMOVER
Draw out pinion mate shaft and remove pinion mate gears, side gears and thrust washers. (Without LSD) NOTE: The gears as well as thrust washers should be marked or kept separated left and right, and front and rear.
Hold companion flange with ST and remove self-locking nut. ST 498427200 FLANGE WRENCH
Extract the companion flange with a puller.
Press the end of drive pinion shaft and extract it together with rear bearing cone, preload adjusting spacer and washer. NOTE: Hold the drive pinion so as not to drop it. ST 39846770 DRIFT
Remove rear bearing cone from drive pinion by supporting cone with ST. NOTE: Place ST so that its center-recessed side faces the pinion gear. ST 498515500 REPLACER
Remove front oil seal from differential carrier using ST. ST 398527700 PULLER ASSY
Remove pilot bearing together with front bearing cone using ST. ST 398467700 DRIFT
When replacing bearings, tap front bearing cup and rear bearing cup in this order out of case by using a brass bar.

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Adjust 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 rear bearing race (rear) into differential carrier with ST1 and ST2. ST1 398477701 HANDLE ST2 398477702 DRIFT Press front bearing race (front) into differential carrier with ST1 and ST2. ST1 398477701 HANDLE ST2 498447110 DRIFT Insert new front bearing cone. Measure and record the thickness of pinion height adjusting washer. NOTE: The used washer can be used after checking that it is not deformed when the tooth contact of drive gear and driven gear is correct during pre-disassembly. Insert ST1 into case with pinion height adjusting shim and new rear bearing cone fitted onto it. Then install preload adjusting spacer and washer, front bearing cone, ST2, companion flange, and washer and self-locking nut. ST1 498447150 DUMMY SHAFT ST2 32285AA000 DUMMY COLLAR Turn ST1 with hand to make it seated, and tighten drive pinion nut while measuring the preload with spring balance. Select preload adjusting washer and spacer so that the specified preload is obtained when nut is tightened to the specified torque. NOTE: Use a new self-locking nut. Measure the preload in direction of tangent. 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 498447150 DUMMY SHAFT Tightening torque: 191 N.m (19.5 kgf-m, 141 ft-lb) Adjusting drive pinion height Adjust drive pinion height with shim installed between rear bearing cone and the back of pinion gear. Set ST3. ST1 498447150 DUMMY SHAFT ST2 32285AA000 DUMMY COLLAR ST3 498505501 DIFFERENTIAL CARRIER GAUGE Measure the clearance N between the end of ST3 and the end surface of ST1 by using a thickness gauge. NOTE: Make sure there is no clearance between the case and ST3. ST1 498447150 DUMMY SHAFT ST2 498505501 DIFFERENTIAL CARRIER GAUGE Obtain the thickness of pinion height adjusting washer to be inserted from the following formula, and replace the temporarily installed shim with this one. NOTE: Use 1 to 3 shims as required for adjustment. T = To + N - 0.05 (mm) where T = Thickness of pinion height adjusting shim (mm) To = Thickness of shim originally installed (mm) N = Reading of thickness gauge (mm) H = Figure marked on drive pinion head (Example of calculation) To = 0.15 mm N = 0.1 mm T = 0.15 + 0.1 - 0.05 = 0.2 mm Result: Thickness = 0.2 mm Therefore use the 32295AA220. Install the selected pinion height adjusting shim on drive pinion, and press the rear bearing cone into position with ST. ST 498175500 INSTALLER Insert drive pinion into differential carrier, install the previously selected bearing preload adjusting spacer and washer. Press-fit front bearing cone into carrier with ST1, ST2 and ST3. ST1 32285AA000 DUMMY COLLAR ST2 399780104 WEIGHT ST3 899580100 INSTALLER Insert spacer, then press-fit pilot bearing with ST1 and ST2. ST1 399780104 WEIGHT ST2 899580100 INSTALLER Fit a new oil seal with ST. NOTE: Press-fit until end of oil seal is 1 mm (0.04 in) inward from end of carrier. Apply grease between the oil seal lips. ST 498447120 OIL SEAL INSTALLER Press-fit companion flange with ST1 and ST2. NOTE: Be careful not to damage bearing. ST1 899874100 INSTALLER ST2 399780104 WEIGHT Install self-locking nut. Then tighten it with ST. ST 398427200 FLANGE WRENCH Tightening torque: 191 N.m (19.5 kgf-m, 141 ft-lb) Assembling differential case (Without LSD) Install side gears and pinion mate gears, with their thrust washers and pinion mate shaft, into differential case. 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: 0.05 - 0.15 mm (0.0020 - 0.0059 in) Adjust the side gear backlash as specified by selecting side gear thrust washer. Check the condition of rotation after applying oil to the gear tooth surfaces and thrust surfaces. After driving in pinion shaft lock pin, stake the both sides of the hole to prevent pin from falling off. Install crown gear on differential case. NOTE: Tighten diagonally while tapping the bolt heads. Tightening torque: 62 N.m (6.3 kgf-m, 45.6 ft-lb) Press side bearing cone onto differential case with ST. ST 498485400 DRIFT Assemble holders. Install oil seal into right and left holders. ST 498447100 INSTALLER Install bearing race into right and left holders. ST 398477702 BEARING OUTER RACE DRIFT Install the differential case assembly into differential carrier in the reverse order of disassembly. Perform adjustment of backlash of pinion crown gear set and adjustment of preload of differential side bearing. Turn drive pinion with ST for better fitting of differential side bearing. ST 498427200 FLANGE WRENCH Screw in side (left-side) holder until light contact is made with ST. ST 499785500 WRENCH Back off side (left-side) holder approximately 1 1/2 teeth of holder, and tighten left-side holder by approximately 2 teeth (approximately 1 1/2 + 1/2 teeth). [Back off amount of side (left-side) holder + 1/2 tooth.] This + 1/2 tooth gives preload. Temporarily tighten lock plate. NOTE: Turn over lock plate to displace holder 1/2 tooth. Measure the crown gear-to-drive pinion backlash. Set magnet base on differential carrier. Align contact point of dial gauge with tooth face of crown gear, and move crown gear while holding drive pinion still. Read value indicated on dial gauge. NOTE: If measured backlash is not within specified range, repeat procedures for pinion crown gear set backlash adjustment and differential side bearing preload adjustment. Backlash: 0.10 - 0.15 mm (0.0039 - 0.0059 in) Draw a matching mark on both differential carrier and holder. Remove holder one side at a time. Replace in the original position after inserting an O-ring and applying grease to threaded portion. Tighten bolt of lock plate to specified torque. Tightening torque: 25 N.m (2.5 kgf-m, 18.1 ft-lb) Re-check crown gear-to-pinion backlash. Backlash: 0.10 - 0.15 mm (0.0039 - 0.0059 in) 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 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 patter 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. NOTE: Be sure to wipe off red lead completely after adjustment is completed. If proper tooth contact is not obtained, once again adjust the drive pinion height and the differential side bearing preload (already mentioned) and the hypoid gear backlash. Install new gasket and rear cover, and tighten bolts to specified torque. Tightening torque: 25 N.m (2.5 kgf-m, 18.1 ft-lb)

Differentials: Overhaul Subaru Outback BP