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Differentials: Diagnosis Subaru Forester SJ

Differentials & Drive Axles 8 illustrations ~980 words

INSPECTION

Wash all the disassembled parts clean, and examine them for wear, damage and other defects. Repair 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 Replace if cracks, scoring or other defects are evident on the tooth surface. Replace if thrust washer contact surface is worn or scored. 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 the side gear and pinion mate gear Replace if seized, flawed, abnormally worn or having other defects.
  5. Oil seal Replace if deformed or damaged, and at every disassembling.
  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.

Wash all the disassembled parts clean, and examine them for wear, damage or other defects. Repair 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 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 the side gear and pinion mate gear Replace if seized, flawed, abnormally worn or having other defects.
  5. Oil seal Replace if deformed or damaged, and at every disassembling.
  6. Differential carrier Replace if the bearing bores are worn or damaged.
  7. Differential case Replace if its sliding surfaces are abnormally worn, burned, or cracked.
  8. Companion flange Replace if the oil seal lip contact surface shows cracking.

Make sure that there is no leakage from front oil seal portion. If there is any leakage replace the oil seal and inspect the propeller shaft.

Scheme 10

Scheme 10
Scheme 10

Scheme 11

Scheme 11
Scheme 11

Scheme 12

Scheme 12
Scheme 12

Scheme 13

Scheme 13
Scheme 13
  1. Shift the select lever or gear shift lever to neutral.
  2. Disconnect the ground cable from battery.
  3. Release the parking brake.
  4. Lift up the vehicle.
  5. Drain differential gear oil. < Ref. to «REPLACEMENT»(ref-662127-S42594422432014101300000) , Differential Gear Oil. >
  6. Remove the rear exhaust pipe. 2.5 L non-turbo model < Ref. to «REMOVAL»(ref-662139-S39836269742014101300000) , Rear Exhaust Pipe. > 2.0 L turbo model < Ref. to «REMOVAL»(ref-662147-S19685566712014101300000) , Rear Exhaust Pipe. >
  7. Remove the heat shield cover.
  8. Remove the propeller shaft. < Ref. to «REMOVAL»(ref-662131-S39075214892014101300000) , Propeller Shaft. >
  9. Check the initial torque and write it down.
  10. Remove the self-locking nut while holding the companion flange with ST. ST 498427200 FLANGE WRENCH
  11. Extract the companion flange using the ST. ST 399703600 PULLER ASSY
  12. Remove the oil seal using ST or screwdriver. ST 398527700 PULLER ASSY
  13. Using the ST, install the oil seal. NOTE: Use a new oil seal. Apply differential gear oil to the oil seal lips. ST 498447120 INSTALLER
  14. Install the companion flange. NOTE: Use a plastic hammer to install companion flange.
  15. Tighten the self-locking nut to the specified torque so that the initial torque of companion flange becomes the same as that of before oil seal replacement. NOTE: Use a new self-locking nut. Before installing the self-locking nut, apply the seal material to the threads of the drive pinion shaft and to the seating surface of the self-locking nut. Seal material: THREE BOND 1324 (Part No. 004403042) or equivalent Tightening torque: T-type 167 - 196 N.m (17.0 - 20.0 kgf-m, 123.2 - 144.6 ft-lb) VA-type 162 - 220 N.m (16.5 - 22.5 kgf-m, 119.5 - 162.3 ft-lb) ST 498427200 FLANGE WRENCH
  16. Hereafter, perform assembly in the reverse order of disassembly.
  17. Fill differential gear oil. < Ref. to «REPLACEMENT»(ref-662127-S42594422432014101300000) , Differential Gear Oil. >

Check that there is no oil leakage from the side oil seal. If there is any leakage, replace the oil seal.

Scheme 14

Scheme 14: REPLACEMENT
Scheme 14: REPLACEMENT

Scheme 15

Scheme 15
Scheme 15

Scheme 16

Scheme 16
Scheme 16
  1. Remove the rear differential. < Ref. to «REMOVAL»(ref-662127-S36563148422014101300000) , Rear Differential (T-type). > < Ref. to «REMOVAL»(ref-662127-S39799607872014101300000) , Rear Differential (VA-type). >
  2. Remove the rear differential side oil seal using a ST or screwdriver wrapped with vinyl tape to prevent the side retainer from scratching. ST 398527700 PULLER ASSY
  3. Using the ST, install the oil seal. NOTE: Use a new oil seal. Apply differential gear oil to the oil seal lips. T-type ST 398437700 DRIFT VA1-type ST 498447100 INSTALLER
  4. Install the rear differential. < Ref. to «INSTALLATION»(ref-662127-S26050899442014101300000) , Rear Differential (T-type). > < Ref. to «INSTALLATION»(ref-662127-S19383524212014101300000) , Rear Differential (VA-type). >

Scheme 17

Scheme 17: REMOVAL
Scheme 17: REMOVAL
  1. Disconnect the ground cable from battery.
  2. Lift up the vehicle.
  3. Support the rear differential using transmission jack, and then remove the rear differential front member.
  1. Check the rear differential front member for damage, bend and corrosion. If damage, bend or corrosion is excessive, replace the rear differential front member.
  2. Check the bushings of rear differential front member for cracking, hardening and damage. If cracking, hardening or damage is excessive, replace rear differential front member.

Check the rear differential mount bushing for cracks, hardening or damage. If cracking, hardening or damage is excessive, replace rear differential mount bushing.

Symptom or troublePossible causeRemedy
1. Oil leakage(1) Worn, scratched, or incorrectly seated front or side oil seal. Scored, battered or excessively worn sliding surface of companion flange.Repair or replace.
(2) Clogged or damaged air breather cap.Clean, repair or replace.
(3) Loose bolts on the side retainer, or incorrectly fitted O-ring.Tighten the bolts to specified torque. Replace the O-ring.
(4) Loose rear cover attachment bolts or damaged gasket.Replace the gasket, and tighten the bolts to specified torque.
(5) Loose filler plug or drain plug.Apply liquid gasket, and tighten to the specified torque. (T-type) Replace the gasket, and tighten to the specified torque. (VA-type)
(6) Wear, damage or incorrect fitting of drive shaft, side retainer or oil seal.Repair or replace.
2. Seizure NOTE: Seized or damaged parts should be replaced, and also other parts should be thoroughly checked for any defect and should be repaired or replaced as required.(1) Insufficient backlash for hypoid gear.Readjust or replace.
(2) Excessive preload for side, rear or front bearing.Readjust or replace.
(3) Insufficient or improper oil used.Add recommended oil to the specified level.
3. Damage NOTE: Damaged parts should be replaced, and also other parts should be thoroughly checked for any defect and should be repaired or replaced as required.(1) Improper backlash for hypoid gear.Readjust or replace.
(2) Insufficient or excessive preload for side, rear or front bearing.Readjust or replace.
(3) Excessive backlash for differential gear.Replace gear or thrust washer.
(4) Loose bolts and nuts such as hypoid driven gear bolt.Retighten.
(5) Damage due to overloading.Replace.
4. Noises when starting or shifting gears NOTE: Noises may be caused by differential assembly, universal joint, wheel bearing, etc. Find out what is actually making noise before disassembling.(1) Improper tooth contact of hypoid driven gear and drive pinionReadjust. (drive pinion adjustment and backlash adjustment)
(2) Excessive backlash for hypoid driven gearReplace the gear or the pinion height adjusting washer.
(3) Excessive backlash for side gear.Replace gear or thrust washer.
(4) Insufficient preload for front or rear bearing.Readjust.
(5) Loose drive pinion nut.Tighten to the specified torque.
(6) Loose bolts and nuts such as side retainer attachment bolt.Tighten to the specified torque.
5. Noises when cornering(1) Damaged differential gear.Replace.
(2) Excessive wear or damage of thrust washer.Replace.
(3) Broken pinion mate shaft.Replace.
(4) Stuck or damaged side bearingReplace.
6. Gear Noise NOTE: Since noises from engine, muffler, transmission, propeller shaft, wheel bearings, tires, and body are sometimes mistaken for noises from differential assembly, be careful in checking them. Inspection methods to locate noises include coasting, accelerating, cruising, and lifting-up all four wheels. Perform these inspections according to the condition of trouble. When listening to noises, shift the gear into four-wheel drive and fourth speed position, trying to pick up only differential noise.(1) Improper tooth contact of hypoid driven gear and drive pinionReadjust or replace the hypoid gear set.
(2) Improper backlash of the hypoid driven gearReadjust.
(3) Scored or chipped teeth of hypoid gear.Replace hypoid gear set.
(4) Scuffed hypoid gearReplace hypoid gear set.
(5) Improper preload for front or rear bearings.Readjust.
(6) Stuck, scored or chipped teeth of front or rear bearingReplace.
(7) Stuck, scored or chipped teeth of side bearingReplace.
(8) Vibrating differential gear.Replace the differential gear.
NOTE
Seized or damaged parts should be replaced, and also other parts should be thoroughly checked for any defect and should be repaired or replaced as required.
NOTE
Damaged parts should be replaced, and also other parts should be thoroughly checked for any defect and should be repaired or replaced as required.
NOTE
Noises may be caused by differential assembly, universal joint, wheel bearing, etc. Find out what is actually making noise before disassembling.
NOTE
Since noises from engine, muffler, transmission, propeller shaft, wheel bearings, tires, and body are sometimes mistaken for noises from differential assembly, be careful in checking them. Inspection methods to locate noises include coasting, accelerating, cruising, and lifting-up all four wheels. Perform these inspections according to the condition of trouble. When listening to noises, shift the gear into four-wheel drive and fourth speed position, trying to pick up only differential noise.

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