Unit Overhaul
C: DISASSEMBLYNOTE: 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
1) Set ST on vise and install the differential assembly to ST.
ST 398217700 ATTACHMENT
2) Drain gear oil by removing plug.
3) Remove the air breather cap.
NOTE: Do not attempt to replace the air breather cap unless necessary.
4) Remove rear cover by loosening retaining bolts.
5) 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.
CAUTION: 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 differential assembly from differential carrier.
CAUTION: Be careful not to hit the teeth against the case.
7) When replacing side bearing, pull bearing cup from side bearing retainer using ST.
ST 398527700 PULLER ASSY
8) Extract bearing cone with ST.
CAUTION: Do not attempt to disassemble the parts unless necessary.
NOTE:
- Set puller so that its claw catch the edge of the bearing cone.
- Never mix up the right and left hand bearing cups and cones.
ST 399527700 PULLER SET
9) Remove crown gear by loosening crown gear bolts.
CAUTION: Further disassembling is not allowed.
10) Drive out pinion shaft lock pin from crown gear side.
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
11) Draw out pinion mate shaft and remove pinion mate gears, side gears and thrust washers.
NOTE: The gears as well as thrust washers should be marked or kept separated left and right, and front and rear.
12) Hold companion flange with ST and remove drive pinion nut.
ST 498427200 FLANGE WRENCH
13) Extract the companion flange with a puller.
14) 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
15) 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 498515500 REPLACER
16) Remove front oil seal from differential carrier using ST.
ST 398527700 PULLER ASSY
17) Remove pilot bearing together with front bearing cone using ST.
ST 398467700 DRIFT
18) When replacing bearings, tap front bearing cup and rear bearing cup in this order out of case by using a brass bar.
D: INSPECTION
Wash all the disassembled parts clean, and examine them for wear, damage, or other defects. Repair or replace defective parts as necessary.
1) Crown gear and drive pinion
- If abnormal tooth contact is evident, find out the cause and adjust to give correct tooth contact at assembly. Replace the gear if excessively worn or incapable of adjustment.
- If crack, score, or seizure is evident, replace as a set. Slight damage of tooth can be corrected by oil stone or the like.
2) Side gear and pinion mate gear
- Replace if crack, score, or other defects are evident on tooth surface.
- Replace if thrust washer contacting surface is worn or seized. Slight damage of the surface can be corrected by oil stone or the like.
3) Bearing
Replace if seizure, peeling, wear, rust, dragging during rotation, abnormal noise or other defect is evident.
4) Thrust washers of side gear and pinion mate gear Replace if seizure, flaw, abnormal wear or other defect is evident.
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 worn or cracked.
8) Companion flange
Replace if the oil seal lip contacting surfaces have flaws.
E: ASSEMBLY
1) Precautions for assembling
- 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 cups of the bearings.
- Replace the oil seal with new one at every disassembly. Apply chassis grease between the lips when installing the oil seal.
2) Adjusting preload for front and rear bearings
Adjust the bearing preload with spacer and washer between front and rear bearings. Pinion height adjusting washers are not affected by this adjustment. The adjustment must be carried out without the oil seal inserted.
1. Press rear bearing race into differential carrier with ST1 and ST2.
ST1 398477701 HANDLE
ST2 398427703 DRIFT 2
2. Insert ST1 into case with pinion height adjusting washer and rear bearing cone fitted onto it.
CAUTION:
^ Re-use the used washer if not deformed.
^ Use a new rear bearing cone.
3. 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
4. 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 with ST2.
ST1 398507704 BLOCK
ST2 398507702 DUMMY SHAFT
CAUTION: Use a new lock nut.
NOTE:
^ Be careful not to give excessive preload.
^ When tightening the drive pinion nut, lock ST1 with ST2 as shown in the figure.
Tightening torque: 181±15 Nm (18.5±1.5 kg-m, 134±11 ft. lbs.)
3) Adjusting drive pinion height
Adjust drive pinion height with shim installed between rear bearing cone and the back of pinion gear.
1. Install ST1, ST2 and ST3, as shown in the figure, and apply the specified preload on the bearings.
Adjust preload for front and rear bearings.
NOTE: At this time, install a pinion height adjusting shim which is temporarily selected or the same as that used before.
2. 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 398507702 DUMMY SHAFT
ST2 398507703 DUMMY COLLAR
ST3 398507701 DIFFERENTIAL CARRIER GAUGE
3. 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)
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
(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.
4) Install the selected pinion height adjusting shim on drive pinion, and press the rear bearing cone into position with ST.
ST 398177700 INSTALLER
5) Insert drive pinion into differential carrier, install the previously selected bearing preload adjusting spacer and washer.
6) Press-fit front bearing cone into case with ST1, ST2 and ST3.
ST 398507703 DUMMY COLLAR
ST 399780104 WEIGHT
ST 899580100 INSTALLER
7) Insert spacer, then press-fit pilot bearing with ST1 and ST2.
ST 399780104 WEIGHT
ST 899580100 INSTALLER
8) Fit a new oil seal with ST.
NOTE:
- Press-fit until end of oil seal is 1 mm (0.04 inch) inward from end of carrier.
- Apply grease between the oil seal lips.
ST 498447120 OIL SEAL INSTALLER
9) Press-fit companion flange with ST1 and ST2.
CAUTION: Be careful not to damage bearing.
ST1 899874100 INSTALLER
ST2 399780104 WEIGHT
10) Install self-locking nut. Then tighten it with ST.
ST 498427200 FLANGE WRENCH
Tightening torque: 181±15 Nm (18.5±1.5 kg-m, 134±11 ft. lbs.)
11) Assembly of differential case.
12) Install side gears and pinion mate gears, with their thrust washers and pinion mate shaft, into differential case.
CAUTION:
- 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.
1. Measure the clearance between differential case and the back of side gear.
2. Adjust the clearance as specified by selecting side gear thrust washer.
Side gear backlash: 0.1 - 0.2 mm (0.004 - 0.008 inch)
3. Check the condition of rotation after applying oil to the gear tooth surfaces and thrust surfaces.
4. After inserting pinion shaft lock pin into differential case, stake the both sides of the hole to prevent pin from falling off.
5. Install crown gear on differential case.
CAUTION: Before installing bolts, apply Lock Tight to bolt threads.
Lock Tight: THREE BOND 1324 or equivalent
NOTE: Tighten diagonally while tapping the bolt heads.
Tightening torque: 103±10 Nm (10.5±1.0 kg-m, 76±7 ft. lbs.)
13) Press side bearing cone onto differential case with ST1.
ST1 398487700 DRIFT
14) Adjusting side bearing retainer shims
1. The driven gear backlash and side bearing preload can be determined by the side bearing retainer shim thickness.
2. Install the differential case assembly into differential carrier in the reverse order of disassembly.
3. Install side retainer shims and O-rings to the left and right retainers from which they were removed.
NOTE:
^ Replace broken or cracked O-ring with new one.
^ Replace broken or corroded side retainer shim with new one of same thickness.
4. Align arrow marked on differential carrier with that marked on side retainer during installation.
CAUTION: Be careful that side bearing outer race is not damaged by bearing roller.
5. Tighten side bearing retainer bolts.
CAUTION: Before tightening the two side bearing retainer bolts, apply Lock Tight to bolt threads.
Lock Tight: THREE BOND 1105 or equivalent
Tightening torque: 10.3±1.5 Nm (1.05±0.15 kg-m, 7.6±1.1 ft. lbs.)
Fig. 15 Measuring Backlash:
6. 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.
Backlash: 0.10 - 0.20 mm (0.0039 - 0.0079 inch)
7. At the same time, measure the turning resistance of drive pinion. Compared with the resistance when differential case is not installed, if the increase of the resistance is not within the specified range, readjust side bearing retainer shims.
NOTE: If measured backlash is not within specified range, repeat procedure for adjustment of side bearing retainer shims.
Turning resistance increase: 2.9 - 10.8 N (0.3 - 1.1 kg, 0.7 - 2.4 lbs.)
Fig. 15 Measuring Backlash:
15) Re-check crown gear-to-pinion backlash.
Backlash: 0.10 - 0.20 mm (0.0039 - 0.0079 inch)
Fig. 16 Measuring Runout:
16) 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 inch)
17) Checking and adjusting tooth contact of crown gear
1. 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.
2. 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.
18) 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.
1. Drive pinion height
ST1 398507702 DUMMY SHAFT
3T2 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
Fig. 15 Measuring Backlash:
2. Hypoid gear backlash
Backlash: 0.10 - 0.20 mm (0.0039 - 0.0079 inch)
19) Install rear cover and tighten bolts to specified torque.
Tightening torque: 29±5 Nm (3.0±0.5 kg-m, 21.7±3.6 ft. lbs.)