Rear Axle-9 1/4

PINION DEPTH BEARING PRELOAD GEAR BACKLASH





Ring gear and pinion are supplied as matched sets. Identifying numbers for the ring gear and pinion are painted onto the pinion gear shaft and the side of the ring gear. A plus (+) number, minus () number or zero (0) along with the gear set sequence number (2) (01 to 99) is on each gear. This first number is the amount (in thousandths of an inch) the depth varies (1) from the standard depth setting of a pinion marked with a (0). The next two numbers are the sequence number of the gear set. The standard depth provides the best teeth contact pattern.





Compensation for pinion gear (5) depth variance is achieved with select shims (4). The shims are placed behind the rear pinion bearing (3).
If installing a new gear, note the depth variance number of the original and replacement pinion. Add or subtract this number from the original depth shim/oil slinger to compensate for the difference in the depth variances. The numbers represent thousands of an inch deviation from the standard. If the number is negative, add that value to the required thickness of the depth shims. If the number is positive, subtract that value from the thickness of the depth shim.
Pinion Gear Depth Variance Chart: Note where Old and New Pinion Marking columns intersect. Intersecting figure represents plus or minus the amount needed.

PINION GEAR DEPTH VARIANCE:

PINION DEPTH MEASUREMENT
Measurements are taken with pinion bearing cups and pinion bearings installed in the housing. Take measurements with Pinion Gauge Set and Dial Indicator C3339 (1).





1. Assemble Pinion Height Block 6739 (3), Pinion Block 8542 (6) and rear pinion bearing onto Screw 6741 (5).





2. Insert pinion block (1), pinion height block (2), rear bearing, and screw into the housing through pinion bearing cups.
3. Install front pinion bearing and Cone Nut 6740 onto the screw. Tighten cone-nut until Torque To Rotate the screw is 1.7 Nm (15 inch lbs.).





4. Place Arbor Disc 8541 (1) on Arbor D1153 (3) in position in the housing side bearing cradles. Install differential bearing caps on arbor discs and tighten cap bolts to 41 Nm (30 ft. lbs.).





5. Assemble Dial Indicator C3339 (3) into Scooter Block D1152 (2) and secure set screw.
6. Place Scooter Block/Dial Indicator in position in axle housing so dial probe and scooter block are flush against the rearward surface of the pinion height block. Hold scooter block in place and zero the dial indicator. Tighten dial indicator face lock screw.
7. Slide the dial indicator probe across the gap between the pinion height block and the arbor bar (1) with the scooter block against the pinion height block. Continue moving the dial probe to the crest of the arbor bar and record the highest reading.
8. Select a shim equal to the dial indicator reading plus the drive pinion gear depth variance number marked on the shaft of the pinion. For example, if the depth variance is -2, add +0.002 inch to the dial indicator reading.

DIFFERENTIAL BEARING PRELOAD AND GEAR BACKLASH





The following must be considered when adjusting bearing preload and gear backlash:
^ The maximum ring gear backlash variation is 0.076 mm (0.003 inch).
^ Mark the gears so the same teeth are meshed during all backlash measurements.
^ Maintain the torque while adjusting the bearing preload and ring gear backlash.
^ Excessive adjuster torque will introduce a high bearing load and cause premature bearing failure. Insufficient adjuster torque can result in excessive differential case freeplay and ring gear noise.
^ Insufficient adjuster torque will not support the ring gear correctly and can cause excessive differential case freeplay and ring gear noise.

NOTE: The differential bearing cups will not always immediately follow the threaded adjusters as they are moved during adjustment. To ensure accurate bearing cup responses to the adjustments:
^ Maintain the gear teeth engaged (meshed) as marked.
^ The bearings must be seated by rapidly rotating the pinion gear a half turn back and forth.
^ Do this five to ten times each time the threaded adjusters are adjusted.

1. Through the axle tube use Wrench C4164 to adjust each threaded adjuster inward until the differential bearing freeplay is eliminated. Allow some ring gear (2) backlash approximately 0.25 mm (0.01 inch) between the ring and pinion gear. Seat the bearing cups with the procedure described above.
2. Install dial indicator (1) and position the plunger against the drive side of a ring gear tooth. Measure the backlash at 4 positions, 90 degrees apart around the ring gear. Locate and mark the area of minimum backlash.
3. Rotate the ring gear to the position of the least backlash. Mark the gear so that all future backlash measurements will be taken with the same gear teeth meshed.
4. Loosen the right-side, tighten the left-side threaded adjuster. Obtain backlash of 0.076 to 0.102 mm (0.003 - 0.004 inch) with each adjuster tightened to 14 Nm (10 ft. lbs.). Seat the bearing cups with the procedure described above.
5. Tighten the differential bearing cap bolts 136 Nm (100 ft. lbs.).
6. Tighten the right-side threaded adjuster to 102 Nm (75 ft. lbs.). Seat the bearing cups with the procedure described above. Continue to tighten the right-side adjuster and seat bearing cups until the torque remains constant at 102 Nm (75 ft. lbs.)
7. Measure the ring gear (2) backlash. The range of backlash is 0.12 to 0.20 mm (0.005 to 0.008 inch).
8. Continue increasing the torque at the right-side threaded adjuster until the specified backlash is obtained.

NOTE: The left-side threaded adjuster torque should have approximately 102 Nm (75 ft. lbs.). If the torque is considerably less, the complete adjustment procedure must be repeated.

9. Tighten the left-side threaded adjuster until 102 Nm (75 ft. lbs.) torque is indicated. Seat the bearing rollers with the procedure described above. Do this until the torque remains constant.
10. Install the threaded adjuster locks and tighten the lock screws to 10 Nm (90 inch lbs.).

GEAR CONTACT PATTERN
1. Wipe clean each tooth of the ring gear.
2. Apply gear marking compound to all of the ring gear teeth.
3. Verify bearing cap bolts are torque to specification.





4. Apply parking brakes lightly to create at 14 Nm (10 ft. lbs.) pinion rotating torque.
5. Rotate the pinion/pinion yoke 4 full revolutions in each directions.
6. Read gear tooth contact pattern.
Gear contact pattern is correct. Backlash and pinion depth is correct.





Ring gear too far away from pinion gear, coast side toe (1) and drive side heel (2). Decrease backlash, by moving the ring closer to the pinion gear using the adjusters.





Ring gear too close to pinion gear, drive side toe (1) and coast side heel (2). Increase backlash, by moving the ring away from the pinion gear using the adjusters.





Ring gear too far away from pinion gear, drive side heel (1) and coast side heel (2). Decrease backlash, by moving the ring closer to the pinion gear using the adjusters.





Ring gear too close to pinion gear, drive side toe (1) and coast side toe (2). Increase backlash, by moving the ring away from the pinion gear using the adjusters.





Pinion gear set too low. Increase pinion gear height, by increasing the pinion depth shim thickness.





Pinion gear set too high. Decrease pinion depth, by decreasing the pinion depth shim thickness.

SIDE GEAR CLEARANCE





When measuring side gear (2) clearance, check each gear independently. If it necessary to replace a side gear, replace both gears as a matched set.
1. Install the axle shafts and Clocks and pinion mate shaft.
2. Measure each side gear clearance. Insert a matched pair of feeler gauge (1) blades between the gear and differential housing on opposite sides of the hub.
3. If side gear clearances are no more than 0.005 inch. Determine if the axle shaft is contacting the pinion mate shaft. Do not remove the feeler gauges, inspect the axle shaft with the feeler gauge inserted behind the side gear. If the end of the axle shaft is not contacting the pinion mate shaft, the side gear clearance is acceptable.





4. If clearance is more than 0.005 inch (axle shaft not contacting mate shaft), record the side gear clearance. Remove the thrust washer and measure its thickness with a micrometer. Add the washer thickness to the recorded side gear clearance. The sum of gear clearance and washer thickness will determine required thickness of replacement thrust washer.
In some cases, the end of the axle shaft will move and contact the mate shaft when the feeler gauge is inserted. The Clock is preventing the side gear from sliding on the axle shaft.
5. If there is no side gear clearance, remove the Clock from the axle shaft. Use a micrometer to measure the thrust washer thickness. Record the thickness and reinstall the thrust washer. Assemble the differential case without the Clock installed and remeasure the side gear clearance.
6. Compare both clearance measurements. If the difference is less than 0.012 inch (0.305 mm), add clearance recorded when the Clock was installed to thrust washer thickness measured. The sum will determine the required thickness of the replacement thrust washer.
7. If clearance is 0.012 inch (0.305 mm) or greater, both side gears must be replaced (matched set) and the clearance measurements repeated.
8. If clearance (above) continues to be 0.012 inch (0.305 mm) or greater, the case must be replaced.