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 01 to 99 is on each gear. This first number (1) is the amount in thousandths of an inch the depth varies from the standard depth setting of a pinion marked with a zero 0. The next two numbers (2) are the sequence number of the gear set. The standard depth provides the best teeth contact pattern.





Compensation for pinion depth variance is achieved with select shims (4) located 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 6774 and Dial Indicator C-3339 (1).





1. Assemble Pinion Height Block 6739 (2) Pinion Block 8542 (1) and rear pinion bearing onto Screw 6741.
2. Insert assembled height gauge components, rear bearing, and screw into the housing through pinion bearing cups.
3. Install front pinion bearing and Cone-Nut 6740 on screw. Tighten cone-nut on screw until Torque To Rotate screw is 1.7 Nm (15 inches lbs.).





4. Place Arbor Disc 8541 (1) on Arbor D-115-3 (3) in position in the housing side bearing cradles. Install differential bearing caps on arbor discs and tighten cap bolts to 136 Nm (100 ft. lbs.).

NOTE: Arbor Discs 8541 has different step diameters to fit other axles. Choose proper step for axle being serviced.

5. Assemble Dial Indicator C-3339 into Scooter Block D-115-2 and secure set screw.
6. Place Scooter Block/Dial Indicator in axle housing so dial probe and scooter block are flush against 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 (3) probe across the gap between the pinion height block and the arbor bar (1) with the scooter block (2) against the pinion height block. Move 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 inches 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 inches)
- 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 free-play and ring gear noise.
- Insufficient adjuster torque will not support the ring gear correctly and can cause excessive differential case free-play 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 C-4164 to adjust each threaded adjuster inward until the differential bearing free-play is eliminated. Allow some ring gear backlash approximately 0.25 mm (0.01 inches) 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 (2) 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 - 0.102 mm (0.003 - 0.004 inches) with each adjuster tightened to 14 Nm (10 ft. lbs.). Seat the bearing cups with the procedure described above.
5. Tighten differential bearing cap bolts to 136 Nm (100 ft. lbs.).
6. Tighten 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 backlash. The range of backlash is 0.12 - 0.20 mm (0.005 - 0.008 inches).
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 136 Nm (100 ft. lbs.).
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 is too far away from the pinion gear, coast side toe (1) drive side heel (2). Decrease backlash by moving ring closer to the pinion gear using the adjusters.





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





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





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





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





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

SIDE GEAR CLEARANCE
When measuring side gear 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 C-locks and pinion mate shaft.





2. Measure each side gear clearance. Insert a matched pair of feeler gauge (1) blades between the side gear (2) and differential housing on opposite sides of the hub.





3. If side gear clearances is 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 C-lock is preventing the side gear from sliding on the axle shaft.

5. If there is no side gear clearance, remove the C-lock 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 C-lock installed and re-measure the side gear clearance.
6. Compare both clearance measurements. If the difference is less than 0.30 mm (0.012 inches) add clearance recorded when the C-lock was installed to thrust washer thickness measured. The sum will determine the required thickness of the replacement thrust washer.
7. If clearance is 0.30 mm (0.012 inches) or greater, both side gears must be replaced (matched set) and the clearance measurements repeated.
8. If clearance (above) continues to be 0.30 mm (0.012 inches) or greater, the case must be replaced.