Rear Axle - 11 1/2 AA

PINION DEPTH-BEARING PRELOAD-GEAR BACKLASH

PINION DEPTH MEASUREMENT






Ring and pinion gears are supplied as matched sets. Compensation for pinion depth variance is achieved with a select shim, located between the rear pinion bearing and pinion gear head.


Measurements are taken with pinion bearing cups and pinion bearings installed in the housing. Take measurements with Pinion Gauge Set and Dial Indicator C-3339A (1).

1. Assemble Pinion Height Block 6739 (3), Pinion Block 8897 (6) and rear pinion bearing onto Screw 6741 (5).




2. Insert assembled 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 1.7-2.26 Nm (15-20 in. lbs.).




4. Place Arbor Discs 8289 (1) on Arbor D-115-3 (3) in position in the housing side bearing cradles.
5. Install differential bearing caps on arbor discs and snug the bearing cap bolts. Then cross tighten cap bolts to 281 Nm (207 ft. lbs.).

NOTE: Arbor should rotate freely in the arbor discs.




6. Assemble Dial Indicator C-3339A (3) into Scooter Block D-115-2 (2) and secure set screw.
7. Position Scooter Block/Dial Indicator flush on the pinion height block. Hold scooter block and zero the dial indicator.
8. Slowly slide the scooter block across the pinion height block over to the arbor. Move the scooter block till dial indicator crests the arbor (1), then record the highest reading.
9. Select a shim equal to the dial indicator reading.




10. Install select shim between rear pinion bearing and the pinion gear head.
11. Install pinion gear and establish Pinion Torque To Rotate (PTTR) with an inch pound torque wrench (2).

DIFFERENTIAL CASE BEARING PRELOAD AND GEAR BACKLASH






Backlash is adjusted by moving the adjusters in and out or both. By moving the adjusters the case/ring gear will move closer or further away from the pinion. In most cases this adjustment can be used to achieve the correct gear tooth pattern and set the case bearing preload.

1. Remove adjuster lock bolts (3) and adjuster locks (2).
2. Loosen the differential bearing caps (4).
3. Slide differential case toward the pinion gear until the gears make contact/zero backlash. If zero backlash cannot be obtained, turn the pinion side adjuster until zero backlash is obtained.




4. Holding the differential case (2) toward the pinion gear, turn bearing adjusters with Adjuster Wrench 8883A (1) until adjuster makes contact with the differential bearings/cups.
5. Back off the ring gear side adjuster 4 holes, to obtain initial ring gear backlash.
6. Install ring gear side adjuster lock and bolt. Do not tighten adjuster lock bolt at this time.
7. Tighten pinion gear side adjuster firmly against the differential case bearing cup.
8. Rotate the pinion several times to seat the deferential bearings.
9. Loosen pinion gear side adjuster until it is no longer in contact with the bearing cup, then tighten it until it makes contact.
10. Tighten pinion gear side adjuster an additional:
- New Bearings: 6 Adjuster Holes
- Original Bearings: 4 Adjuster Holes
11. Install pinion gear side adjuster lock and bolt.
12. Tighten bearing cap bolts to 281 Nm (207 ft. lbs.).
13. Tighten adjuster lock bolts to 25 Nm (18 ft. lbs.).




14. Measure ring gear backlash with a Dial Indicator C-3339 (1) and Pilot Stud L-4438 at eight points around the drive side of the ring gear (2). The backlash should be 0.08-0.25 mm (0.003-0.010 in) with a preferred backlash of 0.13-0.18 mm (0.005-0.007 in).

NOTE: Backlash measurement should not vary more than 0.05 mm (0.002 in) between measuring points. If measurement does vary inspect the gears for burrs, the differential case flange and ring gear mounting.

GEAR TOOTH 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 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 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) coast side toe (2). Increase backlash, by moving the ring away from the pinion gear using the adjusters.






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






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