Rear Axle - 302RBI

DIFFERENTIAL BEARING PRELOAD AND GEAR BACKLASH

GEAR IDENTIFICATION






Ring and pinion gears are matched parts and must be replaced as a set. Gear identification numbers are stamped on to both gears.

- Matched Gear Set Number - (1)
- Part Number - (2)
- Ring Gear Teeth - (3)
- Pinion Teeth - (4)
- Manufacturing Number - (5)


PINION BEARING PRELOAD






Pinon bearing preload is set using a select preload spacer (1) located between the pinion bearings (2).





Measure Pinion Torque To Rotate (1) (PTTR) with an inch pound torque wrench (2). Pinion torque to rotate is 2.3 - 4.5 Nm (20 - 40 in. lbs.). Pinion torque to rotate (PTTR) is measured without the pinion seal.

Spacers are available in sizes from 27.23 - 28.1 mm (1.07 - 1.10 in.). A 0.025 mm (0.001 in.) change in spacer thickness will change pinion torque to rotate approximately 3.38 mm (30 in. lbs.).

NOTE: To increase PTTR install a thinner spacer. To decreases PTTR install thicker spacer.


DIFFERENTIAL BEARING PRELOAD AND GEAR BACKLASH






1. Install pinion and establish PTTR.
2. Install ring gear side (2) bearing cap finger tight with new bolts.
3. Turn ring gear side adjuster clockwise with Adjuster 10066 (1) until ring gear (2) contacts the pinion gear to achieve zero lash.




4. Install Adjuster 10066 (1) into ring gear side differential bearing adjuster with indicator marks showing.
5. Mark first indicator mark on the bearing cap (2). Rotate adjuster counter clockwise until the third indicator mark is aligned with the bearing cap mark (2).




6. Turn pinion gear side adjuster (1) with Adjuster 10066 in until bearing cup (2) just starts to turn to achieve zero lash.




7. Install pinion gear side bearing cap finger tight with new bolts.
8. Install Adjuster 10066 (1) into pinion gear side differential bearing adjuster with indicator marks showing.
9. Mark first indicator mark on the bearing cap (2). Rotate adjuster clockwise until the third indicator mark is aligned with the bearing cap mark (2).




10. With Dial Indicator C-3339A (1) measure ring gear (2) backlash. Backlash is 0.15 - 0.46 mm (0.006 - 0.018 in.). If backlash is not within specification move adjusters equally one indicator mark and check backlash again.

NOTE: One indicator mark on Adjuster 10066 equals about 0.08 mm (0.003 in.) of backlash.

11. Tighten bearing cap bolts to 190 Nm (140 ft. lbs.).
12. Recheck ring gear backlash.
13. Measure ring gear runout.


RING GEAR RUNOUT






1. Measure radial runout with dial indicator (1) plunger on top of the ring gear (2). Rotate ring gear and record the highest reading. Radial runout should not exceed 0.25 mm (0.01 in.).




2. Measure lateral runout with dial indicator (1) plunger on the side of the ring gear (2). Rotate ring gear and record the highest reading. Lateral runout should not exceed 0.25 mm (0.01 in.).
3. Check gear contact pattern.


GEAR TOOTH CONTACT PATTERN






The gear and pinion gear tooth contact patterns will show if the ring gear backlash has been adjusted correctly. The backlash can be adjusted within specifications to achieve desired tooth contact patterns.

Ring and pinion gear tooth description:

- Toe - (1)
- Land - (2)
- Drive Side - (3)
- Root - (4)
- Heel - (5)
- Coast Side - (6)

Paint six ring gear teeth 180 degrees apart with marking compound. Turn the gear to obtain a contact pattern.

NEW GEAR PATTERN






A new gear pattern should be slightly below center on the ring gear tooth with lengthwise contact up off the toe (1). Length of the pattern in an unloaded condition is approximately one-half to two-thirds of the ring gear tooth. Pattern can very in length but should cover one-half or more of the tooth face. Pattern should be evenly centered between the tooth land.

USED GEAR PATTERN






A used gear pattern will normally have a pocket at the heal (1) end of ring gear. The more the gear is used the more dominate this pattern. The pattern should be evenly centered between the tooth land and root off the toe. Length and shape of the pattern are highly variable but considered acceptable as long as it does not run off the tooth. Adjust used gear sets to this same pattern or to pattern observed before disassembly.

RING GEAR ADJUSTMENT






Contact pattern is too close to ring gear toe (1). Move ring gear away from pinion gear to increase backlash.





Contact pattern is too close to ring gear heel (1). Move ring gear towards pinion gear to decrease backlash.