Front Axle - C205F

PINION DEPTH-BEARING PRELOAD-GEAR BACKLASH





Ring gear (3) and pinion are supplied as a 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 is the amount (in thousandths of an inch) the depth varies 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 depth variance is achieved with select shims (1) located between the rear pinion bearing cone and pinion gear head.

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 cups and pinion bearings installed in housing. Take measurements with a Pinion Gauge Set 6774, Gauge Block 8177 (6), Arbor Discs 8541(8) and Dial Indicator C-3339 (1).
1. Assemble Pinion Height Block 6739 (3), Gauge Block 8177 (6) and rear pinion bearing onto Screw 6741 (5).





2. Insert assembled height gauge components (1, 2), rear bearing and screw into the housing through the 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 2.0 Nm (18 inch lbs.).





4. Place Arbor Discs 8541 (1) on Arbor D-115-3 (3) in position in the housing side bearing cradles. Install differential bearing caps on arbor discs (1) and tighten cap bolts 61 Nm (45 ft. lbs.).
5. Assemble Dial Indicator C-3339 into Scooter Block D-115-2 and secure set screw.
6. Place Scooter Block/Dial Indicator in position in the housing so dial probe and scooter block are flush against the 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 (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. Slide 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 gear using the opposite sign on the variance number. For example, if the depth variance is -2, add +0.002 inches to the dial indicator reading.
9. Remove the pinion depth gauge components from the housing.

DIFFERENTIAL BEARING PRELOAD





Differential side bearing preload and gear backlash is achieved by selective shims (2) (4) inserted between the bearing cup and the housing. The proper shim thickness can be determined using slip-fit Dummy Bearings 8398 in place of the differential side bearings and a Dial Indicator C-3339. Before measuring differential bearing preload and gear backlash, measure pinion gear depth and prepare pinion for installation. Pinion gear depth is essential to establishing gear backlash and tooth contact patterns. After measuring shim thickness to take up differential side play, install pinion and measure gear backlash shim thickness. Overall shim thickness is the dial indicator reading and preload specification added together. The gear backlash measurement determines the shim thickness used on the ring gear (3) side of the differential case. Subtract gear backlash shim thickness from overall shim thickness to determine shim thickness for pinion gear side of the differential.

SHIM SELECTION
1. Remove side bearings from differential case.





2. Install Dummy Bearings 8398 (4) on differential case.
3. Install differential case in the housing.
4. Insert Dummy Shims 8107 (1) starting point shims between both dummy bearings (4) and the housing.





5. Install the marked bearing caps in their correct positions. Install and snug the bolts.
6. Using a dead-blow hammer (1) seat the pinion side (3) differential dummy bearing.





7. Using a dead-blow hammer (2) seat the ring gear side (3) differential dummy bearing.





8. Install Pin C-3288-B (2) in cover bolt hole below ring gear.
9. Attach Dial Indicator C-3339 (3) to post and position dial indicator plunger on a flat surface on a ring gear bolt head.





10. Push and hold differential to the pinion gear side (1) of the housing and zero dial indicator (3).





11. Push and hold differential case to the ring gear side (3) and record dial indicator (1) reading.
12. Add the dial indicator reading to the starting point shim thicknesses to determine the total shim thickness necessary to achieve zero differential end play.
13. Add 0.2 mm (0.008 inches) to the zero end play total. This new total represents the shims needed to preload the new differential case bearings.
14. Rotate dial indicator out of the way on pilot stud.
15. Remove differential case, dummy bearings and dummy shims from the housing.
16. Install the pinion gear in the housing. Install the companion flange and establish the correct pinion rotating torque.
17. Install differential case and Dummy Bearings in the housing with a single dummy shim on the ring gear side of the axle and tighten retaining cap bolts.
18. Position the dial indicator plunger on a flat surface between the ring gear bolt heads.
19. Push and hold differential case toward pinion.
20. Zero dial indicator face to pointer.
21. Push and hold differential case to ring gear side of the housing.
22. Record dial indicator reading.
23. Subtract 0.05 mm (0.002 inches) from the dial indicator reading to compensate for backlash between ring and pinion gears. Add the resulting measurement to the thickness of the single dummy shim. This is the thickness of shim required to achieve proper backlash.
24. Subtract the backlash shim thickness from the total preload shim thickness. The remainder is the shim thickness required on the pinion side of the housing.
25. Rotate dial indicator out of the way on pilot stud.
26. Remove differential case, dummy bearings and dummy shim from the housing.
27. Install new side bearing cones and cups on differential case.
28. Install Spreader W-129-B and Adapter Plates 8142-A on the housing and spread open enough to receive differential case.

CAUTION: Never spread over 0.50 mm (0.020 inches). If the housing is over-spread, it could be distorted or damaged.

29. Place the side bearing shims in the differential housing against the housing shoulder.
30. Install the differential case in the housing.
31. Rotate the differential case several times to seat the side bearings.

GEAR BACKLASH





1. Position the dial indicator (1) plunger against a ring gear tooth (2).
2. Push and hold ring gear upward while not allowing the pinion gear to rotate.
3. Zero dial indicator face to pointer.





4. Push and hold ring gear downward while not allowing the pinion gear to rotate. Dial indicator reading should be between 0.12 mm (0.005 inches) and 0.20 mm (0.008 inches). If backlash is not within specifications transfer the necessary amount of shim thickness from one side of the differential housing to the other.
5. Verify differential case and ring gear runout by measuring ring to pinion gear backlash at eight locations around the ring gear. Readings should not vary more than 0.05 mm (0.002 inches). If readings vary more than specified, the ring gear or the differential case is defective.
After the proper backlash is achieved, perform the Gear Contact Pattern procedure.

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 61 Nm (45 ft. lbs.).
4. Apply the brakes lightly to create a 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) drive side heel (2). Decrease backlash by moving the ring closer to the pinion gear.





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






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





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.





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.