Differential Bearing Preload and Ring Gear Backlash

Assembly of Differential Case Into Housing

Condition 1

Follow this procedure when gearset replacement only is required and the differential bearings and differential case do not require replacement.

1. Remove the differential caps and bolts. Identify the RH cap, RH cup and shim spacer to keep these components as RH and LH sets.

2. Remove the differential case subassembly using the pry bar method. Reasonable effort will be required to remove subassembly if preload is within specification range. If subassembly can be removed by hand, use Condition 2 for assembly.

3. Replace the ring and pinion members utilizing the differential shim components from the original assembly and select the hypoid pinion shim as outlined. (Shim may be reused with the exception of pinion shim which will require regauging to specification before assembly.)

   NOTE: Tighten ring gear bolts in a criss cross pattern.

Condition 2

Follow this procedure when original differential shims are not available or when axle housing, differential case or differential bearing replacement is required.

1. With pinion depth set and pinion installed, place the differential case/gear subassembly with bearings and cups in carrier.
   
   
   
   

2. Install a 0.265-inch shim on the LH side.
   
   
   
   

3. Install LH bearing cap finger-tight.
   
   
   
   

4. Install progressively larger shims on the RH side until the largest shim selected can be assembled with a slight drag feel.
   
   
   
   

5. Install RH side bearing cap and differential bearing cap bolts. Tighten to 95-115 Nm (70-85 lb-ft).
   
   
   
   

6. Rotate the assembly to ensure free operation.
   
   
   
   

7. Check gear and pinion backlash. If backlash is within specification, go to Step 14. If backlash is not within specification, go to Step 10. If zero backlash is measured, proceed with Step 8.
   
   
   
   

8. If a zero backlash condition occurs, add 0.020 inch to the RH side and subtract 0.020 inch from the LH side to allow backlash indication.
   
   
   
   

9. Check backlash. Repeat Step 7.

10. If backlash is not to specification, correct backlash by increasing thickness of one shim and decreasing thickness on the other shim by the same amount. Refer to the following illustrations for approximate shim change.

11. Install shim and bearing caps. Tighten caps to 95-115 Nm (70-85 lb-ft).
    
    
    
    

12. Rotate assembly several times.
    
    
    
    

13. Recheck backlash. If backlash is within specification, proceed to Step 14. If not, repeat Step 10.
    
    
    
    

14. Increase both LH and RH shim sizes by 0.006 inch and install for correct differential bearing preload. Make sure the shims are fully seated and, the assembly turns freely.

15. Pattern legibility can be improved by connecting the driveshaft and rotating both tires in the drive and coast direction.
    
    
    
    

Tooth Contact Guidelines

Pattern inspection allows the technician to detect gross errors in set-up prior to complete assembly. Pattern contact should be within the primary area of the ring gear tooth surface avoiding "narrow" or "hard" contact with the outer perimeter of tooth (top to root, toe to heel). Pattern inspection should be on the drive (pull) side. Correct assembly of drive pattern will result in satisfactory coast performance. If gross pattern error is detected, with preferred backlash, 0.305 to 0.381mm (0.012 to 0.015 inch), check pinion shim selection.