Backlash

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





PROCEDURE
1. With pinion depth set and pinion installed, place the differential case/gear subassembly with differential bearings and differential bearing cups in rear axle housing.





2. Install a 6.75 mm (0.265-inch) differential bearing shim on the LH side.





3. Install LH bearing cap finger-tight.





4. Install differential bearing shims progressively on the RH side until the largest differential bearing 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 ft. lbs.).





6. Rotate the assembly to make sure differential assembly rotates freely.





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 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.

Differential Shim Size Chart:

Differential Shim Dimensions:

Differential Shim Identification (Part 1 Of 2):

Differential Shim Identification (Part 2 Of 2):

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





11. Install differential bearing shim and bearing caps. Tighten cap bolts to 95-115 Nm (70-85 ft. lbs.).





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 differential bearing shim sizes by 0.10 mm (0.004 inch) and install for correct differential bearing preload. Make sure the shims are fully seated and the assembly turns freely.





15. Use a white marking compound to obtain a tooth mesh contact pattern in the assembly. Pattern legibility can be improved by connecting the driveshaft and rotating both tires in the drive and coast direction.
Gear Pattern

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