Balance Shaft: Service and Repair

Balance Shaft Backlash

Special Tool(s)






General Procedure

1. Install the 303-507 and rotate the crankshaft slowly clockwise until the crankshaft balance weight is up against the 303-507. The engine is now at TDC (Top Dead Center).





2. Mark the balancer unit and shafts on the top for reference that the balancer unit is at TDC (Top Dead Center).





3. NOTE: Due to the precision interior construction of the balancer unit, it should not be disassembled.
Remove the 4 bolts and the balancer unit.





4. Remove the adjustment shims from the seat faces of the balancer unit.

5. NOTICE: Visually inspect the balancer unit gear for damage and verify that the shaft turns smoothly. If there is any damage or malfunction, replace the balancer unit.

Install the master adjustment shims (No. 50) on the seat faces of the balancer unit.

6. With the balancer unit shaft marks at the TDC (Top Dead Center) position, slowly install the balancer unit to the cylinder block to avoid interference between the crankshaft drive gear and the balancer unit driven gear.





7. Install the balancer unit bolts.
- Tighten in the sequence shown in 2 stages.
- Stage 1: Tighten to 25 Nm (18 lb-ft).
- Stage 2: Tighten to 42 Nm (31 lb-ft).





8. Remove the 303-507.

- Rotate the crankshaft to confirm that there are no meshing problems between the balancer unit gear and the crankshaft gear.






9. Install the 303-507 and rotate the crankshaft slowly clockwise until the crankshaft balance weight is up against the 303-507.

- Remove the 303-507.






10. NOTE: Measure the backlash and verify that it is within specified range at all of the following 6 positions: 10 degrees, 30 degrees, 100 degrees, 190 degrees, 210 degrees and 280 degrees. It will be necessary to reset the measuring equipment between measurements.

NOTE: The measurement must be taken with the 100-002 (TOOL-4201-C) , a 5-mm Allen wrench and worm clamp set up as shown. Mark the Allen wrench with a file 80 mm (3.149 in) above the driven gear shaft center. Make sure the worm clamp and Allen wrench are not touching the balance shaft housing.

NOTE: For an accurate measurement while measuring the gear backlash, insert a screwdriver as shown into the crankshaft No. 1 crankweight area and set both the rotation and the thrust direction with the screwdriver, using a prying action as shown.
Position the 100-002 (TOOL-4201-C) as shown. Measure the gear backlash.

- Position the 100-002 (TOOL-4201-C) (1) on the Allen wrench 80 mm (3.149 in) above the driven gear shaft center (2) on the balancer unit.
- Rotate the crankshaft clockwise and measure the backlash at all of the following 6 positions: 10 degrees, 30 degrees, 100 degrees, 190 degrees, 210 degrees and 280 degrees.






11. NOTE: If maximum backlash exceeds 0.101 mm (0.003 in), install a new balancer unit.
Using the backlash measurement, select the proper shims from the Adjustment Shim Selection Table.

- Remove the balancer unit from the cylinder block.
- Install the selected adjustment shims on the seat faces of the balancer unit.






12. Install the 303-507 and rotate the crankshaft slowly clockwise until the crankshaft balance weight is up against the 303-507. The engine is now at TDC (Top Dead Center).





13. With the balancer unit shaft marks in the TDC (Top Dead Center) position, slowly install the balancer unit to the cylinder block to avoid interference between the crankshaft drive gear and the balancer unit driven gear.





14. Install the balancer unit bolts.
- Tighten in the sequence shown in 2 stages.
- Stage 1: Tighten to 25 Nm (18 lb-ft).
- Stage 2: Tighten to 42 Nm (31 lb-ft).





15. NOTE: Remeasure the backlash and verify that it is within specified range at all of the following 6 positions: 10 degrees, 30 degrees, 100 degrees, 190 degrees, 210 degrees and 280 degrees. It will be necessary to reset the measuring equipment between measurements.

NOTE: The measurement must be taken with the 100-002 (TOOL-4201-C) , a 5-mm Allen wrench and worm clamp set up as shown. Mark the Allen wrench with a file 80 mm (3.149 in) above the driven gear shaft center. Make sure the worm clamp and Allen wrench are not touching the balance shaft housing.

NOTE: For an accurate measurement while measuring the gear backlash, insert a screwdriver as shown into the crankshaft No. 1 crankweight area and set both the rotation and the thrust direction with the screwdriver, using a prying action as shown.
Position the 100-002 (TOOL-4201-C) as shown. Measure the gear backlash.

- Position the 100-002 (TOOL-4201-C) (1) on the Allen wrench 80 mm (3.149 in) above the driven gear shaft center (2) on the balancer unit.
- Rotate the crankshaft clockwise and measure the backlash at all of the following 6 positions: 10 degrees, 30 degrees, 100 degrees, 190 degrees, 210 degrees and 280 degrees.
- If the backlash exceeds the specified range of 0.005 to 0.101 mm (0.00019 to 0.0039 in), install a new balancer unit and repeat the procedure.