Crankshaft Measurement

Crankshaft Measurement

^ Tools Required
- J 7872 Magnetic Base Dial Indicator





1. Using a suitable fixture, support the crankshaft.





2. Install the J 7872.
3. Measure the crankshaft runout using J 7872.





4. Measure the crankshaft thrust wall width (1) for wear using an inside micrometer.
5. Measure the crankshaft thrust wall surface (2) for runout using J 7872.
6. If the crankshaft thrust walls are damaged or worn beyond specifications, replace the crankshaft. No machining of the crankshaft thrust wall is allowed.





7. Check the crankshaft main journals for undersize using an outside micrometer.





8. Check the crankpins for undersize using an outside micrometer.
9. Compare your measurements with those listed in the Engine Mechanical Specifications. If the crankshaft journals are worn beyond the specified limits, the crankshaft must be replaced. Crankshaft machining is not allowed and there are no undersized bearings available for service.





10. Measure the main bearing and crankpin journals for out-of-round using the following procedure:
10.1. Using an outside micrometer, measure the journal at the extreme front and rear locations on the journal. Call these points A and B.
10.2. Measure the journal in two new locations exactly 90 degrees from the first points. Call these points C and D.
10.3. Subtract A from C and B from D. The differences will indicate journal out-of-round.
10.4. The out-of-round should not exceed 0.004 mm (0.00016 inch) maximum.
10.5. If the specifications are exceeded, replace the crankshaft.
11. Measure the main bearing and crankpin journals for,taper using the following procedure:
11.1. Using an outside micrometer, measure the journal at the extreme front (A) and rear (B) of the journal parallel to the crankshaft centerline.
11.2. Subtract the smallest from the largest measurement. The result will be the journal taper.
11.3. If the main bearing journal taper exceeds 0.004 mm (0.00016 inch), replace the crankshaft.
11.4. If the crankpin journal taper exceeds 0.004 mm (0.00016 inch), replace the crankshaft.