Why Crankshaft Polishing is as Important as Grinding
When is Crankshaft Grinding Necessary?
- Rod Knock: A deep, rhythmic knocking sound from the engine. It is caused by excessive clearance between the connecting rod bearing and a worn crankshaft journal.
- Low Oil Pressure: Wide gaps from wear allow engine oil to escape too easily.
- Metallic Glitter: Metal shavings appearing in your engine oil.
- Setup: The crankshaft spins slowly on specialized machinery.
- Cooling: A constant coolant flow prevents overheating and warping.
- Material removal: A high-speed grinding wheel cleans and rounds the journal.
- Sizing: Technicians grind the journal to a specific undersize dimension.
- Bearing match: Thicker bearings are installed to restore original factory clearances.
- Fillet radius: Technicians carefully shape the curved transition area.
- Stress prevention: Smooth curves prevent sharp corners that cause crank breakage.
The Final Polish
- Minimizes friction: Smooth surfaces reduce drag between crankshaft journals and bearings.
- Sustains lubrication: High-quality finishes allow a stable, unbroken oil film to form.
- Prevents contamination: Eliminates microscopic metal peaks that could break off into the oil.
- Extends engine life: Crucial for achieving thousands of hours of reliable operation under load.
Crankshaft grinding and polishing is a precision process that restores the most critical surfaces inside your engine to their exact original specifications. Grinding ensures the dimensions are correct, while polishing creates the perfect surface for a long and reliable service life.
In order to prep your con rods for machining, you will need to have a few items. First, you’ll need a shop press. Goodson recommends you ask yourself a few questions when looking to add a shop press.

