Main bearings may not be a popular choice for modifying. Changing them won't give a big increase in horsepower. However, a good set of main bearings is important to ensure that the crankshaft runs efficiently to transfer power to the wheels. Read these pointers on what is a good set for you, whether you are on the market to replace worn-out bearings, or to upgrade your engine.
Main bearings can be made from different materials and compounds. However, there are two common alloys that makers use for main bearings: aluminum, and copper-lead. Here is a quick overview of each material.
- Copper-lead: This is very common for most cars, especially high power racing cars. It boasts great strength in handling the force, and great smoothness surface for a flowing crankshaft. American makes, like Ford and General Motors, prefer to use this for their cars. The great advantage of a copper-lead bearing is its high tolerance of dirt. This bearing is ideal for trucks or racing cars.
- Aluminum: Manufacturers prefer aluminum because it is less expensive to make. Mother Nature loves aluminum because it is lead-free. Other positives include its lightness, and improved durability in high temperatures. Japanese makes slowly shift fitting their cars with these. The biggest downside of aluminum is its sensitivity to dirt. Pick these if for your everyday city-driving car.
Manufacturers apply different coating technologies on their bearings to make them easy on the crankshaft. A balance of two factors should be considered when choosing a coating.
- Smoothness: The coating should provide a very smooth surface for the crankshaft to glide on. A decently coated bearing will lessen any metal to metal contact.
- Clearance: There should be enough space between the crankshaft and the coating itself. More contact equals more friction. More friction equals less power.
As a final note, always handle the bearings in a clean environment. Dirt is dangerous. No matter how expensive your new bearings may be, if installed on a dirty engine, expect them to wear out by 300 to 500 miles.