Main Bearings, .040 Case, .030 Crank, Standard Thrust

OVERVIEW

When you are deep into a performance engine rebuild or restoring a classic Volkswagen powerplant, precision is the only language that matters. These EMPI/Mahle Main Bearings are engineered specifically for engines where the magnesium or aluminum case has been line-bored to .040 inches (1.00mm) over and the crankshaft journals have been ground down to .030 inches (0.75mm) under. In the world of air-cooled VWs, finding the right combination of bearing sizes is critical to maintaining proper oil pressure and ensuring the longevity of your rotating assembly. These bearings provide the necessary clearances to rescue a seasoned engine case and a high-quality forged crankshaft that might otherwise be destined for the scrap heap, allowing you to maintain tight tolerances and a smooth-running bottom end.

Crafted with the high standards associated with the EMPI and Mahle brands, these bearings feature a robust steel backing coupled with a high-grade babbitt lining designed to handle the unique thermal expansion characteristics of the VW Type 1 engine block. The standard thrust configuration ensures that if your case thrust surface is still within factory specifications, you won''t have to worry about unnecessary machining on the flange. Whether you are building a rugged off-road rail, a daily driver Beetle, or a weekend-warrior Ghia, these bearings offer the metallurgical integrity required to withstand high RPMs and the heat cycles inherent to air-cooled operation. By choosing these precision-sized components, you are investing in the foundational stability of your engine, ensuring that every revolution is supported by world-class engineering.

FITMENT

These main bearings are designed for Type 1 based air-cooled engines (1200cc to 1600cc+ configurations). Please verify your case and crank machining dimensions before ordering.

• Volkswagen Beetle: 1961 through 1979 (Standard and Super Beetle).
• Volkswagen Karmann Ghia: 1961 through 1974.
• Volkswagen Bus / Type 2: 1961 through 1971 (1200cc-1600cc engines).
• Volkswagen Type 3 (Squareback, Fastback, Notchback): 1961 through 1973.
• Volkswagen Thing (Type 181): 1973 through 1975.
• Custom Applications: Sand Rails, Dune Buggies, and Trikes utilizing Type 1 VW engine cases.

SPECS

• Part Number: 111-198-487
• Brand: EMPI / Mahle
• Case Bore Diameter: +1.00mm (.040" Oversize)
• Crankshaft Journal Diameter: -0.75mm (.030" Undersize)
• Thrust Bearing Width: Standard (No cut to the case thrust surface)
• Material: High-strength steel-backed alloy with babbitt lining
• Engine Application: Type 1, 2, and 3 Air-cooled (1200-1600cc based)
• Oil Holes: Pre-drilled and chamfered for optimal lubrication flow
• Set Includes: Full set of main bearings for one complete engine build

PRO TIPS

1. Always Verify Machining with a Micrometer

Never assume that your machine shop''s verbal confirmation is the final word. Before installing these bearings, use a high-quality outside micrometer to measure your crankshaft journals and a dial bore gauge to measure the line-bore of your engine case. You are looking for a case bore that is exactly 1.00mm larger than stock and a crank journal that is exactly 0.75mm smaller than stock. Even a few ten-thousandths of an inch of error can lead to oil pressure failure or a seized engine. Measuring twice is the hallmark of a master engine builder and prevents the heartbreak of a premature teardown.

2. Check Oil Hole Alignment and Dowel Pin Seating

During the mock-up phase, place the bearings into the case halves and ensure that the oil supply holes in the case align perfectly with the holes in the bearings. Sometimes, aftermarket cases or heavy line-boring can cause slight offsets. Additionally, ensure that the dowel pins in the case are in good condition and that the bearing "sits" fully on the pin without rocking. If the bearing is held up by a proud dowel pin, the case halves will not torque down correctly, leading to a distorted bearing shell and immediate engine failure upon startup.

3. Perform a "Dry" Rotation Test

Before final assembly with assembly lube, perform a dry fit (or use a very light oil) with the crankshaft installed and the case halves torqued to spec. The crankshaft should spin freely with just the flick of a finger. If you feel any binding or "tight spots," it indicates that either the case is warped, the line-bore is not straight, or the crankshaft is slightly bent. Identifying these issues while the engine is still on the bench is significantly easier than trying to diagnose a "tight" engine once it is fully assembled and installed in the vehicle. Always use a high-quality assembly lube on the final pass to protect the babbitt surface during the critical first few seconds of initial startup.