Main Bearings, .020 Case, .030 Crank, .040 Thrust

OVERVIEW

When you are deep into a professional engine rebuild, you know that precision is the difference between a motor that lasts twenty years and one that fails in twenty miles. These EMPI Silverline main bearings are the gold standard for restoring an air-cooled Volkswagen engine case and crankshaft that have seen significant service. In many instances, a factory-standard case has suffered from "pounding" where the main bearing saddles become out-of-round or oversized due to decades of heat cycles and vibration. By machining the case .020 inches (0.50mm) over, you create a fresh, concentric seat for the bearings. Likewise, a crankshaft that has experienced scoring or wear requires a .030 inch (0.75mm) grind to ensure a perfectly smooth journals. This specific bearing set is engineered to bridge that exact gap, providing a tight, reliable fit for a heavily machined rotating assembly.

Beyond just the journal diameters, this set addresses the critical "thrust" surface of the engine case. The number one main bearing (closest to the flywheel) takes the brunt of the lateral force every time you step on the clutch. Over time, the engine case thrust face wears down, leading to excessive crankshaft end-play. This set is designed for a case that has had the thrust surface machined .040 inches (1.00mm) to true it up. Featuring a high-quality steel-backed construction, these Silverline bearings offer superior heat dissipation and structural integrity compared to inferior all-aluminum alternatives. Whether you are building a rugged off-road rail, a classic Beetle daily driver, or a vintage Transporter, these bearings provide the exact tolerances needed to maintain high oil pressure and protect your investment for the long haul.

FITMENT

This main bearing set is designed for Type 1 based air-cooled engines (1200cc to 1600cc) with specific machining requirements. Please verify your machinist''s measurements before ordering.

• Volkswagen Type 1: Beetle and Super Beetle 1961-1979
• Volkswagen Type 2: Bus, Transporter, Kombi 1961-1971
• Volkswagen Type 3: Fastback, Squareback, Notchback 1961-1973
• Volkswagen Karmann Ghia: 1961-1974
• Volkswagen Thing: 1973-1974
• Custom Applications: Sand Rails, Dune Buggies, and Trikes using VW Type 1 engine cases.

SPECS

• Brand: EMPI / Silverline
• Case Bore Machining: .020 inches (0.50mm) Oversize
• Crankshaft Journal Machining: .030 inches (0.75mm) Undersize
• Thrust Surface Machining: .040 inches (1.00mm) Oversize
• Material: High-strength Steel-Backed Alloy
• Part Number: 111-198-477OS
• Compatibility: 40hp, 1300cc, 1500cc, and 1600cc based dual-relief or single-relief cases.

PRO TIPS

1. Triple-Check Your Machinist''s Numbers

The most common mistake in engine assembly is ordering bearings based on a "guess" rather than a micrometer reading. Before purchasing, confirm with your machine shop that the case was indeed cut .020 over, the crank was ground .030 under, and the thrust face was cut .040. Even a difference of .010 can lead to a catastrophic loss of oil pressure or a seized engine. Always dry-fit your bearings into the case halves first to ensure they seat fully and that the locating pins align perfectly with the holes in the bearings.

2. Verify Oil Hole Alignment

During the manufacturing process, or due to variations in aftermarket cases, the oil holes in the bearings may not always align 100% perfectly with the oil galleries in the engine case. Before final assembly, place the bearings in the case and use a small pick or a flashlight to ensure the passage is clear. If the bearing shell is shrouding the oil hole even slightly, it can restrict flow to the journals. It is a standard pro-builder practice to slightly chamfer or "port" the oil holes in the bearings to match the case for maximum lubrication efficiency.

3. Manage Your End-Play Correctly

Since these bearings are designed for a .040 oversized thrust cut, you must be extremely diligent when setting your crankshaft end-play. After the case halves are torqued to spec with the crank inside, use a dial indicator to measure the lateral movement. You will use three shims behind the flywheel to achieve the factory specification (usually .003 to .005 inches). Never use more or fewer than three shims, as they act as a "bearing" surface against each other. If you cannot reach the spec with standard shims, re-verify that your thrust surface machining and bearing width match perfectly.