ACL 4B1606H-.025 Race Rod Bearing Set +0.025mm Audi VW 1.6 1.8T 2.0L EA113

Vehicle Fitment

• 1983-2001 Audi A3, A4, A6, TT, 80, 90, 100 - 1.6L (1595cc), 1.8L (1781cc, incl. 1.8T Turbo), 2.0L (1984cc) Inline-4
• 1983-2003 Volkswagen Polo, Caddy, Golf, Jetta, Passat - 1.6L (1595cc), 1.8L (1781cc, incl. 1.8T Turbo), 2.0L (1984cc) Inline-4

Fitment Notes

• This bearing set is for connecting rods WITH a locating notch (tang) - the EA113 Gen 1 engine family. Later Audi/VW engines from approximately 2000 onward use connecting rods WITHOUT a notch and require a different bearing set (4B1609H series). Verify your connecting rod type before ordering.
• The .025 suffix designates this as the +0.025mm oversize bearing set - intended for use when the crankshaft rod journals have been ground 0.025mm undersize. The thicker wall restores correct running oil clearance on a lightly reground crankshaft.
• Do NOT use on a stock, unground crankshaft. For standard journal diameter, use 4B1606H-STD. For crankpins ground 0.25mm undersize, use 4B1606H-.25. For crankpins ground 0.50mm undersize, use 4B1606H-.50.
• Always measure crankshaft rod journal diameter with a micrometer before selecting bearing size. Confirm actual clearance with Plastigage or a dial bore gauge after assembly.
• Sold as a complete set of 8 bearing shells - sufficient for one full 4-cylinder engine build.
• UPC: 9315726396902

Features

• Tri-metal construction: copper-lead alloy lining bonded over a hardened steel backing, with a high-strength overlay plate - engineered for the high-RPM and high-boost demands of performance-built Audi and Volkswagen inline-4 engines.
• Hardened steel backing on all rod bearings improves structural support of the bearing lining and maintains crush under high sustained loads.
• High-strength overlay plate with reduced thickness provides improved fatigue resistance compared to OEM-spec bearings - critical in turbocharged 1.8T and performance 2.0L builds operating above stock power levels.
• Increased bearing crush and tighter wall tolerances ensure consistent, secure seating in the connecting rod housing bore, reducing the risk of bearing spin.
• Enlarged ID chamfers on bearing edges accommodate the larger fillet radii found on performance and aftermarket Audi/VW crankshafts.
• 3/4-groove design optimizes oil supply to the rod journal and maximizes load-carrying surface area across the bearing face.
• Elimination of flash plating on bearing backs improves heat transfer and maximizes grip between the bearing shell and rod housing bore.
• Increased eccentricity compensates for bore distortion at high RPM and assists in the formation of a stable hydrodynamic oil film under load.

Specifications

• Part Number: 4B1606H-.025
• Product Line: ACL Race Series
• Application: Connecting Rod Bearings (With Notch / Tang)
• Engine Family: Audi/VW EA113 Gen 1 - 1.6L, 1.8L (incl. 1.8T), 2.0L Inline-4
• Crankshaft Size: +0.025mm Oversize (for crankpins ground 0.025mm undersize)
• Shaft (Crankpin) Diameter: 47.758-47.778mm (1.8802-1.8810 in)
• Tunnel (Housing Bore): 50.600-50.619mm (1.9921-1.9929 in)
• Maximum Wall Thickness at Crown: 1.405mm (0.0553 in)
• Maximum Overall Length: 19.00mm (0.748 in)
• Bearing Material: Tri-Metal Copper-Lead Alloy / Hardened Steel Backing
• Quantity: Set of 8 Shells (complete engine set)
• UPC: 9315726396902

Included Components

• 8x Race Series Connecting Rod Bearing Shells - +0.025mm Oversize, With Notch

Product Description

The ACL Race Series 4B1606H-.025 connecting rod bearing set is the +0.025mm oversize option for Audi and Volkswagen EA113 Gen 1 inline-4 engines - the long-running 1.6L, 1.8L (naturally aspirated and 1.8T turbocharged), and 2.0L four-cylinder family that powered a wide range of Audi and VW models from 1983 through the early 2000s, including the A4, A6, TT, Golf GTI, Jetta GLI, Passat, and more. This set is selected when the crankshaft rod journals have been lightly reground 0.025mm undersize to clean up surface condition during a rebuild.

A critical fitment note: this bearing is designed for connecting rods that use a locating notch (tang) for bearing retention - characteristic of EA113 Gen 1 hardware. Later engines (from approximately 2000+) switched to a no-notch rod design requiring the 4B1609H series. Always verify rod type before ordering. Built on ACL's Race Series tri-metal platform, these bearings offer superior fatigue resistance and oil film stability over OEM shells. Sold as a complete set of 8 shells for one engine.