040-903-161 VW Finned Alternator Pulley - Beetle, Bus, Ghia, Thing

Finned Alternator Pulley – 040-903-161

The 040-903-161 is a high-performance finned alternator pulley specifically designed for 12-volt setups on upright air-cooled Volkswagen engines. Unlike standard smooth-faced pulleys, this version features integrated cooling-fan fins on the back side of the pulley face. These fins are engineered to pull additional cooling air through the fan shroud, which directly supports the cooling of the alternator and helps maintain correct internal engine clearances.

This pulley is built to the Brazil/Mexico production spec and serves as a highly effective upgrade for vintage VWs operating in warmer climates. It is a direct replacement for part numbers 040-903-109 and 040-903-161, ensuring that the charging system remains at a safe operating temperature even during extended drives. It is sold individually and is a crucial component for anyone performing a 12V conversion or an alternator upgrade.

Detailed Vehicle Compatibility

VW Bug (Beetle):

• 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976, 1977

VW Super Beetle:

• 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979

VW Karmann Ghia:

• 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974

VW Thing:

• 1973, 1974

VW Transporter (Bus):

• 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976, 1978, 1979

Product Highlights & Features

• Integrated Cooling Fins: Built-in fan blades pull air through the charging system, preventing heat soak and extending the life of the alternator.

• 12-Volt Optimized: Specifically designed for the 12V charging systems standard on 1967 and later upright engines.

• OEM Brazil/Mexico Spec: Manufactured to strict factory tolerances for a perfect fit on the alternator shaft.

• Enhanced Airflow: Supports overall engine cooling by assisting the primary fan in pulling air through the shroud.

Technical Specifications

• Part Number: 98-9012-B

• Interchange: 040-903-109

• Application: 12V Alternator or Generator

• Engine Type: Upright Air-Cooled (Type 1) & Pancake (Type 4)

Installation & Maintenance Tips

• Required Hardware: This pulley is sold individually. You will need the appropriate Woodruff key, pulley nut, and adjustment shims for a complete installation, as they are not included.

• Shim Adjustment: Proper belt tension is achieved by placing shims between the two pulley halves. Ensure the belt has about 1/2 inch of deflection for optimal performance.

• Shaft Alignment: Before tightening the nut, ensure the Woodruff key is seated flat in the shaft. A misaligned key can cause the pulley to wobble and eventually shear the fins or the key itself.

• Check for Clearance: After installation, rotate the pulley by hand to ensure the fins do not contact the fan shroud or any other engine components.