Billet Aluminium Top Pulley Shim - 7 Required

Replacement pulley shims with a larger internal diameter, specifically designed for use with billet aluminium top pulleys that feature a larger square centre boss. These are not suitable for standard factory pulleys and are intended only for aftermarket billet pulley setups.

On aircooled VW engines, pulley shims are used to adjust fan belt tension by spacing the two halves of the crank or alternator/generator pulley. Adding or removing shims between the pulley halves changes how tightly the belt sits in the pulley groove. Correct belt tension is critical—too loose and the belt can slip, too tight and it can cause premature wear to bearings and components.

With billet pulleys, the centre boss is often larger than standard, meaning original shims will not fit correctly. These larger ID shims ensure proper fitment on the pulley shaft, maintaining accurate alignment and allowing precise belt tension adjustment.

Each pulley typically requires 7 shims in total, distributed between inside the pulley (for adjustment) and stored under the outer pulley nut (as per VW design). Having the correct number of shims ensures proper adjustment range and prevents damage to the pulley or belt.

Sold individually, allowing you to replace missing or incorrect shims as needed. Ideal for performance engines, custom builds, or vehicles running billet pulley systems.

For best results, ensure your pulley halves, belt, and retaining hardware are in good condition when setting belt tension.

Fitment

Aircooled VW

• Beetle Saloon & Cabriolet 1960–1979
• T1 Split Bus 1960–1967
• T2 Bay Window 1968–1979
• Karmann Ghia Coupe & Cabriolet 1960–1974
• Trekker (Type 181) 1968–1983
• Buggy / Baja (Type 1 based) 1960–1979

Product Details

• Application: Alternator/Generator pulley (billet only)
• Type: Large internal diameter shim
• Quantity required: 7 per pulley
• Sold as: Individual shim