Alternator Belt Pulley Shim. Porsche 964 C2 / C4 1989-94

Alternator Belt Pulley Shim.
The Porsche Alternator Belt Pulley Shim is a genuine OEM spacer washer used in the alternator belt pulley assembly. Designed to fine-tune pulley alignment, this 0.5 mm shim ensures the alternator belt runs true, preventing misalignment, premature wear, and belt noise.
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Fits:

• Porsche 964 (911) C2 1989-93
• Porsche 964 (911) C4 1989-93

What This Product Does:

• The shim adjusts the axial spacing (depth) of the alternator pulley relative to the housing or bearing so that the alternator belt alignment is correct.
• It ensures the pulley is neither too far in nor too far out, thereby avoiding misalignment with the belt path, which could cause wear, noise, or belt slip.
• Proper spacing is critical for belt tension, pulley alignment, and smooth operation of the alternator / drive belt.
  
  

Signs / Symptoms A New Shim May Be Needed:

• There is belt misalignment — the belt rides off center or rubs on pulley edges or guides.
  
• Unusual belt noise such as squealing or chirping, especially under load or at startup, which might indicate pulley or belt misalignment.
  
• Excessive belt or pulley wear — uneven wear on belt ribs or pulley surfaces.
  
• When installing a replacement alternator / pulley you find the original shim is missing, damaged, or of unknown thickness.
• You notice vibration or play in the alternator pulley assembly, possibly due to improper spacing.

Why Replacement Matters:

• Belt Misalignment – Without correct spacing, the alternator belt may track incorrectly, slip, or ride off the pulley edges.
  
• Premature Wear – Misaligned belts put stress on both the belt and pulley, causing them to wear out faster.
  
• Noise and Vibration – A missing or damaged shim often results in squealing, chirping, or vibration under load.
  
• Charging Issues – A poorly aligned belt can slip, reducing alternator efficiency and risking undercharging of the battery.
  
• Avoidable Damage – Replacing a small shim prevents more expensive damage to the alternator, pulleys, and belt system.
  
  

Diagram Ref No 15

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

96410626800

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