HD Transmission / Gearbox Mount Bush. Porsche 964 C4

HD Transmission / Gearbox Mount Bush.
Eliminate drivetrain slop and restore crisp gear changes with this HD Transmission / Gearbox Mount Bush.
Designed for the Porsche 964 C4, this heavy-duty mount uses a stiffer, high-durometer rubber compound (approximately 25 % firmer than factory rubber) to control gearbox motion and maintain precise alignment under load.
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Fits:

• Porsche 964 (911) C4 1989-93

Diagram Ref No 23

What This Product Does:

• Securing the Transmission - It keeps the transmission firmly in place, resisting movement under torque, acceleration, or deceleration.
• Absorbing Vibration & Noise - The rubber or elastomer element isolates drivetrain vibrations so they don't transmit harshly into the cabin.
  
• Controlling Movement / Deflection - Under load, transmissions tend to twist or shift slightly. A stiffer mount reduces that movement, improving shift feel, drivetrain alignment, and response.
  
• Maintaining Drivetrain Geometry - By limiting transmission motion, it helps preserve correct angles and alignment of drive shafts, couplings, and linkage.
  
  

Symptoms Of A Failing Or Weak Transmission Mount Bushing:

• Clunks or thuds when shifting or applying torque
  
• Movement or slop in the transmission under load
  
• Delays or vagueness in shifts due to misalignment
  
• Excess vibration or drivetrain shake in the cabin
  
• Wear or stress on driveline components (e.g. drive shafts, joints)
  
• The transmission might feel “loose” under acceleration or deceleration

Why Upgrading Matters:

• Improved Shift Feel & Precision - A stiffer mount reduces movement that can dull shift quality or introduce slack.
  
• Better Drivetrain Alignment Under Load - Less motion keeps the transmission geometry stable, which protects driveshafts, joints, and couplers.
  
• Sharper Response - With less flex, the car responds more directly to throttle inputs without drivetrain “lag.”
  
• Balance of Comfort and Control - The HD rubber design offers more rigidity than stock but isn’t as harsh as solid mounts, so you still retain usable vibration isolation.
  
• Durability - A stiffer compound is more resistant to deformation, aging, oil, and heat, giving longer service life.
  
• Cost-Effective Upgrade - If the original bushing is degraded, installing an HD version is often a worthwhile performance upgrade.

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Related, superseded, cross reference or alternative numbers for comparison.

96437505502

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