IsoFlex Coupling 4 Bolt

IsoFlex Flexible Gearbox Coupling reduce noise and isolate vibrations.

Prevent premature wear on your driveline, engine or machinery.

Extend the time between services and maintenance.

Why install Isoflex Marine and Industrial Gearbox Couplings?

  • IsoFlex have developed a specialized machining technique used to eliminate run-out and consequent vibration.
  • Internal hex-shaped fittings, mean the possibility of inserts turning in the flexible coupling are minimized.
  • IsoFlex Flexible Gearbox Couplings are easy to install. No cutting required and your boat can remain in the water.
  • While designed for marine use, these couplings are used in many industrial driveline applications too.
  • Assist IsoFlex Engine Mounts in doing their job by allowing controlled engine movement.

How to measure?

Let us take the guesswork out of selecting the right coupling for your application. Please follow the “How to Measure” Instructions.

Have a Gearbox coupling you would like to replace?

Here you will find the correct GEARguard Coupling to replace other commonly used couplings.

Only have transmission information? No Problem

Here you will find the correct GEARguard Coupling to use with a variety of transmissions, organized by manufacture.


As gearbox manufacturer’s dimensions and specifications are subject to change, it is necessary to check all dimensions to ensure fit and suitability of the gearbox coupling.

All IsoFlex Flexible Couplings are manufactured from engineering grade polymers. Although these materials are thermoset polymers, there may be dimensional changes from those specified, depending on ambient temperature conditions.

The tolerance on all IsoFlex machined index rings is +/-0.002″ (+/-0.05mm) @ 25°C (77°F) ambient temperature.

All other dimensions: +/-0.020″ (+/-0.5mm) @ 25°C (77°F) ambient temperature.


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