Factory-replacement Eaton spring-loaded Heavy Duty torsional isolator (coupler) for Magnuson MP 112 truck superchargers, TRD 4.0L supercharger, and many early Jaguar superchargers.
The supercharger coupler mates the front drive cover (also called the nose drive) to the gears that spin the supercharger rotors. It isolates the gears and rotors from vibrations and shocks from throttle load that would otherwise chew up the supercharger gears or damage the rotors.
If your coupler is failing, it will sound like there are rocks rattling around in your supercharger at idle, but the noise will soften up at speed. Replace worn couplers as soon as possible, before they start to damage the supercharger internals. Only use Genuine Eaton isolators in your supercharger, and the knock-offs are known to wear quickly and fail
Eaton part number: 100040