Marine Design Corporation

DriveGuardian SSM

DriveGuardian for SCS Crashbox

DriveGuardian NXT with HD Damper

DriveGuardian Bravo


There are a number of solutions for strengthening a stern drive’s components to reduce failures that have shown some limited improvement in reliability. And there are many complete swap-out solutions that can absolutely solve the reliability issue, but can be expensive and/or impact the boat’s performance or handling characteristics. 

The cause of many gear and shaft failures is the enormous torque spike that is generated each time the propeller exits, and then re-enters the water after hitting a wave.  These spikes are generated by the inertia of the rotating engine assemblies and can be 2X-4X the actual torque output of the engine.  Each spike lasts only a fraction of a second and throttling alone cannot eliminate them.  Every spike causes stress to the gears, shafts, bearings and propeller blades. Eventually, something is going to fail.

DriveGuardian is a patented device (US 8,771,087) that replaces the Bravo rubber coupler or damper plate with a torque-limiting clutch that absorbs and dissipates the spikes. DriveGuardian eliminates the source of the damage instead of playing a losing game of trying to make each component strong enough to handle 4X the engine’s torque.  Because that is what it would take to make this issue go away.

DriveGuardian uses billet aluminum housings, Kevlar clutch plates and heat treated hubs. The SSM and Crashbox versions include a HD damper plate for increased reliability over the factory units. Installation
is a direct bolt-on with no additional modifications required

Each DriveGuardian is bench tested and precisely calibrated to ensure maximum performance. . Includes a 1-year Manufacturer Warranty.

The torque at which DriveGuardian will engage is greater than the peak torque of the engine so that the clutch will only slip during a torque spike.  Fix your drive reliability issue at the source, with DriveGuardian.


DriveGuardian  Bravo          $2,495.99ea

DriveGuardian  NXT            $1,995.99ea

Drive Guardian  SSM           $2,995.99ea

DriveGuardian  Crashbox   $2,995.99ea

DriveGuardian Ilmor            $3,195.99ea

         with an Indy Drive