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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.

About DriveGuardian


  • DriveGuardian Bravo, IMCO, Bmax - $2,695.99

  • DriveGuardian NXT - $2,495.99

  • Drive Guardian SSM - $2,995.99

  • DriveGuardian Crashbox - $2,995.99

  • DriveGuardian Ilmor V10 - $3,195.99

DriveGuardian test run

DriveGuardian uses billet aluminum housings, Kevlar clutch plates and heat treated Chromoly hubs. The SSM and Crashbox versions include a HD damper plate with forged hubs and Chromoly backing 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 and includes a 2-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.


The team runs a 32’ Cobra that is approximately 8,500lbs with 650HP Saris Racing Engines and Bravo XR Drives, IMCO -2 lowers and 4-blade BBlades Props.  They installed DriveGuardians for the 2014 season using the SAME props, SAME engines and SAME drives as 2013.  In 2014 the team ran five races that included some very rough open ocean events and unlike 2013, there was ZERO pitting of the teeth on the upper gear sets!

With nothing more than changing the gear lube the team ran the 2015 AND 2016 race seasons for a total of twelve races on the same upper and lower gear sets!  The gears showed zero signs of pitting and have since been reinstalled in the drive.  Proof positive that DriveGuardian eliminates the torque spikes and significantly improves sterndrive reliability.


2013 - Three Races with Stock Coupler

2014 - Five Races with DriveGuardian

2015 & 2016 - 12 Races with DriveGuardian

“Fantastic results and DriveGuardians have made our Bravos withstand the abuse” -Jason Saris

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