TRS Drive Gear Failures

The TRS drive as supplied by Mercury Marine was originally delivered on engines of up to 465 Horsepower. In our experience, they usually work pretty well up to 550 HP or so. After that, the lower gear set has a limited life span. If you are lucky enough to catch a gear set before it breaks, there is usually severe pitting on the load face of the drive gear teeth. A fatigue crack will start at these pits and soon the tooth will fail. The upper drive shaft housing and gears seldom break.

After consulting with a metallurgist who specializes in  Winston Cup Nascar components, we have developed a revised heat treat and surface treatment for the TRS lower gears. This will just about eliminate the surface pitting so common to these gears. Note that all machine marks have been removed from the processed gear.

We have also used this process effectively on Alpha and Speedmaster gears.

Pitted TRS gear

Pitted gear, ready to fail

Processed TRS gear

Processed gear


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