|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
Pitted gear, ready to fail