9. Why does my reversing gear slip out of “forward” whenever I advance the throttle much above half power?

While there are two sets of small pinion gears within the reversing gear assembly, neither forward nor reverse are achieved through the meshing or unmeshing of these gears. Instead, the functions of both forward and reverse are obtained through the engaging and disengaging of two separate clutch mechanisms.

The forward clutch assembly consists of six steel disks (three plain, and three bronze-faced) which are locked together when the shifting lever is moved into the forward detent. If the adjustment of the forward clutch assembly becomes slightly loose (meaning that the shifting lever goes into the forward detent a bit too easily), the clutch will begin to slip at higher power settings.

Remember that power delivered by the engine increases as RPM increases, so the instant that the clutch begins to slip, engine speed increases and the engine delivers more power. Increasing power with increasing RPM means that the more the clutch slips, the more it is going to slip. The resulting rapid increase in RPM gives the impression that the reversing gear has somehow “slipped out of gear”.

All that is necessary when the forward clutch begins to slip is to tighten the forward adjusting collar one or two notches. You can find the notched adjusting collar just behind the forward clutch disk assembly, near the center of the reversing gear. When adjusting the forward adjusting collar, pretend that you are standing behind the engine, facing forward. From this vantage point, you would turn the collar in a clockwise direction to tighten it (just like a regular nut). If you have the Moyer Marine Service and Overhaul Manual, Chapter 6 contains detailed instructions (with pictures) for adjusting the reversing gear.

Basically, the forward adjusting collar is like a large round nut with notches all around its circumference. It is kept from turning by a 1/2” hex-headed retaining bolt. When adjusting the clutch mechanism, loosen this retaining bolt just enough so that you can turn the adjusting collar, and then retighten the retaining pin. When retightening the retaining pin, be sure that the tip of the pin is definitely in one of the notches before applying any significant force. If the end of the pin contacts the collar between the notches, it is very easy to break the cast iron part into which it is threaded. - Updated: November 4, 2003