Reply To: 1957 Evinrude Big Twin 35 Skeg interferes with gears.

[Don]

OK, well you tried the original skeg and that made no difference either.  And yes, the rythmic grinding you hear while tightening and turning  are the gear teeth getting jammed together too much.  You tried another driveshaft which made no difference, I hope you didn’t spend alot on that piece.

So, the probable issues are one or more of the following:

The pinion gear is being pushed down too far into the gearcase.  So, the thrust washers/ bearing may be the wrong pieces or oriented improperly.  Are you using the same thrust washers that were installed prior to the failure, or could they have gotten mixed up with parts from a different gearcase?  It is important to note that the back face of the pinion gear should not be rubbing on bottom face of the pinion gear needle bearing housing.  There is definitely something wrong if the gear is rubbing on the bearing case.  Either the pinion bearing housing is improperly installed, or there is something wrong with the pinion thrust bearing/washer set up.  I suppose that the new pinion gear could have been mismachined, but that seems unlikely.

Something is wrong with one/both of the new gears that you installed, or perhaps something on the prop shaft is limiting the outward movement of the gears.  Like I said, you could try assembling the gearcase installing just one of the gears with the pinion to see if that makes a difference, then try installing just the other gear with the pinion.  If the pinion is still tough to turn with either of the gears installed one at a time, then I would suspect that pinion depth is to blame.  If the pinion turns freely with one of the gears installed, but tough when just the other one is installed, then I would suspect a problem with one of the new gears or its positioning on the prop shaft.

Finally, it is important to go back and look at all the new parts installed.  I am assuming all the gears/pinion/bearings were replaced, along with seals and other items that wouldn’t really have an effect on gear lash.   So, let’s start with the model number of the engine you are working on, and the assumption that its gearcase is original.  Let us know if you feel the gearcase is not original to the engine.   Then list all the new part numbers installed.  It doesn’t seem likely, but there have been many subtle changes to these gearcases through the years, perhaps one of the new pieces you installed was not the correct part number.