In looking at the parts diagram, it looks like if you made the
thrust plug longer, that it would push the prop shaft, and
hence driven gear, further away from the drive gear, and
ending up in “more” backlash. Then again, without
the actual parts in front of me, I’m just guessing.
My little bit of automotive training almost 50 years ago,
taught us to use bluing grease on the pinion and differential
gears, rotating them, to check the actual gear mesh, making
sure the gears were meshing near full depth and in the
centers of the teeth.
On the lower horse power motors, I pretty much go by “feel”
when checking the backlash, but none of my motors
see much use.
Prepare to be boarded!
