Prop shaft splines closed Evinrude 1967 V4 60HP

"Is it normal for the splines

"Is it normal for the splines on the prop shaft on my Evinrude 1967 V4 60HP to be open at the front (forward gear) end and closed at the back (reverse gear) end? That is, the dog clutch will slide on from the front but not the back.

I'm asking because the thrust washer between the reverse gear and the spline end was flattened enough to be trapped in the groove (i.e. wouldn't move along shaft), which suggested a very heavy impact on the prop end of the shaft. This could have turned down the ends of the splines but it'd take an enormous impact on the prop end to flatten them and probably do more damage to the gearcase and shaft, so I suspect that the splines are machined that way.

It doesn't make any difference I can see to the operation of the dog clutch. About the only difference between forward and reverse would be that the lugs on the dog clutch are stopped fractionally before they hit the reverse thrust washer but they're still far enough in to engage reverse.

Thanks for any help."

They do NOT machine splines th

They do NOT machine splines that way! This happens from normal running ( the reverse gear spins in opposite direction to the prop shaft) and it does not affect operation of the clutch dog in any way.

"ssparky

Thanks.

Your po

"ssparky

Thanks.

Your post made me look closer at the parts.

There's an irregular (i.e. not the same all the way around) internal ridge at the spline end of the reverse gear, a bit like the ridge on the top of a combustion cylinder where the rings don't reach. The ridge stops the bronze bushing from sliding through the gear.

Either a manufacturing fault or a later metal deposit on the reverse gear on the seat for the thrust washer stops the washer seating flat.

I suspect that the thrust washer has been canted a bit and has been brushing the ends of the splines at a slight angle and closed them over.

If the thrust washer sat flat the splines should be open like the ones on the forward gear end, which has the same thrust washer and face to the splines.

Maybe the thrust washer internal diameter narrowed a fraction from being canted and squeezed against the cog and or spline end."