Difference In Shift Dogs

[Mumbles]

A friends ’56 Johnson QD-17 needs a shift dog and the part number is 375711, same as used in ’57 and older FD motors. 305191 is listed for ’58 and newer FD’s while ME shows 329795 for the ’57 QD’s. So the question of the day is, what’s the difference in them if the gearcases are basically the same?

Looking at the photos, the lugs on the dogs look to be shaped slightly different with one being more rounded. It seems to me the FD gears were more helical to starting around ’58 or ’59 somewhere while the earlier ones were more square cut. The other question, can a later FD dog be used in the ’56 QD gearcase?

Just noticed, but the one shown for ’57 QD’s might be wrong. It looks more like the ’58 and later style similar to the ones used in 5.5 and 7.5 horse motors.

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[chris-p]

If I remember correctly you have to swap the whole gear set, including the pinion. Let me go downstairs and do some remember’n.

I believe I tried it once without swapping the whole gear set and it locked up on me. Width of total lugs end to end is wider on one of them?

[Steve D]

quote Mumbles:

So the question of the day is, what’s the difference in them if the gearcases are basically the same?
The other question, can a later FD dog be used in the ’56 QD gearcase?

Mumbles, What I’ve found is the later FD dog (305191) cannot be used in the earlier QD gearcase because it has one more tooth/spline and won’t fit on that prop shaft.

As for the 375711, every time I’ve ever ordered one it always comes in like the one you have there with the box. But that’s different from what I pull out of the gearcase which is what you show in the bottom picture, but that’s also 375711. 😕

[Mumbles]

OK, this all makes sense, width and spline count. Thanks guys!

[Author]

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