Speeditwin Gear Case Cap?

[Buccaneer]

I purchased a propshaft and gear case cap for my 1950 6039 Speediwin
to replace broken parts. The most important part, the propshaft is correct.
The gear case cap is evidently for something “beefier” than what I have.
It uses 7/16″ bolts, is bigger around on the outside, and does not use
the big o-ring to seal the gear case. (My bolts are 3/8″)
Any idea what it fits?
Not sure I can use it, but may save for a future project.
The prop shaft threads were shot. Used to be 3/4″ x 16 tpi.
I re-threaded it on the lathe for 5/8″ x 18 tpi, but will need to come up with,
or try to make a brass nut.
I’ve been thinking about the worn areas of the shaft. The most concerning
are the “seal” area, and where the prop mounts. $50 for a 25 mm Speedi
Sleeve doesn’t seem like money well spent, so may have to come
up with a cheaper fix.
I may use the broken gear case cap by fitting a plate, or “yoke” type
affair around the cap so it can be bolted down with two bolts.
Any one try this? Probably won’t be too “aerodynamic” though, or
in this case, “Waterdynamic”!

Prepare to be boarded!

[frankr]

You say you have a lathe. Also have a mill or access to one? Considered just make a new shaft?

[squierka39]

The cap may be for one of the other speeditwin feet. Hopefully Garry will chime in with his factory drawings of them. The speeditwin had a few versions of lower units.

[Buccaneer]

frankr wrote:

You say you have a lathe. Also have a mill or access to one? Considered just make a new shaft?

Frank, I have an old Logan lathe, and managed to cut new threads for the prop shaft.
I considered trying to make a new prop shaft. I have no milling machine. I have no
woodruff keyway cutters, and if I did come up with one, it would have to be used in the
lathe with my little Palmgren milling attachment. I cut a straight slot keyway
once that way, but it was a little “iffy”.
Also, not sure what “hardness” of 25 mm shaft material would be hard enough
and not too hard to machine.
Thoughts appreciated. Thanks!

Prepare to be boarded!

[David Bartlett]

The other cap fits the later style lowers on the SpeediTwin and SpeediFour motors.

David Bartlett
Pine Tree Boating Club Chapter

"I don't fully understand everything I know!"

[Buccaneer]

David Bartlett wrote:

The other cap fits the later style lowers on the SpeediTwin and SpeediFour motors.

The broken one is off my 1950 Speeditwin, which I think
was the last year for the 6039 models.
Going by the good cap and the number stamped on it,
it must be off of something prior?

Prepare to be boarded!

[David Bartlett]

Tom,
I had a 1948 SpeediTwin and SpeediFour. Both were like the piece on the left. Both also had the heavy gearcase with the pad on the bottom of the skeg.

David Bartlett
Pine Tree Boating Club Chapter

"I don't fully understand everything I know!"

• This reply was modified 4 years, 4 months ago by David Bartlett.
• This reply was modified 4 years, 4 months ago by Mumbles.

[Buccaneer]

My “Notifications” say I have a reply from “Garry in Michigan”, but I’m not seeing it!

Prepare to be boarded!

[garry-in-michigan]

[ccolor=blue]
There were three basic lower unit (Gearcase) designs for Speeditwins. from about 1932 to 1942 they used an Elto patern, very streamlined.During WW2 the Stormboat motor {Made by modifying the 460 racing motor} used a beefed up model that could be run up on coral beaches. It had wings to protect the propeller. After the abrupt end of the war, Evinrude had thousands left they used on the larger outboardsThose ran out in 1`9438 and The one with the “O” ring gasket came out. Last models added a water scoop on the exhaust outlet behind the propeller.[/color]

_________ 1940 ____________

_________1946 ____________

_________1949 ___________

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