Fitment Question for Gear Case Assembly 54 Fleetwin

[fleetwin]

And I’m assuming the 55 housing does not supercede to the 56 number…. Very interesting…. How about the driveshaft/shift rod numbers, are they different? I wonder if OMC compensated for the different exhaust hsg heights with the height of the upper gearcase half?

• This reply was modified 4 years, 1 month ago by fleetwin. Reason: addition

[frankr]

Here is a 1955 CD-12 (5.5hp)

[drifter]

I am going to take some drive shaft and shift rod measurements today. I dug into my parts bin again and found two drive shafts with the same machining but different lengths.
They are identical from the impeller drive pin to the bottom, but one is 1/4″ longer from the drive pin to the top. So, I will measure the shaft length from the impeller plate to the top of the shaft using the 54 cases then measure the same shaft and distance for the 57 cases (once parts are installed).
Maybe the case p/n changes were due to what Gary said relevant to the line cutter cutouts in the 57 cases that are not in the 54 cases.
Frank, you were right about the flashing or webbing in the prop hub possibly interfering with the 57 case cutouts. A tiny bit of grinding will eliminate that problem.
Stay tuned. Got a lot of scrubbing and cleaning to do on the 57 cases before assembly and measuring.
Thank you all again, for your kindness in helping me with your vast knowledge and tremendous expertise.
Nick

[drifter]

I just did a quick check of the case dimensions and both cases are identical.

[fleetwin]

OK, well the driveshaft part numbers are different for the 55 vs 57 gearcases, but the shift rod part numbers are the same…. So this kind of kills my “different exhaust hsg height” theory. It will be interesting to hear about the driveshaft measurements drifter is going to make…
This makes me wonder what problems might occur if the upper driveshafts are inadvertently swapped…. I suppose if the longer driveshaft is used instead of the shorter one, this could jam up the powerhead. If the shorter driveshaft is accidentally used, then I would expect accelerated/strange spline wear.

[drifter]

I just looked again at the two drive shafts I have and the longer one is marked “7.5hp”. I think (pretty sure) it’s from a 1957 Evinrude Fleetwin.

[frankr]

Ah, so the plot thickens, as they used to say. So the drive shaft is longer, but the shift rod stayed the same? Now I’m wondering, did the distance from the shifter handle shaft to the powerhead gasket surface change?

[fleetwin]

frankr wrote:

Ah, so the plot thickens, as they used to say. So the drive shaft is longer, but the shift rod stayed the same? Now I’m wondering, did the distance from the shifter handle shaft to the powerhead gasket surface change?

I was wondering this same thing…..

[drifter]

OK, I took measurements with both casting assemblies.

First, I measured the casting in my earlier photo (Model 7516 – 1954 Fleetwin 7.5hp). I used the drive shaft that was in the motor when I bought it. Measuring from the top of the shock absorber to the tip of the drive shaft measures 18″. Measuring from the impeller plate to the tip of the drive shaft it measures 16 13/16″.

Now, going to the other casting assembly (Model 5514 – 1957 Fisherman 5.5hp), and using the same drive shaft, the measurements are identical (18″ and 16 13/16″).

Bottom line, this drive shaft should be transferable between the two castings. Only difference I can see in the two castings is the line cutter notches in the Fisherman castings.

Just to muddy the waters a bit more…..while digging around in my parts bin I came across a drive shaft labeled ” 1956/1957 7.5hp Evinrude”. This drive shaft measures 1/4″ longer than the drive shaft in the 1954 Fleetwin. From the impeller drive pin to the bottom it measures the same but from the impeller pin to the top it measures 1/4″ longer.

Ever onward through the fog.
Drifter

[Author]

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