Topic: ’71 Evinrude 40HP long shaft to short conversion

This topic has 13 replies, 7 voices, and was last updated 7 years, 8 months ago by frankr.

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August 30, 2017 at 12:55 am #8072
nj-boatbuilder57
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Hey folks,

Very first post on this forum!

I have a line on a very good deal for a ’71 Evinrude 40HP long shaft….model # 40153G. Thing is: my boat needs a short shaft.

Is conversion as simple as a.) dropping the lower, b.) removing the extension piece, c.) replacing the shift rod & shaft with the shorter versions, and d.) reassembling? Is that all there is to it, or am I missing something?

The deal on the engine is very good, leaving me with enough cash to find / buy a short rod & shaft…..if that’s all there is to it.

Thoughts?

Thanks!

Mark in NJ
August 30, 2017 at 3:02 am #64029
retiredoz
Participant
Prolly need to do something about the water tube, but otherwise that should do it…
August 30, 2017 at 11:13 am #64030
fleetwin
Participant
US Member
You can cut 5" off the water tube, but changing the shift rod isn’t an easy chore. I’m thinking you would have to disassemble that gearcase to change the lower shift rod, which is a pain. I suppose there is the slim chance that this was a short shaft to begin with and someone added the shift rod and water tube "extensions", but I wouldn’t count on that. I suppose you could avoid disassembly by carefully cutting the shift rod and beveling out the shift rod for the connector screw.
August 30, 2017 at 2:27 pm #64036
Anonymous
Wouldn’t model number indicate if it was originally a long shaft?
Kirk
August 30, 2017 at 5:45 pm #64048
fleetwin
Participant
US Member
quote kirkp:

Wouldn’t model number indicate if it was originally a long shaft?
Kirk

You are right, the model number should describe the original shaft length, I just don’t have access to the manual that would spell it out….
August 30, 2017 at 6:53 pm #64050
retiredoz
Participant
Pretty sure the ‘3’ in the model # indicates LS…
August 30, 2017 at 6:56 pm #64051
retiredoz
Participant
http://www.marineengine.com/parts/evinr … /52947.gif
August 30, 2017 at 10:16 pm #64054
nj-boatbuilder57
Participant
quote retiredoz:

Pretty sure the ‘3’ in the model # indicates LS…

Correct.

It’s a LS…no doubt. I was just curious if the conversion is as simple as I believe it to be, and it sounds like the answer is "yes".

Thanks!
August 31, 2017 at 12:33 am #64063
Anonymous
Replacing the shift rod means opening up the gearcase and re-sealing it, which means getting (and dealing with) suitable gooey sealer, cutting new spaghetti seal to the right length and square endedness, and wondering if it might make sense to replace the shift shaft o-ring, which (at least on the smaller gearcases I’ve worked on) is a frequent cause of water intrusion…. None of it is rocket science, but it took me two tries to get the 10hp and 18hp gearcases I’ve put back together buttoned up to where I’m only slightly worried about water getting back in!

OMC Gurus: The late 40hp’s like the one in question use the single wall (non-super silent) leg; Is it safe to use the gearcase from a short shaft 1950’s (non-super silent) 35hp or a 1960’s 33hp? 1960’s 28hp??
August 31, 2017 at 2:27 am #64072
garry-in-michigan
Participant
Lifetime Member
The 25, 28, 30 horse gear case has a smaller pinion bearing and would not last very long when fed 40 horses. 33, 35 & 40 horse gear cases are the same. . . 😀
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