Topic: 1953 25 HP Johnson – Antique Outboard Motor Club,Inc

This topic has 17 replies, 6 voices, and was last updated 3 years, 6 months ago by trex014.

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May 24, 2021 at 3:43 pm #238880
bwanadon
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US Member
Hi Guys

I found a 25 hp Johnson RD-14 (53) for my 14 foot Sea Nymph. Right now it’s a long shaft and I need to convert it to a short shaft. What all do I need to convert this over to short shaft?

I have ordered a parts manual off ebay and it will be here next week. Where can I get a repair manual or owners manual for this?

Don
May 24, 2021 at 3:56 pm #238881
bwanadon
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US Member
Having trouble posting pics. Can anyone help me out?

Can x that request. I figured it out. lol
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May 24, 2021 at 6:58 pm #238892
bwanadon
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US Member
May 24, 2021 at 7:47 pm #238896
bobw
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US Member
For the short shaft conversion, you need the shorter driveshaft and shift rod. Original part numbers for the short version were:

Driveshaft – 302624
Shift rod – 303472

I believe that motor had an integral water channel in the casting so you don’t need a different water tube. Both of the replacement parts are available at Marine Engine but you can probably find less expensive options on Ebay or by posting an ad in the Classified section here on the AOMCI website.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

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bwanadon
May 24, 2021 at 8:15 pm #238897
crosbyman
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Canada Member - 2 Years
can you raise the transom 2 inches…. solves the problem and gives you 2 inches more to stop a backwash 🙂

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May 24, 2021 at 9:26 pm #238907
bwanadon
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US Member
I can get 3.5 inches, if I remake the transom straight across. I do take water over the transom on occasion on Lake St. Clair.
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May 24, 2021 at 11:49 pm #238919
opposedtwin
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The difference between long and short shaft is 5 inches if memory serves me. The consideration is the relationship between the anti-cavitation plate and the bottom of the hull. The plate should be in the same plane as the bottom or ever so slightly lower than that plane.

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bwanadon
May 25, 2021 at 6:39 am #238923
bwanadon
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opposedtwin wrote:

The difference between long and short shaft is 5 inches if memory serves me. The consideration is the relationship between the anti-cavitation plate and the bottom of the hull. The plate should be in the same plane as the bottom or ever so slightly lower than that plane.

So I need to move the transom up3.5 and have a jack plate for the remaining 1-1/2. I could just do all 5 inches with a jack plate. Don’t know how that would look though.
May 25, 2021 at 6:41 am #238924
crosbyman
Participant
Canada Member - 2 Years
short to long conversion with a Merc Classic 50 on a princecraft 16 footer

I think short to long is about 2 inches diff. wasn’t 25 inch extra long ?

anyway my Classic 50 with power tilt was installed on a raised transom the back end was rebuilt 2 x3/4 inch special 7 ply waterproof porch plywood all bolted up with a large angle iron all across of the transom. top

home made steering box with cable

never had any issues

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May 25, 2021 at 6:58 am #238929
crosbyman
Participant
Canada Member - 2 Years
fyi if you do modify looking at the video it looks like abouta 5 inch extension…

https://www.youtube.com/watch?v=NrSR2wfymNM

all up to you now

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