Longshaft @ 23"?

jasoutside

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Dec 20, 2009
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Hi fellas, I just picked up a 1983 Johnson 25HP engine. This morning I started to put together an engine stand for it and pulled out the measuring tape to check the height. Bracket to the cavitation plate is 23". Huh? So wait, I thought that a long shaft motor was at 20" (give or take an inch or two).

So what have I got here? Is a 23" shaft standard for this vintage? Do I really want 3 extra inches dragging in the water?

:confused:

Thanks in advance guys!
 

jasoutside

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Re: Longshaft @ 23"?

Sorry my auzzie bro, I don't have an eye on it at the moment. I can post it up later...:)
 

jasoutside

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Re: Longshaft @ 23"?

Yup, all the measurements that I have seen puts a 23" into the extra long shaft category (all be it by only a half inch). Hmmmmmmm......
 

mark1961

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Re: Longshaft @ 23"?

Okay, so watcha got on the smokercraft measurement wise?.....
 

jasoutside

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Re: Longshaft @ 23"?

Well, she is currently at 15" (actually about 15.5").
P1080387.jpg


I planned to build it up to full height which is 20" (easy job). I have no interest in going any higher than that though. I could mount the engine just a touch high to eat up .5 - .75 of an inch but that's bout it.

See my challenge? Should I be concerned with the extra 2.5" dragging in the water? I'd hate for my performance to be messed up right otta the gate here, ya know.
 

Chinewalker

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Re: Longshaft @ 23"?

That's standard issue long shaft motor for use on 20-inch transom. They make them on the long side for variance between boat hulls, keels, bottom designs, etc. Much easier to jack a motor higher than to cut a transom lower....
 

archcycle

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Re: Longshaft @ 23"?

My brother has an old johnson tiller with an extension on the midsection that adds a few inches. Got one of those?
 

jasoutside

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Re: Longshaft @ 23"?

My brother has an old johnson tiller with an extension on the midsection that adds a few inches. Got one of those?

Yup, it's got the 5" extension on it. But in my mind, taking it off will add more problems that it would solve (plus work and $) making the shaft @ 18", knowwhattamean?
 

Chinewalker

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Re: Longshaft @ 23"?

You have a short shaft boat. I would think taking the extension out and getting a short driveshaft would be a lot easier than adding a proper long shaft transom to your boat... You would have to pull the lower unit to put a new waterpump impeller in anyway. You were going to do that, right? ;)
 

ezmobee

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Mar 26, 2007
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Re: Longshaft @ 23"?

You have a short shaft boat. I would think taking the extension out and getting a short driveshaft would be a lot easier than adding a proper long shaft transom to your boat.

Do that.
 

archcycle

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Re: Longshaft @ 23"?

right wouldn't it be free to just unbolt the extension and bolt the LU back to the midsection?
 

jasoutside

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Re: Longshaft @ 23"?

The mechanic I just bought it from just did all that biz with the water pump, so, no need to pull it all apart.

If I pull the 5" extension off that puts me at 18" on a 15" transom which means I haven't solved my extra length in the water.

As I understand it to do this ^^^, I'd need to buy/install a new drive shaft. More work, more cash. (please correct me if I'm wrong on that)

Building the transom to full height is way cheaper/easier that opening up this outboard. I already have the plywood/epoxy/alum/rivets all sitting right here.

If I want to repower down the road a long shaft 25hp is a whole lot easier to find than a short shaft (at least around here anyway).

Also, I have no interest in building the transom to 18" for repower reasons too.


So, is my thinking off here?
 

archcycle

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Re: Longshaft @ 23"?

As far as I know the extension assembly contains its own drive shaft extension. Just unbolt, remove, rebolt. Someone please correct that if it's wrong though. Unbolting it would be a good way to be sure.

Pull that extension off and try everything stock before you go building and modifying. It might be fine.
 

Chinewalker

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Re: Longshaft @ 23"?

I've never seen a shaft extension on a Johnrude. The driveshaft is 5-inches longer than the short one. Jas would need to replace the driveshaft. Water tube may have a 5-inch extension, or may be 5-inches longer. Shift rod may also be either 5 longer or have an extension. Regardless, the conversion would take less than an hour. Short driveshafts aren't hard, nor expensive, to find... They often come disguised as parts motors!

And, running the ostensibly 18-inch motor, on a 15-inch transom is actually normal as ALL of those Johnrudes follow the same pattern and run on similar boats. Shimming it up with a block of wood can get it out of the water some, but the extra length can actually be helpful on those old tin cans as the bottoms aren't really conducive to "clean" water breaking from the transom (think rivets, keel, etc.). Keeping the unit down a little will get it into clean water without the bubbles and turbulence. My old 20hp Johnson has the same lower unit and tended to ventilate easily if I jacked it up on the transom of my 14-foot tinny...
 

hidef

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Re: Longshaft @ 23"?

To convert the engine to short shaft Jas would have to get a new drive shaft and a new water tube. There are no extension for either of those. I had a 1978 25 that I extended to long shaft and I had to procure a new drive shaft, water tube and the 5" leg extension.
 

jasoutside

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Dec 20, 2009
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Re: Longshaft @ 23"?

Well fellas, I know for certain that I won't be pulling this engine shaft apart. I can't see any good reason to do it. No matter what I do I'll have an extra few inches in the water.

I suppose I was mainly wondering that extra length being an issue, but prolly not so much.

But, for discussion purposes, my # is J25RLCTE. So that tells me that this came factory long shaft (correct?).

So, I may be using the "extension" terminology incorrectly (sorry bout that). Anyhow, here is a cell phone shot of what I am looking at...
IMAG0361.jpg



(Nice, subtle metal boat backhand CW;))


Thanks for stopping by guys:)
 

archcycle

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Sep 21, 2009
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Re: Longshaft @ 23"?

You will see more power speed and efficiency if its at the right height, but if it ain't broke..
 
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