Looking for advice on shortening up a Johnson lower unit

windsurfer77

windsurfer77

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Jan 27, 2010
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I have a 1959 50hp Johnson super seahorse. The motor has what looks like a 6" extension above the lower unit.

Can I remove the extension and replace the drive shaft with a shorter one?
I need to be able to do this so the motor fits my boat properly. The previous owner modified the boat to fit the motor as is but I do not want to have it that way.

What should I do?
How much does a used shorter shaft cost, if my way is what I need to do? How difficult is the shaft to change out?:confused:
 

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Chris1956

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Re: Looking for advice on shortening up a Johnson lower unit

The conversion is real easy, if you can get the parts. I just sold the long drive shaft I had for that motor to a guy on this forum. who went to a long shaft motor conversion. Maybe you can buy his short drive shaft and shift rod connector.

You need the shorter drive shaft, and shift shaft connector. Most of those motors have extensions on the water tubes, that may be removed. The extension unbolts, and the drive shaft cover tube slides out.
 
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Reifwj

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Mar 23, 2010
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Re: Looking for advice on shortening up a Johnson lower unit

I just did something similar. I needed a new lower unit. Found a good one at a boat salvage place for $100. It was a short shaft so I had to swap the parts over. If it wasn't for two stuck screws would have taken 30 minutes. I was put in contact with the salvage yard by the marine dealership here in town. Maybe your local marine dealership will have something laying around or know a point of contact to get one.
 
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F_R

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Re: Looking for advice on shortening up a Johnson lower unit

windsurfer, a lot depends on whether the motor came from the factory as a long shaft or if it has been converted. If it is a factory long shaft, it is a bit more complicated than some are leading you to believe. The factory long shift rod will have to be replaced with a short one. That requires gearcase disassembly. You can cut exactly 5 inches off the two water tubes. To do that, you need a compact tubing cutter, easy to find at a good hardware store. It has to be short enough to get up inside the housing and cut the tubes. And of course, you need the short drive shaft.
 
tootallofwa

tootallofwa

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Re: Looking for advice on shortening up a Johnson lower unit

It would be easiest to get a short shaft gear housing and just swap them.

The drive shaft pulls out easy (supposed to.) The water tubes have extensions that are simply removed. The shift rod requires you to take the gear box apart. It's tricky to get it back together but if you pay attention as you disassemble, it's pretty simple.

It must be from another "super quiet" model (eternal exhaust housing and two water tubes) like yours.
 
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F_R

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Re: Looking for advice on shortening up a Johnson lower unit

As I attempted to point out, there are no water tube extensions in a factory long shaft motor. You have to cut the water tubes to shorten them. Here is the handy-dandy tube cutter that will fit up in the housing to do the deed. Actually, access to the cut is no problem on one of the tubes, just the one up inside.
 

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windsurfer77

windsurfer77

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Re: Looking for advice on shortening up a Johnson lower unit

Thanks for the great tips, this will help a great deal. Would you be able to contact the guy with the short shaft and see if he would sell it to me?
 
tashasdaddy

tashasdaddy

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Re: Looking for advice on shortening up a Johnson lower unit

why not just install a transom elevator.
 
windsurfer77

windsurfer77

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Re: Looking for advice on shortening up a Johnson lower unit

When I got the boat the transom had been modified to raise the motor up, the mod was removed. I did not like how they did it, can you send me a picture of how I can do this right? otherwise I will need to shorten the motor.
 
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