Swaping lower units help.

[1970kayhydro]

I have a 1971 40hp johnson longshaft and I need it shortshafted. I recently came by a 1958 35hp johnson shortshaft. I pulled both lower units and they look the same besides a few things. The 58 prop shaft has a threaded end and the prop nut is metal and threads on. They both have the cotter pin holes but the 40hp has a plastic prop nut. Will this work? Would the gearing be different? The bolt holes are all in the right spot and the shaft ends are the same. Here are some pics.. Any advice is greatly appreciated!!

 

[tashasdaddy]

Re: Swaping lower units help.

what about water tube?

 

[freddyray21]

Re: Swaping lower units help.

I believe you will find the water pumps to be different. the 58 will have a single hole and the other will have a two hole pump if I am correct. Other than that they should work fine, but somebody smarter than me will post hopefully. you can always post at www.aomci.org and they will know.

 

[1970kayhydro]

Re: Swaping lower units help.

The 40hp looks like its just a extention that i will have to remove. Then my plans are to hopefully put the longshaft on the 35 and see if I can sell it for 50-60$ like I paid for it. If not I'll just hold on to it for a back up. Should I just put the 40hp on the stand and put it together?

 

[freddyray21]

Re: Swaping lower units help.

the extension comes off and the shorter lower goes on. nothing more than that. be sure and line up the water tubes.

 

[1970kayhydro]

Re: Swaping lower units help.

Yeah the extention came right off and the lower unit did fit on. Im more concerned about the gearing. will it be the same? and the prop nut thing? should i use the threaded one or the plastic one it will thread on.

 

[freddyray21]

Re: Swaping lower units help.

the gears should be the same. Use the prop nut that came with the lower you are putting on the 40.

 

[asdasc]

Re: Swaping lower units help.

Why not just run the 35 shortshaft and leave them both alone?

 

[freddyray21]

Re: Swaping lower units help.

imo the forty has a lot more torque for getting on a plane. Works better for skiing.

 

[1970kayhydro]

Re: Swaping lower units help.

yeah I want to keep the extra 5 hp. the boat is rated up to a 45. I put it all together and it gets f&r. will the extra 5hp cause trouble? it fitted up great and all. what should I try to get for the 35hp longshaft?

 

[asdasc]

Re: Swaping lower units help.

well, considering you live about an hour away, and one of those would be great to put on my pontoon boat, I would start out asking about $20 for it. I will be there on Saturday to pick it up!

 

[freddyray21]

Re: Swaping lower units help.

around here a 58 35hp not running can be bought for 50 bucks. Not sure if the long shaft will hurt it or not. The boats I run are short shaft boats, but guys do need long shafts. The extra 5hp is not a problem at all.

 

[1970kayhydro]

Re: Swaping lower units help.

I'll probably just hold on to the other motor for the lower unit. I think I could get the power head to start real easy, its got good compression and spark on both plugs. Thanks for the help!
asdasc do you need a motor? pm me if so.

 

[samo_ott]

Re: Swaping lower units help.

But what about looks? The '58 35 is a way better looking engine that the fibreglass 40's!

 

[F_R]

Re: Swaping lower units help.

The 35 and 40 have the same gear ratios, but the 40 has the improved "snap shift" clutch dog arrangement.

 

[tashasdaddy]

Re: Swaping lower units help.

1970kayhydro, do not sell anything, until you try the motor out. the 35 lower unit may have a bad clutch dog. which would not be good.

 

[freddyray21]

Re: Swaping lower units help.

1970kayhydro, do not sell anything, until you try the motor out. the 35 lower unit may have a bad clutch dog. which would not be good.

agreed

 

[1970kayhydro]

Re: Swaping lower units help.

Noted! Will do, when and if I ever get the boat put back together. I should probably just keep it for a back up anyhow. Even the G/F said that and she would be happiest if I never got into this.

 

[1970kayhydro]

Re: Swaping lower units help.

The 35 and 40 have the same gear ratios, but the 40 has the improved "snap shift" clutch dog arrangement.

Should I use that and just switch the shaft and shift rod? the cav plate on the 40 has a peice missing above the prop about 2" of it.

 

[asdasc]

Re: Swaping lower units help.

Do I NEED another motor? Does anyone?

Nah, I have more than enough. I would love to find a decent big twin someday, as they seem pretty nice acording to everyone on here. I like tinkering with them. My Fastwin 18 runs fine and has been very reliable since I replaced all the ignition, water pump, seals, rebuilt carb, etc. I have it on a very old and heavy pontoon boat, and faster would be good, but I don't need it for what I do and where I go.

Someday one will pop up nearby when I am weak and will be mine! If ever you get tired of storing in, let me know.

Thanks and good luck!