1978 johnson 25 hp SS 25r78 drive shaft

[anyquist]

I just bought a 1978 Johnson 25 hp, the guy that had it before me sheered the drive shaft. I am having some trouble locating the shaft but may have one lined up.
Could anyone provide some instructions on replacing the drive shaft? I have the lower unit off. The drive shaft out, and the exhaust is out also. Anything else I should service while I have it apart aside from the impeller?

If anyone has a PDF or image out of a repair manual with blow up that may help too.
thanks in advance,
Aaron

 

[Daviet]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

What do you mean the exhaust is out?

 

[anyquist]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

the exhaust pipe that runs next to the shift shaft is is removed. I have been calling around and many shops are confused as to which shaft my motor should need. I looked a bit closer last night and it appears that both ends of the shaft should be about the same. (upper drive shaft) One end was sheered off like I stated before. and the piece was gone when I got the motor. If some one knows this motor or has a service manual listing the part number for the right shaft that would be helpful. thanks

 

[jasper60103]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

Check out the shop2.evinrude website site and lookup your motor. All the part numbers are listed there.

http://shop2.evinrude.com/Index.aspx?s1=544c632561e0db7f8d3c002367d96e61&catalog_id=0&siteid=1

 

[anyquist]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

thanks, I have been looking at different sites, some are showing diffrent model number options for this year/ horse power. ie.(25r78, 25802c) the plate with model and serial is gone, waiting to get it from old owner (he removed it for paint job a couple years ago)

25802c- 25= HP, 8=1978, 2=short shaft, C= change made? , 0= not sure???

could anyone break this down

thanks

 

[R.Johnson]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

Can you post a picture of that engine? If that engine is truly an SS, these were the small racing engine's as I recall. Does it have a shifting gearcase?

 

[anyquist]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

it shifts from Reverse-neutral-Forward, if you are referring to multiple 1-2-3-4... then no.
When I typed SS I am talking about Short Shaft.

I will post a picture later.

**Bump**
thanks, I have been looking at different sites, some are showing different model number options for this year/ horse power. ie.(25r78, 25802c) the plate with model and serial is gone, waiting to get it from old owner (he removed it for paint job a couple years ago)

25802c- 25= HP, 8=1978, 2=short shaft, C= change made? , 0= not sure???

could anyone break this down

 

[anyquist]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

What do you mean the exhaust is out?

Sorry, I was referring to the copper water pipe.

 

[F_R]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

You are trying to make it too complicated. 25R78 is a Johnson, 25802 is an Evinrude. Same motors with different hood and paint.

25 = horses
8 = 1978
0 = special features (none)
2 = short shaft
C = to be ignored unless there was an engineering change on the part you need. If there was, the parts book will indicate it.

Broken drive shafts are usually caused by bent housings, either the gearcase or exhaust housing. If that is what happened, it will break another one some day. If you want to prevent that, the housings must be checked for alignment on a surface plate and height gauge dial indicator. A machine shop can do that for you. You have to tear it down first.

 

[anyquist]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

You are trying to make it too complicated. 25R78 is a Johnson, 25802 is an Evinrude. Same motors with different hood and paint.

25 = horses
8 = 1978
0 = special features (none)
2 = short shaft
C = to be ignored unless there was an engineering change on the part you need. If there was, the parts book will indicate it.

Broken drive shafts are usually caused by bent housings, either the gearcase or exhaust housing. If that is what happened, it will break another one some day. If you want to prevent that, the housings must be checked for alignment on a surface plate and height gauge dial indicator. A machine shop can do that for you. You have to tear it down first.

Thanks, I will check that also. The guy that had the motor before me hit a rock in the river with it. That's what sheared the drive shaft prop side.

 

[OLDIRON]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

Thanks, I will check that also. The guy that had the motor before me hit a rock in the river with it. That's what sheared the drive shaft prop side.

What you are saying happend should have damaged only the prop. Don't understand the "prop shaft" thing.

 

[anyquist]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

What you are saying happend should have damaged only the prop. Don't understand the "prop shaft" thing.

Normally yes, would only damage the prop, or at worst break the prop shear pin or strip out the plastic splines in the prop depending on the set up. This motor doesn't have the exhaust that comes out of the prop. After inspecting everything in the lower unit gears, everything looks perfect. My guess would be that the drive shaft was already fatigued and the rock the previous owner hit finished the job.

As for "Don't understand the "prop shaft" thing." I am not really sure what you are referring to. I spoke about the drive shaft breaking on the prop side, meaning the drive shaft broke right above the splines that drive the prop shaft.

My new shaft should come in today, and I will post the results after a quick test run.

 

[bktheking]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

Broke above the pinion gear is where you are talking about.

 

[F_R]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

My guess would be that the drive shaft was already fatigued and the rock the previous owner hit finished the job.

Yes, that is a very good assumption. And it goes along with my suggestion that the case is bent. That is what fatigues it. Then you pop a rock and it goes snap.

 

[boobie]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

My question would be, is it a very clean break like you cut it off with a hacksaw or is it a jagged break ? Jagged breaks normally come from bent housings and clean breaks come from high impact (hitting something).

 

[anyquist]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

My question would be, is it a very clean break like you cut it off with a hacksaw or is it a jagged break ? Jagged breaks normally come from bent housings and clean breaks come from high impact (hitting something).

Well guys I got the new shaft in. $65 and about 45 labor and she works great!
The old shaft was a clean break. The housing was checked by local shop and is perfect condition. Now to put in new fuel lines, and plugs.

One last thing, does anyone have any ruff idea about how fast this motor (1978 Johnson 25hp short shaft) should push a basic 1964 Crestliner 14' aluminum boat? With me at almost 200 pounds and my 200 pound friend my GPS fish finder was saying I was doing just over 20 mph. I am going to try and adjust the angle of the motor and see if that helps..
thanks a bunch!
\Aaron

 

[bktheking]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

Should be quicker than that, my Mercury KH7 with me and my 200 pound buddy pushed my crestliner to 22MPH , the KH is rated at 10 hp (really 16+), my 15 hp Evinrude did 18. Try it on the second pin if it's not there and make sure the motor isn't too deep in the water, the transoms on those boats are not the right height as I had to add a jackplate to mine.

 

[anyquist]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

Should be quicker than that, my Mercury KH7 with me and my 200 pound buddy pushed my crestliner to 22MPH , the KH is rated at 10 hp (really 16+), my 15 hp Evinrude did 18. Try it on the second pin if it's not there and make sure the motor isn't too deep in the water, the transoms on those boats are not the right height as I had to add a jackplate to mine.

Thanks I will look into that. when putting the new fuel lines in I noticed the fuel filter, it's a bit different then the system on my Johnson 9.5 hp. Can the filters be just be cleaned like on the 9.5? If they are easy to find and reasonable price I would just buy one. But searching the web leaves me empty handed on this part.

thanks for the help

 

[bktheking]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

Probably an add on piece, the only one I see on the diagram is built into the fuel pump unless that is the one you are talking about.

 

[anyquist]

Re: 1978 johnson 25 hp SS 25r78 drive shaft

Probably an add on piece, the only one I see on the diagram is built into the fuel pump unless that is the one you are talking about.

Yea, it is built into the fuel pump. Would the filter come with fuel pump kit? I guess the pump functions good but, I would like to just clean the filter if possible or just buy a new one w/out the pump kit.

thanks again