Converting 75hp OMC from 20" shaft to 25" shaft.

[Landof9000lakes]

Is this possible?

 

[Bosunsmate]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

im not sure, it probably is- shorter driveshaft and mid section and shift shaft..
I have a 60hp that i wanted to be 5" smaller so instead of going about it the expensive new part way i just added a 5" jackplate to the transom.
Cost me a little bit for the wood/metal bracket and paint but i i now get less splash over the stern in heavy seas

 

[racerone]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

No model # given so I will say on some models it can be done.----BUT----The best way is a donor motor for the parts otherwise it gets expensive.--------On a saltwater motor it can be frustrating.-----------------You need a longer midsection / exhaust housing.--You need a 5 " longer driveshaft.------Lower unit must come apart to install that driveshaft.------The replacement driveshaft must be shimmed properly.------Then again there may be an aftermarket extesion availabel from Bay manufacturing as well.

 

[Landof9000lakes]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

The real answer is a new E-Tech 90HP H.O. Tiller.

That's not happening for a few years. And since I want the boat to have a 25" transom not 20" AND I'm rebuilding the boat now I'd like to convert the OMC to 25" and use it for a few more years.

That E-Tech is going to take some convincing w/my wife.

 

[Landof9000lakes]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

I don't have access to the model number. It's in storage and not on my property.

It is a 76 Evinrude 75 HP. It runs fine and any replacement parts I may need for it are readily available so I won't be replacing it until I add a much newer if not brand new engine.

 

[F_R]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

They didn't even make 25" models in 1976

 

[racerone]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

Not sure why folks will not post with model # / year info.-------------I guess some folks still think that they are all the same !!

 

[boobie]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

NO, that's not it. They think we know what they have even before we start answering questions.

 

[V153]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

They didn't even make 25" models in 1976

Really? Not to doubt you but I thought they were makin em by then. When did they start?

 

[boobie]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

If push comes to shove try BayManfacturing.com.

 

[racerone]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

I am not sure if the 3 cylinder OMC was ever offered as a 25" model.----Even if it was on the newest models , they have a different spline on the crank.--------------------Bay manufacturing.com or custom machine work would be required.

 

[Landof9000lakes]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

Not sure why folks will not post with model # / year info.-------------I guess some folks still think that they are all the same !!

....

 

[Landof9000lakes]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

Not sure why folks will not post with model # / year info.-------------I guess some folks still think that they are all the same !!

NO, that's not it. They think we know what they have even before we start answering questions.

Instead of the snarky responses you could always read the posts above your own. As I said I don't have access to the engine and won't until weather gets warmer.

However your responses were very helpful so thank you for that.

 

[Landof9000lakes]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

I am going to rebuild the transom to 23". I'll lower this engine and then when I re-power I'll just order a 25" model and raise it a bit.

 

[emdsapmgr]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

Did you try the website boobie suggested? Welcome

 

[Landof9000lakes]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

Ya I did.....They don't have one listed for the year I need but I was planning to call them later today to double check.

I guess the 25" transom/outboards are a recent change in boating.

 

[racerone]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

V-4 and V-6 motors were offered as extra long shaft ( 25 " ) in 1976 just not the 3 cylinder motors as there was little demand at that time..Most manufacturers now offer 30" models in the big HP ranges.

 

[F_R]

Re: Converting 75hp OMC from 20" shaft to 25" shaft.

The earliest 25" (XL) motor I can find was the 1976 200hp V6. The 1977 140hp V4 was also offered in XL. A matter of demand, as boats got bigger and motors got heavier, and people wanted to put two of them on and go offshore.