Can I swap flywheels?

[scuppers28]

Can anyone tell me if I can swap the flywheel from a 1957 35 HP E-rude Lark (25532) with a 1956 Johnson RDE-18 30HP. Id rather not pull the 35 apart if it's not going to fit. Any help would be appreciated.<br /><br />Thanks<br />Pete

 

[scuppers28]

Re: Can I swap flywheels?

Both engines are electric start. From the top they look the same.

 

[R.Johnson]

Re: Can I swap flywheels?

As I recall, it should go right on. Is the 30HP electric star?

 

[rodbolt]

Re: Can I swap flywheels?

if you do the swap make sure you carefully lap the tapers with medium lapping compound and check the fit after cleaning with a #2 puncil and 3 marks 120* apart. if they dont fit well your next topic will be about shearing flywheel keys<br />what is the reason for the flywheel swap ?

 

[R.Johnson]

Re: Can I swap flywheels?

Rodbolt! I have to ask, what on earth are you talking about lapping taper's on these old engine's? I was running them as a school kid, never did shear a key. Never had one come loose either.

 

[alcan]

Re: Can I swap flywheels?

It is always prudent to make sure you have a good fit between the flywheel and the taper (crank shaft). Certainly when replacing a flywheel from a different motor. I checked my parts manuals for these years, the part #'s don't match. I don't know for sure, but I think the 30hp was closer to earlier 25hp. As I recall the 35hp had a larger crank shaft. Let us know what you find Scuppers.

 

[rodbolt]

Re: Can I swap flywheels?

R.Johnson<br /> in almost 30 years of playing with them I have seen many, I even caused a few . had a bright idea once many moons ago to use anti-seize on the taper to aid future removal. it worked well. the next removal was about 2 min after engine start . but it popped right off <br /> the key only index's the flywheel. the interference fit of the two tapers is all that holds it.<br /> so now part of any service I at a minimum check the taper fit and if I swap flywheels for any reason I re lap them. to test carefully clean all surfaces with acetone,alchohol or other substance that leaves no residue. remove the crank key. place 3 pencil lines, vertically at 120* spacing. place the flywhell on and lightly press down. while holding the crank steady, rotate the flywheel 90*. remove it without rotating it. inspect the pencil marks. if all 3 are not evenly wiped off its time to lap the tapers.

 

[R.Johnson]

Re: Can I swap flywheels?

Rodbolt:<br /> I agree! that sound's like a good method, and I did come across to brusque in my reply. I certainly agree that the key is only an index.

 

[scuppers28]

Re: Can I swap flywheels?

Thanks for all the advise guys. The reason for the flywheel swap is stupidity as usual. The Woodrif key on the 30HP was warn when I dissassembled the engine, my local OMC shop did not have a replacement key so I ground down a new one from bar stock. I did not get the shape correct and the flywheel spun, damaging the key way on the flywheel. <br /><br />I did the swap from the 35, and it fit like a glove, used the key from the 35 and it fired right up and ran smooth. The 35 is a spare engine, so I have so time to look for a replacement flywheel. Are there any suggestions for used flywheels out there.

 

[rodbolt]

Re: Can I swap flywheels?

hello<br /> more the reason to properly fit the two tapers<br /> no way did the flywheel spin and not damage the crank taper. the cause of the worn key was the flywheel moving on the crank in the first place.cause the tapers did not fit or the flywheel was loose. either way the tapers are damaged. if you have never seen a crank snout snap off at WOT you will be impressed what that rotating mass will do while ricocheting about.