Sheared flywheel key damge 1959 Johnson 10hp

[thull]

I didn't tighten the flywheel nut while working on this motor and sheared the key. The flywheel keyway was slightly damaged (see pics). It's widened out at the bottom and has a lump on the bottom face. The cam was cracked too. The crankshaft keyway is ok. I can get a cheap used cam. I read I can lap the shaft and flywheel with valve grinding compound, but if I do that for the lump on bottom wouldn't it grind of the word "top" on the cam and make setting points difficult? I could buy a used flywheel but don't want to spend $50 on that when I haven't got this motor running yet to confirm it'll actually run well. Any advice?

 

[Chinewalker]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Lap the flywheel without the cam in place. Make sure you torque the flywheel nut properly. Someone else should chime in with the torque value as I don't have a manual handy at the moment.

 

[Tim Frank]

Re: Sheared flywheel key damge 1959 Johnson 10hp

but if I do that for the lump on bottom wouldn't it grind of the word "top" on the cam and make setting points difficult?

The "top" marking refers to orientation of the cam...."top" goes "up".....not as a reference for setting the points.

 

[thull]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Thanks Chinewalker, I have the torque setting somewhere. I just wasn't ready to crank it down yet. So I guess I'd lap with the washer and spring under the cam off and out of the way too.

 

[F_R]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Lapping the taper will not cure the beat out keyway. My humble opinion says you need a flywheel.

 

[Chinewalker]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Keyway actually doesn't look too bad. Damage seems to be localized at the bottom corner. Your call...

 

[boobie]

Re: Sheared flywheel key damge 1959 Johnson 10hp

The flywheel key is just a guide to position the flywheel correctly. It's the correct flywheel torque that holds it in this position. The old " morse taper" trick. Torque is 40-45 ft lbs.

 

[thull]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Thanks all. After reading FR's post here and on other similar threads I decided to get a flywheel. That way I won't have a problem that keeps getting worse. I contacted Tim's Outboards on the TOP SECRET FILE marine salvage yard list and got a cam and flywheel for just $30!!! Thanks again for your help.

 

[thull]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Something else I noticed is a little bit of play in the armature plate (see video). Is my wobble within the range of tolerance? If not, how do I fix that? Getting the points gapped and timed right (using an ohm meter hooked to points screw) to produce a spark that jumps 1/4" has been difficult. I haven't gotten more than a 3/16" jump in the spark. Maybe this is due to the wobble.



1959 10hp Johnson armature plate wobble - YouTube

 

[thull]

Re: Sheared flywheel key damge 1959 Johnson 10hp

The c/s and flywheel tapers still seem smooth as glass. If that's the case, is lapping really necessary? On another note, the flywheel I ordered from a salvage yard arrived and has seen worse days than the one I have!!!! The keyway is wallered out at the bottom. I'm just gonna use the one I have. I filed down the bump on the bottom so it's flush. That bump and the widened bottom of the f/w keyway were the only damaged parts (besides the key of course).

 

[thull]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Seems like other posts recommend the lapping. I just tried a "dry" lapping test with just a few little wiggles of the f/w to see how this would work. The c/s wants to try and move with the f/w as I wiggle. This seems to be because the tapers create a snug friction fit. How can I lap them if they are moving together??? Seems like the c/s should stay still while I turn the f/w to do this procedure. Any help on this???

 

[Woodstock60]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Most of the armature plates I have wobble slightly I could be wrong but I don't think its a concern

 

[Tim Frank]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Seems like other posts recommend the lapping. I just tried a "dry" lapping test with just a few little wiggles of the f/w to see how this would work. The c/s wants to try and move with the f/w as I wiggle. This seems to be because the tapers create a snug friction fit. How can I lap them if they are moving together??? Seems like the c/s should stay still while I turn the f/w to do this procedure. Any help on this???

You could try pulling the plugs and feeding a length of 1/4" or 3/8" rope into one cylinder....don't lose the end
The piston will come up against the rope and you can lap in one direction.

 

[thull]

Re: Sheared flywheel key damge 1959 Johnson 10hp

I lapped the flywheel and crank using Tim's rope trick. Looks good. Trying to install the woodruff key. I know it's suppose to parallel the crank and have the little mark on the end facing down. It's a very tight fit, but I got it from the dealer so it's likely the right one. Do I tap it in with a rubber mallet? Seems very likely to damage the crank if I hit it too hard. Any help on the right way to install the key without screwing up the crank???

 

[Tim Frank]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Some motors the key is meant to be parallel to the shaft taper, some are supposed to be parallel to the shaft centre-line.
If you don't have the OEM manual to know for sure, hopefully someone will weigh in that is 100% certain.

You may have created a small burr on the mouth of the key-way.
You might have to break that edge lightly....but be gentle.

 

[thull]

Re: Sheared flywheel key damge 1959 Johnson 10hp

I found this 1971 document that indicates the 9.9hp alignment is with the crank taper, so I assume it was likely the same for the predecessor 10hp.



Here's a photo of how far I can get the key to go in the crank keyway without more than light tapping with a rubber mallet. I also tried a C clamp and two little pieces of wood but that didn't seem to drive it in any further. The wood kept wanting to pivot on the crank. Anybody have a good method for installing the key??? Thanks for any help.

 

[Daviet]

Re: Sheared flywheel key damge 1959 Johnson 10hp

As long as the key way is not damaged, I just use a small hammer and gently tap it into place.

 

[Tim Frank]

Re: Sheared flywheel key damge 1959 Johnson 10hp

blah...blah..., so I assume ...etc. etc.

Oh oh....trouble in River City....

 

[thull]

Re: Sheared flywheel key damge 1959 Johnson 10hp

Yah...I know what you get when you ASSume The photos I took before disassembly also show that at least the last person to work on this motor lined up the key parallel with the crank taper. I see Daviet taps it in with a hammer, assumably (there I go again) with no ill effects. I was nervous to do that because of a lot of what I've read on various forums warn against hitting the crankshaft, even indirectly, with a hammer, for example, when trying to pop off the flywheel. I'll give it a few more heartier, but careful, taps. I actually almost have it flush now since I posted the pic. The edges of the key that mate with the crank (top and bottom) are probably about 1/32" still sticking out from flush with the crank.

 

[Daviet]

Re: Sheared flywheel key damge 1959 Johnson 10hp

TAPS is the key word in my statement. If you have the key that far in, you should have it seated.