Flywheel Wobbles

[58CorrySuburban]

Motor: 1958 Evinrude Bigtwin 35 hp.

When I first started the motor I noticed that it (the entire motor) wobbled. When I realized that only one cylinder was firing I atributed the wobbling to that, but after I got both firing it continued to wobble. I then noticed that the flywheel was out of level. I took the flywheel off again, looking for a mangled key, but it seemed fine.

Reinstaling the flywheel, I aligned it with the key and placed a socket over the bolt (not on/in contact with the bolt) and gave it a few taps with a hammer. Tightening the nut it never seemed to go as far down on the threads as when me and my brother-in-law both did it. I held the flywheel, and he turned the wrench. By myself, I can only get it so tight.

Any ideas on how I (one person) could secure the flywheel while I tighten it?

Is there any other reasons that my flywheel would wobble, and is this why my motor shakes at low rpms? It only vibrates a higher rpms.

Thanks,
-Josh

 

[david_r]

Re: Flywheel Wobbles

electric start? if so your local auto parts store should have a flywheel holding tool (it grabs the teeth on the flywheel)for sale and if your lucky you may be able to borrow one from the store.

also dont forget the flywheel has a set torque spec. youll need this to do the job right.......also make sue both surfaces are free of rust,etc.

maybe someone on here can tell you the proper torque specs.

 

[rolmops]

Re: Flywheel Wobbles

Even if your flywheel is less than tight than specs require,it should not wobble.
I suspect that you have a crank shaft bearing issue.That would also account for the vibrations at a high rpm.
As for a one man tightening of the flywheel nut.You can use strap that goes around the flywheel ( home made special tool) Or get a factory supplied special tool.

 

[58CorrySuburban]

Re: Flywheel Wobbles

Thanks,

OK, so there is a certain tool for the job. I know the torque setting is 720-780 (per SELOC). It is free from dust and debris.

-Josh

 

[rolmops]

Re: Flywheel Wobbles

You did not hear this from me,but some people take a big screw driver and stick the shaft in one of the sprocket teeth of the flywheel while they stick the point of the screw driver behind the starter so it wont move while you are tightening the flywheel nut.It is less than ideal for numerous reasons,but it does work.
As for me,I would never do such a thing,or did I?

 

[1946Zephyr]

Re: Flywheel Wobbles

RolMops....I love your methods here. It actually works fine. I did it several times.

You gotta be careful though and do it right, because you could **** up something, but for the most part, it'll work okay.

Flywheel wobbling huh? This is interesting. Never seen it happen, but quite odd....

 

[58CorrySuburban]

Re: Flywheel Wobbles

Ah yes,

Unfortunately I am a mechanical hack, and therefore use craftsman tools. I?ve already snapped a few standard heads just trying to free seized bolts?considering the force necessary I can just see stabbing myself in the chest when the teeth snap the head off.

So (at this point in the thread) I just have to man-up and crank that b***h down.

This is great news. Saturday, looks like the last decent day to take her out (65 deg. +/-).

Is there anyone else that thinks that I may have a bigger (crank shaft bearing) issue?

What are the ramifications of running a motor with an "un-level/un-balanced" flywheel?

 

[1946Zephyr]

Re: Flywheel Wobbles

Well, take the flywheel and see if you can lift it up and down, or jiggle it back and forth. If so, then you may have a toasted upper bearing. There is a small tube, mounted in the block, where fuel mix is circulated by pressure, up to that upper bearing and if that tube is broken or kinked, then it will starve the upper bearing from oil. The center and bottom bearing will be fed, by gravity, but the upper one will not get much, without that tube.

 

[jbjennings]

Re: Flywheel Wobbles

I'm just guessing because I've never worked on the 35hp from '58. But, is there a chance that the flywheel itself is not balanced, for example, the weight opposite the flywheel magnet is somehow not there? I thought that the weight opposite the magnet is integral into the flywheel and can't be "lost", but maybe I'm wrong and it isn't and therefore it's possible it could be missing. Other than an imbalanced flywheel, it would almost have to be either a bad crank bearing or a bent crankshaft top where the flywheel sits, I would think.
Myself, I would not run a motor that I knew wasn't balanced correctly because I'd think there could be the possiblity the flywheel could shatter or cause the motor to throw a rod through the block and kill me.
I hope you figure it out as I'd be interested in hearing the answer,
JBJ

 

[58CorrySuburban]

Re: Flywheel Wobbles

Thanks,

The thing is, it is not a "left-to-right" wobble (vertical deviation). It is a horizontal (yawing from horizontal) wobble (out of level, not out of plumb) as if I just didn't crank it down tight enough.

So in conclusion: Compress it until its level.

I just wanted to make sure, that by forcing it, I wasn't going to screw anything up.

I'll go ahead with this info unless someonelse hits the breaks on this threat.

Thanks guys,
-Josh

 

[F_R]

Re: Flywheel Wobbles

OK, first you must check that flywheel for being bent. That happens when some cretin tried to remove it with a puller that grabs the outer rim. Slowly rotate it and see if it wobbles at the rim. If it is bent, it is garbage....dangerous garbage.

Secondly, check the bearings. That is easy to do, just see if you can move the flywheel/crankshaft sideways. It should not move more than a microscopic amount.

Third, you MUST use a torque wrench and tighten it to specs. That is after you make sure you have the key installed correctly. Some follow the taper and some are installed vertical.

That motor was built about the time that OMC changed the flywheel hub design. Early hubs cracked loose from the flywheel. I would have to hunt up the service bulliten to get the details.

 

[Chinewalker]

Re: Flywheel Wobbles

I'm with FR on this one - check the flywheel itself. Once upon a time, I had a motor tilted up to access the lower unit, mounted on a wheeled stand. Well, when I pulled the unit off the CG changed enough that the motor and stand tipped right over frontwards as I was turning around to put the lower unit in my vice fixture. The motor landed right on its flywheel and bent the heck out of it. Fortunately it was just the flywheel and didn't hurt the crankshaft...
- Scott

 

[HybridMX6]

Re: Flywheel Wobbles

Just noting this, but he says it moves up and down, not so much side to side. Unless I'm just reading it wrong.

 

[bowman316]

Re: Flywheel Wobbles

this sounds like a serious problem, it there is a problem at all.
So prob not worth sinking the money into.
so i would just run the motor till it breaks, and then buy a new one.
but it may be ok, and never break.
just my opinion.

 

[58CorrySuburban]

Re: Flywheel Wobbles

Thanks guys, and nice pics Scott. I attached a before and after of my 1958 MFG Corry Suburban restoration.

While I was tightening it, I never noticed the crank shifting left to right. It does move verticaly a bit, but it is a constant amount and I guessed it was supposed to for some reason. I'll have to check the actual wheel, making sure it?s not bent. I just didn't think that a massive piece of steel would be subject to deformation.

I do have a torque wrench, and a parts motor with an extra flywheel.

That reminds me. Does anyone know if the flywheel from (serial No. 25937) and (serial No. 25930) are interchangeable? Though it seems obvious, after I got both cylinders firing (using the slightly taller condenser from the other) I decided to switch flywheels also. The one flywheel seemed like a magneto had come loose and ground the interior of the flywheel.

After I changed the flywheels, it seemed to rub. I wasn't sure if it was just because of the magnet passing the magneto (magnetic attraction/resistance) or friction from contact. I didn't hear any scraping so, I started the motor up and don't recall if it wobbled or not. I stalled the motor right away, just fired it and killed it.

The next time I went to fire it, I was getting no spark at either cylinder. Long story short. I had sheered a key. Needless to say, I switched back to the original flywheel.

I've never worked on motors before, but have found that I actually enjoy it. Not trying to be a kiss a**, but thanks again for enabling me to do this. I'd still be standing there trying to