1987 90hp flywheel

[retiredmrbill]

I made a dumb *** mistake and put lube on my flywheel key and stud after replacing my trigger and stator. It ran great until I increased the rpm's and spun the flywheel. It broke the key and left some pretty big grooves on the spindle and inside the flywheel. I cleaned out the key chases on both and got a new key. I had to take the dremel to the inside of the flywheel to smooth it out to get it to reseat. I got it back down on the shaft but I noticed a slight wobble in the flywheel even though the nut was on. It ran well but I am concerned I may have ruined the flywheel. Does anyone have experience with this and should I replace the flywheel to be safe? Everything else seems good. Thanks

 

[Barnacle_Bill]

Re: 1987 90hp flywheel

Lube on that key shouldn't hurt a thing. Did you torque the flywheel nut down to specs?

 

[retiredmrbill]

Re: 1987 90hp flywheel

I did. The manual I have says 85ft lbs and that is what I torqued it to.

 

[Chris1956]

Re: 1987 90hp flywheel

Was that on a Merc or a Johnnyrude?

 

[CharlieB]

Re: 1987 90hp flywheel

There is NO allowable 'wobble' between a flywheel and the crank. It WILL fail again, at best shearing the key, at worse, breaking the nose off the crank, releasing a spinning flywheel to create havoc whichever direction is chooses to go.

I have found a flywheel key that was too thick, it did not allow the flywheel to fully 'seat' and I had to file it down until it just cleared.

I found this problem with a 'wobbly' flywheel by inking the crank taper and the exposed key, installing, torquing the nut, then removing the flywheel to inspect the ink for contact marks. The key was wiped clean leaving a lot of the taper untouched. Careful filing of the key allowed the flywheel to seat fully on the taper.

Also check the taper contact without the key installed, you should have 90% or better contact, if not you can try using valve lapping compound to work the flywheel and taper into a better fir, once seating is established then reinstall the key and re-check the fit.

 

[Dave1027]

Re: 1987 90hp flywheel

I don't know. If it was me I'd replace the flywheel. I have always wondered what would happen if the flywheel came off at 5500 rpm. I don't want to find out the hard way.

 

[CharlieB]

Re: 1987 90hp flywheel

Sometimes the 'fit' after a sheared key is not the fault of the flywheel but the 'smear' of metal transfer onto the crank, or the 'raised' ridges alongside a line/scrape around the crank, either/both interfer with the full seating of the flywheel to the crank.

A new flywheel doesn't always cure this mis-fit and careful attention must be paid to the crank.

HOWEVER, sometimes the damage IS to the bore of the flywheel and when inking indicates such, then a new flywheel can be required.

At all depends on the amount of contact revealed by the inking process. Even a new flywheel should be checked to determine contact.

 

[j_martin]

Re: 1987 90hp flywheel

Mr bill has gone after the precision taper in the flywheel with a stone on a Dremel tool. I'm afraid the wheel is toast, and possibly also the crank.

Any mis-fit at all will likely result in a magnetic flying saucer that won't even slow down as it goes through the cowl in a random direction.

just my 02
John

 

[CharlieB]

Re: 1987 90hp flywheel

Yup!

And it ain't safe to be anywhere near when that happens!

 

[Faztbullet]

Re: 1987 90hp flywheel

Before you throw in the towel, lap the flywheel to crank taper with some fine lapping compound. This is a must on OMC motors to get a snug fit...an never see a flywheel become a flying saucer,they sit there and spin for a minute tearing up stator and trigger.(been there and done that)