1990 force 50hp keeps shearing flywheel keys.

[boatnut1978]

As title states. I have a 50hp force that the flywheel key will work for about 10 seconds and then breaks in half and throws the timing off.
It looks like the area that the key sits in is to damaged to hold it.
Another thing I noticed is that the flywheel seems loose.
Any ideas?

 

[Frank Acampora]

Re: 1990 force 50hp keeps shearing flywheel keys.

You need to know that the flywheel nut needs to be torqued to 95 foot pounds. The key does not hold the flywheel, it merely locates it a top dead center.

The flywheel should sit snugly on the crankshaft taper and contact at least 85-90% of it. If it does not, you need to use some lapping compound and work the flywheel hub into the shaft.

However, if the shaft is too badly galled or worn to the point where the flywheel hub contacts the land or cam on the shaft, it will never be possible to tighten it enough.

 

[fucawi]

Re: 1990 force 50hp keeps shearing flywheel keys.

I have had exactly this on a 35 HP Chrysler.....the way around it is to seperate the key for the ignition and the flywheel ..then if the flywheel moves a bit it wont throw the timing ....
Remove flywheel and ring that does the timing( marked this side up ) . Then with a die grinder or dremel tool put a small flat on the crank (10 thou is plenty) below the main keyway slot. Then locktite the ring into place and push a home made key in to the timing ring ..nice and tight. cut off level with top of ring ...
Now the flywheel .... remember the key is not there to take the load its for location only ....use the top half of a new key clean well ..locktite flywheel into place and tighten to 75 ft lb.. If you need to get flywheel off just heat the end of the crankshaft......mark nut and shaft and flywheel with paint mark so you can see if it moves.....If it does not good but it wont change the timing and kill the motor ......worked for me

In the extreeme grind the end of the crankshaft to a D shape ..make a D washer 1/4 thick to go over it very tight and bolt down into the three holes in top of flywheel..loctite and prayer ...then a quick sale on e bay ....

 

[Litetwin4]

Re: 1990 force 50hp keeps shearing flywheel keys.

Frank, please confirm how to hold the flywheel stationary in order to torque the nut. Thanks in advance.

 

[jerryjerry05]

Re: 1990 force 50hp keeps shearing flywheel keys.

Lift the bendix up to engage the flywheel.Then insert a screwdriver in between the teeth.
This will hold it so you can tighten the flywheel.
Post some pics of the top of the shaft and inside the flywheel.
You sure your using the right key??
Using something that fits isin't good enough.You need the right one????

 

[Frank Acampora]

Re: 1990 force 50hp keeps shearing flywheel keys.

If there is a land or any strong projection on the block or head, use a socket or chunk of aluminum wedged between the flywheel teeth and the projection. Back about a week ago Tater and I had a post with photos about how to do this.