1975 Johnson 40hp, flywheel key shearing

[Pwrstrktech]

My manual start 40 hp, keeps shearing the flywheel key, it started after I had it off, the original key was partially sheared, but my replacement completely sheared after an hour of runtime or so... im assuming im under tightening it?? They keyway is just from hardware store.. not original. Dose anyone have the spec for tourqe on nut...??? Thanks.guys!!!

 

[Daviet]

Re: 1975 Johnson 40hp, flywheel key shearing

Do not use a flywheel key from a hardware store, get the OEM one and torque your flywheel to 105 ft lbs.

 

[tx1961whaler]

Re: 1975 Johnson 40hp, flywheel key shearing

105 ft-lbs using a torque wrench. No guessing on this one.
Shear the key one too many times and the crank and flywheel will be trashed.

 

[Pwrstrktech]

Re: 1975 Johnson 40hp, flywheel key shearing

I figured as much the 105 lbs-ft was with a wench. Ive been using the 3 white knuckle method so far Ha ha.. so t thanks for the spec!! Hopefully the marinea has a key.. or a couple tomorrow, should there be a washer under the nut ?? Or just the nut on the flywheel

 

[Daviet]

Re: 1975 Johnson 40hp, flywheel key shearing

No washer.

 

[Pwrstrktech]

Re: 1975 Johnson 40hp, flywheel key shearing

Awesome! Thanks guys!

 

[DBWilson]

Re: 1975 Johnson 40hp, flywheel key shearing

The problem is that you greased or put oil on the shaft. The shaft MUST be completely dry. Use a solvent to clean the shaft. I learned this the hard way.

 

[Pwrstrktech]

Re: 1975 Johnson 40hp, flywheel key shearing

DB this is a very old thread but the reason was not contamination but a bad touque spec


She's been running strong for over a year now at 105 lbs-ft