Big twin flywheel torque question

[BoatBuoy]

I have noticed that the flywheel nut torque spec for the 1959 35hp is 60-65 lb. while the torque spec for the 1960 40hp is 100-105 lb. That's quite a difference and it aroused my curiosity. Does the 40 use that much larger thread and nut?

 

[lark2004]

Re: Big twin flywheel torque question

good question, As far as I have seen they are all 105 ft-lbs. This may be one of those things where they changed the spec due to the original spec causeing problems, like say a sheared flywheel key?<br /><br />Maybe CAT, Paul or Joe knows.

 

[CATransplant]

Re: Big twin flywheel torque question

The Seloc book shows that 60-65 ft-lb for the 57-59 35 hp models, and so does the OMC factory master service manual. <br /><br />However, I torque mine to 105 ft.-lb., just like the later 40 hp models. The crankshaft size and flywheel are the same, so I use the same torque. So far, no harm has come to my outboard due to this, and the crankshaft key has not sheared since I torqued it to that setting.<br /><br />Perhaps Paul will have the information that they changed the torque specs.

 

[R.Johnson]

Re: Big twin flywheel torque question

Your 35 has a smaller crankshaft stub than the later 40's. I have never bothered to measure, but the taper, or angle may be different. Over-tightening could spred, or possibly crack the flywheel hub at the key way.