Merc 9.9 4-stroke prop tightening torque?

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I've searched high and low for the propeller tightening torque for a Mercury 9.9, 4-stroke with a 12-spline hub. Anyone know what it is supposed to be?

Ian
 
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Sorry I don't have an answer. But it is sad commentary for Mercury if it is this hard to find. A very basic spec. Which is why Honda is to be praised. Their service info for cars, bikes, OPE, everything, is easy to find to and very complete. Well written and illustrated manuals.

The availability of service info weighs greatly when I purchase.

Edit: I just googled this subject and found tons of info very quickly. How hard did you look?
 
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I looked for about an hour googling "mercury 9.9 prop nut torque". None of the recommendations were less than 55 lb-ft so all recommendations were worthless. The nut is bronze and small in diameter so 55 lb-ft could strip the nut. I'm probably going to use 10-15 lb-ft and call it a day.

Ian
 
Originally Posted by IanInCalgary
I looked for about an hour googling "mercury 9.9 prop nut torque". None of the recommendations were less than 55 lb-ft so all recommendations were worthless. The nut is bronze and small in diameter so 55 lb-ft could strip the nut. I'm probably going to use 10-15 lb-ft and call it a day.

Ian


You can also purchase a proper prop wrench which will not allow over tightening. They are made of plastic and can be purchased at any marina and likely on line as well? (Amazon)

Truthfully, I have never used a torque wrench on mine. I just tighten it until it is snug but not so tight that I can't move my prop in and out a few millimeters. Once I am there, I bent the lock tabs over and call it a day. It is also a nylock nut so I have no worried about it ever coming off.

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I have never, ever used a torque wrench on a prop. Always use an impact to remove it. I get it pretty tight, then a bit more if needed to align the cotter pin to the hole in the shaft and call it a day.
 
I'll have to recheck but I want to say the Mercruiser Bravo I drive on my parents boat is 150 foot lbs. I know it's not the same thing, but it gives an idea. That said, 55 doesn't seem unreasonable to me.

A new nylon nut and a torque value of just about whatever you want below 55 should be fine IMO. Double check torque after the first run.
 
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