Prop nut - how tight?

[robdew]

My manual doesn't say. Plenty of info on removal but none on installation or replacement or nut torque.

There shouldn't be any play in the prop front to back on the shaft, right?

70hp mercury force.

[lakerunner]

I tighten snug then back off or tighten to get 3 lock tabs to line up

[Lurch77]

I've looked around, and exact details are pretty hit or miss online. For some, you need to know what model propeller you have, as well as the engine. And generally the bigger the engine, the higher the torque value. For example, Mercury lists their Flo-Torq at 100 in/lb for 6-15 HP engines, 16.7 ft/lbs for 18-25hp, and 55ft/lbs for 30-60hp. The best bet is to call or stop in at your dealer and ask.
http://www.mercurymarine.com/media/merc ... o-Torq.pdf

[Bryden24shp]

I go until they are tight, then go alittle more until the tab or cotter pin holes line up. I put a block of wood between the prop blade and the cav plate. Use to hold them until I got a nasty gash from a Lab finished prop on my Baja. As far as back and forth movement, some will move, as the gear set is pre-loaded. Not alot, but some. Maybe a few 32's of an inch.

[RonKMiller]

I tighten snug then back off or tighten to get 3 lock tabs to line up

Yep, you want to "seat it" very firmly, then back off slightly.

I wouldn't stress out about torque settings since they are going to vary dramatically depending on how clean the shaft is, the condition of the splines, how clean the threads are, etc. In a perfect factory world with all new components they would be valid...

[Lurch77]

I wouldn't stress out about torque settings since they are going to vary dramatically depending on how clean the shaft is, the condition of the splines, how clean the threads are, etc. In a perfect factory world with all new components they would be valid...

As someone who wrenches on things for living and for a hobby, I gotta say that's going to be the case with any fastener. On my motorcycles I tighten the axles nuts to spec despite grime and grease being present. Same with engine head bolts, steering head bolts, etc. The manufacturers have a specification, and if it is available to the end user, I would use it. Same goes with large HVAC components I work on, like steam or chiller piping and valves. And improper torque will void warranties. I don't know how, but they can tell. Over tightening will deform threads, ruin seals, and break things. Under tightening will allow sloppy fit and attachment failures. Are we going to see problems by not doing it in the case of a propeller? Most likely not, according to posts here. But if they are available, why not do it right?

[robdew]

Let me ask this a different way, ignoring specific torque settings.

Once I reach a certain point of snugness on the prop nut, I start to feel resistance turning the prop by hand. How freely should the prop spin? Completely freely? One turn? None at all?

[BobG]

Let me ask this a different way, ignoring specific torque settings.

Once I reach a certain point of snugness on the prop nut, I start to feel resistance turning the prop by hand. How freely should the prop spin? Completely freely? One turn? None at all?

When the nut is torqued all the way, the prop should still spin freely.
If not, you may have missed the thrust washer.