prop torque

[captn tj]

I am installing a new prop on my 2005 4 stroke 225. Do I need to use a torque wrench for final tightening and if so how many ft/lbs.

Thanks

[captn tj]

Thanks Fairdeal - wasn't sure if there was a science to it.

[boscoe99]

Torque wrenches are so cheap and widely available that I would not try and service a motor without one. If you do almost any further servicing work yourself then you are going to be in need of a torque wrench. Maybe get two. One for low values and one for medium values. In some applications torque can be real critical.

Studies have proven time and time again that most people (even top notch trained mechanics) will over tighten a fastener. With a torque wrench there can be no doubt that the fastener is tightened correctly. OK, some can screw up even using a torque wrench but hopefully it won't be you.

Yamaha is light on torque values for their propeller nuts. As a consequence many Yam owners have a problem with the thrust bearings becoming loose which can allow the propeller to move forward and eat into the lower unit. If you decide to torque the propeller nut to 40 lb-ft then be sure and recheck the torque after the first hours of hard use. Retighten as necessary. From time to time thereafter inspect the propeller to lower unit clearance when you do your "walk around" inspection.

And one other point. If the holes for the cotter pin don't line up after the nut is torqued to 40 lb-ft then tighten the nut further as needed to get the holes to align.

[captn tj]

boscoe99

From your message am I to assume that the nut should be tighter than 40 lb-ft? Also if there is a cotter pin to lock in the nut shouldn't the prop stay in position vs needing retightening - just trying to understand.

[boscoe99]

boscoe99

From your message am I to assume that the nut should be tighter than 40 lb-ft? Also if there is a cotter pin to lock in the nut shouldn't the prop stay in position vs needing retightening - just trying to understand.

Just go to 40 lb-ft with the torque wrench and then tighten further, if necessary, just to get the holes to align.

The cotter pin will keep the nut from loosening but the thrust washer fully seating further can cause a loosening effect when the motor is operating. So, just to be on the safe side after about an hours use remove the cotter pin and retorque the propeller nut, then tighten if necessary to get the holes to line up, and reinstall the cotter pin.

Chances are you might not need to do this. But, there is a chance that you might. Since we don't know what the future will be we sometimes take a bit of preventative measure to further our chances of success. Think of a cotter pin. Chances are that the nut won't loosen on its own. But there is a small chance that it might. So we take the extra step of installing a cotter pin just to be on the safe side.

It takes all of five minutes to retorque a propeller nut. It is a longer and more costly ordeal to have to change out the gear case if it were to become damaged due to a thrust washer failure due to insufficient tightness.

[fairdeal]

Boscoe, I have deleted my earlier post in the light of your more extensive reply.

BTW perhaps OP should also be advised regarding greasing

[boscoe99]

Absolutely positively on the greasing bit.

How do yo delete a post? I did not know this could be done?

[captn tj]

Boscoe, I have deleted my earlier post in the light of your more extensive reply.

BTW perhaps OP should also be advised regarding greasing

Fairdeal

That was a teaser - greasing? Your recommendation?

[fairdeal]

sorry, did not intend to "tease"

here is a typical Yamaha instruction for propeller installation:

1. Apply Yamaha marine grease or a corrosion resistant grease to the propeller shaft.
2. Install the thrust washer and propeller on the propeller shaft.
3. Install the spacer and washer. Tighten the propeller nut to the specified torque.
4. Align the propeller nut with the propeller shaft hole. Insert a new cotter pin in the hole and bend the cotter pin ends.

Boscoe has provided considerable amplification to points 3 & 4.

I was suggesting that you would benefit from guidance on #1-
as that is generally regarded as "important"
(even by non-experts such as myself)

No doubt there is "more to it" regarding that part of the procedure, as well.

[99yam40]

And take things apart often to re-grease,( at least once a year)
Nothing like spinning a hub, and then not being able to remove the old prop or thrust washer to install the spare.
I had a thrust washer stick to the old prop so I could not install the spare because I did not have a spare thrust washer.
Long ride back at low RPM to keep hub from slipping