The Boating Forum - How Tight is your prop nut?

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View Full Version : How Tight is your prop nut?


kenergy
09-07-2007, 03:04 AM
I was doing a bit of maint on the old girl and I found that the prop nut was loose :o . The locking tabs were bent back out of the way almost as if someone had done it on purpose. so how tight do I need to do it up?
140hp Suzuki o/b
Thanks


onokai
09-07-2007, 03:46 AM
Mine is the torque yami specs-if I recall right its 55#s. Mark

76GMC1500
09-07-2007, 03:50 AM
On my Volvo, not very. I run it on snug and then run the jam nut down to 10-15 ft lbs.


ggibby
09-07-2007, 06:06 AM
Hi, on a 115 DF suzuki I think it is 60 ft lbs. Of course, you have to engineer it in such a a way that the cotter pin lines up! That makes it a little more tricky to get somewhere near the torque and still be able to get the cotter pin through the castle nut.

Your descvription sounds somewhat different. Are you using a cotter pin or a different set up?

kenergy
09-07-2007, 06:34 AM
ggibby - 9/7/2007 9:06 PM

Hi, on a 115 DF suzuki I think it is 60 ft lbs. Of course, you have to engineer it in such a a way that the cotter pin lines up! That makes it a little more tricky to get somewhere near the torque and still be able to get the cotter pin through the castle nut.

Your descvription sounds somewhat different. Are you using a cotter pin or a different set up?


Hi there, not a cotter and castle nut, there is a washer of sorts with 6 tabs that can bend up and lock onto the side of the nut. This is an old motor - mid 80s!! I have the manual for the motor and it gives no figure for the torque.

ggibby
09-07-2007, 07:12 AM
Then I would torque it to 50 ft lbs, figure out how much farther to turn it until the tangs can be bent perfectly, turn it just enough to get it to that spot, and bend the tangs.

gordon

JollyMonNJ
09-07-2007, 07:19 AM
Kenergy,
I had a similar problem on a Mercury I owned. Found the locking tabs on the washer bent back and the prop nut loose. Mechanic speculated that the lock washer had been used and re-used a few times, as I used to store the boat with the prop off, and that's why it came loose. Spent a couple of bucks on a new washer, tightened it up(don't know the torque) and never had another problem.
Good Luck,
JollyMonNj

warthog5
09-07-2007, 09:13 AM
The spec's for your DF-140 Suzuki are 40ftlbs. I have the "Factory" manual. Not sure what year you have,as mine are '03's and use a cotter pin not a locking tab.

My '98 Yamaha C-90 is also 40ftlbs. [as per manual]

I set my torque wrench to 38ftlbs. Tighten until it clicks. then I tweak it just a touch tighter to align the cotter pin. It works great like that. If I set it to 40ftlbs I have to tighten it much tighter to get the alignment for the cotter pin.


EDIT: Now I see you have a DT-140. Lack of info in your original post. :(

nsh
09-07-2007, 10:29 AM
I run mine up until its tight then turn to align the cotter pin. Been doing this for 25 years. Not a problem..

Tom W Clark
09-07-2007, 10:58 AM
Mercury outboards call for 55 ft/lbs or torque on most of their motors, I am not sure what the Suzuki spec is but I am sure it is something similar.

HOWEVER, after using the boat a few hours after installing a prop you should RETIGHTEN the prop nut as it will very often need more torquing. I have found that after running my boat the prop nut can be undone very easily and sometimes by almost by hand.

I suspect that running the boat allows the propeller to fully seat on the thrust washer and come into alignment with the shaft. ALWAYS retighten your prop nut after the first run.

dmeswi
09-07-2007, 12:27 PM
Tom's right. I have a 40 hp Mercury and a 225 hp Mercury Verado. Both motor manuals specify 55 ft lbs of torque for the prop nut.

Dennis

Wheresjoe
09-07-2007, 05:30 PM
My DF140 manual says 36 to 43 lbs torque then continue until hole lines up for cottor pin. Don't forget to clean and apply fresh grease to the splines :)

Rude1
09-07-2007, 05:33 PM
I run them up finger tight and stick the cotter pin in, no problems ever.

troutpioneer
09-07-2007, 05:38 PM
Not to jack the thread but Im curious... how often does one 'spin a prop' or have related issues like that. I know it happens, but I dont hear about it from any of my friends that boat and its never happened to me.

DooFighter
09-07-2007, 05:47 PM
Correct me if I'm wrong, I thought the cotter pin were only holding the prop nut on in reverse direction. Isn't the spin of the prop such that it is tightening the nut as the boat moves forward? In this case, the cotter key only has any force on it in reverse. I've been tightening to snug then backing off or on a little, whichever is closer, to align for the cotter pin.

Mr. Demeanor
09-07-2007, 10:20 PM
I use a McGuard prop lock on my labbed Rev4. No locking tabs. It just has a nylock style nut withthe nylon insert. I have been running this same one, on and off more times than I care remember, for 8 years. Never loosens up. Much easier to work with when changing props on the water. Just get a nylock style nut and throw the tab thingy in the garbage.

Tom W Clark
09-08-2007, 12:22 AM
DooFighter,

No, do not "back off" the nut after it is snug, torque it to the specified value. The cotter pin or tab washer is there as insurance. It is not the primary piece of hardware holding the prop on, the propeller nut is and it needs to be tight. Specified torque values should be considered minimums. More torque is not bad. For some mercury hub kits, 100 ft/lbs. is specified. I torque to no less than 60 ft/lbs.

Mr. Demeanor,

Again, the tab washer is a secondary measure. ALL Mercury prop nuts and hub kits use nylock prop nuts on their large outboards. A Nylock is NOT a substitute for a cotter pin or tab washer.

DooFighter
09-08-2007, 09:33 AM
Tom W, thanks for the clarification.



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