Torque values wet or dry?

[baytonemus]

Just as I was about to really put the hurt on my flywheel nut with the torque wrench, I realized that the anti-seize compound I had just put on the threads was going to potentially change the amount of torque I need to use.

1) Does anyone know if the torque values in the factory service manual are for dry or lubricated threads?

2) If they are for dry, any idea how much less torque (than the specified 100-105 foot lbs for my '63 40hp) I should use?

Thanks.

 

[ezeke]

Re: Torque values wet or dry?

The flywheel nut and the taper as well as the threads on the crankshaft should be absolutely dry and clean - no sealer, lubricant, or threadlock of any kind.

Torque to 100-105 foot pounds.

 

[baytonemus]

Re: Torque values wet or dry?

The flywheel nut and the taper as well as the threads on the crankshaft should be absolutely dry and clean - no sealer, lubricant, or threadlock of any kind.

Torque to 100-105 foot pounds.

Thanks for your response, ezeke. I am aware that the flywheel and shaft tapers are to be completely dry. I wiped them thoroughly (and carefully) with lacquer thinner before I put the flywheel back on. Only then did I apply a very small amount of anti-seize, so the tapers are still dry.

The factory manual doesn't specifically say anything about the nut and threads. What is your concern about the anti-seize compound? You can achieve the same effect with dry or lubed threads on any bolt or nut, but they require different amounts of torque. Many service manuals indicate clearly whether the values they specify are for one or the other. I can't find that info in the Evinrude book.

 

[F_R]

Re: Torque values wet or dry?

Dry. Notice there is no lock washer?? Friction is what holds the nut. Why would you want to slick it up with any anti-friction stuff?

 

[ezeke]

Re: Torque values wet or dry?

As F_R says, you need friction to make a good bond. The techniques that are known to work well have been around for quite a while. Click the thumbnail and note the date.

The older members can only tell you what we do and why we think it is correct. You will have to develop your own opinion of the efficacy of those approaches before you pass it on to the next generation.

 

[baytonemus]

Re: Torque values wet or dry?

I very much respect the experience of both of you and I don't wish to be argumentative or difficult. I will only make the following final comments.

Oil, grease, anti-seize compound, etc, reduce but do not eliminate friction. They do generally reduce corrosion, however, which facilitates later removal. There are a great many critical engine parts (e.g., if they come loose the engine could be ruined) )on lots of different types of vehicles for which oiled or otherwise lubricated torque values are specified. You can tighten a lubricated bolt such that it will not wiggle loose.

It was neat to look at that service bulletin you attached. I do have to point out, though, that it is very specific with regard to which parts need to be dry, and it doesn't mention the nut or threads.

Thanks again, guys. I genuinely appreciate your input and hope you don't take my comments the wrong way. They are only meant as observation, not criticism.

 

[ezeke]

Re: Torque values wet or dry?

I am well aware of exactly what the bulletins says and does not say which is why I said "The older members can only tell you what we do and why we think it is correct. You will have to develop your own opinion of the efficacy of those approaches before you pass it on to the next generation."

This is about beat to death, don't you think?

 

[vettenuts]

Re: Torque values wet or dry?

From memory with a simplified bolt calculation, to obtain the same bolt preload with lubricated vs. dry the conversion is approximately 0.15/0.2 or 75% of the dry value.

 

[baytonemus]

Re: Torque values wet or dry?

From memory with a simplified bolt calculation, to obtain the same bolt preload with lubricated vs. dry the conversion is approximately 0.15/0.2 or 75% of the dry value.

Thanks, vettenuts. That was about what I was remembering from other projects.

 

[wilde1j]

Re: Torque values wet or dry?

Dry, dry, dry! Means absolutely nothing on the threads! The same with the flywheel taper.

The taper, and not the key, is what holds the whole deal together. Any lube on the taper will cause a sheared key, since the key's only purpose is to provide a fixed position for the flywheel to be installed. This is not very complicated. The torque value provides a specific amount of bolt stretch, which in turn, in the case of a flywheel nut, a specific preload on the taper. The idea, in this case is the taper load, not so much keeping the nut in place. Lubrication and a lesser torque value will not achieve this result.