Topic: Installing/Torqueing Nuts and Bolts - Wet or Dry?

[Magpie]

Do you torque them dry of lube them first?
Thanks,
Cliff.

[HavocTurbo]

Not sure why you would "lube" them before you torque them....

But just like new head bolts for cars some tend to be "lubed" in rust preventative oil first.

I personally have never oiled a bolt that needed to be torqued.

Loc-tite is a different story though. 

[martin99]

If I want to prevent bolts from seizing, there is a compound for that - I use coppaslip or something similar. Of course, depending on the application you may want to be sparing with it, or don't use it at all. Personally I would avoid oil, unless you're careful. It has a nasty habit of pooling in blind holes, and can cause your bolt or stud to shear before it's been fully turned home, or give a premature 'click' on the torque wrench.

[MCRider]

Wow: these questions can make me think and dispel bad habits. i always lubed bolts and nuts before torquing. My theory was you did not want friction of the threads interfereing with the torque.

Upon a google search i found this  (and several others that confirm) lubricant should not be used. Torque values are determined with clean dry threads. If you lube them you have to reduce the torque values accordingly. But there is no way for us to know what "accordingly" is. So, no more lube.

http://www.zerofast.com/torque.htm

The discussion on lube starts below the chart. But its all interesting.

[elquenada]

well im glad someone else asked cause this has been on my mind lately.  I actually asked a mechanic and he told me just do what it says in the manual.  i dont think i'll be lubing now that Ive read the info posted above.

 

[Magpie]

Thanks guys - dry it is.
Cliff.

[BobbyR]

Not so fast. I teach proper torquing and certify people who work on safety critical high stress assemblies. First you never use oil. That is a lubricant and has poor anti sieze propeties and if the part is exposed to heat, can make things work.

Anti sieze compounds are used such as moly coat, copper grease or most anti seize products out there for your application.

When you torque a bolt, you are stretching the bolt. The bolt will want to return to it's normal size and thereby maintain a constant pressure against the mating threads. An over torqued bolt or a bolt torqued several times will stretch to a point it will not want to spring back, so it's ability to fasten will be reduced to almost nothing.

The use of anti seize or even loctite (until dry) will reduce the friction and thereby reduce false torque wrench responses. In general wet torque values should be called out in a manual.

The rule of thimb is simple. If a bolt has a dry value of 100ft lbs, the wet torque value is reduced 20%, so you set your wrench for 80 ft lbs.

The advantage of using a proper wet coating allows you to remove the bolt more easily and actually reduce the possibility of breaking off the bolt or damaging the threads on removal due to corrsion. The use of a proper anti seize not compromise the clamping force of the bolt.

[Don R]

The connecting rods in my race car have published torque values for oil and antisieze. The rod bolts should be tightened close to torque spec several times just to seat the new threads into each other. Then the torque spec will read right. If you have ever tightened rod bolts with a stretch gauge it will scare the beegeesus out of you they get so tight. Way more than I ever torqued them.

[Frankenkit]

I'm probably going to add a touch of anti-seize to the new bolts I'll be using on the 350 to replace the rusted philip's bolts holding the case covers on. I thought something was said, also, about using antiseize in conjunction with stainless steel bolts and aluminum cases to prevent the electrolysis and galling?

[UK Pete]

what a good useful topic, i bet quite a few of us have been getting it wrong, well done Magpie for bringing it up
Pete

[MCRider]

I'm probably going to add a touch of anti-seize to the new bolts I'll be using on the 350 to replace the rusted philip's bolts holding the case covers on. I thought something was said, also, about using antiseize in conjunction with stainless steel bolts and aluminum cases to prevent the electrolysis and galling?

My understanding is that if the two threaded pieces are the same, the need for anti-seize diminishes. Steel nut on a steel stud for example. I think from what I'm learning here I would stick to clean dry threads for that application.

Certainly, if you use stainless into the aluminum threads of the cases, use antiseize so you can get them out later. Pretty much mandatory. And for those, I just tighten each to snug, then go around for a skosh more. Just enough to keep the cover from leaking. No reason to crank on them.

[BobbyR]

On similiar metals I would still use and antiseize. It will make diaassembly much easier in the future. There is stainless steel and there is satainless steel. Some will corrode more easily than others. It is a matter of preference if you use it or not. 

[MCRider]

On similiar metals I would still use and antiseize. It will make diaassembly much easier in the future. There is stainless steel and there is satainless steel. Some will corrode more easily than others. It is a matter of preference if you use it or not. 

Thanks, understood.

[HavocTurbo]

On similiar metals I would still use and antiseize. It will make diaassembly much easier in the future. There is stainless steel and there is satainless steel. Some will corrode more easily than others. It is a matter of preference if you use it or not. 

You bring up a good point Bobby. I had forgotten about anti-seize.

I use AS only on higher torque applications. Anything above 50psi usually. And even then I might not. Cars are a different matter though. So is Stainless and Ti.

I have come across a factory manual specifially stating the use of AS in a low torque setting but that was for suspension pieces.

I would NEVER use anti-seize INSIDE a motor. Just my own personal fear though.

[BobbyR]

On similiar metals I would still use and antiseize. It will make diaassembly much easier in the future. There is stainless steel and there is satainless steel. Some will corrode more easily than others. It is a matter of preference if you use it or not. 

You bring up a good point Bobby. I had forgotten about anti-seize.

I use AS only on higher torque applications. Anything above 50psi usually. And even then I might not. Cars are a different matter though. So is Stainless and Ti.

I have come across a factory manual specifially stating the use of AS in a low torque setting but that was for suspension pieces.

I would NEVER use anti-seize INSIDE a motor. Just my own personal fear though.

We recommend the use of AS no matter what the Torque is. There are bolts that approach 450 ft lbs. I would never use it inside a motor. It is a matter of preference where and when you use it..