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Torquing G5 con rod bolts

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Falcone
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    Posted: 09 Jan 2020 at 21:49
So...

When torquing these rather critical fasteners, should the threads be dry or oiled?

And, if oiled, what grade of oil?

Cheers 
Grahame Smile
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jan 2020 at 22:47
http://www.thisoldtractor.com/moto_guzzi_tonti_torque_specifications.html

The above is from Greg Bender's site. 33 to 35 foot pounds.It doesn't specify wet or dry I'm afraid.I have done my two Loops to the above spec' wet.The oil was just 20/50 engine oil. Nothing has come undone in tens of thousands of miles.

Edited by Dave P. - 09 Jan 2020 at 22:57
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jan 2020 at 22:59
I would always do those dry, I oil bolts open to atmosphere, but not those internally.
Obviously there will be oil around on the journals as you assemble.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 09 Jan 2020 at 23:05
It's a strange one, some manuals, not necessarily guzzi insist on oiled threads some don't.It would be handy if they would specify.
If you lubricate a thread more of the applied torque goes to increase clamping force rather than overcoming friction or risking galling of the thread.

Edited by Dave P. - 09 Jan 2020 at 23:34
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

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1970 T120 Bonnie. 2009 500 Bullet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pentode Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 04:41
Tricky innit.....

A lubricated (wet) fastener compared to a dry one, with the same torque applied can have 30 - 40% more tension on it - a bit scary with something like big end bolts. It would  be nice to know what's right Geek

I feel the general consensus is, that unless a drop or two of a certain grade of oil is specified, then it's torqued up with clean, dry threads. 

What you say people? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Richard Hyatt Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 06:44
Usually dry is best practice.

I remember a discussion I had with the champion spark plug technical people years ago about torqueing plugs (about 25nm).
Should I use anything on the threads and the answer was no , torque them dry.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 07:42
You can be absolutely certain that they are assembled and torqued up dry in the factory.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 09:46
I think a definitive answer is hard to come by but my experience has always led me to believe that wet is the way to do it.Cummins diesel engines of various designs and capacities have all of their crucial bolts including big ends and cylinder head torqued up wet. How do I know that? Because I used to torque them up. Failing to oil such bolts could involve disciplinary procedure.
So unless the book says don't, I shall.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ben. Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 10:55
Wet or dry it might be an idea to test your torque wrench so you know exactly what force you're applying.
An accurate spring balance fixed one foot from the socket lets you test through its range.
Or for those like me, without a torque wrench, just use the spring balance on your tommy bar.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 12:18
Let's add a little more fuel to the fire!

From Guzziology section 5-33.

"It is very important that their threads be clean,undamaged and LUBRICATED when they are installed so that they can be properly torqued."

You pays your money and makes your choice.

TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pentode Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 13:15
Yup, it's there! Why didn't I look there first....? Doh!! 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote c13pep Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 14:09
Surely the only consistent is if the threads are dry as different lubricants will have different outcomes on the torque (thread lock will lubricate differently to oil for instance)
However I would have thought that bolts that come from the factory with thread lock on then the quoted torque would be for that set of circumstances
I`ve never seen a manual quote `wet or dry` when giving torque values

CHRIS
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iansoady Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 14:39
I've always thought that "dry" was the recommendation but have just looked at my Land Rover Discovery manual which specifies "Oil thread lightly before tightening to ensure a free running thread, except in the case of threads treated with sealant/lubricant, and self-locking nuts"
Ian
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 21:27
The object is the put the bolts under the correct tension, i.e. stretch, like with cylinder studs, which I think is beyond the point where lubrication will have much effect. Initially, yes, but not at the maximum end.

I think anyway.

Big smile

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pentode Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jan 2020 at 19:13
Thanks for all your comments people 🙂

It's a bit of a minefield really. 

I think I'll run with solvent cleaning the threads then popping a drop of engine oil on before whackin' 'em up!

Should a rod should suddenly make a bid for freedom at any point I'll be sure to let you know! 😁

Cheers 
Grahame 
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