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Torquing bolts

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I have always use antiseize and a torque wrench to the service manuals specs. Recently while cleaning the bike for winter. My upper left subframe bolt stripped. It was a pain to get out.. I always follow the proper torque specs.. What gives? I have done this for 10 yrs on many bikes with no issues.

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I have always use antiseize and a torque wrench to the service manuals specs. Recently while cleaning the bike for winter. My upper left subframe bolt stripped. It was a pain to get out.. I always follow the proper torque specs.. What gives? I have done this for 10 yrs on many bikes with no issues.

 

Bolt manufacturers generally recommend roughly 25% less torque (compared to dry) on fasteners lubricated with anything (oil, grease, etc.) and roughly 40% less torque on fasteners coated in anti-seize compound.

 

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Unless specified, never use any sort of substance on a torqued bolt. Antiseize isn't really necessary on any part of your bike (maybe swingarm pivot). When using a lubricant like antiseize, the torque applied is actually much greater than indicated due to less friction of metal to metal contact on the bolt.

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Antiseize? I thought maybe you meant loctite.  I would worry about bolts vibrating loose with antiseize.

 

Strictly speaking, the "torque" is not more when you use lubrication or antiseize. The difference is that it has less friction on the threads to counteract the applied torque. The result is more stretch on the bolt and more stripping force on the threads. 

Edited by Badunit

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I never put a bolt into aluminum dry,and I almost never glue them in unless specifically instructed to do so.I only use a torque wrench on critical components.

 

The threads in aluminum tend to wear out from repeated disassembly.My bike has lots of helicoils in it because of this (07 with over 600 hours so it's been apart many times).

 

6mm bolts are the worst about this,because of the 1mm thread pitch it ought to be 1.25mm instead or do away with 6mm bolts al together.

 

These are my opinions, but based on 40 years experience as a mechanic (24 years as a professional).

 

And yes a lubricated bolt requires less torque,but a dirty or gummed up bolt reguires more torque to reach the same clamping force as a new one and stands a good chance of damaging the aluminum treads.I spend a good amount of time cleaning bolt threads with a fine wire wheel on a bench grinder.They need to be clean and shiny to prevent galding the threads on reasembly.

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Finally some sound advice on Thumpertalk! I'm going to say bolt stretch gotcha, even though the use of antiseize is supposed to prevent it. I remember reading a study on bolt stretch testing antiseize, motor oil, and assembly lube (synthetic). The antiseize showed the best repeatability.

Edited by JBFL

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Bolt manufacturers generally recommend roughly 25% less torque (compared to dry) on fasteners lubricated with anything (oil, grease, etc.) and roughly 40% less torque on fasteners coated in anti-seize compound.

 

 

I can see how that would make sense, given that when the threads are lubricated, the bolt can be torqued a lot more. 

 

Just think about how rough things go when she's not lubed up properly.. friction, resistance.  More pain for the "bolt" and the "threads.."

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Manufacturer's torque values are on the high end.  With time you will learn what proper torque feels like by hand.  And anti-seize is your friend.  Most of the bolts on your bike are M6-1.00.  8-10ft lbs is all they need.  Drain plugs only need about 15-20ftlbs, not the 35+ spec'd in the manual.

 

Just remember, as you tighten a bolt you will feel it get harder to turn as you turn it further.  You will eventually get to a point where it does not take any additional force to continue to make the bolt rotate.  At this point you have reached the yield point of either the bolt or the aluminum casting (the steel bolt should fail first but after multiple torquings the strength of the aluminum casting will have diminished so much that it will be the failure point) anyways you never want to yield a fastener or its hole unless its a torque to yield fastener (found in some head bolt applications).

Edited by 1987CR250R

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Huh? The substance itself doesn't affect the length of bolt stretch.

Re-torque the same bolt 10 times then get back with me on that. Use a lubricant on one and dry with the other, which one will stay within spec the longest?

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I am surprised the video didn't start with dry torque for comparison.  

 

I was taught that the torque specs are for clean and dry threads, not lubed by anything. That has always led me to believe that lube is not recommended. 

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I am surprised the video didn't start with dry torque for comparison.  

 

I was taught that the torque specs are for clean and dry threads, not lubed by anything. That has always led me to believe that lube is not recommended. 

 

You can lube it, but you must look up the torque specs for wet installation.

 

For loctite though, keep the same torque specs as dry installation.

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From what I understand in the video.  If you lube it and torque it. You are actually undertorquing the bolt.  Except for that one lube that caused it to overtorque.  Am I correct?

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I wouldn't say manufacturer's are on the higher end of torque , they usually seem about right to me or well under the breaking point. I don't see why anti seize would need to be used unless the book says so. Maybe it is just me but the contact force holding a bolt in is friction so why would you want to use friction reducing agents on the bolts then? Locktite can be used be I'd only ever use it on something that isn't going to get hot because it will just melt and drain out anyway. This oil on the bolts thing just seems completely counter intuitive to me haha

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Antiseize is used to extend the life of the threads especially the threads in the frame.  Once those are wore out you have to tap it larger for the next size bolt.  Im just trying to find the proper torque setting for use with antiseize.  I think the best advice I got was go by feel except on critical components.  Motor, Axels, etc.  The only thing I use Loctite on are the small screws in the swingarm for the guide and guide for brake line.  Other than that I have never lost a bolt riding.

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I torque dry. I used to use the feel method until modern alloys proved it didn't work for me. Steel, yea sure. Spark plugs, I use anti-seize and torque by rotation/feel. I'm 55 and can think of one thread failure. isn't helicoil great.

Mike

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What is helicoil?

That is what you need when you've stripped the threads in a hole. You drill the hole larger, tap it, then thread in a helicoil insert. The outside threads of the helicoil match the thread of your freshly enlarged and tapped hole.  The inside threads match the threads of the bolt. You can look this up on the Internet or ask at your local shop.

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