Lubricate bolt threads - graphite?

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I know this sounds way OTT but when I was engine building performance/competition engines, on critical fasteners - head bolts, rod and main bearings, etc - we would install, run the fasteners down to 3/4 torque and remove/clean them several times before performing the final installation/full torque.

NOT suggesting this needs to be done..;)
 
So, we're all over the place on this. Personally, I prefer a small amount Nickel anti-seize on things that screw into things other than nuts so except for the type of anti-seize I mostly agree with Fast Eddie. However, since I maintain this page: https://www.gregmarsh.com/MC/Norton/Norton Commando Torque.pdf on Norton torque and lots of people use it, I would like to be as accurate as possible. Any real engineering studies on this are interesting to me.

In the changing valve seals thread, the video below was posted. To me it is interesting for two reasons.
1) The type of thread repair chosen doesn't matter.
2) The testing has a fault because if true we would all be ripping the studs out of our heads. If a timesert or helicoil can only withstand 33.3ft-lbs, there's no hope! In the tests, he lubed the studs so he was getting more actual pulling force (my term) than the torque indicates.

Personally, I clean the head and studs thoroughly with the studs removed. I want to inspect the threads in the head and on the studs. Then I install them with blue locktite. I've never had one pull out and I use a tiny bit of Nickel anti-seize on the nut end of those studs.





 
On 500 mile re-torque there is almost always some oil somewhere.
So if some are dry and some are oily, you have the worst condition, uneven torque. If left alone from there ,that's how it goes off into the world.

Better to use the anti-seize right off, then all are equal. The anti-seize hangs in for a long time.

Also, if you are using a small amount of anti seize on the nut end now, you aren't torquing dry, aren't you are doing much the same as Jim does in the video?


Glen
 
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worntorn said:
On 500 mile re-torque there is almost always some oil somewhere.
So if some are dry and some are oily, you have the worst condition, uneven torque. If left alone from there ,that's how it goes off into the world.

Better to use the anti-seize right off, then all are equal. The anti-seize hangs in for a long time.

Also, if you are using a small amount of anti seize on the nut end now, you aren't torquing dry, aren't you are doing much the same as Jim does in the video?


Glen
Click to expand...
I'm trying - real hard - to be clear. Doing a poor job, I guess so I'm out of both discussions.
 
Hi all,
I think some contributors have suggested that lubricated threads (particularly with very high tech moly products) put additional stress on the threads etc due to the higher pull down loads that are obtained.
im battling to understand this? Surely torque is torque. If very high coefficients of friction exists on threads, then the torque would be more applied to the first few threads but in a zero friction scenario the torque and therefore the linier load acting to pull the thread out of the parent material, would be applied along the entire thread length. Not sure if this makes sense to others.
obviously lubricated threads achieve greater pull down load therefore are more likely to crush or damage whatever is being torqued down (cylinder head?), but no more load is applied to the threads or the bolt when being tightened.

As a last thought, i guess the real test is what did the manufacturer do when the bike was made. I’d bet London to a brick that the heads arrived on the bench, hopefully reasonably cleaned and the assembler whipped the bolts that were pre lubricated with a bit of oil and torqued them up in one quick movement with a minimum of mucking about or special technique.
alan
 
I think of it as the torque applied has two effects, it overcomes the friction in the threads and it creates a stretch in the stud. The lower the friction (due to lubing) the greater the proportion of the applied torque that goes into stretching the stud.
 
Torque is used as a proxy for tension on the fastner and therefore the two surfaces being held together. Because resistence to turning the threads against each other must over come friction before any twisting happens, a percentage of twisting force/torque is applied to overcome friction. Less force is then left over to actually turn the fastner before the click wrench clicks, thus less tension gets applied. With lubrication, friction required is lowered, more turn force actually turns fastner prior to click, more tension on parts.
If we had an easy way to measure fastner tension directly while fitting fastners, that would be best. No adjustments needed for lubing threads.
 
Has ANYONE ever suffered ANY issue from lubricating threads whilst adhering to standard Norton torque settings…?
 
"If we had an easy way to measure fastner tension directly while fitting fastners, that would be best. No adjustments needed for lubing threads."

We do... Torque to Yield fasteners are used more and more on assemblies where proper/even torque is specified - like cylinder heads, etc. Some car manufacturers engines that I work(ed on began using them in the 1980's - maybe earlier. They eliminate the issues with lubricants/torque settings. The disadvantage is that in general, once they are loosened, they are to be replaced, not reused. That is not feasible on a Norton since current use seems to indicate they need to be apart more than they are together! ;)

"Has ANYONE ever suffered ANY issue from lubricating threads whilst adhering to standard Norton torque settings…?"

Although not having that experience specifically with a Norton, I have seen stripped threads quite a few times with steel bolts into aluminum and broken bolt heads on a couple of occasions with steel bolts into steel/cast iron. Broken bolt heads is one of the worst "Oh S&^t!!!!!" moments! :eek:
 
The broken bolt would occur from too much torque (twist) for that particular bolt, dry or wet threads shouldn't change anything there.

Glen
 
fiatfan said:
I´m finally completing the reassembly of the upper part of my 850 motor, and I´m using Norman White´s book for help and tips since I haven´t done any work on a Norton in a long time. I´m just about to put the cylinder and head back on, and reading about Normans way of doing this I get a little confused. He say´s you should use a graphite (graphene?) based grease on all the threads but doesn´t mention anything about the torque settings. Can you grease the threads and use the standard torque settings? Will that be correct? I mean he should know what he talks about, yes? (I´m not sure I´ll use a torque wrench, never did back in the day, but we´ll see.)
I´m also having trouble finding grease with graphite, but that I can probably fix. (Small town problem)
Click to expand...
He does list the torque specs on page 105, 30 ft lbs for the 3/8" and 20 for the 5/16". These figures are the same as in the Norton Workshop Manual.


A side note, there is a potential problem not mentioned in Norman White's book.
The two 5/16" studs often break through into the pushrod tunnel in the cylinder. This is definitely a problem with 850s, perhaps not with 750s.
If the studs are not sealed, oil will push up and weep out under the washer at the nut end.
A good friend recently fully restored his 850 and forgot to seal those threads.
He spent most of last weekend removing and replacing the head to fix the leak.
Some good thread sealer on those threads in the cylinder is all that is needed.


Glen
 
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Fast Eddie said:
Has ANYONE ever suffered ANY issue from lubricating threads whilst adhering to standard Norton torque settings…?
Click to expand...
Not I. But the only bolts that I lubricate are the 4 hex bolts on the top (numbers 3-6). And they're lube'd with anti-seize because they're stainless.
 
worntorn said:
The broken bolt would occur from too much torque (twist) for that particular bolt, dry or wet threads shouldn't change anything there.

Glen
Click to expand...
A case of over torquing

Rocker Feed Oil Lines

Thought I'd reach out to you folks for help with replacing the rocker feed oil lines on my stock '73 Interstate. Venhill has a stainless braided line kit. It seem from reviewing this site, this product has issues with the metallic jacket, length, routing, etc. I like the OEM look Andover...
www.accessnorton.com www.accessnorton.com
 
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