loctite or not. whos going to experiment

Status
Not open for further replies.
K

kerinorton

Joined
Feb 12, 2013
Messages
1,563
Country flag
Ok. Who going to set up an experiment to show the differences between a dry bolt, an oiled bolt and a loctited bolt, when torqued up to 25 foot pounds.

I guess all we need is a pressure sensor compressed once each by an identical set of bolts. Doesn't have to be Norton con rod bolts to prove the point.

Dereck

ps I would be surprised if it mattered at 25 foot pounds pressure.
 
A pissant 'experiment' in a back shed will probably just confound the issue.
Here you go.
Start with this one (https://www.jstage.jst.go.jp/article/js ... 5/_article) then search 'Google Scholar' (http://scholar.google.com.au/) for more of the science of dry or lubricated fasteners.

Here's another - http://www.sciencedirect.com/science/ar ... 0710001676

More: http://www.engineeringtoolbox.com/frict ... d_778.html
Read for Friction Coefficients i.e. 'Steel / Steel' under 'Clean and Dry Surfaces' vs 'Lubricated and Greasy Surfaces'.
Ta.
 
I guess all you REALLY need is a micrometer, to measure elastic bolt extension.
The extension will be proportional to the pre-load on the bolt, when you've torqued it.
 
From the equation below, if everything else remains constant then T = F.
So if the coefficient of friction (F) for steel / steel drops from a dry 0.50 - 0.80 to an oily 0.16 then a 25 ft.lb dry torque will now only need a 5 to 8 ft.lb (oily) torque. Now, who is keen to do that experiment on their conrods? Conversely, if you have been using 25 ft.lb on oily fasteners then they are overtorqued (a lot!).
Rohan is correct on this one (locktite lowers the friction coefficient) so use new locking nuts, cleanse all the threads and contact faces with non-residual solvent (I use metho) then torque the nuts to 25 ft.lb. Done.
Ta.
People knew this stuff even before there was rocket science.
 
needing said:
so use new locking nuts, cleanse all the threads and contact faces with non-residual solvent (I use metho) then torque the nuts to 25 ft.lb. Done.
Click to expand...

Loctite make a wick-in product, so torque the rodnuts dry like you say and use the loctite after ?

Oil wouldn't usually lower the friction that much, that would be an extreme example ?

If Mick Hemmings is using loctite in the assembly, then maybe these things are tough enough or basic enough that it doesn't really matter (?).
Early dommies didn't have a torque value quoted for the conrods, they were just given a heave to suit.
That would/could cover a fair old range of torque values ?!

The rods probably weren't designed to suit a particular torque value either,
but rather an approx torque value to suit was simply quoted (?).

I must say, I don't feel inclined to experiment on my rods.
Someone else can do that, tell us how it goes !
 
Just get two bolts/nuts and use threadlock on one and try the difference , no need for torquing . The stuff i use will strip of the treads before un screwing . from finger tight. Providing the glue is high temp it will keep the parts together. if used on rod bolts.
 
I did not experiment with Ms Peel but went by solid state physics measures of known bolt stretch to seek so polished up threads with a few dry runs then oiled to relieve bolt twist and cranked down till .0065" reached then a lttle rap to settle Van der Wahls bonds interfaces, checked em again and closed up. Loctite til it sets up is a pretty good lube so a good thing for that but uneeded if stretched right to stay tight with oil inbetween. Rod bolts were only items Norton factory used a T-wrench on and set levels on the slightly lower conservative side for the size, length and quality of the bolts so 25 lb ft puts ya pretty close to .006". The real nic pickers on rod and head and barrel bolts are the vintage garden tractor pullers that also take into account the temperature of parts being assembled. Do as your level of comprehension and study dictate.
 
ARP knows a little about quality fastener tightening/preload and here are some of their thoughts on the subject. Hit each grey colored tab in the white window (overview, design, installation, etc) to see each topic.

http://arp-bolts.com/p/technical.php

Relating to torque lube, at the link below are 8 pages of ARP slides to view and a full length article located in the lower part of the page. Click the "down arrow" at the bottom of the article to expand it and make it easy reading, or use the last URL below which is a direct link to the article.

http://arp-bolts.com/p/arpultratorque.php

http://issuu.com/arpbolts/docs/ut_detai ... 07/4062479
 
X-file said:
I guess all you REALLY need is a micrometer, to measure elastic bolt extension.
The extension will be proportional to the pre-load on the bolt, when you've torqued it.
Click to expand...


All you really need is a micrometer when you are tightening your rod nuts with locktite. It doesn't matter how much torque it took to get to the correct amount of stretch. Jim
 
And the correct amount of stretch in Commando rod bolts is ???

Don't recall seeing that quoted in the manual anywhere, nor from any of the latter day suppliers ?
And if latter day supplier bolts are different, would they be the same stretch anyway ?
 
Keri,

I have done this experiment. When using a proper anti-seize lube (not oil or loctite) the clamping force will increase significantly with the same torque.

As was pointed out, if you want a bulletproof conrod joint. Apply a drop of wicking Loctite 290 after torque to 25 ft lb.

George
 
Rohan said:
And the correct amount of stretch in Commando rod bolts is ???

Don't recall seeing that quoted in the manual anywhere, nor from any of the latter day suppliers ?
And if latter day supplier bolts are different, would they be the same stretch anyway ?
Click to expand...


The figure I settled on several years ago was .0055 in. with used bolts and .006 with new.

I got that figure using a rod bolt stretch gauge and a fairly accurate torque wrench and have used it since but I can't vouch for it's technical precision.

I don't trust them even with new nuts. I always thoroughly coat them with red loctite. Jim
 
I don't trust them even with new nuts. I always thoroughly coat them with red loctite. Jim[/quote]


I cant trust them either.

Many years ago, some manufacturers stipulated, dry or oiled when tightening Big End nuts or bolts. Also many years ago, lock tabs were used.
Why didn't Norton specify oiled or dry?

For the purists, use the new wicking 290 loctite then [ which may not have been available when I was mechanicing ]. Or don't, at your peril. Easy

Dereck
 
kerinorton said:
Why didn't Norton specify oiled or dry?
Click to expand...

If you read up on bolt torques, it mentions in many places that bolt torques are assumed dry.

My car manual (GM based V8) states quite clearly that all torques are dry, unless otherwise specified.
And quotes a few oiled torques, mostly in the oil pump and torque converter.

Early dommie conrods had drilled bolts and castellated nuts, and a split pin that went in.
Positive locking, at its finest. And probably expensive...
 
hobot reasoning is shoot for least thread friction to resist turning twist into stretch clamp force. Ya know I am a magic goop testing kind of lazy guy - & now one with nil faith in locktite at rod cap temps and vibration so only depend on the nut torque. I do not think it wise to use a bolt you do not thrust long term with .006+ stretch. May be the most beneficial item to have cryo tempered. Seek out online scope on rod stretch ranges to see where lawnmower vs hot rods use.
 
hobot said:
hobot reasoning is shoot for least thread friction to resist turning twist into stretch clamp force. Ya know I am a magic goop testing kind of lazy guy - & now one with nil faith in locktite at rod cap temps and vibration so only depend on the nut torque. I do not think it wise to use a bolt you do not thrust long term with .006+ stretch. May be the most beneficial item to have cryo tempered. Seek out online scope on rod stretch ranges to see where lawnmower vs hot rods use.
Click to expand...

A clean new lightly engine oiled Norton rod bolt stretches .006 the first time it is torqued to 25 ft lbs.
When the torque is released it comes back to around .0005 longer than it was before it had been torqued.

I agree, it always sounded like a lot to me also. Jim
 
Perhaps it should be asked if they keep doing that if you keep retorquing and undoing them ?!
 
Ok Jim good to know how much stretch is expected for normal reuse and stretch reduction compensation. I did not look into re-use specs. This makes me wonder if a pre-stretched bolt may be better if it holds its tension better than an *unbroken in* bolt. Nuts are disposables. Oh yeah Trixie crank w pistons out on floor so can check if their stretch changed or if can twist nuts any a bit past 25 lb ft. Glad Ken took this task off my mind in Peel.

Got 2 head studs retrieved now for you to twist test, after sending to cryo with a 2S cam and chain saws so might give clue to cyro worth on cap bolts.
 
Rohan said:
Perhaps it should be asked if they keep doing that if you keep retorquing and undoing them ?!
Click to expand...


At least through the dozen or so cycles I have tried they returned to the same length.

I have tried the test with old used bolts also and seen around .0055 stretch at 25 ft lbs.

3/8th Ford rod bolts that are about the same length as a Norton bolt specify a stretch of .006 so I figured it was not too far out of line. Jim
 
Status
Not open for further replies.

Similar threads

C
  • Locked
To Loctite or not to Loctite
Replies
7
Views
1,281
grandpaul
grandpaul
debby
  • Locked
studs, loctite or not?
Replies
7
Views
3,853
pommie john
pommie john
Back
Top