loctite or not. whos going to experiment

I have just looked at the spec for loctite and found only one so far that works to 200 degress C. Is that high enough to work on a commando big end? It is interesting because I have used loctite all my working life and trusted the suppliers when they said this one or that one worked. Most water cooled petrol/diesel engines cranks would not get near 200 degrees C as far as I could tell.
It is amazing that I cant find anywhere so far which locktite is recommended for con rods or internal combustion engines. Does that mean HENKEL ARE TRYING TO HIDE FROM RESPONCIBILITY.
The site needing has referred us too suggests we need to tighten bolts up about 5 times before they are useable. ??????????. Must be misinterpreting something here.

I guess that means we are left between a rock and a hard place. Don't trust anyone else scenario. What's best???

If your big end are running at 200°C, your oil will fail first and take out your bearings. The noise preceding bolt failure will warn you of impeding disaster.
Ta.

When I had some (BMW) con rods re-sized the guy who machined them wanted to know the torque setting and what kind of oil was specified to lubricate the nut. When I said I thought they were meant to be assembled dry he laughed and said no big end bolt should be assembled dry. He was also dismissive of loctite on big end bolts. This is a guy who works on some top performing V8 race engines so I went with his recommendations. That was: BMW specified torque with a drop of 20/50 engine oil on the threads.

comnoz said:

I don't trust them even with new nuts. I always thoroughly coat them with red loctite.

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Careful, some people here frown on that type of activity, then berate you on other forums...

grandpaul said:

comnoz said:

I don't trust them even with new nuts. I always thoroughly coat them with red loctite.

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Careful, some people here frown on that type of activity, then berate you on other forums...

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It's alright, I've been berated before. At least my nuts haven't fallen off....

comnoz said:

......It's alright, I've been berated before. At least my nuts haven't fallen off....

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:shock:

Ugh when my nuts are twisted too tight and glued down its my bolt head that pops off, sheeze.
OK so which physics logic should be de-rated - comnoz vs hobot?

Even if there is a loctitie that can stand about boiling temps in big ends what good does it do as if torque/stretch is not enough on its own to stay put, so I chuckle with the V8 builder on dry threads or locitite faith. Norton factory practice is not known to be best examples - so suspect they just T-wrenched dry and hoped for the best yet rod caps comming loose is not part of lore on factory issued Norton let downs.

IF comnoz finds that our rod bolts torqued to 25 lbft for .006 stretch become permanently elastically deformed .0005 longer, does this not imply that one ends up with only 20 lb ft and .0055 in actual operation so better to hobot stretch to .0065 to end up with .006 stretch in actual operation - long term?

hobot said:

Ugh when my nuts are twisted too tight and glued down its my bolt head that pops off, sheeze.
OK so which physics logic should be de-rated - comnoz vs hobot?

Even if there is a loctitie that can stand about boiling temps in big ends what good does it do as if torque/stretch is not enough on its own to stay put, so I chuckle with the V8 builder on dry threads or locitite faith. Norton factory practice is not known to be best examples - so suspect they just T-wrenched dry and hoped for the best yet rod caps comming loose is not part of lore on factory issued Norton let downs.

IF comnoz finds that our rod bolts torqued to 25 lbft for .006 stretch become permanently elastically deformed .0005 longer, does this not imply that one ends up with only 20 lb ft and .0055 in actual operation so better to hobot stretch to .0065 to end up with .006 stretch in actual operation - long term?

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Stretch is what counts -not ft lbs of torque. Torquing a bolt is just an inaccurate way of trying to get the right stretch. Jim

FWIW, Carrillo recommends torqueing the 5/16" SPS bolts in their Norton rods to .005" - .007" stretch, but not to exceed 45 ft-lbs. That's with the bolts dipped in oil for lube. Just another point of reference.

For stock rods, I use red Loctite and 25 ft-lbs torque. Bolt threads are dry, except for the Loctite. The Loctite is just extra insurance, and I can't see how it can hurt. Not as scientific as measuring stretch, but I haven't had any come loose so far.

Ken

Ken, I would imagine the liquid locktite works just as well as a drop of oil as far as overcoming dry thread bind etc?

Glen

worntorn said:

dry thread bind etc?

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Thread bind is what a torque wrench operates against.
Overcoming it entirely would negate a torque wrench almost entirely ?

Dry thread bind AND contact face friction.
Another cat for the pigeons: for thread lubricators amongst us, do you lubricate the contact face too?
Ta.

Rohan said:

worntorn said:

dry thread bind etc?

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Thread bind is what a torque wrench operates against.
Overcoming it entirely would negate a torque wrench almost entirely ?

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Statement or question?

No it will not negate the need for a torque wrench, there is still the torque being exerted on the bolt acting through the helix angle of the thread which in turn provided an axial force. Which is what we actually want to know - hence actually measuring the bolt extension. Or alternatively using torque to yield bolts which provide a very easy way of assembling something to a given clamping force.

Thread bind is what a torque wrench operates against.
Overcoming it entirely would negate a torque wrench almost entirely ?

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Yep exactly what I want to approach. With dunces like me I know i do not know enough to judge proper grain of salt on secondary measuire-feedback of torque attempts. So the only real question w/o worry of blurry twist measuring - is best final stretch for out particular bolts? Which color of rabbit foot key fob or loctite to use in engine fasteners gives similar level of security.

Let's see what ARP know about high tensile fasteners.
This is for the big end nuts (new) and all grade 5 & 8 fasteners on my bike at reassembly - teardown in progess to chase down ferrous particles showing in oil analysis (last teardown 1989).
Ta.

With the proviso that ARP note on their web pages

"Are ARP’s torque recommendations the same as the vehicle manufacturer’s specifications?

Sometimes ARP will recommend using torque specifications that are different than the manufacturer, but not always. Our kits are engineered for specific applications, factoring in the necessary clamp load we’re trying to achieve, material type, block or head material, etc. To achieve our target clamp load, it may be necessary to use a different torque figure than what the factory calls out.

The torque/stretch number listed for my after-market connecting rod is different than what ARP calls out for the same bolt.
Which specification do I use?

Refer back to the rod manufacturer and use their torque/stretch value."

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

Here a quote from above AAP article to take in for install and next removal lengths.

if any of them have taken a permanent set and have stretched by .001” or longer, you should replace them immediately.

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Hi.
The new conrod nuts finally arrived.
Existing bolts were reused.
I assemblied the rods using ARP Ultra-Torque on the threads but not the friction faces of nut and cap.
Initial torque to 25ft.lbs did not achieve minimal stretch as recommended by comnoz.
Torque was increased in 5ft.lb increments until 35ft.lbs attained a 0.0055" bolt stretch.
Now I wait/ride and see for the next decade.
Ta.

hobot pointed out the error prone use of T-wrench vs bolt stretch and now point out comnoz mis-logic error you are following > as he reported rod bolts take on a permanent PLASTIC stretch of .0005 so unless following hobot
(trained in solid state physics of inorganic metals to biological tissues) you will end up with only .005 stretch in use and loss of clamp-spring tension force - if not further stretching to my recommend .0065 - which in my rods showed between 33-36 lb ft. We want to stretch bolts enough the permanent Plastic Deformation is compensated for so the bolts clamp-hold with remaining Elastic Deformation. It is not best practice to leave seating surfaces dry as that can spike torque readings and distort metal interfaces that release when heated and shocked to let surfaces slip-release strain which reduces aimed for stretch-clamp force. Not a big deal unless bolt lets caps get loose or come off. After I charted this torque vs stretch in Peel I only measure stretch now so have 2 useless low mileage T-wrenches taking up space. We want only the nut to turn w/o any bolt twist or resistance that then relaxes in use. On critical fasteners I rap on them to try to shock release twist tensions, recheck then close up.

Hi hobot.
Thanks for the concern but traditionally I would just dry torque to 25 ft.lb per manual and trust.
I have now wet torqued to 35 ft.lb to achieve 0.0055" stretch with old bolts and new nuts.
This revised method I have gleaned from the pages of this forum, ARP and others.
To achieve 0.0065" would take me way beyond my confidence in the structural strength of my bolts (given my traditional torque usage) so I baulked at 35 ft.lb. Neither shock load 'rap' was used nor multiple torquing (to 'lap' the threads). Time will tell: as in life and all other experiments.
Ta.