Do nylocks go wrong if exposed to heat? I only ask because I recently found out that 2 of the 3 nylocks I was using to hold on my radiator fan had completely come undone and come off!!

Would they be effected by being next to a 100degC radiator?

Or is it just that it was one of the first things I bolted to the car and I did a bobbins job?

Even if not near the melting temperature when warm Nylon like thermo plastics suffer from low temperature creep --- however one reason could be your bolts might be to short, nylocs need at least 3 threads out the end showing to be fully effective.

Use spring or star washers and or a drop of thread locking compound.

The usual reason for nylocs coming loose is that they have been used more than once, which destroys the nylon insert.

Yup. I did wonder if I did and un-did them a few times when bodging it all together....

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Originally posted by BenB
Yup. I did wonder if I did and un-did them a few times when bodging it all together....

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To be honest, it was such a long time ago, I might have only temporarily fitted it and forgotten to swap plain nuts to nylocks...

Nylocks and threadlock it is then
Belt's and braces.....

I work in aviation so deal with a lot of safety critical applications. There are people (not me) who specialise in fastener engineering. Fortunately a lot of their knowledge is available in a more accessible format in the Carroll Shelby books! In outline -

Good quality nylocs are reusable to a large degree, assuming a correctly formed bolt thread (ie not one that's been cut shorter)! The K nuts used on aircraft are highly reusable (though not on aircraft generally). They are available (at a price) from Merlin et al. I would not advocate the use of spring washers due to creep and subsequent loss of preload. Star washers are useful on soft alloy or polymer components. A correctly designed and torqued fastener should not rattle loose, but a drop of the correct grade thread lock will provide additional insurance (assuming clean threads)! If its critical it should be physically locked using split pins, R clips or lock wire. Tab washers shouldn't be relied on.

I hope this is of some help.

Cheers,

Dom.

Loctite 442 - works great, is oil resistant and does not set hard. It was designed for Ford transmissions so takes plenty of vibration without working lose, whilst allowing for dissasembly.

Steve

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Originally posted by mangogrooveworkshop
In that place it wouldnt affect them. use thread lock on them as a matter of habit.
Sevens like bikes rattle everything loose.
We know of a chap who does tests on runways and he says that he has never found a rattle proof fastner....judgeing by what he finds on the runway.

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if your going to use loctite make sure the bolt and nut are clean and use the correct grade. you want the weakest one you can get away with as the strong formulas will pretty much destroy the nut and bolt before coming apart.

also avoid over tightening fasteners with thread lock the optimum tightness for non preloaded nuts/bolts is surprisingly low and much lower than non thread locked ones.

Loctite produce an excellent guide to their product lines, you can often pick a copy up in engineering suppliers. Alternatively I expect the same information is available on the website.

so what about these?

metal nyloc

Described as steel all metal locking nuts; look like nylocs but in steel.

Would they be re-usable, and how many times?

[Edited on 10/8/07 by 02GF74]

[Edited on 10/8/07 by 02GF74]

They are steel versions of nylocs. They might take a little more effort to undo them but the same principle applies - only use them once or twice. They would be heatproof though.

[Edited on 10-8-07 by RazMan]

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Originally posted by Fatgadget
...............Apparently these guys have invented a shake proof fastener....http://www.nord-lock.com/default.asp?url=51.16.37

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We use them at work in the food industry, they do last better than nylocks but generally destroy the stud or bolt that they are fitted to if undone more than a few times as the working principle is a bit like crossthreading the top of the nut.
I have used them on my exhaust manifold but find that the studs get damaged when removing it at times.
Paul.

quote:

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Originally posted by 02GF74
so what about these?

metal nyloc

Described as steel all metal locking nuts; look like nylocs but in steel.

Would they be re-usable, and how many times?

[Edited on 10/8/07 by 02GF74]

[Edited on 10/8/07 by 02GF74]

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