Why so many seized nuts and bolts?

[petemell]

Is it about time that the motorcycle manufacturers started making the nuts and bolts out of anti-corrosove materials. Most non-stress fixings on a motorcycle can be ok in stainless which is cheap enough.

[The Tot]

It's not as simple as that. Bike components are made out of compromised materials because there is always an offset between cost and benefit.

I do agree with you there, but all the processes that are required to implement corrosion inhibitors on materials will yield their disadvantages in terms of processing costs and effects on microstructure. There are so many processes that can be looked into but at the moment titanium seems to be the wonder material. Whilst it's not perfect, it has the required characteristics.

It's all about supply and demand. The aerospace industry is in huge demand for titanium fasteners because it has the desired properties, unfortunately for us, this bumps the price up.

Looks like composites and nanotechnology is the way forward mate, hence why metallurgists think "if it ain't broke, don't fix it" - it'll be interesting and could be something to think about for my disertation - i'm a materials engineering student.
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The Tot 2019 Z1000SX - 2007 R1
Never argue with autism

[Blau Zedong]

Simple solution.

Use Grease.
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18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth

[Steve-D]

Even simpler solution, Don't take any of them out.
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Tristan The said 'Dunno what my pace will be like, fastish slow puncture on the rear and if I go too fast I risk my 'keys' falling out'

[petemell]

But is annoying when you are trying to undoo a nut that was last touched in Japan 10 or so years ago.
Then the inevitable happens, twist then snap.
OK it's only an exhaust port stud.

[The Tot]

I've read somewhere that some manufacturers don't even grease their head bearings!

Copperslip is nasty stuff, i applied it to my caliper bolts which aren't too bad. I just WD40 my bolts every time i wash them.
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The Tot 2019 Z1000SX - 2007 R1
Never argue with autism

[iooi]

[MattHirst]

Rather than them being made out of monkey metal (which most of them are), it is more of a case of the thing it is screwing into/onto is made out of a different type of metal.

The bolt/component effectivley 'fuses' (i know that isn't right spelling but im having a blonde moment). So when you try and undo them, the allen head rounds off or the bolt shears where is isn't effected.

It is more noticeable with aluminium bolts/screws going into steel.
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It's all fun and games until someone gets hurt, then it's bloody hilarious!!!

[Ariel Badger]

Electrolytic action between disimilar metals and sacrificial plating metals all add to the problem worsend by salt and heat. Stainless in ali is particulary bad as is Zink plated steel in anything.
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[The Tot]

Yeah, i edited this out from my original posts, but metals each have an electron potential. Disimilar metals, such as aluminium and steel when combined have a great electron potential difference. What you are effectively doing is producing an electrolytic cell. Once a suitable electrolyte, such as salty winter mist or dissolved road salt, it will be able to allow the flow of electrons from the aluminum to the steel (ally having a more negative electron potential of something like -1.73eV or something like that (i'm not sure about the units, it's been a good year or two since I last did my electrochemsitry lectures). This is why you see the ally furring and eventually splitting on aluminium braided steel. As Matt rightly said, the two dissimilar metals effectively fuse together with an electrochemical bond which is weak enough to break with mechanical force, but by the time you do that, it's too late. I'll try and dig up my lecture notes to show the electron potentials of common metals to show which metals would be suitable for use as fasteners or which ones are a definite no-no.

You do however need to consider the mechanical properties of the metal, would you want something ductile, hard, brittle, elastic etc. That's why i think materials engineering is really interesting.

I've always had this analogy - Mechanical Engineers "Make stuff", Materials Engineers "Figure out why the stuff that mechanical engineers made has broken". All in all, i find it a very interesting and underrated field of study.

Zinc is used as sacrificial protection hence it reacts with the environment due to it being more reactive than steel.
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The Tot 2019 Z1000SX - 2007 R1
Never argue with autism

[MattHirst]

Thats what i was trying to say, in a none boffin context
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It's all fun and games until someone gets hurt, then it's bloody hilarious!!!

[loply]

I have to say that the decision about the type of fastened head to use - allen head cap, or hex bolt - often seems illogical.

From my experience bolts with an allen head are ridiculously easy to round off, yet they are often used in locations where this is very likely to happen.

I can only think of one hex head bolt that I've rounded off and I was still able to remove it with perseverence.

A few of my bikes have even had cross-head screws in really daft locations where (even with a perfectly matched screwdriver) there simply wasn't enough material on the head to allow removal.

As for exhaust studs, I can't help but think if they were a bit bigger (instead of M8) they would fair better!
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