Rust proof bolts

[wirral_cyclist]

Galling is a problem with many metals, but galling doesn't occur with a nut and bolt joint. Galling needs movement...

[profpointy]

Galling is a problem with many metals, but galling doesn't occur with a nut and bolt joint. Galling needs movement...

umm, isn't screwing up the bolt "movement"
?

[wirral_cyclist]

Think repeated movement, I meant 'nut and bolt STATIC joint' oops

[Philip Benstead]

The bolts I use have the following mark on their head

FS 42.70

I term of strength and sear resistance, is this quality suitable to replace existing bolts in cycle bits.



All you need to know about stainless streel

http://www.bssa.org.uk/

[Neilo]

I have had many stainless steel bolts.usually A4, jam. I didn't know it was called galling.
It is normally when loosening the bolts that there is a problem.
Smaller bolts, tend to shear. larger bolts,above M8 require cutting off.
Lubrication on assembly normally stops it.
Lubrication also helps if you are screwing a bolt into a different metal, eg. steel bolt into aluminium stem. the lubricant provides a barrier between the metals to lessen dis-similar metal corrosion.

Neil

[Brucey]

The bolts I use have the following mark on their head

FS 42.70

I expect that actually says A2.70

I term of strength and sear resistance, is this quality suitable to replace existing bolts in cycle bits.

It depends which bolts you are replacing. You need to identify what they are before you can say if the stainless ones are strong enough or not.

cheers

[Brucey]

If the old bolt had a locking washer, spring washer, nylock, or thread locking compound on it from new, you need to put it on the replacement bolt too.

I must say that this point has been on my mind, as I want to replace the rusting chrome plated bolts on an ahead stem. The existing bolts have non standard washers that are flush with the bolt head. Regular washers would foul the stem moulding.

Is it safe to substitute the washer with threadlock?

It depends what kind of washer it was, exactly and why it was fitted.

cheers

[Philip Benstead]

The bolts I use have the following mark on their head

FS 42.70

I expect that actually says A2.70

I term of strength and sear resistance, is this quality suitable to replace existing bolts in cycle bits.

It depends which bolts you are replacing. You need to identify what they are before you can say if the stainless ones are strong enough or not.

cheers

I use them for

Rear rack
Mudguards
Toe clips

Would they be ok for handlebars?

Quill stream
Ahead stream
Derailleur

[CREPELLO]

If the old bolt had a locking washer, spring washer, nylock, or thread locking compound on it from new, you need to put it on the replacement bolt too.

I must say that this point has been on my mind, as I want to replace the rusting chrome plated bolts on an ahead stem. The existing bolts have non standard washers that are flush with the bolt head. Regular washers would foul the stem moulding.

Is it safe to substitute the washer with threadlock?

It depends what kind of washer it was, exactly and why it was fitted.

cheers

These are the integral (non removable) washers used on ahead stem bolts. As you know, they're a normal type of washer, except they are the same diameter as the bolt head. Surely as long as the bolt head was evenly formed, then threadlock would do the job of keeping the bolt firmly in place, without any repercussions?

Otherwise it seems that normal SS cap head bolts won't be suitable

[Brucey]

they may;

- have a different radius on the bottom (i.e. allowing a little articulation)
- have a different friction coefficient against the bolt or the stem
- have a spring/belleville washer effect (by virtue of the way they bear against matching radii under the bolt head and the seat in the stem
- may have a slightly larger diameter than the bolt head, or centre on a slight corner radius, to keep the bolt head from scuffing inside the counterbore.

or they might not be that important....

FWIW if you can fit ordinary capheads in the stem, you may find that they bear against the corner radius only, scuff the seat, scuff the bore, won't tolerate a slight angular misalignment... any of which is bad.

cheers

[wirral_cyclist]

I have had many stainless steel bolts.usually A4, jam. I didn't know it was called galling.
It is normally when loosening the bolts that there is a problem.
Smaller bolts, tend to shear. larger bolts,above M8 require cutting off.
Lubrication on assembly normally stops it.
Lubrication also helps if you are screwing a bolt into a different metal, eg. steel bolt into aluminium stem. the lubricant provides a barrier between the metals to lessen dis-similar metal corrosion.

Neil

Never had a simple static joint gall, in fact it has only ever happened with dissimilar metals or perhaps diverse grades? But only ever reliably with a carbon steel tap (for threading) and the tapped material being another softer steel (and alloy always!) - AND/BUT only in big sizes of say an inch or above.
If you look at the root of the bolt/tap you'd find where the thread/tap will have 'picked up' the softer material, I could see it build up over only dozens of passes alloy, and hundreds with 'steel' - but never on one use?
You sure you aren't talking about 'something not galling' that binds threads? I'm not saying I'm right but even the posted research from them that know does favour what I observed.

Lubrication always helps with threads - unless torque settings say dry

[Brucey]

FWIW I have had many stainless bolts of all sizes gall in various other applications, but none on bikes, provided I used a load of copper-ease on them when I assembled the parts, and they fitted correctly.

cheers

[wirral_cyclist]

FWIW I have had many stainless bolts of all sizes gall in various other applications, but none on bikes, provided I used a load of copper-ease on them when I assembled the parts, and they fitted correctly.

cheers

So do you think it is the loading of them?

[Brucey]

I didn't list the circumstances in which I've had galling occur because none of them will apply to bicycles, provided you use anti-seize like you should do.

But FWIW

- bone-dry assembly, high torque can cause galling
- modest torque, clean (properly clean) in a vacuum chamber
- any repeated assembly/disassembly if anti-seize is not used, esp into a tapped hole in stainless steel, Ti, or aluminium)
- if not deburred properly (eg from shortening the stainless bolt; just unwinding a nut to push the burrs straight is not at all good enough if the bolt is to go into a tapped hole, esp if the hole is in soft material)
- no washer under the head of the bolt
- use at high temperatures (exhaust manifolds/exhaust joints)

In addition if a stainless bolt is put into a tapped hole in another material (with no anti-seize), it may encourage corrosion in the other material, and then seizure.

Re the loading, I think it is important, but if there is fault in the assembly (eg a burr) then the local loading can be very high and that is what causes the rot to set in; once the surfaces start to pick up on one another, they don't quit, and one lot of debris begats another.... By contrast if you (say) use a brass nut on a high tensile steel bolt the nut can wear but the resultant debris rarely causes complete seizure even if there is precious little lubrication present.

cheers

[CREPELLO]

So is there an off the shelf, suitable SS replacement for stem bolts?

Brucey's multiple proviso's suggest that bolts without washers are a no go. I must admit, I have changed the two steerer clamp bolts on one stem for SS cap head M6 bolts, without washers.