Every link on chain fractured from pin to edge, cause?
Andrew
completely covered in orange surface rust with no trace of lubrication. I
popped the removal link and put it in a bath of dilute phosphoric acid to
remove the rust, in case the chain would prove to be serviceable after.
After cleaning I discovered it is a Sachs PC-41, and that every single link
has a fracture running from pin to plate edge.
Andrew
news:doijuj$shj$1...@bunyip2.cc.uq.edu.au...
<Accidentally hit post>
Here's a picture of part of the chain:
http://www.flickr.com/photos/85942209@N00/76768811/
Is it most likely that the iron oxide formation caused the fracture, or
could the acid bath have done it and I should never attempt to clean a chain
in that manner again?
Now that I think about it, I do recall hearing noises apart from the
bubbling while it was soaking which may have been the links fracturing. How
could being immersed in dilute H3PO4 have cause failure in this form?
Andrew
Werehatrack
This is common in older, corroded chains in my experience,
particularly on bikes that have been idle for long periods with the
chain rusty.
I will note that if there was enough corrosion to merit the use of
phosphoric acid to remove it, the chances are good that the chain's
outer plates were already fractured before the acid was employed.
Since the first time that I saw this symptom, I have been more careful
to examine old, poorly-maintained or weathered chains before allowing
them to return to service.
--
Typoes are a feature, not a bug.
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Words processed in a facility that contains nuts.
Kinky Cowboy
<a.bla...@minmet.uq.edu.au> wrote:
>I am in the process of restoring a ~1991 Shogun Trail Breaker. The chain was
>completely covered in orange surface rust with no trace of lubrication. I
>popped the removal link and put it in a bath of dilute phosphoric acid to
>remove the rust, in case the chain would prove to be serviceable after.
>
Why? Basic SRAM chains are so cheap that almost any cleaning agent is
more expensive than just replacing the chain.
Kinky Cowboy*
*Batteries not included
May contain traces of nuts
Your milage may vary
Werehatrack
<a.bla...@minmet.uq.edu.au> wrote:
>Is it most likely that the iron oxide formation caused the fracture, or
>could the acid bath have done it and I should never attempt to clean a chain
>in that manner again?
I've seen this kind of cracking (though not as extensively) in
corroded chains that had not been run through a corrosion removal
bath, so I suspect that at least some of the cracks were there before
it was soaked. OTOH, the acid etches the surface of the metal as well
as removing the oxide, particularly with certain alloys. I would not
be surprised if the failure was aggravated by the acid bath, but I
think the chain was likely junk before it was dipped.
>Now that I think about it, I do recall hearing noises apart from the
>bubbling while it was soaking which may have been the links fracturing. How
>could being immersed in dilute H3PO4 have cause failure in this form?
See above; note that the surfaces of the plates are etched. The next
time I have a worn-out chain that I'm going to discard, I'll inspect
it for cracks, remove any links that have failed, and toss the rest in
the acid bath to see what happens.
me
can dissolve alloying elements at the grain boundaries. Google up some
"stress-strain corrosion cracking' or similar and you will get the idea.
Simple Green soaks are also said to cause cracking in some chains.
Chains are cheap. Body parts aren't, so ...
Jeffrey
"Andrew" <a.bla...@minmet.uq.edu.au> wrote in message
news:doijuj$shj$1...@bunyip2.cc.uq.edu.au...
Phil, Squid-in-Training
> Using acid like that on almost any steel used in chains is a BAD
> idea. You can dissolve alloying elements at the grain boundaries. Google
> up some "stress-strain corrosion cracking' or similar and you
> will get the idea.
> Simple Green soaks are also said to cause cracking in some chains.
>
> Chains are cheap. Body parts aren't, so ...
Replace all your body parts with chains to save money?
--
Phil, Squid-in-Training
Werehatrack
SRAM says their chains aren't guaranteed to be compatible with other
makers' groups, though.
sunderland
"I had this metal part, I dipped it in acid and it isn't the same
afterwards. Why?"
Duh.
Andrew
news:1135460457.6...@g43g2000cwa.googlegroups.com...
> The original chain IS a SRAM. (Sachs became SRAM some time back).
I think you missed the joke there. Think six million dollar man.
> "I had this metal part, I dipped it in acid and it isn't the same
> afterwards. Why?"
>
> Duh.
What a well thought out response. I expected it to be different after the
bath, just not fractured at every link. I have used dilute H3PO4 solutions
before to remove surface rust with great success. But *every* chain link
either being cracked already, or cracking during cleaning was unusual.
The chain was always going to be replaced, but if I could remove the rust
and the old chain/cluster would be servicable for light duty while
replacements arrived, so much the better.
Thanks for the input werehatrack.
waxbytes
I would never use an acid bath to clean a chain, if it's so rusty it
needs replacing.
My guess, and it's only a guess, is that the rust around the pins and
rollers expanded so tightly against the plates as to cause the plates
to crack. Iron oxide (rust) has way more volume that iron alloy
(steel).
--
waxbytes
Earl Bollinger
I would have to agree with the others in that the links were likely already
cracked before the acid bath.
Any sounds you heard were probably other parts you can't see or hadn't
noticed yet cracking or breaking.
Or if any links hadn't cracked before the acid bath it is possible that
during the process they popped in the acid bath.
Since the cracks all look so uniform, I would think that as the iron oxides
formed and caused all the surfaces and joints to expand, that the pressure
would have caused the cracks.
Mike DeMicco
news:Hb-dnSNV2uO...@comcast.com:
> Simple Green soaks are also said to cause cracking in some chains.
Simple Green seems to be much maligned. If you look at the MSDS sheet,
concentrated it has a pH of 9.5 (mildly basic). It should be diluted
anyway, which will reduce the pH. As long as you leave a chain soaking in
it for about a half an hour, and remove by flushing with water, I don't see
how it could cause damage to the chain. I've been using it for years and
have not had a problem. I would not leave a chain soaking in it overnight;
nor would I leave a chain soaking in water that long either (unless I
wanted a rusty chain).
--
Mike DeMicco <blast...@comcast.net>