Browser
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| posted on 11/5/10 at 07:24 PM |
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Anybody ever heard of galvanic corrosion?
No? Well, anyone who owned a Japanese motorcycle in the seventies is. So I am told, it used to eat engine/transmission casings unless you religiously
kept them clean.
So, I shouldn't have been suprised when I removed the transmission casing shields from my Honda F400 rotovator this afternoon to replace the
axle water/oil seals, to find that the seal housings looked like this:
I've fitted the new seals:
I am now hoping that, because the axle does not rotate at high speed and there is no internal pressure in the casing, the new seals will stay ion
place and hold in the oil.
Otherwise it's going to be serious thinky time about either getting a used trans casing (kinda difficult as these machines are getting very
scarce) or getting another machine. Wish me luck!
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dhutch
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| posted on 11/5/10 at 07:35 PM |
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Galvanic corrosion is a topic that comes up about once a month on my forum (honestly i kid you not) however i wouldnt be surprised to hear many have
not!
I guess if it came to it you could have some weld built up on the casing.
Very temping to suggest painting it, but if done wrong it could be worse than without.
Daniel
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les g
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| posted on 11/5/10 at 07:56 PM |
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hi i have seen seals held in that sort of thing by building up with belzona or one the newer epoxy or two pack metals and if in desperation i know a
bloke who built up the surrounding area with bodyfiller
you might be surprised at what you can get away with
cheers les g
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Thinking about it
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| posted on 11/5/10 at 07:56 PM |
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And I've just picked up the wheels for it
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PSpirine
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| posted on 11/5/10 at 09:25 PM |
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With the seals in place, I'd chemical metal the gaps etc. Surprisingly hardy stuff. Just treat it like the casing's made of priceless
crystal...
It's at a stage where you may as well give it a go.. if it starts leaking etc. then you can just replace it and be no worse off.
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mangogrooveworkshop
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| posted on 11/5/10 at 10:31 PM |
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Go to a marine supplier and get a anode..it wont reverse the damage...but will stop it in its tracks
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MikeRJ
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| posted on 11/5/10 at 10:41 PM |
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quote:
Originally posted by PSpirine
With the seals in place, I'd chemical metal the gaps etc. Surprisingly hardy stuff. Just treat it like the casing's made of priceless
crystal...
That's what I'd do as well. Devcon is good for this kind of thing but quite expensive.
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Browser
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| posted on 12/5/10 at 12:08 AM |
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quote:
Originally posted by Thinking about it
And I've just picked up the wheels for it
I'm being very Australian about it bud, i.e. "it'll be right!".
Once those wheels get here all my problems'll disappear
Cheers for the chemical metal tips gents, a colleague has already suggested that approach.
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02GF74
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| posted on 12/5/10 at 06:14 AM |
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quote:
Originally posted by Browser
So, I shouldn't have been suprised when I removed the transmission casing shields from my Honda F400 rotovator this afternoon to replace
the axle water/oil seals, to find that the seal housings looked like this:
It is ROTAVATOR - easy to remember as it is the longest pallindrome in English language, unlike Bolton.
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mad4x4
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| posted on 12/5/10 at 06:33 AM |
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Ahhh galvanic corrosion. US landrover owners know all about that.... That is where the ally body disolves at the mounting holes to the chassis. Also
know as Mix Metal Corrosion....
Real Pain in the Ass
Scot's do it better in Kilts.
MK INDY's Don't Self Centre Regardless of MK Setting !
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britishtrident
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| posted on 12/5/10 at 08:08 AM |
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In the late 1960s and early 1970s we used to get simca 1100 coming in at less than 2 years old with the side/flasher lamps not working -- a quick
glance would show the lamp housings completely dissolved nothing left ---- they were made from Zamac the Zinc-Aluminium alloy that Dinky cars
were made from it didn't take too well to being exposed to road salt.
It amazes me that the french and italian car industries survived they made cars from such such s**t .
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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ironside
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| posted on 12/5/10 at 11:01 AM |
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This is a problem on Lotus Elises too, particularly where owners have replaced the stock mild steel bolts with stainless steel ones near aluminium
things.
The further away the two metals are from each other in the galvanic series table the faster the reaction is in the presence of an electolyte (like
salty water). Stainless steel is much further away from Aluminium in the series than mild steel which creates a problem that wasn't really there
before.
Lotus specify the use of Duralac jointing compound when interfacing dissimilar metals together. You can get it at:
http://www.seamarknunn.com/acatalog/info_PBDL-1115.html
or more cheaply:
http://www.lasaero.com/site/products/article?id=P002OHHP1
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