 | Home > Maintenance & Modifications > Corrosion between stainless steel and aluminium..? |
 
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610   
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It will definately cause dissimilar metal corrosion. Whatever you use 'wet assemble' it with a reputable sealant to seal against water ingress and air and you'll be ok. Best case scenario the rivnuts should always be of the same 'medium' into which they are being fitted.
http://www.defender2.net/forum/topic11669....dissimilar http://www.defender2.net/forum/topic8555.h...dissimilar If you go through life with your head in the sand....all people will see is an ar5e!! Treat every day as if it is your last....one day you will be right!! |
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6th Dec 2012 10:46am |
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| Landlord Member Since: 27 Oct 2009 Location: Hampshire Posts: 582 
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Yes.
Galvanic corrosion between dissimilar metals is high in stainless to aluminium unless a barrier is placed in between. Even greater risk in salt laden environments by the coast. Lanacote on the s/s thread and surfaces touching the aluminium should reduce the risk of corrosion. http://www.aquafax.co.uk/html/product_details.asp?ID=11126 2007 TD5 90 Hard Top |
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6th Dec 2012 10:53am |
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| couplands Member Since: 31 Aug 2011 Location: Peak District & Cornwall Posts: 1826 
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Thanks both...!
Some great reading material there. I have some Sikaflex and ACF available, but now my idea of using stainless rivnts and screws is doesnt seem too good. What have others done to keep the treadplate properly fixed and corrosion free..? cheers simon |
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6th Dec 2012 11:03am |
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610
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Someone else mentioned the 'Sikaflex' word!
 Bit of a forum joke as I am a great advocator for 'that stuff' especially the 29i Marine Grade variety. Have I ever mentioned it? 
I replaced my treadplate for a stainless one..... Old....Showing the effects of dissimilar corrosion from the swarf left behind on build.  Click image to enlarge New.... Click image to enlarge In your case I would probably use aluminium rivnuts and dependant on what the new treadplate is made of (if stainless) possibly heatshrink the shaft of the bolt and place plastic washers under the heads to insulate the bolts as much as possible from the plate and wet assemble the whole lot. It really depends how fastidious you wish to be. Me I'm a fussy bu993r and it needs to be as near perfect as one can get!  If you go through life with your head in the sand....all people will see is an ar5e!!
Treat every day as if it is your last....one day you will be right!! |
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6th Dec 2012 11:22am |
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| couplands Member Since: 31 Aug 2011 Location: Peak District & Cornwall Posts: 1826
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I saw the reaction to your previous mention of the "S" word, so thought I'd do it for you...!
I'm fussy too, so keen to get these things right...at the moment I'm using the original tread plate (which looked like yours) but now wirebrushed and looking pretty good for the moment. If I decide to keep the 90, I'll put a stainless plate on. At the moment I want to get the fixings right, so aluminium rivnuts sound a better idea. Thanks for the great advice. cheers simon |
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6th Dec 2012 11:35am |
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| K9F Member Since: 12 Nov 2009 Location: Bournemouth Posts: 9610
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For my sins I unfortunately found myself in at work today. There has been much discussion about corrosion and the interaction between aluminium and steel. Thought I'd stick up a couple of photos for anyone that may be vaguely interested I took whilst whiling away my time today at work of the result of aluminium and steel together.....
Sorry about the quality, poor light and Cwapberry I'm afraid! Click image to enlarge Click image to enlarge If you go through life with your head in the sand....all people will see is an ar5e!! Treat every day as if it is your last....one day you will be right!! |
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9th Dec 2012 3:50pm |
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| Green Machine Member Since: 19 Nov 2010 Location: North Yorkshire Posts: 1226 
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@couplands - I replaced mine recently with a stainless threshold strip. All of the self-tappers from the old one sheared off with mine too. Tried drilling them out, but didn't get anywhere fast, so I just re-drilled the aluminium panel and installed the new threshold 5mm over to one side with new self-tappers. Used ACF50 Corrosion Block grease to assemble it all (coated back of new threshold strip as well).
Duralac jointing compound is another option to isolate against galvanic corrosion, I've got some somewhere, but used the Corrosion Block in this instance. Used the Duralac on all my stainless door bolts and haven't had any issues with corrosion so far. 2005 Td5 | 90 Station Wagon | Tonga Green |
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9th Dec 2012 4:23pm |
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| couplands Member Since: 31 Aug 2011 Location: Peak District & Cornwall Posts: 1826
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I swapped to aluminium rivnuts and have installed them (after drilling out the original self tappers...a tough job) using a good dab of Sikaflex. I'm using allen headed button screws and will be using plated steel instead of the stainless steel ones I had planned to use. I've also got some nylon washers and some heatshrink on the way, to cover the threads.
I'll cover with a Duralec/Lanotec type compound (someone also suggested anhydrous lanolin - ...?). I'll finish off with a covering of ACF. We'll see if this works. cheers simon |
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9th Dec 2012 8:15pm |
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