gruntus Posted October 21, 2009 Share Posted October 21, 2009 Gents, As the post suggests, what have you all used in the past to prevent the above? Today I pulled off the battery box, a few brackets and the ribs that that rear tub sits on to get sent away to be galvanised. I noticed that where the seat belt brackets sit under the tub and sandwich the aluminium of the tub is completely corroded. Also where the tub ribs sit under the rear floor space is perforated where the two metals have also had at it I was wondering what to do moving forward and thought of insulating the two from one another. Obviously if just using a compound or sealant the two metals will inevitably touch at some point and wondered if anyone has used thin plastic before to keep the metals seperated? I thought using this with plastic washers on the bolts as well? Whats your thoughts? All answers appreciated! Cheers G Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted October 21, 2009 Share Posted October 21, 2009 I considered using a thin sheet of rubber cut to size. Pond liner would work well, about 1mm thick and can easily and accurately be cut. Might not be advisable for critical connections though, don't know how the rubber insert would affect the torque loadings of the joint. Quote Link to comment Share on other sites More sharing options...
western Posted October 21, 2009 Share Posted October 21, 2009 a alloy use jointing compound would be better, this has been talked about before a fair while ago, try a search for jointing compound or similar Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted October 21, 2009 Share Posted October 21, 2009 I wrote to Fascinating Finishes (ebay name), Kingstonian Paints in the real world, asking the same question. They took the question seriously, consulted amongst themselves, and came back with two alternatives. The cheapest has a bit of Bitumen in it, so is OK if it's out of sight, or never going to be painted over (chassis black excepted) as the bitumen will bleed through eventually. The slightly more expensive has no bitumen and can be painted over. No user review as buying some is still on my 'to do' list. Cheaper Sold as Fish Pond Paint Water Proof Ornamental Garden Ponds. 290151377562 Less cheap Sold as Swimming Pool Paint Water Proof Garden Fish Pond Pools. 290151365703 Ebay Shop site http://stores.shop.ebay.co.uk/Fascinating-Finishes-Ltd__W0QQ_armrsZ1 Don't panic over the price difference, it's just that of the two items I've hit, one is 750ml, the other is 2.5L. I think they do sell them both in 750ml size, I just didn't find them. HTH Quote Link to comment Share on other sites More sharing options...
Retroanaconda Posted October 21, 2009 Share Posted October 21, 2009 Interesting. From what I know of pond paint products, I was under the impression that they require a porous surface to adhere to (such as concrete, brickwork etc). So painting them onto metal (non-porous) would just end with it falling off Although I guess that where it's sandwiched between two mating faces that wouldn't be an issue. And that second one there does say it will adhere to steel. My fish shop sells a litre of black pond paint for £15 odd...if it's the same stuff (which I think, looking at that page, it is) then that eBay shop seems a bit more expensive. Quote Link to comment Share on other sites More sharing options...
gruntus Posted October 21, 2009 Author Share Posted October 21, 2009 Aha, thanks Ralph found your old thread here So it may be ok using some DPC or similar material and use the compound to sandwich between them all. Thanks for all the replies chaps! Cheers Grant Quote Link to comment Share on other sites More sharing options...
landroversforever Posted October 21, 2009 Share Posted October 21, 2009 I was thinking with this... would it work if you wired all the earth's back to the battery and one little earth strap to the body. would that stop the corrosion? Quote Link to comment Share on other sites More sharing options...
western Posted October 21, 2009 Share Posted October 21, 2009 I was thinking with this... would it work if you wired all the earth's back to the battery and one little earth strap to the body. would that stop the corrosion? doubt it, it's because the 2 materials a disimilar,the alloy becomes a sacraficial material, only way is to keep the apart but tightly joined so moisture cannot get in between. Quote Link to comment Share on other sites More sharing options...
ajh Posted October 22, 2009 Share Posted October 22, 2009 I just galvanized a bunch of the take-off washers and will use those where I use stainless bolts to keep them from the alloy directly. Quote Link to comment Share on other sites More sharing options...
Timmy511 Posted October 22, 2009 Share Posted October 22, 2009 my uncle was a fisherman, he keeps telling me i need to grind an area clean on the chassis and fit a sacrificial anode (as this what they used on the boat), this then rots befor the aluminium and steel due to it being lower in the galvanic series hence protecting the steel and ally. an explanation wikapedi sacraficial anode Tim. Quote Link to comment Share on other sites More sharing options...
GL88 Posted October 22, 2009 Share Posted October 22, 2009 http://secure.silmid.com/varius.engine?w=2&ref=16&language=1&code=SURA03 I haven't used this yet but they have others on the site too Quote Link to comment Share on other sites More sharing options...
mcdan Posted October 22, 2009 Share Posted October 22, 2009 my uncle was a fisherman, he keeps telling me i need to grind an area clean on the chassis and fit a sacrificial anode (as this what they used on the boat), this then rots befor the aluminium and steel due to it being lower in the galvanic series hence protecting the steel and ally. an explanation wikapedi sacraficial anode Tim. we spoke about this solution in an italian Land Rover Forum, and everybody wrote that this is a right way for boats not for cars... to let work the sacraficial anode you will put all the materials in a conductive liquid (water and salt)to perform just like a battery, anyway the study to position of anode is very difficult, there are a lot of test to calculate the right place of galvanic current! Quote Link to comment Share on other sites More sharing options...
ejparrott Posted October 22, 2009 Share Posted October 22, 2009 We use anodes on the narrowboat, you have to have them the right size and in the right place, they will not work on a LandRover, unless the chassis is permanently immersed in water. Quote Link to comment Share on other sites More sharing options...
Daan Posted October 22, 2009 Share Posted October 22, 2009 I reckon, the fact that you galvanised the metal parts, virtually solved the problems. I mean whenever you remove the galvanised body capping from your body, the metal undeneath is usually in mint condition. For this reason, When I rebuilt mine on a galvanised chassis, I did nothing. Daan Quote Link to comment Share on other sites More sharing options...
gazelle Posted October 22, 2009 Share Posted October 22, 2009 Zinc will corrode in preference to both the steel and the aluminium. However zinc and some aluminiums are very close in potential, so I would not rely on that alone. Duralec can be found at yacht chandlers in relatively small quantities - but it is still not cheap. Martin Quote Link to comment Share on other sites More sharing options...
headhunter Posted October 22, 2009 Share Posted October 22, 2009 Duralec is a paste used on boats, most often between stainless steel fixings to aluminum masts and booms. From my experience where it has been used there is no galvanic corrosion. I cannot say what will happen where the joint is flexible, however in such instances on boats, nylon washers are often used. I suspect galvanic corrosion is worst where a tight fixing is made. John Quote Link to comment Share on other sites More sharing options...
pongo Posted October 22, 2009 Share Posted October 22, 2009 Duralec is a paste used on boats, most often between stainless steel fixings to aluminum masts and booms. From my experience where it has been used there is no galvanic corrosion. I cannot say what will happen where the joint is flexible, however in such instances on boats, nylon washers are often used. I suspect galvanic corrosion is worst where a tight fixing is made. John Duralac is used on aircraft to wet assemble metals. Used properly it will keep moisture out, thus preventing corrosion. surfaces must be clean and dry before assembly. Quote Link to comment Share on other sites More sharing options...
SteveRK Posted October 22, 2009 Share Posted October 22, 2009 What do Land Rover do when fitting the aluminium panels on Classic Range Rovers as these are bolted to the steel inner panels/chassis frame? I would have thought that etch priming both the aluminium and steel surfaces is a good start to keep the surfaces separated? Quote Link to comment Share on other sites More sharing options...
headhunter Posted October 23, 2009 Share Posted October 23, 2009 Land Rover have been experimenting with ceramic coatings for alloy components such as seen here - http://www.keronite.com/index.asp Don't know what progress has been made. Aston Martin use ceramic coatings on it's magnesium door frames. John Quote Link to comment Share on other sites More sharing options...
ChrisM_110 Posted October 23, 2009 Share Posted October 23, 2009 +1 for Duralac, a chandler will have some, it's commonly used on ally-skinned boats. 250ml is about £20, but it does go a long way. I've used some on a boat, but not on my truck yet. It kept a GRP-aluminium-steel-stainless-galv mast to bulkhead joint corrosion free for at least three years out in Cardiff Bay. Quote Link to comment Share on other sites More sharing options...
pinny Posted October 23, 2009 Share Posted October 23, 2009 what about denso tape takes a lot of beating and from memory not expensive Quote Link to comment Share on other sites More sharing options...
ajh Posted October 24, 2009 Share Posted October 24, 2009 You can also get bonded and collared washers to provide proper isolation. Bonded are a rubber and steel washer together so the steel never touches the alloy, collared you would get in nylon and it has a flange that keeps the bolt and panel from touching. Still, a dab of silicone before you put the bolt in will seal the top and prevent water getting in, and without water there is no galvanic reaction possible. For the most part where I am not using stainless I am ust going to overspray the heads and threads with cold galv spray (zinc rich primer basically) for anything I know I will not need to dismantle regularly. Another option is to zinc plate every fastener, you can plate mild steel, stainless steel, and alloy (with the right kit) and then you can renew the plating as it sacrifices over the years.. in a LR the plating is the sacrificial anode at every bolt opening. Using galvanized washers is also a good approach as it will provide a lot more zinc to wear through. Quote Link to comment Share on other sites More sharing options...
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