 | Home > Maintenance & Modifications > Aluminium or steel rivnuts |
 
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| Dinnu Member Since: 24 Dec 2019 Location: Lija Posts: 3414   
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Depends what becomes the anode.
Keep in mind that pure aluminum is the most corrosion resistant by itself. But is practically useless for a mechanical part because it is so soft. Once alloyed, then it is more prone to corrosion. If you want the least galvanic incompatibility but retain strength, then monel is the best choice. But not readily available. Using an isolating paste, such as Duralac is the 2nd best option. I have used a lot of stainless (generally grade A2) in my 90 and been using them for 25 odd years without issues. But I isolate them (and most of the time check isolation with an ohm meter to be sure). But then again where my 90s are is less wet although still salty environment. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing 2012 90 CSW, 2.2TDCI, Santorini Black |
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25th May 2021 6:03pm |
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| Fellrunner Member Since: 28 Sep 2014 Location: Wandering Posts: 257  
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Dinnu - thanks for the answer. Makes me realise I should have paid much more attention to chemistry at school!
So, and bear with me, if I use duralec, it sounds like using steel is the best idea due to strength (both rivnuts and bolts)? |
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25th May 2021 6:26pm |
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| Dinnu Member Since: 24 Dec 2019 Location: Lija Posts: 3414
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With steel bolts there should be less potential (literally) and hence less galvanic corrosion. Try to get ones with decent galvanizing. There are hot dipped galvanized bolts, which are better than plates bolts.
Personally I do not like rivnuts, they can also spin (unless they are haxagonal) and hard to isolate completely. If can reach both sides, bolt nuts and washers is a better solution. I isolate washers by sticking duct tape to the side which will go in contact with the panel and then trim the extra tape with a scissors before installing. Note that the aluminium on later Defenders seem to corrode even when not in contact with dissimilar metal. Look at roofs. They tend to corrode from all edges. Or perhaps galvanic corrosion between different aluminium alloys (roof frame and sheet metal). 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing 2012 90 CSW, 2.2TDCI, Santorini Black |
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25th May 2021 7:59pm |
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| LandRoverAnorak Member Since: 17 Jul 2011 Location: Surrey Posts: 11324 
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It's less of an issue for stuff fitted inside as they won't be constantly exposed to water (even allowing for typical Defender leaks). Generally though, I'd suggest choosing the rivnut to match the material that it is being set into and then isolate the bolt with a suitable paste or grease if that's significantly different. It's much easier that way around. So, aluminium rivnuts in aluminium and stainless bolts coated in Duralac. Darren 110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak "You came in that thing? You're braver than I thought!" - Princess Leia |
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25th May 2021 8:51pm |
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| Fellrunner Member Since: 28 Sep 2014 Location: Wandering Posts: 257
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Many thanks 👍
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26th May 2021 8:05am |
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