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Badly oxidized aluminum (alloy?) parts

Discussion in 'Bling and Appearance' at netrider.net.au started by n4spd, Aug 4, 2013.

  1. i bought a second hand bike, and it must have been sitting in weather for years, the front fork was supposed to be shinny and smooth but the front side of them are badly oxidized and turned gray with texture and the surface feel rough, similar condition with other parts such as handle bar and engine area, wheels.... i think these are all aluminum alloy?

    what can be done to make it look better, do i have to use sand paper? thanks a lot i do like this bike and want to look after it. i read the sticky post about cleaning but this seems to be a different thing.
  2. The fork lowers are aluminium painted with a silver lacquer. This chips, then the aluminum underneath oxidises. The quality of the lacquer varies between makes and bikes - they don't necessarily have to sit in the weather for years to look cancerous.

    Anyway, to clean up you have to remove the lacquer, smooth out with wet and dry and/or steel wool and either paint or polish the bare aluminium.

    Other aluminium parts may or may not have a clearcoat on them. If they don't, you might be able to make them look presentable with a kitchen scourer or steel wool. If so, then it's remove the clearcoat and paint/polish.

    With my old VFR I was keen, so I removed the forks, stripped the lowers with paint stripper and a wire brush, sanded with a few grades of wet and dry followed by a few grades of steel wool, then polished (by hand). This was a pain.

    My SV (a 2002) was equally bad - what the heck were Suzuki using as paint?. I couldn't be bothered, so I scrubbed with a scourer to smooth and left them.
  3. hi thanks, i just posted a few pics to show how bad they are. it is a 1999 yamaha zeal. i think this will take a long time to clean it up, i will do it bit by bid, thanks.

  4. I'd be cautious using steel wool on aluminium. I haven't done it myself, but I've heard that it can leave little bits of steel embedded in the aluminium, and these little bits then rust, causing little rust "dots" on the surface...
  5. I think it is more prominent on steel/stainless steel components rather than alloy (ie, aluminium, magnesium), the micro rusts can induce oxidation of the steel causing further rusting...it is slower on stainless than on iron based steel.

    Alloy parts, in this case aluminium alloy, have corroded...nothing you can do since aluminium does oxidise quite quickly. You can sand it back and buff it to a shine, then give a coat of wax or something and that will slow the oxidation, however over time it will go back to the more dull look, unless you keep your bike in an oxygen free atmosphere.

    If you want the parts to shine again, I'd suggest using wet and dry sand paper. Start on something like 800grit then 1000, 1500 and finish up with 2000grit (or higher), then use Autosol/toothpaste, buff it and it should shine. Not sure how long it will last, but with a bit of wax, it might last a little longer than a few weeks.
    • Informative Informative x 1
  6. Not something I saw, but I am a sample size of one. Easy to use finer grades of wet and dry if you're concerned.

    Its worth clarifying the type of corrosion I think the OP is referring to (correct me if I'm wrong). Freshly cut or polished aluminium will oxidise quickly and dull. This dull finish can't be prevented without clear coating or obsessive polishing, but will be pretty stable in the long term.

    On very exposed components like fork lowers (or the trees on my sv) you can get a white crusty scale like corrosion, esp where there's a coating that gets chipped or damaged. I'm sure someone can chime in with the mechanism.

    These deposits can be sanded off. While the metal underneath will dull, the scale shouldn't return as long as its polished once in a while.
  7. If it helps...... I did most of what you want to repair on a friends bike.........most of it you can do without any drama or real expertise..... the fork lowers are easy, the trees and motor are ideally going to require a bit of a sand back and repaint

    anyways....... have a look and see what you ythink........

  8. thanks a lot, i read through your post that is exactly what i need to do with my bike, except that i don't want to change the color of the aluminum parts, so i guess i can just buy some rattlecan clear coat?

    it will take me a long time to be confident enough to put it apart, as a new rider. didn't even know i can sand the ducktail and repaint it! at least i know i can one day.

    but i wonder how much will it cost to get the paint job done by professionals, so change the color of the front mud fender, tank and ducktail? my tank also has a small dent (3cm diameter) on it so it would be more than just sanding and repaint.

  9. My chemistry is getting old now, but iron will cause aluminium to oxidise to keep the iron nice and shiny - a standard redox reaction I believe. You will see it on wheels if left for a period as iron brake dust will fall on the aluminium wheels.

    Yes... aluminium will oxidise in the time that you are looking at it.