I asked here about removing 'corrosion' from an alloy motorcycle wheel recently and I have now done most of it using a wire brush on an electric drill and hand wire bush. I just have some light corrosion left in fifficult to access castings and don't want to paint over it?
It was suggested that ammonia may be good to 'remove' (convert?) this corrosion (sulphate?) but we don't have any in the cupboard, I'm not sure where I would go on the high street to get some, what form would it come in and would it affect (damage / surface hardnen?) the alloy?
Aluminium alloy (as I expect you have) must be laquered or otherwise protected. It will corrode especially on contact with salt, and will look bad as white aluminium oxide deposits. Laquer as used on alloy car wheels must be applied to emaculately prepared surface which generally can only be achieved by mechanical means from a previously oxidised surface.
You won't remove corrosion with etch cleaners or other chemicals which will leave the surface looking good. Pitting and discolouration are the usual result. The best manual method is Scotchbrite nylon abrasive pads which you can get from engineering supply merchants. This leaves a fine burnished surface without deep scratches. You can wrap small bits round a thin stick to get into fiddly areas. Another way is vapour blasting which is a sort of fine bead blasting with beads suspended in a water jet.
Recap: The front tubeless tyre was leaking at the rim joint so I removed the tyre and found corrosion had lifted the paint in several places and hence the leak. I removed all the corrosion / remaining paint within the rim area and used paint stripper to remove the pain from the reast of the wheel. In some places the paint looked ok but there were areas of corrosion underneath. I now just have a few patches of (white) corrosion left but in the bottom of deep cast holes around the hub and disk brake mounts.
I felt a chemical solution that would remove or 'kill' these few final patches might make the job easier pre a final cleaning and acid-etch priming > paint etc?
All the best ..
T i m
p.s. I have 'painted' many alloy parts (mainly motorcycle) over the years and they are still looking ok .. unless as uou say, the salt get's under it via a stone chip etc. ;-(
Sorry I didn't mention what I was going to do next Dave ... acid etch prime, filler primer, undercoat, top coat and possibly a 'two pack' laquer.
A pain on things that you want to remain 'natural' looking I agree. This front wheel, although pretty well clean of most of the corrosion etc is currently a patchwork of colours, brushed bits, paint stripped bits, hard corroded (black) bits .. ;-(
Or from under the sink ;-)
I used that to remove the little bits that paint stripper didn't quite get. I'll go over the whole wheel with some fine wet-n-dry (wet) to remove any burrs etc next.
Hmm, that sounds easier ;-) I did consider getting the whole wheel bead blasted but it's the finding the right place that would do it for a drink, getting it back, finding they'd missed a bit or been a bit agressive etc etc. Experience has told me d-i-y is the only way I get what *I* want.
A few years back I bought my daughter a little Yamaha TY-80 (4 speed trials bike) that was in a pretty scruffy (but functional) state. I even stripped the spoked wheels down, painted the hubs with an ally looking paint and rebuilt the wheels with new rims and spokes. When I was fininshed it looked pretty good (can't say 'like new' because it was over 15 years old *then*!).
I get great pleasure 'restoring' stuff .. don't think I could do so for a living though .. ;-(
I don't think so Chris .. there is basically nothing wrong with
*this* wheel and I would probably do the same thing to anything but an immaculate / brand new wheel anyway (it's just how I am). ;-(
Whenever I have bought a new (to me) motorcycle I always give it a 'quick once over' but that often ends up with me doing like I'm doing now .. but I only ever need to do it once and then can ride the things into the ground knowing those little matters (like an oversize inner tube for example) aren't going to come back to bite me later on ..?
Also I don't feel a machine is *mine* until I have got to know it's internals a bit ..(and generally I'm the better for doing so *should* something happen on the road ..). Also be personalising it a bit (like these rims were white and I might do them silver / ally) means it's easier to spot / less easy to dispose of should it get knicked?
Alumium oxide is hard - go with Garryflex abrasives instead of the Scotchbrites.
I'm just in from an hour or two in the workshop polishing an old 1940s suitcase, in what appears to be Birmabright (15% magnesium). I guess it's demob kit, made from old Lancasters. A filthy job!
As to chemically pickling alumium, then there are plenty of easy recipes for it. The tricky bit is though that they're much aster on bare alumium than they are on the oxide - so as soon as you have a pinhole you rapidly have a big hole in the metal and you still haven't removed the oxide film. You can use a quick pickle on alumium to clean it immediately before coating (and I mean immediately!), but it's not an effective way to remove appreciable grot beforehand - stick with abrasives.
Ah (and we don't want to do that!) the 'corrosion' I'm talking about here sits on top of the ally in the form of a white patch that on the worst bits was quite soft and brushes off reasonably easily (it comes off in the form of a while powder)l? The darker (black), harder bits I'm happy to leave as the acid etch primer seems to stick / bond to that fairly well?
Hmm, just this is down inside some pretty deep casting / webs (front bearing hub and disk mount legs) and although I could leave it there (as it can't be seen once the disk is on) I'd rather not let anything get a toe-hold under the paint again? I *might* be able to get the Dremel down there but I couldn't see what I was doing at the same time. ;-(
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