We bought a 2011 NC a few months ago. Prior to this we had a NB. Over the years we’ve also owned several cars with alloy wheels. It seems that at some point all alloys start to corrode and bubble. Right now our NC has no corrosion or bubbling on the alloys, nor any sign of curbing around the rims.
I’m interested to know what starts (or assists) the corrosion process. For example is it breaking the alloy coating through curbing or, perhaps less likely, debris being thrown up by the road? Secondly, what preventive action can we take to maintain the corrosion free state of the alloys on our NC?
Regular washing and drying. That’s all I did to my previous cars alloys. Getting into the difficult parts with a soft brush too.
It does help that I hardly used my MX-5 in winter, I did but not when the roads were bad with salt. I kept it garaged too and never put it away wet, dirty probably but never wet.
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The problem with many alloy wheels is that they have sharp edges such as around the valve mounting and at the back of the spokes etc. Due to the process used for anodizing these sharp edges cause the anodizing layer to be very thin in these areas and consequently relatively low corrosion resistance. Any electrolytic conversion process (anodising) or electrostatic process (powder coating) creates poor conversion or coating depth on sharp corners. The best way to provide further protection is to hand spray them with a good clear lacquer or colour coat taking particular care to ensure a good coat on sharp edges.
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We’ve had a number of cars that have had wheels with machined finish then lacquered areas (Mazda/BMW/MERC) and I’ve just kept them clean using normal car shampoo (halfrauds usually - got good reviews and minimal foaming) as part of the car washing process, then once clean and dry just sprayed the wheels with silicone based shine stuff - often black trim / bumper shine, whatever I’ve got really. This also makes cleaning them next time easier.
In addition I also take them off the cars twice a year or so to clean and polish the barrel and back of the spokes. Barring one wheel on a cx5 (which was replaced under warranty) I’ve never had a corrosion problem.
Also I have never used a wheel cleaner type spray, or gone to a ‘Polish’ car wash as in my opinion as well as cleaning the brake dust off they strip any other protection, wax etc, off as well as they are usually a strong alkaline solution.
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Inflate with nitrogen stops alloys from corrosion! At any ATS garage think it’s less than £5.00 for all 4 inflation . Nitrogen doesn’t create condensation, all alloys rot around the valves due to internal condensation, nitrogen doesn’t
Alloy corrodes. The only way of stopping it is by a waterproof coating. Painted wheels where the primer etches into the metal will provide a better protection than a lacquered wheel. Any cracks in the coating will allow the moisture through. If there is any moisture under the lacquer that will cause problems too. My brother in law has a BMW with lacquered alloys and one of the wheels started corroding half way up one of the spokes. Zero damage to the lacquer.
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Wash them whenever you wash the body, I just use normal car shampoo but they are specialist products such as BiltHamer AutoWheels that react with iron in the brake dust. Make sure you get in all the nooks and crannies.
Anywhere the laquer is damaged (i.e. kerbing or stone chip), touch it up ASAP before corrosion can take hold.
However, expect that eventually they will go and require to be sent for powder coating refurbishment. It’s just something Japanese wheels seem to do. My ND’s are showing some bubbling around the centre badge, not much can be done.
Acidic wheel cleaners will damage lacquered and painted finishes. I use Valet Pro Bilberry Wheel Cleaner. Around £25 for 5L and it can be diluted 10:1 and used in a spray bottle. Enough to last for years. Works really well and smells nice too!
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Very good point from Roadie, avoid acidic wheel cleaners - WonderWheels being the classic example of this. They are fine until the laquer is compromised, once they get underneath that they start eating the wheel as well as the dirt though!
The colour change iron remover ones tend to smell a bit like sick, IronX and aforementioned BH AW unfortunately!
