My 2 Ltr Spider has the original 14” Cromadora knock on hub wheels.
I want to restore them as it’s something easy to fix and instant gratification. They have chips on the rims and beneath the silver paint there is orange colored metal showing thru. Are these wheels magnesium?
Has anyone tried powder coating or is that a heinous crime. It’s just such a good finish on steel rims.
Also is there an official colour for the silver finish? I’ll post a few pics later today.
Thanks in advance
Michael
I have personally powder coated lots of magnesium wheels, as well as the magnesium Dino cam covers and oil fillers. You can add layers of pounder to reduce surface defects if you have corrosion damage, that isn't as easy with paint, unless you fill and sand before painting. When I have something too large for my ovens, I take it to the local powder coating place. The owner told me that you can fill thin blemishes with JB Weld metal formula and it will hold up to the 400F temperature of the powder coating process. I have not tried that yet, but a good tip. The Dino engine that just sold on Bring A Trailer looked like it had a powder coated oil sump as well cam covers and oil fillers. If my Cromadora [bolt on] wheels weren't in such good condition, I would powder coat them if I was going to refinish them.
I don't have the color match for the silver wheels, but you can order free swatches from many of the powder coat places online, like Prismatic colors or Powder by the Pound. It is shocking how many different "silvers" there are.
Ben.
before you do anything make sure your wheels have no cracks and are not porous..Magnesium can be powder painted at low curing heat(usually done when the ovens are turned down at the end of the day..) but before you do so magnesium has to be treated otherwise it will slowly rot under the powder paint..especially if the wheels have been blasted by the powder paint shop before painting..Sure you can powder paint magnesium..but will it last if not treated..no it will not.. the valve cover on that engine if not treated will rot from inside if they have been blasted inside and not treated(i hope not painted inside.. powder paint on internal engine parts is not recommended for obvious reasons) ...
I have one wheel left that has been treated and powder painted correctly..if interested send me a Pm..i also have other good wheels that could be powder painted..
Remember magnesium is light but very fragile if not treated properly and after all, this is what separates your life from the asphalt..
There's a fair amount of controversy about refinishing Cromodora wheels. They were originally made in a magnesium/aluminium alloy under the brand name Elektron. I doubt it is high in magnesium though because they don't seem to corrode the way some mag wheels do. They were originally passivated with a pickling solution made by DOW chemical that is pretty much outlawed for being so toxic and carcinogenic. You can still get kits though and the recipe is hanging around the internet. Alodine used to make a kit but they also make one for aluminium - I know, I bought some. I've seen people advising that the Alodine - aluminium is good for mag wheels but I highly doubt that. I've also bought some Permakote - which is a new non-toxic plastic undercoat used in aeronautics magnesium applications.
High magnesium content mag wheels aren't supposed to be powder coated because they can continue to corrode under the surface.
I replaced my wheels with high quality and faithful reproduction rims available from Superformance (and others). I just didn't want to trust my life to 50 year old magnesium alloy that may have lived a tough life. You can always refurbish your original wheels for shows and posterity.
Hi Hugo,
I have 5 cars on 20 original Cromodora CD rims (plus 5 spare wheels). All have been duly restored. And I have restored some more 40 rims for friends and buyers. None had shown any signs of aging. No cracks. The ones that showed dents from contact with curbstones or corrosion wear under balancing weights were sorted out obviously.
In my opinion the reproductions suffer one significant disadvantage to be considered. Those are much heavier than originals. I once weighted them, if I remember correctly, the reproductions weight more than the double of the originals. This non suspended weight has a negative impact on all suspension parts.
And I have seen one set repros that was poorly powder coated. No comparison to nicely sprayed originals.
Therefore, I will continue to enjoying my originals on my cars.
Georg
interesting discussion - pro's and con's for both sides.
- in contrast to original Minilite and Campagnolo wheels, I have never heard that any Cromodora wheel is broken - neither in Alfa 105 nor Fiat 124 forums nor here (except after gross misuse or neglicence).
- Original Cromodoras were produced under stable serial conditions and with full serial quality control (of 1970) - who guarantees this with low volume prototype parts?
- ageing of material is one topic, but failure is frequently caused by notch fatigue, which could be an issue with reproductions even if they are overdimensioned.
On the other hand:
- even Aluminium does not have eternal endurance strength
- the original wheels are significantly lighter, meaning "lean" design AND magnesium content.
I didn't know about the weight difference, that is definitely a consideration. Also great points about the relative reliability of originals vs repros. I always learn more from this forum than I contribute. Luckily I have my original wheels, so I still have the choice.
. They have chips on the rims and beneath the silver paint there is orange colored metal showing thru. Are these wheels magnesium?