Chromodoras

[164QV]

So, I got me a really cheap set of Chromodoras for my Junior. ($70) They are a bit beat up, but with some paint I think they will turn out really nice. Now, I think these are REALLY light - could they be magnesium? How can you tell a magnesium wheel from a aluminium wheel?

[67GTV]

You could try to melt them!
Magnesium ignites (literally) at a much higher temperature and burns at 5000 degrees farenheit!

(sorry no help here)

[164QV]

Kai, you're so funny! If I had 5 wheels, I guess I would've done that - but theres only 4! Does anyone here have an aluminium Chromodora wheel (with or without tire) they could weigh?

[gvisconty]

Try this

http://lists.kjsl.com/pipermail/beec...rch/022125.htm

[164QV]

I did, the page doesnt work....

[fgc]

Hi jorgen,

where did you get your wheels? I am looking for spare chromodoras. what design are the spokes? the 5 spoke stars?

I have a set of chromodoras on my 67 duetto. They are made of magnesium. I had some curbings on mine and I wanted the curbed rim repaired by welding new material on the rim and machining it back. I brought it to a rim repair shop and I told them it could be magnesium. They were apprehensive about welding mags because unless the welders have special equipment to weld mags, the whole wheel can go up in flames and it burns really hot and bright and I am told that a fire extinguishers is useless to put out the fire except I suppose flooding the thing with halon or whatever.

To cut a long story short, he filed some filing off a curbed damaged area onto a piece of paper and then put a light under the paper. after a few seconds, you could see the mag filing flash before your eyes even in the bright noon sun here in the tropics.

So I guess if your wheel is has some damaged, it doesn't hurt if you were to file a little to try this experiment... those with chemistry background can perhaps suggest a better solution?

Anyway, like you, I was looking for information about mag rims etc and I have attached one of the hyperlinks to this site which is quite fun and interesting to read.

http://www.sportcompactcarweb.com/te...cc_wheelguide/

Have fun

fgc

[gvisconty]

sorry about the bad link. I can't find the original now, but this site :

http://www.welding-advisers.com/Mate...ification.html

Says :

"One can readily distinguish between light alloys like aluminum and magnesium with a simple test, but you should use the help of a chemist. Aluminum is attacked by caustic soda (NaOH), which is a dangerous material, and also by alkaline solutions, while magnesium is not. Conversely magnesium is attacked rapidly by usual inorganic acids (excluding hydrofluoric and chromic acid), while aluminum is not attacked by acids like nitric and sulfuric. Also aluminum density is about twice that of magnesium. "

This site says that "Magnesium is white and will not polish":

http://www.englishcustompolishing.co...aluminum1.html

[67GTV]

Quote:

Originally posted by fgc ...the whole wheel can go up in flames and it burns really hot and bright and I am told that a fire extinguishers is useless to put out the fire except I suppose flooding the thing with halon or whatever.

[emr5503]

Horse hockey.
I've got mag wheels on my 1750, Bobsy SR3 & Royale FF. All polish very nicely, thank you.

[John M]

For what its worth and I am not for sure....its my understanding that none were solid magnesium. They were all a magnesium/aluminum alloy. From the my old chemistry days, I remember that solid magnesium is highly volatile in air. To the point its explosive. The older ones (60s...early 70s) did have a much higher content of magnesium than ones from like the 80s. I think its safe to say, the lighter the wheel, the more magnesium it has...providing dimensions are equivalent. Be careful when shopping for true cromodoras to ensure that there is no deterioration around the center. The heavy mag content cromos are known to rot in the centers.....even to the point where big chucks come out of the center. This I know for sure as I have seen cromodora wheels that it has happened to.

Best Regards,
John M

[gvisconty]

emr5503, what they say on that page is is that alloys with more than 20% magnesium are white and will not polish. Either the people at englishcustompolishing.com are full of it, or your "mag" wheels are made from less than 20% magnesium.

I had a Navy friend that said they used (pure) magnesium to destroy sensitive data in computers in case they needed to abandon them. They would rig up magnesuim (powder?) on top of the computer hard drives, so if they needed to get out quick, they would ignite the magnesium and run. Burning magnesium is really difficult to put out.

[emr5503]

They once had a Lotus 11 or Elva burn to the ground at the 6 Hr race at Marlboro. Was said it had a Mag. body. They couldn't put it out, but it sure was bright for awhile.

[nino1969]

Hi Jorgen,

As I know Cromodora wheels are magnesium. (if you have the original old items and not the reproduction which are made of aluminium).
I have weight a Cromodora wheel and if I remember well its weight is about 5 and a half kilos!!

You can also ask my best man TAKIS who wears them on his 1750 GTV.

[164QV]

It most definitely says "chromodora" on my wheels, but I believe they were made in both magnesium and aluminum. I havent gotten the tires off yet, but when I do, I will put the wheels on a weight.

Attached a pic from the fire in California - apparently those werent magnesium wheels.....

[BigSwede]

67GTV: I'll add that piece of mahgnesium to the top ten list of what not have in your pocket in a car accident...

I wouldn't put on old magnesium wheels on my car, I've heard so many stories of old wheels shatteting the low weight isn't worth it..
Just above 5Kg? 14"? Doesn't sound like magnesium to me, some kind of alloy maybe with some magnesium content. 5Kg is ****loads of magnesium...
A light 15" modern rim weighs less then 5Kg.

Wasn't all non-steel wheels called "mags" a while back?