We just picked up a nice set of the 5 slot mags for my 74. A buddy saw them the other day & said they were magnesium not aluminum. I thought that all of them(originally optioned)were aluminum type? I've seen several 73 Mustangs at shows & they have them on-even original ones & they are of the shiny aluminum style & have a black cirlce painted band around them. The ones we picked up are a darker type(mag maybe), & there is no black band around it. The black painted band was actually in a recessed area about 1/4 wide all around the rim. Also on a 73 Comet brochure I have, there is a nice yellow GT in the back pages that has the rims on it, but they are not the shiny type & no black band either. So, were there both style of rims that were on the Mavs/Comets(alum or magnesium) & some with the black band & some without???
They were aluminum from the factory, magnesium is a lighter weight and much more expensive and is primarily used in racing applications for several reasons.... Where aluminum rims will bend when a pothole or curb in encounter the magnesium rims tend to crack and shatter which can be very dangerous if you are driving down the road and hit a pothole. The case being if you hit a big pothole with an aluminum rim it will bend the rim and you can still pull off to the side of the road. Whereas the magnesium will have a tendency to crack and shatter leading to failure of the entire wheel. Such a failure can cause the driver to lose control of the vehicle, and also create a fire hazard. The upkeep on mangesium is horrendous it is affected by the moisture in the air and corrodes and pitts very easily, so scratches and pitts have to be repaired quickly. This is why magnesium rims always leave the factory either sealed or painted. Also as we know magnesium in its singular element is very flammable, the automotive rims are a mixture of magnesium and some aluminum but still retain some of the flammability so if you are in an accident and have magnesium rims on your car they can ignite. Magnesium burns white hot and it can reach temperatures of 3100 degrees C or 5610 degrees F. If you try to extinguish a magnesium fire with water it vaporizes the water breaking it into its core components of hydrogen and oxygen and both act as an accelerant, it is usually bad enough it will burn holes through asphault. So if you got in an accident in a car with magnesium rims the fire department would have to send out a chemical based fire truck to extinguish the fire. So nope there is a good chance they are not Magnesium, and no Ford did not put cars out with magnesium rims on them from the factory for the general public especially not on a standard consumer car, the costs and the manufacturer liability would be way too high. The most common name associated with magnesium rims was Halibrand back in the 60s and 70s. Sorry.. they have been out of buisness for several years. But here is some good information on what halibrand wheels look like, and the page also has several pictures of the oxidation and pitting that can happen to these wheels. http://www.roadsters.com/wheels/#Halibrand
The GOOD thing about magnesium is that you can drill into it and catch the shavings, or scrape chunks off with a blade, and put a match to it, and it burns hot and bright as a welding rod!!! Cool stuff, when you want to amaze your friends. Sorry...imagine me getting off topic Interesting to read about the dangerous shattering of the Mg, though.
I use to machine both magnesium and zirconium(no not cubic zirconium) which are flammable metals, and hafnium(hafnium is used for liners in neuclear reactors because of its density or atomic mass) we were under contract with Western Zirconium... We were making chemical mixing systems and the chemicals reacted to most materials, when one of the 12" x 16" blocks of magnesium got mislabled as aluminum and stuck in a verticle machining center, well the chips ignighted because he was hogging material off of it at a pretty good feed rate,(after all he thought it was aluminum) and because it was an emulsion coolant (water/oil) it lit the mill up pretty good. Burned about a 14 inch hole right through the table, bedways and base of the okuma mill in a bright flash of light and a big cloud of smoke... The mill was a total loss because of the damage to the base... Yeah magnesium is some pretty nasty stuff.
markso!!! Scary crap! I worked in machine shops, and couldn't imagine how freaky that was! i hope the question was appropriately answered in the second post, because I have a feeling I may have jacked it up! Well, maybe it was on it's way to a jack IN the second post!
Watch this crap...about 1:10 or 1:15, water hits the lit magnesium of the bell housing on this suv... [nomedia="http://www.youtube.com/watch?v=KY9ri-UOoLo"]YouTube - Magnesium's reaction to water on vehicle fire[/nomedia]
Yeah they are starting to use magnesium alloys more and more but its really easy to see why they can be very dangerous...And most of the components they use magnesium in are away from the heat and elements to reduce the corrosion problems.(like seat tracks or steering wheel frames ect ect are usually made from something like an AZ91 magnesium alloy which is 9% aluminum by weight and 1% zinc by weight) The magnesium wheels like the halibrands knockoffs have a higher content of magnesium then what they used in the bell housing on that transmission. And are extremely succeptable to the problems raw manesium has. The newer technologies are allowing different alloys then they did in the 60's and 70's, and they have reduced some of the major drawbacks the old magnesium components use to face.
I have two complete sets of 73 aluminum slots. All eight wheels have the black stripe on the edge. I believe all these wheels had the stripe. If yours are missing it must have been worn away or removed.
