mk1-forum.net

So, the name might be obvious, but are these wheels made of aluminium or magnesium?

Nobody?

Weigh one of them. Magnesium is about 40% less dense than aluminium so it should be fairly obvious. Failing that you will need to remember school physics lessons and work out the volume by displacing some water out of a bucket.
Full details on request.
Nick

What I would do is this.

Get a vessel, fill it to the top with water (very very top)

Put the wheel in it on a very small piece of cord, allow the water to overflow.

Pull the wheel out carefully and allow it to drip in the vessel.

Then take a set of digital scales and put a measuring jug on them.

Tare the scales.

Add a known volume of water. Could be 1000.0g, or 978.6 or whatever. Fill the container up. Find out the exact weight of water you used to fill the vessel up to the top.

Now, taking 1g of water to equal 1ml. Work out the volume of your wheel.

Measure the mass of the wheel.

Calculate your density by X mass (g)/ y volume (cm^3).

Compare it to the wiki data for pure mag, or pure ally.

Consider the various alloys used.

Report back here and I'll tell you some more, if you need it to be.

(last job was a metallurgist)

This sounds long winded, but it's how you get pretty good accuracy with house equipment. Measuring jugs are no good, measuring cylinders are better, but you really need masses to work from. +/-0.1g is not bad accuracy as far as we are concerned.

Set fire to them, if you find you are blind afterwards they're mags...!

We had a psychotic next door neighbour (in nice village, I may add) who burned the big shed in our garden down. I had 5 6" JA Pearce mags which were like new.

They melted as there was insufficient oxygen for them to burn.

I just got these as I did infact buy them. It weighs the same as a 7X12 Mag Minilite, so I guess they're magnesium. The Minilite is a bit more robust and "bigger", but they feel the same. Measured by my own useless hands.

I'd guess as you say that if they were aluminium, they'd be significantly heavier.

I think these will look great in black. I hope

MAG = Mill Accessory Group, not necessarily what they are made off. Probably LM20 as most wheels of the 1970's. Nice looking wheels.