Morning all. These have come up relatively locally. Appear to be proper magnesium. A bit of pitting, but to be expected after 20+ years. Asking price is equivalent to £700 for the set. Am I taking a risk on these having degraded over time? Or is it a rare bargain that I should snap up?
I have run magnesium wheels from this era but had the luxury of having someone who knows, check them over and refurbish them. IMO, the wheels look to be in pretty poor condition and I would not be interested in buying them. Andy
I'd be getting an opinion from a mag-wheel specialist before doing that deal. There's a lot of pitting (can that be anything other than corrosion?) but a bit difficult to tell from here...
I'm sure you understand that the issue with Magnesium wheels with any age to them, (and actually even new ones) is cracking, which can emanate from stress raisers including pits. Before use I think I'd want them crack tested and X-rayed. If the seller will let you, and little bit of peace of mind can be had with some Talcum powder and food colouring, but it takes time and a good eye to be confident with what you are looking at.
If you take the chance, I've crack tested Outboard engine blocks and heads this way, which in this case would help decide if they are worth spending the money having them professionally Tested. Note an outboard breaking down at sea is bad, but not as bad as a bike wheel breaking up at speed. Mix some Food colourant, Green or Blue show up well, into some very light Oil like Diesel. Thoroughly degrease and oven dry the test piece, then soak it in the coloured Oil by spraying it on all over, preferably whilst it's still warm. After soaking for a few minutes dry it off really well with clean rags or Paper towels. Then sprinkle on the best quality Talcum powder you can steal from the Lady of the House. You'll be surprised at how the coloured Oil in any cracks will show as a coloured line in the Talcum Powder.
Thanks for all the replies. There's no real opportunity for me to test them before purchase (they're actually just over the border in michigan), but I was tempted given the rarity of stuff like this in my neck of the woods. Too much risk, will pass.
Excuse my ignorance, but whilst we have the wheel SMEs here, can someone opine on what material these are please from a 748R?
As I have often told my colleagues at work when they send me pictures of corroded parts - please just blend away the corrosion deposits/pitting. They often respond that this will require removal of material which will mean the thickness will become less than the published minimum and the part requires repair (or replacement). I will normally respond with words along the lines of - the strength of aluminium (or magnesium) oxide is very low (or basically f-all) so please just get rid of it so we know how much good material remains, once that is done then we will know if the part is acceptable or not. Those wheels appear to have areas that need treatment as above. Not sure if Marchesini have published thickness/cross sectional area rework limits (very much doubt it) so, basically, they are FUBAR.
What can the peanut gallery tell me about the hoops on my old 95 916 war horse? Forged magnesium… correct? I do not believe they have ever been stripped/painted. Is there any chance the front wheel has the provision to use the factory style mechanical speedo drive?
Hard to tell from your pics … If your spokes are flat faced as per post #1 they are mags, if they have a profile like post #10 & #17 they are aluminium
