Help Identify these rims.
#6
This BAT listing shows the same part numbers but deviates on the composition stampings.https://bringatrailer.com/listing/po...ium-wheel-set/
#7
This BAT listing shows the same part numbers but deviates on the composition stampings.https://bringatrailer.com/listing/po...ium-wheel-set/
MG7 = 7% Magnesium?
AL7 = 7% Aluminum?
Si12 = 12% Silicon?
...and why would they be different front/rear and on different production runs.
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#9
#10
Three Wheelin'
Joined: Dec 2012
Posts: 1,398
Likes: 13
From: Marco Island , FL --- Red River Valley, midwest
Yes to all above correct answers...
Note the one casting which states "Aluminum Silicate Magnesium" on the backside spoke. The finish is much like any magnesium part found on Porsches: very rough casting features and not a real smooth surface.
They are very brittle and often show chipping or cracking well before 30-35 years on. I wouldn't weld near them or expose them to any open flame. Magnesium burns with a very high temperature and brilliant flame; the use of water on the fire compounds the problem. Google fire videos of Porsche 914 or 911s to see how devastatingly hot the engines, transmissions, and magnesium wheels go up in a roaring, white-hot flame.
From the factory they had an almost Pearl white look. Super expensive to find good ones today. Look them over very carefully;
I would dearly love a good set.
Note the one casting which states "Aluminum Silicate Magnesium" on the backside spoke. The finish is much like any magnesium part found on Porsches: very rough casting features and not a real smooth surface.
They are very brittle and often show chipping or cracking well before 30-35 years on. I wouldn't weld near them or expose them to any open flame. Magnesium burns with a very high temperature and brilliant flame; the use of water on the fire compounds the problem. Google fire videos of Porsche 914 or 911s to see how devastatingly hot the engines, transmissions, and magnesium wheels go up in a roaring, white-hot flame.
From the factory they had an almost Pearl white look. Super expensive to find good ones today. Look them over very carefully;
I would dearly love a good set.
#13
Those are not the magnesium cup wheels.
They are the similar, but about 22% heavier, permanent-mold produced aluminum wheels with 12% Silicon and 0.5% magnesium. They have much better fatigue strength than the earlier, real magnesium wheels.
And they will not burn like magnesium, not even the machining shavings.
They are the similar, but about 22% heavier, permanent-mold produced aluminum wheels with 12% Silicon and 0.5% magnesium. They have much better fatigue strength than the earlier, real magnesium wheels.
And they will not burn like magnesium, not even the machining shavings.
#14
Those are not the magnesium cup wheels.
They are the similar, but about 22% heavier, permanent-mold produced aluminum wheels with 12% Silicon and 0.5% magnesium. They have much better fatigue strength than the earlier, real magnesium wheels.
And they will not burn like magnesium, not even the machining shavings.
They are the similar, but about 22% heavier, permanent-mold produced aluminum wheels with 12% Silicon and 0.5% magnesium. They have much better fatigue strength than the earlier, real magnesium wheels.
And they will not burn like magnesium, not even the machining shavings.
#15
@edfishjr They are absolutely magnesium Cup wheels, it’s just that the composition of the wheels changed over time. The part numbers of those wheels are listed in the 1987 Turbo Cup parts list from the factory.
The first of the Cup-style wheels really were magnesium, alloyed with a small amount of aluminum that made them not nearly as brittle and crack-prone as the earlier "Mag" wheels of the '60s and '70's.
The wheels being discussed here are aluminum alloyed with a very small amount of magnesium. They have very different properties from Magnesium Cups.
It may be typical to call these Magnesium Cups, I don't know. If so, then what is really meant is that they are Magnesium Cup-style wheels made from aluminum. But, if we call these Magnesium Cups, what do we call the Magnesium Cups that are actually made from magnesium?