Star Wheel Material

LP · Post by LP » Thu Dec 02, 2004 9:38 pm

Aaron asked about this in another thread, and I thought I'd bring it up separately. Aaron was asking if anyone knew what the Star wheels were made of. . I've been curios about this as well.

I wondered about this a while back, so years ago I weighed one bare (without the center steel adapter-bolt-nut assembly). As I recall it came in at 13 pounds - give or take a bit. I even did a volume measurement using water in a tub, but I forget the results. I do recall it's a very thick cross section, and a back of the napkin calculation didn't seem to be consistent with aluminum. It also corrodes much more like magnesium, very fast and very dark. I suspect either a magnesium alloy, or a very high magnesium content aluminum alloy. I came across a name for the material in a Ferrari manual once. It was an arcane term that I couldn't find referenced anywhere. I'll try to re-locate the name and give the group a crack at it.

David Booth · Post by **David Booth** » Fri Dec 03, 2004 1:19 pm

Assuming you're talking about the Campagnolo cast alloy wheels from the late 60s through the 70s and into the 80s, I can ask 'em. They're a client of mine.

LP · Post by LP » Wed Dec 08, 2004 10:34 pm

[quote="David Booth"]Assuming you're talking about the Campagnolo cast alloy wheels from the late 60s through the 70s and into the 80s, I can ask 'em. They're a client of mine.[/quote]

Oh gee David, wouldn't that be cheating? It's a great idea though, as I've heard this question pop-up more than a few times over the years. It would be nice to get their response to it. Please ask them.

BTW, the material name "Athesia" is what I found referenced to in a Daytona service manual. I can't find any information on it through conventional sources.

Note though, I belive the five star Campies we are interested in were those installed during the late sixties into the mid seventies, ending with the 365GT4 and early boxers. These are the sand cast wheels, and pre-date the very similar looking die cast wheels that came later. The sand cast wheels have much more rounded (+1/4") edge fillets and always used a bolted in spline adapter. The die cast wheels are much sharper edged, and were usually used with direct 5-lug style bolt-on applications.

Dr. Ian Levy · Post by **Dr. Ian Levy** » Thu Dec 09, 2004 3:27 pm

Hi
When I had the wheels on my GTC 4 stripped & repainted I thought they were aluminium.
Before repainting the wheels underwent "aluchrome" treatment.
I was told this prevented oxidation of the aluminium & ensured the paint stayed on.
I thought that they had to be made of aluminium but I don't really know
Ian L
Manchester

Matt F · Post by **Matt F** » Thu Dec 09, 2004 5:09 pm

Hi, guys.

I believe that those wheels were cast from an alloy that was high in magnesium, had some aluminum (less than 10%), and a touch of zinc.

Stephanm · Post by **Stephanm** » Fri Dec 10, 2004 9:59 pm

Yeah, they have alot of Magnesium and can easily be welded. I bought some straight mag. welding rod and it welds as easy as aluminum but is porous

Absolutely need to strip, bead blast then immediately prime them with a magnesius special primer from PPG. They oxidize in front or your eyes just from sitting in the air,

Aaron · Post by **Aaron** » Mon Dec 13, 2004 4:14 pm

LP – thanks for moving this question on to this thread – this turns out to be a much more mysterious question than I though it would be.

The wheels that are presently on my 1972 C4 are labeled “Ferrari” and “Cromodora”, they do not say “Campy” any where, at least as far as I have observed. They have the 5-bolt steel center-lock adapters. Rim size- 15 x 7.5 inches to support the typical 215VR70 15 inch XWX tires. I believe this is all the same “Daytona Star” type that are found on Queen Mary’s, 365gt 2+2 – 400i and Daytona

Does any know -

Are Cromodora and Campagnolo associated companies?

Are the Cromodora’s also magnesium?

(I was actually hoping they were aluminum because I thought the aluminum was both more durable and required less care/maintenance. For my kind of driving which tends to be more social and the basic concept of a “non-race touring car, I was not concerned about the weight.)

Aaron

LP · Post by LP » Tue Dec 14, 2004 12:25 am

Oh my Aaron, your right! Where did I get Campi from? My mistake, thanks for catching it. Delete "Campie", and insert "Cromodora". The description you gave is the same on all C/4s, Daytonas, QMs, early Boxers, and even GT4 2+2s. These (and yours) are the wheels in question. I do belive they are primarily Magnesium, wit a bit of Aluminum thrown in.

Post by **330GT** » Tue Dec 14, 2004 10:11 am

This tech bulletin from 1971 says that they are magnesium:

Technical Information no. 182

Ref./Cromodora Magnesium Wheel Rims

When a respray of magnesium wheels is required, the products to be used are the following:

- Acrylic metallized paint - gray 2427078
(smalto metallizzato acrilico grigio ghisa 2427078)
[ed: literal translation is metallic cast iron gray acrylic enamel]

which can be ordered directly to:

- ITALVAR - Via Privata Bolla, 27 - Milano (Italy)

The paint should be applied with viscosity 37" (Ford type viscosity meter - orifice 3), and baked at 212°F (100°C) for 40 min. in the over or under stoving lamps.

Kindest regards,
FERRARI TECHNICAL ASSISTANCE