Cromadora Wheel Restoration

["Paul Leone" <paulsle@domain.elided>]

>Date: Tue, 22 Jan 2002 14:26:40
-0500                                                                   
>From: David

>Subject: Re: Cromadora
Daytona                                                                            
>Regarding restoration of Cromadora Daytona wheels: 

>Paul Leone
wrote:                                                                                                 
>...Recently I purchased a set of 14 x 6 Cromadora Daytona
style                              > wheels that need to be refinished
before installing on my US spec 1972 GTV...  

 

>Paul,

>Stop right there! Are these 1970s originals or recent production?
Daytonas                        >(I had a set on my Alfetta) are true
magnesium alloy wheels, not aluminum.......

Thanks to all who responded both on and off digest to my initial post on
this a week ago.  As I hoped, the Digest provided info and opinion
aplenty 
regarding the fine points of media blasting, spray painting, powder
coating,
and of course more.
 
While most of my original questions are answered, the concerns mentioned
in
Dave Hammond's post regarding the actual age of the wheels and
condition of the aged metal are coincidentally the 2 things I'm left
wondering, are these wheels older or newer production, aluminum or
magnesium.

A few clues..?  The number 84 appears within a small raised grid cast
into
the back of ea wheel. Could this be a date marker indicating a 1984
casting?
I've noticed that some Daytonas have a finger size groove immediately
inside
the outer rim, then a sort of secondary rim at the outer end of the
spokes.
My wheels don't have the groove, the spokes reach the outer rim, but the
hub
area is of a larger diameter. Is this any indication of an early or a
later
production, as someone suggested.

>Instead of bending, they shatter into particles like rock salt.
Old                          >magnesium wheels are brittle and often have
stress cracks. Start by looking                      >at the center of
the hub area, from the back of the wheel. See any
white,                    >sugar-like deposits? That's your wheel
dissolving, typically from exposure                        >to salty
roads in winter. The center tends to go first. You'll have to
epoxy                      >that area. If there's a pin hole near the
center cap, don't trust hat wheel                         >with your
life. It's weakened and ready to collapse, dissolving like
sugar                        >after hitting a pothole at 70 MPH. Even if
they the wheels look to be in                  >excellent condition,
20-year old used wheels develop stress fractures. I'd                
>suggest being be gentle with them, Keep the surface clean and waxed,
and                  >don't even consider competition with an old set of
wheels. Also, tires need                      >to be hand mounted onto
magnesium rims.

>Dave
Hammond                                                                                                  
>AROC-Detroit

Dave, you nailed that. There is that sugar build up in the hub center,
fortunately on only one wheel. The rest are clean. No evidence (yet) of
any
fatal pin holes, but I'll be watching as the cleaning progresses. The
only other
apparent corrosion is a few bite marks on the outer edge of the rims
caused
by the wheel weights being of a dissimilar metal. While I don't expect to
race, there's always a new crop of unavoidable road hazards.  Does
anybody
know if there's a simple test available to detect cracks or general
deterioration?  Seems like this ought to be done before getting too deep
into the restoration work.

For anyone who still cares, my plan for the restoration of the wheels,
after
mulling over the various suggestions, is to divide the work into the
tasks
that I can do myself, and into the tasks I'll have done by those with the
right equipment and    experience .  This works for me as I can't afford
or justify the $135 per, quoted by a few local  (north of Boston) wheel
restoration specialists who would do the job start to
finish. That price may not be unreasonable, but add that to what I paid
for the wheels and I could almost buy new ones.
 
Here's the plan;

Sub out the media blasting to a shop that regularly  works with plastic
or
glass bead. That'll get rid of the old chipped paint in the impossible to
sand                     places and should reveal any hidden corrosion.
 
Follow up with crack detection.
 
Sand smooth where possible, fill scratches as necessary with  epoxy
filler.
I'll most likely use West System since I'm used to it and have all the
various filler      additives.  I know it sticks forever to a hull
submerged in ocean water, it should                stick to wheels.
 
Next coat with an epoxy primer.

Finally, find an experienced (not me) spray painter, who will agree to
adhere closely to Biba's explicit product and application
instructions for the finish coats. Thanks Biba for divulging your hard
earned secrets!
 
 
Regards to all
 
Paul Leone
72 GTV

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