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Old 02-20-2024, 02:49 AM
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I don't think GM did any of it....meaning my bet is that the roll steel sourced for the dust shields was specified to be galvanized (at the mill,etc). Then the pieces got stamped out from the rolled sheet steel.

Galvanizing served a sort of dual purpose...protected the metal pieces that were stamped out from the rolled sheet AND lessened the wear and tear on the stamping tooling (since zinc is a soft metal). Same thing on alternator fan blades and many other parts.

Just my "speculation" on this.....gas tanks are the same thing/process (albeit a different coating/plating)....at least when it comes to the GM Abody cars of the era.

I'll try to get a pic or two of one of the galvanized dust shields I referred to above.
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Old 02-20-2024, 11:07 AM
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Quote:
Originally Posted by Lynn View Post
Thanks. I have three that look almost that good. Any idea how it is plated?
Silver cad? Galvanized? Painted?

This car is not getting judged, and will have a couple of day two parts. But, I still want it somewhat correct for when I go to sell it.
I was of the opinion cad plated
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Old 02-20-2024, 12:08 PM
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Quote:
Originally Posted by 70post View Post
I don't think GM did any of it....meaning my bet is that the roll steel sourced for the dust shields was specified to be galvanized (at the mill,etc). Then the pieces got stamped out from the rolled sheet steel.

I'll try to get a pic or two of one of the galvanized dust shields I referred to above.
Seems to me that if the roll steel was galvanized and the stamping happened later, that the cut edges would be very prone to rusting. Most moderately used ones that I have seen do not show evidence of this.
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Old 02-20-2024, 03:44 PM
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Have to agree with Dave on this one. I would THINK (not my best arena.... I quit getting lost in thought, as I feel like a total stranger there) that whatever plating was done, it was done after the part was formed. IF they are in fact galvanized, it certainly looks like electroplate galvanizing to me. After a few years, that plating would be virtually indistinguishable from silver cad to the naked eye.

Any chemists on here? Any test I can run on one of the bent up dust shields I have to determine finish? Three of the four extras are as nice as the ones on Tim's 8900 mile car. The fourth one; not so much.
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Old 02-20-2024, 06:57 PM
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Any thoughts about the raw steel being hot dipped and then the plates being stamped out like gas tanks were?

Mike
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Old 02-20-2024, 07:05 PM
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I don't see a problem with it as long as there is no trimming needed after dipping.
In other words the blank is already the exact size needed for the finished item.
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Old 02-21-2024, 01:48 AM
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A great source of Data might be a GM drawing for the J52 or JL8
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Old 02-21-2024, 04:37 PM
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These guys seem to think that they were cad plated.

https://www.ebay.com/itm/174286184364

Although they offer the same part for 68-82.

These guys believe silver cad plated from 65 through 1975, then gold cad plated from 76 through 82.

https://www.topflightautomotive.com/...e-dust-shield/
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Old 02-21-2024, 09:31 PM
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Hi Lynn, According to the NCRS judging guide (6th edition):
Original front-brake backing plates are dull cadmium or zinc plated, while the rear backing plates are punched from a sheet of galvanized metal. The sheared edges are bare steel and may exhibit some rust on the edges. Later service replacement backing plates are a zinc dichromate finish.
Fran
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Old 02-21-2024, 09:51 PM
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Thanks.
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