Z28 Wheel Trim Rings Refinishing

Discussion in 'Original Drivetrain Topic' started by Green hornet, Mar 29, 2020.

  1. secondgenaddict

    secondgenaddict Veteran Member

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    I can see the brushing on the trim rings above.

    Chromium's Effect on Surface Finish
    Chromium duplicates the machined surface finish up to 0.002 thick(decorative chrome is .0002 -.0005) and thereafter a progressive increase in microinch finish is detectable with any increase in thickness of plating (if the brushing is deeper. This condition is slightly exaggerated on shot-peened, brushed, or blasted finishes.

    Chromium never "levels off" or "fills in" surface imperfections. Defects, such as pits, cracks, or scratches are amplified, and if a highly polished surface is desired the surface should be highly polished before plating.
    Light, corrosive atmosphere 0.0002-0.0005 thick
    Most wear applications 0.0007-0.0015 thick
     
  2. COPO

    COPO Veteran Member Lifetime Gold Member

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    IMO bright chrome is what the bumpers are. I would go with post #25, the one on the right below.
    815F0252-39DB-463F-93E8-8CF2042D4A4A.jpeg
     
    Last edited: May 3, 2021
  3. secondgenaddict

    secondgenaddict Veteran Member

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    I agree with MARK the one on the right looks "most" correct.

    I have a disassembled trim ring -I unbent the lip and removed the metal ring and clips -
    I was planning on using approx 4 different grits on it - 1/4 of the ring in 180grit ~ 1/4 - 220 ~ 1/4 - 320 ~ 1/4 - 400 then having it plated with the next batch of stuff I send for chrome.
     
    70lt1z28 likes this.
  4. FlaJunkie

    FlaJunkie Veteran Member Lifetime Gold Member

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    Flash chrome or copper-nickel-chrome? Apparently, the metal finish determines the shine from flash chrome. Will your chrome guy do the job if it isn't up to their standards?
     
  5. COPO

    COPO Veteran Member Lifetime Gold Member

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    Copper, nickel and chrome is what’s best and will outlast flash chrome which is a very thin layer of nickel and chrome only. It doesn't last long and it won't look right on for example, stainless. If it’s stainless, then your better off polishing it.
     
  6. secondgenaddict

    secondgenaddict Veteran Member

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    Pulled from the NCRS forums -
    If the name below isn't familiar to anyone -- he goes by JOHNZ on the first gen boards.

    [​IMG] Originally Posted by John Hinckley (29964) [​IMG]
    This may be too simplistic, but it's the way I've always understood it, and I worked with platers:

    "Show Chrome" - copper, then nickel, then chrome (seldom used in OEM exterior applications).

    "Production Chrome" - nickel, then chrome.

    "Flash" or "Smack" chrome - plated over polished stainless to prevent oxidation, results in the "icy blue" appearance of all C1/C2/C3 OEM exterior stainless parts.

    I had no reason to disbelieve or argue with JohnZ that ALL exterior stainless (including trim rings) was chrome plated for protection (though minimal) and to ensure the color of the moldings was closer between runs. I guess the possibility exists that perhaps he was mistaken about trim rings being flash Chrome.

    I am going to need to send some stuff off in the next few months ... So when I have the ring plated to ILLUSTRATE what the effect of brushing with different grits and then flash Chrome plating the brushed trim ring. Until then we can speculate what chrome does to scratches - whether .0003 of Chrome will fill a 220 -400 sanding scratch.
     
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  7. Jonesy

    Jonesy Veteran Member

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    Heres my original assembly line installed trims ring and wheel on my 74Z. Wheel is original paint, original valve stems and cap IMG_1533.jpg .
     
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  8. FlaJunkie

    FlaJunkie Veteran Member Lifetime Gold Member

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    Just got this pic from GM. It's a brand new pre-sale 70 Z28.

    [​IMG]
     
  9. COPO

    COPO Veteran Member Lifetime Gold Member

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    ^Looks like the trim ring in post 42 on the right.^ Nice find. It’d be nice to get that whole car in a photo.
     
  10. FlaJunkie

    FlaJunkie Veteran Member Lifetime Gold Member

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    Just for you my friend. Maybe next time you visit the states, you'll bring a cell phone so I can connect!
    [​IMG]
     

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