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Thread: What is the correct metal finish for seat rails?

  1. #1
    Senior Member Haasman's Avatar
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    What is the correct metal finish for seat rails?

    I just cleaned up seat rails and I beleive should have some protective coating. Are they anadized?

    911 seat rails smaller.jpg
    Haasman

    Registry #2489
    R Gruppe #722
    65 911 #302580
    70 914-6 #9140431874
    73 911s #9113300709

  2. #2
    Mark Smedley says those are among the few parts that are actually still cad plated.
    Early S Registry member #90
    R Gruppe member #138
    Fort Worth Tx.

  3. #3
    Ed -

    Is there a time period where the cad stopped being used? The ones on my '73 sure look like zinc to me!

    - Rob

  4. #4
    Back in the early 70s I had the rails from my '70T analyzed by two platers and a metallurgist for Champion Spark Plug who just happened to be a PCA member and concours guy.....definately silver cadmium. Multiple restoration projects up through '73 cars...all silver cadmium. Always curious why cadmium....my metallurgist pal suggested that cadmium is softer and created less friction....they were sliders! Subsequent SWB projects and research also confirm cadmium.
    Mark Smedley
    RG #171

  5. #5
    The ones in my '65 coupe were silver zinc. Not an opinion but verified through a plating testing kit given to me by Tim Goodrich years back

  6. #6
    Quote Originally Posted by 718RSK View Post
    The ones in my '65 coupe were silver zinc. Not an opinion but verified through a plating testing kit given to me by Tim Goodrich years back
    Could be. Tim and I had discussed this. My unrestored '64 C had zinc rails. The industry
    was changing in the late 60s. Fasteners went from clear to yellow zinc...rails changed as well.
    Mark Smedley
    RG #171

  7. #7
    Senior Member Haasman's Avatar
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    So these are for my late '65, '66 model year 911.

    silver zinc or cadium?
    Haasman

    Registry #2489
    R Gruppe #722
    65 911 #302580
    70 914-6 #9140431874
    73 911s #9113300709

  8. #8
    The actual build date would only be partially helpful as this is a supplier issue...not a factory specification.
    An educated guess would be to survey the original fasteners in the car. These cars were being built with fasteners who's industry was changing it's specifications, not only actual DIN dimensions but plating.
    If your car was built with predominantly clear (silver) zinc fasteners, go with silver zinc. If you have a lot of later yellow zinc fasteners, go with cadmium on the rails.

    The other issue is that the current zinc plating process results in zinc that is a bright bluish finish...far different from the older dull silver of the original pre-EPA process. If you went with "new zinc" you'd have top knock it down a bit to flatten it.

    In the old days silver zinc and silver cadmium were VERY similar when fresh..thus the confusion. One way to differentiate is old zinc dulls and blackens with break through ferrous oxide. Old cadmium chalks with a white powdery residue and break through rust.
    Mark Smedley
    RG #171

  9. #9
    Senior Member Haasman's Avatar
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    Thanks Mark. Very helpful. These are for #302580 with a build date of 11-2-65. The allen screws are silver color, not yellow.
    Haasman

    Registry #2489
    R Gruppe #722
    65 911 #302580
    70 914-6 #9140431874
    73 911s #9113300709

  10. #10
    The blue finish on zinc plating is a chromate that is similar to yellow chromate. The chromate is a protective coating to help prevent oxidation of the raw zinc. Zinc plating is silver when it comes out of the bath until chromated or left as-plated.

    I am sure you could direct your zinc plating provider to leave parts "raw".
    Paul Abbott
    Early S Registry #18
    www.PerformanceOriented.com
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