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914World.com _ 914World Garage _ Correct finish for a steelie lug bolt

Posted by: doug_b_928 Oct 10 2020, 06:38 PM

Does anyone know the correct original finish for a steelie lug bolt? I know the alloy lug bolt was silver. I see in post #1 of this thread (http://www.914world.com/bbs2/index.php?showtopic=74857) a restored car with steelies with the lug bolts in yellow chromate. My originals looked to have been black, but could have been painted. So, when new did they come with yellow chromate/cadmium; black chromate, or blue chromate (silver)?

Posted by: davep Oct 10 2020, 07:20 PM

AFAIK, the wheel bolts for steel wheels were silver. I just finished stripping 3 sets down to bare metal. My guess is that they were cadmium plated like the alloy wheel bolts. Unlike the alloy wheel bolts, there was no trace of copper plating. I have four sets of alloy wheel bolts, and they all have traces of copper plating on the steel. Whereas the wheel bolts for steel wheels were marked VW on the heads, the alloy wheel bolts were marked VW on the threaded end, and also marked with a K & X. There is very little room for the marks, and the ends are generally not fully flat, so I believe the K & X are short for Kamax; a common supplier for bolts. There are two versions I have seen, the K & X in large and small fonts. I am able to get these cad plated locally, so am gathering sets to be done in a single lot.

Posted by: doug_b_928 Oct 10 2020, 08:10 PM

Thanks, Dave. I medial blasted the originals from my car today. I have two that are shorter (.75" of threads) that I think you had said were probably from a bug, and the rest were the correct length (1" of threads). The correct ones do, indeed, have a VW logo on the head. The shorter ones that are presumably from a bug say "HWE" and have the VW logo (see attached pics below).

So, based on your having just stripped 3 original sets of steelie bolts, your conclusion that the should be finished in silver seems strong. My plan will be to zinc plate them and then use a blue chromate which should give me a fairly similar finish to silver cad.

Attached Image

Posted by: davep Oct 10 2020, 08:48 PM

Yes, Zinc plating should be okay. They need to be baked right after plating to eliminate hydrogen embrittlement. This is critical for a stressed fastener, especially wheel bolts.