brake caliper colour

No doubt that what you see is yellow zinc. It is notable that the plating is a sacraficial coating that deteriorates with time while protecting the metal underneath. Unless you protect the plating with a coating of oil it will change colour over time. That said I do not reccomend oiling your calipers

 

yes yellow zinc for the ATE is perfectly original
regards Matthias

 

Paul,

In order to achieve the gold colour, plating is basically done in 2 steps. First zinc is applied, followed by a very thin yellow chromate conversion coating which gives an extra layer of protection to the zinc and accounts for the yellow/iridescent colour.

The leach is an additional extra step done after the chromate is applied. As the term suggests, this process leaches away some of the coolour in the conversion coating. I can't tell you the precise chemistry involved but I do know that this is a pretty basic operation for any well equipped plating shop and the explanation above should suffice for them to know what you are after.

A few things. I recall my shop telling me that the leach time was short, around 30sec. as I recall. The idea is to just tone down the colour, not eliminate it completely. The second thing is that if your shop is not familiar/comfortable with the procedure the colour will wash out on its own in a short time, particularly on the calipers which see large temperature swings.

Best Regards,
Paul

 

It is more of a lighter color than heavy yellow zinc, almost straw like coloring
Ian (isuk) has captured the correct plating color for the brake calipers during restoration of Dino 03050 and I'm lifting his photos as examples.
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I have a few more photo's of the calipers on 03050 Scott. The flash in some of the shots makes them appear more gold than they actually are.
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thought the metal plate between the two halves should be black oxide?
ed

 

I have only ever seen them zinc and I have seen a LOT of calipers.

Another interesting to note is the position of the hand brake assembly on the cars in the photos. These are E series cars that seem to have the spring and lever assembly on top whereas the earlier M series cars have it on the bottom (as confirmed with reference cars and the parts book).

 

The photo's from the factory homologation certificates show the centre plate as being zinc.
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