Lotus Elan

Caliper finish

PostPost by: rcombs » Mon Oct 13, 2014 5:05 pm

Does anyone know what type of finish, if any, were on Elan brake calipers? Some of the rebuilt units are plated but this may be something the rebiuld companies are doing.

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PostPost by: fasterbyelan » Mon Oct 13, 2014 5:51 pm

None, the plating is a newish trend
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PostPost by: patrics » Mon Oct 13, 2014 7:32 pm

Hi,
The calipers have always been plated but it's doesn't tend to last too long.

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PostPost by: rgh0 » Mon Oct 13, 2014 10:12 pm

My Elan calipers were originally galvanised or maybe it was zinc plated and this is still there. My PLus2 ones have been painted so I don't know whats underneath.

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PostPost by: gus » Mon Oct 13, 2014 10:46 pm

I was sure paint would not stick so put stove black on mine, stayed looking good for years. Maybe I painted the fronts and blacked the backs, it has been too long..........both still look black
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PostPost by: Plus 2 » Tue Oct 14, 2014 5:44 am

Hi,

The calipers, as Steve (patrics) says, for many years were all originally plated and like fasteners back then it was cadmium and identified as the more silver appearance. Cadmium plating was widely and heavily used in the auto industry until it was found to be bodily and atmosphere accumative toxic, a bit like mercury with the 'mad hatters' and lead hence removed from petrol now. Not sure I have seen hot dip galvanising used on calipers but for sure galvanising gives a much thicker and much longer lasting protection

http://www.pcimag.com/articles/95782-ca ... ternatives

Cadmium plating became environmentaly restricted due to poisoning issues but is still essential in many applications like the aero industry, military and marine.

Whilst zinc plating (usually gold appearance but can be coloured with a passivation process) and chroming still have issues indeed choose your poison.......mines French wine :mrgreen:

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PostPost by: rcombs » Tue Oct 14, 2014 12:58 pm

Sounds like the originals were plated. Thanks for the info guys. I new someone here would know the answer.

Rick
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PostPost by: rgh0 » Tue Oct 14, 2014 1:06 pm

Many many years ago as a vacation student I worked in a bolt making plant - the zinc plated bolts were silver in colour and the cadmium plates bolts a gold colour. Interesting that it can be the other way around depending on the process used I guess. In which case my Elan callipers may be cadmium plated originally

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PostPost by: prezoom » Tue Oct 14, 2014 4:37 pm

Clear/silver and gold zinc are both available from my local plater.

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PostPost by: Galwaylotus » Tue Oct 14, 2014 6:55 pm

rgh0 wrote:Many many years ago as a vacation student

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PostPost by: AHM » Tue Oct 14, 2014 7:07 pm

Zinc and Cadmium are 'silver' in appearance.

Electroplating is a galvanising process. (Edit - Electro plated zinc)

Zinc and Cadmium in raw form offer sacrificial protection, so are passivated to give them corrosion resistance.

The passivate determines the colour and to some extent the corrosion protection.

To answer the question - Clear passivated cadmium or zinc. which you can see if you split the two parts. Zinc and yellow is what you will get with rebuilt calipers, but if you don't like shiny 'gold ' calipers paint them with some aluminium heat resistant paint. Which looks original, protects the plating, and can be reapplied at leisure.
Last edited by AHM on Tue Oct 14, 2014 9:00 pm, edited 1 time in total.
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PostPost by: AHM » Tue Oct 14, 2014 7:31 pm

something like this:
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IMG-20121017-00662.jpg and
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PostPost by: Plus 2 » Tue Oct 14, 2014 7:43 pm

rgh0 wrote:Many many years ago as a vacation student I worked in a bolt making plant - the zinc plated bolts were silver in colour and the cadmium plates bolts a gold colour. Interesting that it can be the other way around depending on the process used I guess. In which case my Elan callipers may be cadmium plated originally

cheers
Rohan


The passivation process can change the colours to whatever you want............or the mixtures of silver, gold or lead even I believe with the cadmium may change the colour, however the cheap and cheerful coating used for callipers just gave nothing more than a surface 'shelf life'..........in jewelery cadmium was widely used for both silver and gold items. http://www.thelaboratory.co.uk/legislation_cadmium.html

For sure though I have never seen calipers hot dipped galvanised and I do not know of other ways to galvanise (Lotus Chassis were hot dipped galvanised) but as an 'oldy' I do appreciate modern techniques have moved on. My Brother in law specialises in Chrome on Plastic/Polymers and this has somewhat revolutionised components in the automotive and bathroom industry and his company plates plastic items in many different finishers for the leading European automakers but the volume business is the sanitary/bathroom parts..

Many metal fasteners since cadmium restriction have though been galvanised, especially in the building/fence industry. These fasteners have though to be treated with caution where torque settings may be critical.

One of the biggest problems with the plating process for metal fastenings is hydrogen embrittlement and unless fasteners are correctly baked to relieve this when plated they can shear easily........... something that has again been a big problem with cheap imported fasteners so always buy fasteners from an experienced company using experienced platers.

AHM........ not sure with todays modern changes but base zinc is white and turns yellow through the heat process if I recall from my chemistry 40 years ago, However you will see many items that are silver now stating 'zinc plated'....I am now retired on permanent vacation for the past 10 years but do appreciate how moden techniques and materials have changed things.

Traditionally galvanising and plating as terms were not quite considered the same thing back in my days anyway http://www.azom.com/article.aspx?ArticleID=1380

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PostPost by: AHM » Tue Oct 14, 2014 8:57 pm

Steve,

Zinc is silver grey in appearance. Electroplated zinc appears silver with a clear passivate. With yellow chromate (Cr6- Not very nice) and yellow passivate (Cr3 - nicer) it appears gold.

Hydrogen de-embrittlement is only necessary on high tensile fastners (10.9 /12.9) and there is no way to test if the de-embrittlement process has been successful. That is why the socket cap screws holding the reconditioned calipers together are a black phosphate finish - In critical applications we used to have socket cap screws mechanically plated.

Galvanising is the application of a protective layer of zinc. Hot-dip, electroplating, even paint! Like you, when someone says galvanised I assume hot-dipped!
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PostPost by: Chancer » Wed Oct 15, 2014 9:30 am

Me too but when I see zinc electro-plating or a zinc painted finish described as galvanised I consider it to be either a mistake or a deliberate deception, I once one won damages against a company that supplied me something described as galvanised when it was in fact zinc electro-plated.

For me, galvanised means hot dip galvanised.

Whilst you could galvanise a caliper the bores would have to be re-machined afterwards so I doubt that it has ever been done in production, the mating faces would also need to be re-machined unless it was dipped as an assembly.
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