OzVMX Forum
Marque Remarks => CZ => Topic started by: Ji Gantor on February 08, 2009, 05:34:42 pm
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What is the gold on CZ hubs.
Is it paint, powder coat or anodising.
This gold is not orginal the huds from the factory were black were they not.
Ji
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Ji,
CZ hubs were originally a gold colour. The hubs are made of magnesium and are treated to stop corrosion. I do not know what process the factory used,probably a type of anodising but they were NOT painted.
If the wheels have been sitting awhile carefully inspect the inside of the hub for corrosion (where water may have sat) and look for cracks at the spoke holes in the hub (not uncommon).
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Thanks Canam,
The hubs look fine and should be ready for a finishing treatment soon. I have seen gold paint, anodising and powder coating on these hubs which lead me to this confusion. I do know a fear bit about magnesium and agree that it can not be left untreated, such a pity that previous owners of all the VMX bikes I have did not understand this material.
Ji
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I guess I will have to paint them or have them powder coated.
It would be my assumption that the existing hubs can not be re-anodised due to the heat.
Ji
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Ji,
try contacting Electromold in Melb. The boys have a lot of experience with plating and anodising. I have a mate who does magnesium casting so I'll quiz him today on protective coatings.
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The gold coating/surfacing is very thin and any hubs I've had in my mitts on the coating has mostly faded off. I spray my hubs with WD40 regularly to keep the magnesium 'tooth decay' away. My reason being that I noticed a VW engine block - magnesium was rotting from weather exposure but the places where old oil deposits were baked on the metal was good.
I've seen painted hubs but often in places the paint will break out and spots of corrosion occur.
On my bike it's got a decay hole in the front brake backing plate which I repaired with Bellzona magic bog at the time of her rebuild. WD40 is your friend, no more corrosion seen on my hubs.
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Thanks fellow CZ racer Eno,
I spoke to a powder coater yesterday and for $50.00 he gives a hub a coat of gold paint and then into the over next he gives the hub a coat of clear and then back into the oven. He told me that it is quite close to gold anodising just not see through. He coats inside and outside of the hub without coating the drum.
Ji
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Okay I have just heard the offical word.
The gold treatment on the hubs is a copper mold release agent.
Ji
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Front hub
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Rear hub
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Hi Canam,
I have been told that magnesium can not be anodised.
Ji
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Ji,
yes,I understand that the mag is not anodised.
the gold treatment for magnesium is a gold dichromate. The hubs are bead blasted,etched,treated with a dewatering fluid and then processed wih the dichromate. The hubs can be 2 packed if you want but the dichromate gives the 'transparent' gold finish of the original. There are very few companies in Aust that are specialised enough to do this work. Powder coating is not recommended for this application unless the magnesium has been treated. Contact me if you want more info.
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In America they call it the DIP.
I have been told that it goes brown after a while.
It can look quite close to the original gold colour when first done.
Ji
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Thanks Canam,
I spoke to Steve in Melbourne and this is the deal if you want your hubs dipped gold.
Post your hub to Steve as is and for $75.00 he will bead blast them and gold dip them, if you are not going to paint them he will perform a post oil dip that makes them last for years.
The gold dip is a base material and should be painted.
You can anodise magnesium, it is called hard anodise and I believe there is only one place left in the world doing it in England for the formular one guys. Obviously this is out of my price range. The hard anodise is the finished surface and protective layer.
Ji
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Just a thought but what about approaching the aircraft guys as there is always a shitload of magnesium used?
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Hi
The problem is the different metals involved. the hubs are made of Electron ( a type of magnesium alloy) the brake drum and sprocket is steel and the rivets copper , holding the drum to the hub . the hub was coated in the releasing agent when it was cast which is the gold colouring , then the drum and hub assembled by rivetting together, the only way to restore the original is to dismantle all the components that make up the back wheel assy and have them individually treated .I have yet to find anyone who can duplicate the original finish,but please let me know when you do .
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More importantly, you need to sell that awful twin pipe. I would be willing to help a fellow vmxer by buying it off you! :D
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Hi
Do you mean that "old Jawa trail bike thingy"? still need a few more bits before I start that one,
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Maybe just paint em black :o
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are you saying the only place in the world doing 'hard annodizing' is in England ???
I know Electomold right here in Australia does it
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Jikov is right, There are at least three different metals involved in the hubs. Talking to Steve he dips the lot without stripping. I asked about the drum brakes and he told me that it is not a problem. I have not had this done on mine as the Dip needs to be painted anyway.
Ji
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Jikov ! do you really have a twin pipe?
Can I come and see it and take some photos?
Ji
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Hi LWC3077,
I only made a few inquiries about hard anodising here in Australia. The calls were all STD so after being told a few times the same answer I gave up. Can you call them and find out if they can hard anodise magnesium bike hubs. While you got them on the phone ask them how much.
Ji