Plating Rear Brake Drums?

I'm wondering if anyone knows if you can zinc plate your rear drums. I had some crossdrilled rotors zinc plated on my 4runner a few years back and they were awesome. They kept their bright appearence up until the day I sold it (plating lasted over a couple of years). I'm curious to know if zinc plating the drums is okay to do, or if there is any ill effect in doing so? Price is not a concern, due to the fact my uncle works for a shop, and I get the drums and plating done at cost. I will be doing my fronts with crossdrilled and zinc plated in the near future so I want to do it all at the same time. I'm sick of seeing surface rust on the drums, and even painting drums only last so long, so I'm looking for a little more permanent/longer lasting senario.

 

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Looks great... but I have access to the plating cheaper than even buying the paint. Like I said, the paint will only last so long anyways.

 

wont the plating process change the characteristic of the metal?: it makes it less ductile right?

 

I say go ahead and do it for the price of at-cost, just check them regularly and make sure everything is holding up and be prepared to buy new drums if it ends up being a bad idea. And post up here so the rest of us make sure not to get our drums zinc plated.

 

It can't be that bad if people are using plating on front rotors... but I just don't know if there's something I'm missing about not being able to do drums....

 

I'm probably going to try it out and see how it goes... honestly for the price I'm getting them at, it wouldn't matter if they didn't work out.

 

Zinc plating shouldn't be a problem for drums. You could play it safe and bake for hydrogen embrittlement immediately after plating if you aren't sure what type if metal they are. Bake at 190Celcius for 3 hours or more within 4 hours after plating them. The rule for zinc is "All parts with ultimate tensile strength of 1200MPa and above shall be baked for hydrogen embrittlement relief".
I really, really, really doubt drums are made of any high strength alloy steel that would fall into this category, but it won't do any harm if you do it and they didn't actually require it. If they did require it and you did not perform the bake, the metal becomes brittle and liable to crack.

The reason I wouldn't bother zinc plating them is that I would want to bake them to be safe, but I'd be afraid the bake would warp them.

I would stick with paint if it was me. Not worth the risks. Discs are an inherently more stable shape and less likely to warp, I would think.

 

If I cared about shiny drums, and had the money to burn if they warped at post plate stress relief, I would go with .001" thick electroless nickel plating I think.

The stress relief requirements are different for electroless nickel though - it's based on hardness, which is much easier to check. Just get a machine shop to check it for you. It's about impossible to know the exact metal drums are made of, but it's easy to find out how hard they are. For electroless nickel on steel parts, 33HRC (Hardness Rockwell C) and over needs 275F for 5 hours immediately after plating.

 

Thanks... awesome info... kindof what I was looking for. I'll have to see if they do nickel plating there. But at the very least they should be able to do the baking on site. I doubt 190 degree's is enough to warp that thick of metal, but then again I'm not in the plating industry..

 

I haven't looked at the tacoma drums, but every drum I've seen is either cast iron or cast iron/steel welded to mild steel formed from sheet- nothing high strength. Get them zinc plated if you want. You should also get to pick a color for a chromate- yellow, black, blue.

 

Agreed - always figured they're just cheap cast iron. Can't prove it and I don't want to be on the one that said it's ok when a drum shatters.