hosrom_951

I found a shop locally that does all kinds of plating (including zinc dichromate).

Now, i am sending some items out (heat shields, bolts, washers, etc), but now i want to ask about the turbo downpipe.

Now, the flanges are rusted (duh) and the studs are also rusted, should i:

- Just leave it as it is

- Have it dipped in acid and cleaned off from rust

-Have it plated (but the heat would cause it to flake?)

My main concern is the studs on the downpipe, i am not into doing any cosmetic
thing to it.

billthe3

They can mask off the studs on the downpipe so they won't be plated.

I think the studs are removable, though who knows how hard they are to get out.


To clean off all the rust, they usually sand/bead blast the part, which also cleans off the metal for plating.

hosrom_951

I can see some tack welds where the studs go, i think you have to drill them out?

Tom M'Guinn

I just took a big box of greasey grimey bolts and parts to the plater, and had them dipped and plated in yellow zinc. The dip cleans off virtually all rust and grime. So... I wouldn't worry about the rust -- have it stripped and plated and it'll look brand new.

On a related topic, does yellow zinc get darker (browner) with age? The stuff I just had plated has more yellow/green than the parts that come from germany. Can platers adjust the color?

hosrom_951

Tom,
I think Yellow Zinc plating is also known as Yellow Zinc Chromate, which is just Yellow Chrome which get's effected by heat (over time). Zinc Dichromate has streaks of pink and green and solved the issue related to heat.

Offcourse, i could be wrong, but it is okay to have the downpipe plated?

Voith

I found this thread abouts zinc plating, so I'll ask here.

First of all what kind of plating is on original fasteners, I was reading on this subject and it seems that zinc plating and cadmium plating look the same, but cadmium plating is aluminium compattible and zinc is not?

Second, how do I zinc plate fuel regulators? Is it safe just to dip them, or the holes must be somehow closed?

Chris White

Your down pipe is made of stainless steel – no reason to plate it.

CurtP

Depends on what parts you're talking about. Some of the parts were originally cad plated and some were zinc plated (silver, not yellow).

If I had known then what I know now, I would have inquired about getting my parts cad plated instead of yellow zinc. And I would have used a clear protective coating like Eastwood's Diamond Clear over either plating.

I think there is a lot of misunderstanding on what the platings do, at least in the application that we're using it for. What most of want is decorative. The problem is zinc is a sacrificial anode and will eventually look like it did prior to plating. The big issue with zinc is it happens faster than it does with cadmium plating. Once you have everything plated, you have to be very careful what you use to clean it. Many chemicals will attack the plating and cause discoloration or oxidation.

Voith

I am plating all the yellow stuff from my car including engine and other fasteners that were originally yellow.

The shop that does plating for me, said that the stuff on original yellow parts was yellow zinc coating so they coated first batch of parts with that.



Now if I understand this correct, yellow zinc plating and cadmium plating look the same, but cadmium plating is tougher, is galvanic compatible with aluminum and will last longer?


if that is the case, I will plate it again with cadmium plating.

The problem is that as far as I understand cadmium and yellow zinc plating is forbidden here, so I had a tough job to find a shop that is willing to plate it with this method. Not cheap either.

Darwantae951

Just be careful with cadmium. If you start trying to remove it, it's pretty bad stuff...

67King

Not sure what you are trying to get at with aluminum, but if you are suggesting plating aluminum, why?

Voith

No, I just dont want that all the coated fasteners in engine block have some kind of alergic reaction with aluminum...

67King

Oh, okay. I think zinc is almost always a sacrificial anode. You'll get a couple with any dissimilar metals, it is the difference in their potential that determines the severity of it. But again, the zinc should be the thing that corrodes here, the aluminum should be fine (I would verify that if I were you, but I'm pretty sure that is correct).

Voith

Nobody work with cadmium here no more.

Travis - sflraver

finishing.com has a great discussion board that covers everything from plating to electropolishing of metals. I formulated my electropolishing / de-buring solution from information there.

Here is a good topic on Cad.
http://www.finishing.com/100/89.shtml