Anyone ever used a hot dip process to galvanize a car frame for rust protection?

So I was looking for how best to treat the frame of the Spitfire/Miata project build and was trying to decide if I would sand blast and Por-15 it or just paint it with implement paint. I came across this from some hot rod builders that are doing this for muscle car builds.

http://www.baltimoregalv.com/

I called them and got an estimate of $300 to burn off the paint, dip it in an acid bath and then dip it in a tank of zinc to galvanize it both inside and outside. I'll get back a clean frame and shock towers and can then paint it any color I want and get started on the rebuilding of the car. Since the frame will now be pretty rust proof, I can just paint it with implement paint and this ends up being pretty economical verse sand blasting,  prep and Por-15. Anyone done this before and are there any issues I should be concerned about?

Plenty of newer cars have galvanized unibodies from the factory.  I don't see an issue with doing it.  

All that work for only $300?! That seems like the way to go.

Hot dip galvanizing is kind of wrong for automotive stuff. It's a pretty thick and lumpy layer. I guess it could work but I have not seen it done.

Go to the local hardware store and look at some of the hot dipped galvanized bolts used to put decks together.  Then decide if that is the type of finish you want on a car frame.  I wouldn't.

How much would it be to sand blast and have it powder coated?

I talked with the local power coater. His estimate was $1,500 which is crazy by my standards..... in reading up on powdercoating, apparently it is not the best for car frames as the power does not get in all the nooks and crannies so you can have exposed areas that could rust. The dipped in acid and then in the galvanizing tank coats it inside and out and then my paint is just cosmetic. 

There are a ton of air cooled 911 guys getting their car galvanized during restoration. They all claim it to be a good idea. 

Volvo has done it from the factory since 1985-ish.

You are going to be chasing a lot of threads  in the frame after the dip. Unless there is a way to keep the zinc out of the threaded holes in the frame.

I think the value is outstanding for what they do and would be happy to just have the frame de-rusted for the $300 quoted.

Here is one example (Chevelle frame). Once it is painted, this seems like a really cheap way to prep a frame for building up a car.

Sounds like a bargain. You probably won't get a show car finish on the frame, but do you really need that? 

You will need special paint for going over galvanized surface.  Standard implement paint will more than likely just come off in a short time.  

The special paint is not expensive but you may have to order it at your local paint store.  I know Sherman Williams makes one.  If you want the good stuff look up Tnemec. More $$$$ but it is fantastic stuff. I spec it for clients that only want to paint something once. Usually due to access. 

Lotus did it on the Esprits and up.  No need to on the Elise, as it's extruded aluminum, but all the steel frames post-Europa era.  No paint either.  That just subtracts lightness.

For three bills, if I could figger a way to get it to them, I'd be all over it.

Slight derail: tnemec is cement spelled backwards.  That E36 M3 sticks like herpes.  Far better than por15, but 20 years ago was something like 10 times more expensive.  We used it on the steel winfows we installed in prisons.

On topic: i have never thought about galvanizing.  This is genius! Wonder if theres any local to me?

You guys saying “these people do it” are not speaking of hot dip galvanizing. It’s very different than what any OEM has done. 

tuna55 said:

You guys saying “these people do it” are not speaking of hot dip galvanizing. It’s very different than what any OEM has done. 

Amen!!  Hot dip galvanizing is NOT the same process that car manufacturers use.  And as dean1484 said, you will need some $pecialized paint.   

Roger Williams doesn't recommend this in "How To Restore Triumph TR5/250 & TR6".  He claims the following.

• Significant added weight.
• Molten zinc can distort the chassis.
• Acids get trapped in the box sections and seams.
• Chassis tends to rot from the inside leaving a weak zinc shell.
• Difficulty in future welding.

I paid $600 last year to have a TR6 frame media blasted and powder coated.  This doesn't protect inside the frame, so is better for a car that will be exposed to limited amounts of water.  For my other TR6 (restored over 20 years ago) I blasted and painted the frame myself.  Before painting, I hung the frame so that it could be tilted any direction, taped up the bottom holes, and pored rust converter in various places to coat the insides.  This was a bit messy, so hootus protection was required.

Donebrokeit said:

All that work for only $300?! That seems like the way to go.

 

That’s what I thought.  

On a side note I toured a large galvanized in Joliet, IL and the molten zinc tank was sweet and all I could think of was tossing a dead body in mafia style.  

But what you can use is a process called color galvanizing.  We do it to hand railings down by the docks at the seaport and things. Really cool process and works really well. Looks kind of like power coating when you are done. 

I have had a couple of utility trailers galvanized. That was 20 years ago and the trailers are still perfect. 

I would be concerned about the heat making a car frame warp. Steel moves a good bit when you drop it in a vat of molten zinc. 

What temperature is the hot dip?  I'd be really concerned about getting a pretzel rather than a chassis back.

There are some good cold galvanization products out there.  I think ZRC was the brand that we specified.  We used this as a direct replacement for hot dip galvanization.   The only caveats are that the steel must be media blasted before application, and it is a painting process with all of the effort that requires.