anyone gone through with zinc plating their chassis

[sonunet]

Read one thread here on not to do it -- but was wondering if anyone in this group has opted to have their chassis zinc plated? If so would love to hear your thought. Specifically around the topic of distortion ? if there was any that was identified (i'm sure some will occur). There?s a company here local to me in Denver, CO ? that has a tank that will accommodate the chassis (chassis size: widest part ~ 33 in x longest length ~122 in).

Already know that zinc plating happens around 860 degF and steels annealing properties at 1200 degF. so in theory the 340 degF delta is a wide enough margin that it shouldn't distort. but that's all assuming that the chassis is 100% steel / including the weld, etc...

But really interested in the process, the prep and results. And also the questions you would have asked (now after getting the process done) -- had you known before going in.

UPDATE: so i spoke to the facility, it looks like they use a alkaline-non cyanide zinc plating process. reading up a little more, it seems as though the maximum temperature achieved is around 200 degF (which shouldn't provide any distortion on the steel surface). just for pricing, it looks like it's going to run me a full tank price ($160-). personally i think that's a bargain.


tkx
sonny

[prezoom]

I have used the zinc plating process for nearly every metal part I fabricate, both clear and yellow. About the only negative I have found is when the solution gets trapped in avoid and runs out after removal from the tank. This will lead to streaking of the coating. The quoted price is beyond reasonable, but it is in reality for only one part. Plating hundreds of parts can run into significant money. In doing another restoration, I bead blast and then wire wheel each and ever bolt, bolt and bracket that will be bolted back on the car. Wire wheeling after blasting restores the "shine" to parts. My plater also uses the low temperature process.

Rob Walker
26-4889

[sonunet]

thanks Rob -- that's great feedback. about runs, i'm not too concerned. i'm looking to have all of the suspension parts, chassis and the gas tank stripped / blasted and zinc plated.

the plating facility here is tooled to do government contracting and mainly work on airplane parts (very large contractor for Boeing & Lockheed Martin) -- but the guy at the facility said the chassis and parts shouldn't be an issue as they have the ability and tanks to do it.

now doing a little bit more research, especially the salt tank lab tests -- they indicate that Yellow or Olive Drab have the best results to hold up rust prevention. i'm fine with a yellow tint in the chassis and the suspension.

surprised that racer guys opt for power coating vs plating? especially considering the weight differential.

i'm sick of having to worry about when my last tetanus shot was! enjoy working on clean substrates.

sonny
26/4919

[Madinzeheid]

Hi guys, newbie to the forum.
I've just gone through the dilema (trauma) you're going through now. I spoke to several galvanisers and platers and powder coaters and have just had my chassis sprayed with zinc and then powder coated.
There's a big difference between zinc plating and galvanising.
Galvanising will distort the chassis according to everyone I spoke to including all the galvanisers. The problem is the stress induced by the expansion of the various chassis members due to the heat and not possible annealing of the metal. These stresses are what will cause the distortion.
Plating is a close second but has very limited corrosion resistance and will go white and furry in a short space of time due to oxidation. Powder coating prevents this and keeps the limited cathodic protection the plating offers even if the coating gets scratched.
The most important part of it all though is to get the chassis shotblasted first.
I couldn't get a plater with a big enough tank so opted for the zinc spray instead which I found out actually puts more zinc on than plating would have anyway. The powder coating gives a much nicer surface finish on the rough surface and can be easily painted over if needed.











Hope this helps,

Cheers.

[AussieJohn]

In OZ 25 years ago we used to have them plated [ zinc di-chromate I think ] then two packed; I dont think there have been any problems with this. If full galvanising causes a lot of distortion how did Lotus get around it with the galvanised replacement chassis for Elans and the originals on excels and esprits? cheers, John.

[Elanintheforest]

With a lot of trial and error, John!

On one visit to see Miles Wilkins in the late 1980s, he'd had 10 or so galvanised chassis delivered for Elans. Of those, 2 were within acceptable limits and the rest he had piled up as scrap. He showed me the pile, and a couple of them were visibly twisted. He was not best pleased.

The process is pretty well sorted now, although I have heard of the odd one being duff. It's not a route I'd go down, given that you can now get large items dipped and e-coated / powder coated if you want them to last forever.

A couple of considerations. If you use the car and drive it pretty hard, then the chassis will crack in time around the engine mounts, gearbox mounts, diff mounts and A frame mounts. No amount of galvanising or e-coating will stop that. If you don't use the car much then it won't be exposed to the damp or salt roads much, and a good coat of rust-proof paint will probably protect it just as well.

I put a new chassis on my S3 in 1979. It was a Lotus Replacement, non-galvanised...the only sort available then. I painted it pretty crudely in black Hammerite, and it's still as good today, 30 plus years later.

Mark

[gerrym]

Sonny, if you want the protection of Zinc without the distortion, have you researched the Zinga method.

It won't be cheaper because the prep will cost (Blast clean to SA 2.5), two coats of Zinga, then polyurethane gloss top coat.

I'll post some links later as to lifetimes, damage tolerance and over-coating.

We should insist on this standard of coating as an option on any new chassis.



Regards
Gerry

[rgh0]

Jerry
I presume Zinga is an inorganic zinc primer - The one I used has about 60% metalic zinc in a resin binder. I used this on my Elan 30 years ago with an alkyd enamel top coat. This is a fairly standard paint system in the oil industry and provides very good long term protection. So far the chassis is still perfect apart from stone chips to the front cross member that need touch ups - but then the climate in Australia is far more gentle on cars also and no salt on the roads

cheers
Rohan

[jono]

I had my chassis shot blasted with chilled iron grit, then 3 coats of zinc rich paint followed by 2 pack top coat.

A local firm did the whole job and charged me ?80 They said it will last for ever and it looks as if it will.

Jon