Powder coating

[Matt Neale]

The chassis outriggers are progressing well.  Front and middle are sorted.  I was hoping to get away without changing the rear but one side was almost a half inch out so I decided not to be lazy and regret it later.

The new outriggers and side rails arrive in a few days so I should be finished pretty soon.

I have been advised to get the chassis blasted and powder coated.  What do people think?  I have been using Epoxy Mastic for the underside of the car, should I have it blasted then continue with this?  Is blasting a good idea or is it better to clean it myself and treat with rust eater?

I want to get it right after the years spent on this project.

Thanks

Matt

[69vitesse]

Powder coating is not ideal.
It flakes off if water and rust gets under it.
Also, powder is hard to get into 90 degree corners.

Use a 2 pack epoxy paint. Tougher than a tough thing.

[sam93]

As your doing a full restoration,  I'd go for either blasting or acid dipping. My choice would be getting the chassis dipped as that would clean up the inside of the chassis too. You could even look into getting it galvanised too for ultimate protection.

Whatever you choose, must be a decision that you won't look back on and regret once the car has been on the road for a year. (Rust starting to come through again on the underside).

Sam.

[Mark Hammond]

Galvanising not good as upsets the strength of the chassis.  It can make it brittle on impact.

M.

[piman]

Hello Mark,

"Galvanising not good as upsets the strength of the chassis.  It can make it brittle on impact."

where did that idea come from, it's been done on other production cars. It's only a coating with no metallurgical effect on the base metal?

Alec

[Mark Hammond]

OK, well when I had my Herald restored by Chic Doig we used a new old stock chassis which I wanted to have galvanised.  That was what he said.  Galvanising changes the state of the steel whereas zinc dipping doesn't.  Don't ask me, Im neither a chemist nor a metallurgist.

He apparently has knowledge of this.

M.

[Nick Jones]

I'd think you'd be using hot zinc dipping for this.  Shouldn't affect strength though some small risk of distortion.

This would be my first choice for longevity.  Powder coating would be my last - have seem too much bubbling up and flaking.  Good quality zinc primer and chassis black preferable in my book.

If not chemical dipping and hot dipping I would also suggest blocking up all the holes in the main rails and tipping a gallon of cheap engine oil into the main chassis rails and leaving to soak for a few days while turning/tilting the chassis periodically to get full coverage.  Then drain the excess - you may be surprised how little you get back out - i certainly was!

Nick

[69vitesse]

Do not galvanize the chassis unless you are sure you will not need to weld it again.
A pig to weld and the fumes are very toxic. You will also need to drill it full of holes so the metal and air can get in and out.

[piman]

Hello Mark,

I know the term galvanising is confusing as the majority of galvanising is done by immersing the component in molten zinc rather than electrolysis. (about 450 degrees C so fairly cool for metals).

69Vitesse, yes zinc fumes are nasty but if the weld area is ground clean then it's not a great problem, however, there is little likelyhood of repairs being required once the chassis is galvanised.

Alec

[JensH]

Try taking a galvanized nail and compare it with one that is not.
Galvanisation of a Triumph frame is illegal here in Denmark, but have seen it done with no problems.
I had mine metallized with hot zinc (its a spray process that doesn't affect the strength and done on modern cars thin bodywork).

Not a fan of powder coating my self. Etch prime and 2-pack for me please 8)

[piman]

Hello Jensh,

"I had mine metallized with hot zinc (its a spray process that doesn't affect the strength and done on modern cars thin bodywork).

Unless done electrostatically there must be many areas that will not be coated so it does seem to be a half way measure.
I know that all Reliant chassis after a certain year were galvanised (hot dip) and also I think some Land Rovers so it is a proven process.
I can't say I've noticed any difference between galvanised and non galvanised nails except the latter do not rust quickly.

Alec

[JensH]

Hi Alec,
Its not allowed in Denmark as its not allowed.... (=its not proved from factory). But its also not allowed to put e.g. a zetec engine in a spitfire here; or - its very difficult to get through Danish MOT.
But galvanisation will weaken the steel - but I don't know how much. Has seen it done on a Triumph chassis, so possible.
Metallization will not go inside the chassis, but depending on who is doing the job, IMHO be better than electro galvanisation (might protect some areas of the inside, but difficult to get enough flow around edges etc).

Will need dinitrol or equal inside.
Had all my suspension parts metallized years ago - still like new.

[JensH]

Picture of some metallized parts

[piman]

Hello Jensh,

I don't know of many places that can electroplate zinc on such large items as a car chassis. Hot dip is very common and available in most reasonable sized towns.
How does your country legislate against someone who makes up their own chassis and wants to hot dip that, no factory to refer to?
From The web
According to numerous national and international studies, hot dip galvanizing produces no significant changes in the mechanical properties of the structur­al steels or welds commonly used throughout the world. The galvanized product's underlying steel is chemically and metallurgically equivalent to the uncoated steel.



Alec

[JensH]

Hi Alec,
If you make your own chassis, you will have to prove its an exact copy of the original.
So, if you need a new one for e.g. your Landy, you simple import it from the UK.

But once painted, no one will see - and then: Only a very few know how a chassis on a spitfire should look like.

Its many years ago I had metallurgy (did a degree in engineering) - but have always been told heating steel up to 4-500 deg. will weaken it.
Don't know how much, and have seen a Spitfire Chassis galvanized with no known problems. Was painted though :-)

[69vitesse]

The disinclination to hot galvanize chassis may be connected with  high strength low alloy steel as used in modern vehicles.
This is not regular mild steel and metallurgical changes may result from subjecting it to elevated temperatures.

[piman]

Hello Jens,

I was not talking about making a copy chassis but one to one's own design, if building a special for instance?

With regard to higher temperatures, we happily weld sections on to the chassis, so I don't think that dipping in molten zinc is likely to materially affect it? Certainly on a long term view it is better than having a less protected chassis which could suffer excessive corrosion and be seriously weakened by that?

Alec

[JensH]

Alec,
Agree with your view re. how much hot zinc will affect the chassis compared to rot.
Law is another matter though.
Believe its made out of the simple comparison between a 'blank' nail and a galvanized (try to compare, later one is much softer).

Very difficult to get a special non production car through MOT in Denmark. Even a 'buggy' (VW build) has become difficult due to changes in law.
Don't know the details.

Cheers,
Jens