Chassis clean prior to galvanizing

Hi all sorry another question
I have spent this weekend getting the chassis completly stripped as im doing a rebuild
I have recently found out that the chassis was changed 10 years ago as the original one was shot

anyway the chassis is in reaaly good nick apart from a bad dent at the back
will be getting a new rear cross member from black sheep but it has bits of surface rust everywhere
i wanted to get it galvanized so would i need to get it dipped first or would shot blasting be ok ?

A typical hot-dip galvanizing line operates as follows:
Steel is cleaned using a caustic solution. This removes oil/grease, dirt, and paint.
The caustic cleaning solution is rinsed off.
The steel is pickled in an acidic solution to remove mill scale.
The pickling solution is rinsed off.
A flux, often zinc ammonium chloride is applied to the steel to inhibit oxidation of the cleaned surface upon exposure to air. The flux is allowed to dry on the steel and aids in the process of the liquid zinc wetting and adhering to the steel.
The steel is dipped into the molten zinc bath and held there until the temperature of the steel equilibrates with that of the bath.
The steel is cooled in a quench tank to reduce its temperature and inhibit undesirable reactions of the newly formed coating with the atmosphere.

Waste of time as a chassis should be galvanised from new, it will rot from the inside out otherwise, far worse obviously.

lee3022 said:

Waste of time as a chassis should be galvanised from new, it will rot from the inside out otherwise, far worse obviously.

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How? if chassis is solid and in good nick, galvanize will get on all the surfaces, no different than a new chassis that is dipped

Thor1950 said:

How? if chassis is solid and in good nick, galvanize will get on all the surfaces, no different than a new chassis that is dipped

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i agree if the chassis is in reaaly good nick it can only be a good thing

just called a few places and they galvanize it but dont dip or blast it
i need to get this done before
ball ache or what

I guess you called here Merseyside Galvanizing Ltd Liverpool- Wedge Galvanizing ?

SteNova said:

I guess you called here Merseyside Galvanizing Ltd Liverpool- Wedge Galvanizing ?

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yes they are calling me back

Thor1950 said:

How? if chassis is solid and in good nick, galvanize will get on all the surfaces, no different than a new chassis that is dipped

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A new chassis is new, fresh metal, no rot, an old chassis can have rust on the inside too, anywhere so it's a waste of time as it will rot anyway.

lee3022 said:

A new chassis is new, fresh metal, no rot, an old chassis can have rust on the inside too, anywhere so it's a waste of time as it will rot anyway.

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once they do the different cleaning/pickling/acid/rinse dips, everything will be clean metal for hot dipping

Hmmm, that's interesting. Ten years is a good age, especially if it has been through a lot of mud and seen little wax oil inside the rails. My first thoughts are that even those impressive sounding processes will leave some rust, which will not take the zinc or break through. It's got me thinking about galvanised bulkheads, because most of those are reconditioned before being dipped. Most of which will be ok cos its visible both sides (unlike the chassis rails), but what about the door posts? I've looked at these bulkheads from Ashtree (£800+) and so I'm currently contemplating repairing my own and getting it dipped. The same problem must apply to the inside of the door posts - if it is a problem!

Just checked Ashtree website and they say "The bulkheads (prior to dipping) are pickled in hydrochloric acid to remove any impurities especially hidden cavity rust and paint"

Al203. They put them in a sturdy jig to hold the bulk head in place to minimize/prevent warpage from the hot zinc (approx 660F) when dipping it

Acid dripping will take off all rust
Www.surfaceprocessing.co.uk

Cheers Thor, I've heard about that and been told I would have to bolt a bracing bar across the bottom of the door posts. The more I learn about what's involved the more I get. £800 seems a lot of money for a bulkhead to me. I'm still hoping for a self repair tho. I have spoken to a mate tonight who has a big compressor and an even bigger storage shed. He reckons shot blasters are cheap to hire and so it may be worth at least self blasting mine to see exactly how bad it is.

Al203 said:

Cheers Thor, I've heard about that and been told I would have to bolt a bracing bar across the bottom of the door posts. The more I learn about what's involved the more I get. £800 seems a lot of money for a bulkhead to me. I'm still hoping for a self repair tho. I have spoken to a mate tonight who has a big compressor and an even bigger storage shed. He reckons shot blasters are cheap to hire and so it may be worth at least self blasting mine to see exactly how bad it is.

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A bit more than a bar. Saw a video of a bulk head getting dipped and it was a rather hefty built frame work they used

was that on Youtube? I need to check it out

Al203 said:

was that on Youtube? I need to check it out

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Don't remember, I just looked but not very hard:tea:

What's the cost of all that work compared to buying a new Richards chassis

I wouldn't want to spend £500-600 getting an old one blasted acid dipped galvanised if it was only double that for a brand new one.

I've learned over many years not all savings are worthwhile

lee3022 said:

Waste of time as a chassis should be galvanised from new, it will rot from the inside out otherwise, far worse obviously.

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correct

Thor1950 said:

once they do the different cleaning/pickling/acid/rinse dips, everything will be clean metal for hot dipping

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Incorrect.

Rust on a chassis is not restricted to the outside. No amount of cleaning is going to get inside the chassis rails and the bits you can't see clean. You need an agitator. when your drain is blocked and you pour caustic soda on it does the block just clear? nope. You need to scrub it and agitate it. The same with a chassis.

If you galvanise a chassis that is corroded on the inside you will get 2 years and it will be bubbling through again.

Spend the grand on a new chassis and never worry about it.

Buyer beware.

GINGE said:

Incorrect.

Rust on a chassis is not restricted to the outside. No amount of cleaning is going to get inside the chassis rails and the bits you can't see clean. You need an agitator. when your drain is blocked and you pour caustic soda on it does the block just clear? nope. You need to scrub it and agitate it. The same with a chassis.

If you galvanise a chassis that is corroded on the inside you will get 2 years and it will be......

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I don't think this is right.

When you see car monocoques that have gone off for stripping in the acid bath, they come back as raw clean steel. Obviously where rust has taken hold the steel is thinned or perforated at worst. But there is never any trace of rust left.

Structurally it may be less than ideal but rust coming through the galv after an acid bath......