Galvanising bits - info and opinions, please

Post by **Diamond Hell** » 16 Nov 2005, 16:35

OK, I'm working on a project van at the moment and wanted to know what people think to galv-sipping a couple of bits, namely the rear swingarms and front subframe?

The reason I'm looking into this is corrosion (obviously) but it's as a treatment after shotblasting. I'm modifying the swingarms, so they'll need to be fully treated after that anyway, while there's always the option to powdercoat, or Hammerite them galv-dipping them will probably (to my mind) give the ultimate in corrosion protection to these parts, or will it?

Discuss

I'd be interested in people's opinions of what's likely to happen with the parts when they're dipped - obviously there's a chance of some distortion, but how high is this? And also you're laying another layer of metal on the part and any threads or bearing/bush seating surfaces will need cleaning (is it a big deal?), so let's hear people's opinions on this...

Post by **HarryMann** » 16 Nov 2005, 17:13

I'd be interested in people's opinions of what's likely to happen with the parts when they're dipped - obviously there's a chance of some distortion, but how high is this? And also you're laying another layer of metal on the part and any threads or bearing/bush seating surfaces will need cleaning (is it a big deal?), so let's hear people's opinions on this...

Heat not a big deal, even all over and not that high anyway

Threads - Galv thickness has to be specified - you'd have to agree this first (cost varies). A thick coat might start to tighten high spec. threads (thread clearances a hidden science.black art) but it's normal to blank off grease up tight clearance internal bores/faces.

Neither of these parts suffers fatal corrosion before many more other vehcile parts - I'd paint or powder coat - another 15-20 years?

You know me - £25 for a tin of Eastwoods Rust Encapuslator

Post by **Aidan** » 16 Nov 2005, 17:22

There is often the remains of factory applied flexible underseal inside the swing arms plus any subsequent underseal applied, you'd have to be pretty scrupulous at cleaning all that out - but then that would apply to paint or powder coating too. Good luck with it.

Post by **Diamond Hell** » 16 Nov 2005, 17:26

The thing is, Clive, say you've got a vehicle that's in excellent body condition, or has had significant repairs to it and is then very sound. When you build back up, or re-fit parts you want the main sub-assembly to be as solid as possible.

What are the pros and cons of powdercoat vs galv vs Hammerite?

Post by **HarryMann** » 16 Nov 2005, 18:10

Can't speak for hammerite, have used it of course around the garden, but no real experience - not sure if its used commercially a lot?

Technically, there are many more reasons why a painted or powder coated component's surface protection will fail than that of a hot-dipped galvanised one. There's only one major factor with galvanising and that's surface prep, which is controlled within a process which is well understood. Galvanising won't even happen if this is wrong, or it'll be patently obvious - whereas you can paint almost any paint on any surface and wouldn't have a clue how it will perform tomorrow or 20 years time other than guess.

Aidan makes a good point - interior cannot be inspected in the same way, so consider cleaning, inspection techniques and possibly treat with additional waxes paints.

Painting or powder coating hot dipped components succesfully has to be done at time of galving (elimating normal post galv passivation) or a another surface pre-treatment (careful controlled shot blasting) required..

Comparative cost/hassle

Unless whole van is done, or all the vulenerable components, is it not a matter of the weakest link?

Post by **Diamond Hell** » 16 Nov 2005, 18:17

Presuming that I'm going to get said items thoroughly shotblasted first (which I of course, AM) then the surface prep should be good.

Clive surely, you of all people should endorse someone trying to reduce the number of weak links, gawd knows you spent enough time finding them on that yellow thing of yours......

Post by **matt** » 16 Nov 2005, 18:32

been told that hammerite is ok on solid stuff, like gates etc, but bad for box section stuff, as seals in moisture??

Post by **Mudlark** » 16 Nov 2005, 19:19

Get them chromed .. you know it makes sense

Post by **Hacksawbob** » 16 Nov 2005, 19:29

not sure about the ins and outs of it but these guys will plate just about anything
http://www.rschrome.co.uk/

Post by **HarryMann** » 16 Nov 2005, 20:21

Presuming that I'm going to get said items thoroughly shotblasted first (which I of course, AM) then the surface prep should be good.

That'd be good for starters, but even the type of shot might important for final finish - but I meant that it's an integral part of their process to ensure its chemically clean and will accept the galv - maybe a quick chat with them about the pros and cons of galving components that have been in use and rusted might be in order - i.e. find a better source than me, we never had a galving plant, but tons of anodising, cadmium nd hard chrome plating in aircraft - and anything old would be stripped back and rebuilt to a spec. that made it almost indistinguishable from new.

Clive surely, you of all people should endorse someone trying to reduce the number of weak links, gawd knows you spent enough time finding them on that yellow thing of yours......

Yes, yes, but I'm not 'not endorsing' what you're trying to do, but just saying that unless the majority of susceptible components are treated, then there's going to be a mismatch in lives. It's a great idea if you're going to hang on to those parts for ever and a day, moving from vehicle to vehicle (like I did with a worked cylinder head, lcb exhaust, a home-made Porsche style steering wheel and special ignition module - ending up on 3 Minis over 10 years) - then galv 'em!
Having found a lot of rot, I could see some obvious weak links elsewhere and where possible have treated them, with a few variations but roughly in the same way...

..be interested to know roughly how much galving those bits might cost - to have a complete demountable sub-frame/diff built up and in top-nick and some (extended?) trailing arms, a bullet-proof transaxle and rear shafts to take from body to body, sounds a

- judging by the rate you get through syncro bodies

Good general linc on zink

Post by **Louey** » 16 Nov 2005, 20:38

Mudlark wrote:Get them chromed .. you know it makes sense

We are talking about Thomas here.

Post by **Mick** » 16 Nov 2005, 21:05

Our local insists on parts being shotblasted first. They acid dip first then submerge in molten zinc - it will cover all, inside and out, can completely fill small hollow bits. Sometimes get uneven coating as it's hoisted up to drip. Good finish though usually.

Post by **Diamond Hell** » 16 Nov 2005, 21:25

Thanks Mick.

Clive in case you hadn't noticed I already have a 'portable' gearbox (engine soonish) and now I'm just extending that across to the other components. The trailing arms won't be extended, but I do plan to remove and then plate over with heavy duty plate and seam weld that nasty lip on the outer side of them. If you're really unlucky rocks can get trapped there and then shred your tyres

One of the key reasons for - bloody hell, there's a gritter truck going past on the ring road, is it really THAT cold - sorry, where was I....... oh yes key reasons for doing the subframe is that the galv coats inside and out, thus stopping any nasty inside out rusting of that component and obviously it gives me the basis for a nice portable front set up.

I've had stuff galv-ed before, just wondered whether anyone had any thoughts on tolerances once these relatively complex stuff has been dipped.

After you with the chroming, Mark.

Matt, when did you last see a solid metal bar gate?!

Post by **HarryMann** » 16 Nov 2005, 22:19

Yes Mick, it's that acid stripping step that creates the surface that'll take the zinc.. galvers used to have a quite short life, in fact any platers - nasty environment !

... and Thomas, yes I had noticed, soon you'll be turning up in an open chassised Subaru Syncro - just think, no body damage and you'll be able to drag race it as well

but not tonight! - it is in fact freezing here, just lined the shed roof with 40mm Kingspan/celotex - most out of a skip over the road - it's about 3 degrees in there, with a small fan heater set to frost cover (no, no, the shed, not the skip!) Now to discover how to get a quart into a pint pot, all my Aladdin's Cave hooks and hanging points have gone, so I'm down to my last sq.ft. of floorspace - no such thing as a free lunch - unless you're in PR

Post by **syncroand101** » 17 Nov 2005, 09:17

Now to discover how to get a quart into a pint pot, all my Aladdin's Cave hooks and hanging points have gone, so I'm down to my last sq.ft. of floorspace - no such thing as a free lunch - unless you're in PR

Clive, what ARE you talking about?