Just had a few more thoughts. Zinc is a reasonably ductile metal so will flex as the chassis does so little likelihood of cracks, which can occur with other brittle finishes. Mixing different metals is also an area to avoid without a physical barrier between. Corrosion is an elctrochemical process and each metal has a different rating. This difference causes a corrosion cell to form when an elctrolyte is present - eg water or worse still, salty water! So, a coating to keep water at bay is also reccomended.
I don't disagree at all with what you say but two thoughts still strike me: (1) given the proensity of the chassis to flex, surely this must crack the coating and undermine it to an extent (2) in similar vein, as soon as any hole etc is drilled throgh a galv surface, doen't this, again, detract from the protection?
I may be wrong here and I'm no metallurgist but I thought this was why all the best resto jobs went for powder coating? As I said, happy to be corrected Cheers, G
No - the galv wont crack. At the interface with the steel it forms a compound so the zinc is very stronngly bonded to the steel. Yes any hole will will ultimately reduce the protection because the zinc round the hole gradually gets used up protecting the otherwise unprotected steel bolt ie the zinc coating is sacrificial. So eventually when all the local zinc has gone both the bolt and the chassis around it start to corrode. How long this takes depends on the thickness of the zinc - no time at all if its electroplated steel but a decent time if its hot dip galvanised.
If you could only do one coat to a restored chassis it would be galv every time rather than powder coat. The latter is a good form of paint but [paint is what it really is.
When I was working I had a factory making steel fabrications and that included a galvanising plant as well as paint booths. Doesnt mean I know all the answers ( I'm not a metallurgist either) but I picked up saome knowledge along the way.
If lord and lady Docker had had owned a Morgan, the chassis would have been GOLD plated. Now that would last for ever and any holes drilled would leach and be re-coated. Personally I would like to see a 4/4 totally plated in 24 carrot.
If you are doing nothing, how do you know when you are finished?
I don't disagree at all with what you say but two thoughts still strike me: (1) given the proensity of the chassis to flex, surely this must crack the coating and undermine it to an extent (2) in similar vein, as soon as any hole etc is drilled throgh a galv surface, doen't this, again, detract from the protection?
I may be wrong here and I'm no metallurgist but I thought this was why all the best resto jobs went for powder coating? As I said, happy to be corrected Cheers, G
No - the galv wont crack. At the interface with the steel it forms a compound so the zinc is very stronngly bonded to the steel. Yes any hole will will ultimately reduce the protection because the zinc round the hole gradually gets used up protecting the otherwise unprotected steel bolt ie the zinc coating is sacrificial. So eventually when all the local zinc has gone both the bolt and the chassis around it start to corrode. How long this takes depends on the thickness of the zinc - no time at all if its electroplated steel but a decent time if its hot dip galvanised.
If you could only do one coat to a restored chassis it would be galv every time rather than powder coat. The latter is a good form of paint but [paint is what it really is.
When I was working I had a factory making steel fabrications and that included a galvanising plant as well as paint booths. Doesnt mean I know all the answers ( I'm not a metallurgist either) but I picked up saome knowledge along the way.
Thanks, That is really good clarifiction and much appreciated regards, G
Yeh, but just to get a little bit of perspective, she also wore a leopard skin coat and he was the man who said( when Honda first introduced the CB92 Benly to the UK) " The British motorcyclist does not want gimmicks such as twelve vote electrics and electric starts"
Would YOU have had a BSA Bantam when you could have had this!! Nuff sed 'bout Sir Bernard I think
Ah! in this case, the plinths were provided by the organisers. This bike was RIDDEN there ( Just as well it wasn't a Bantam- he'd still be on the way!!) G
PS Dave, as the current ' Mr Concours' please advise just how far up the inside of the exhaust pipe I hvae to polish? I've lost two electric toothbrushes already
Yes I hear they are having a bit of drizzle out there in the old penal colony - Ashes to Ashes dust to dust Ricky Pontin go he must ! A bloke walks into a brothel and says: "I'm a bit kinky, how much for total humiliation?" The madam replies “£60”. "Wow, what do I get for that," he says. She says: "A baggy green cap and an Australia cricket shirt”.
Last edited by 4/4sportsfun; 09/01/1104:48 PM.
2009 4/4 Henrietta 1999 Indigo Blue +8 2009 4/4 Sport Green prev 1993 Connaught Green +8 prev
Nuff sed 'bout Sir Bernard I think
