Galvanized Chassis
Discussion
I looked at galvanizing first as the company who did mine could do either hot zinc or galvanize. It was the manager (who is also our RO for the TVR club) who put me off the idea of galvanizing. He advised that drilling so many holes into the chassis and also the issue of the chassis twisting due to the heat he didnt think it would be a good idea, so I went for his expert advice.
GreenV8S said:
R8nan said:
the company who did mine could do either hot zinc or galvanize.
What's the difference, in your view? The protection that Zinc gives is galvanic, so whether you're using hot dip in liquid zinc, or cold spray with a suspension of Zinc, it's still galvanising.There we go :-
"The process of hot-dip galvanizing results in a metallurgical bond between zinc and steel with a series of distinct iron-zinc alloys."
All that heat must do something
over and above zinc paint.Sorry if misunderstood your query and repeated what you already know.
Another question. If the hot dipping is risky, then wouldn't it have been possible for individual tubes to be galvanised prior to welding up in a jig.
I'm sure there is a response to this which will now show up my lack of welding knowledge!
A typical annealing temperature is 650c to 690c (not that I am any kind of expert, just a quick google) so I wouldn't be worried about that. Distortion is mainly caused by uneven heating, since the chassis is fully dipped that does not seem a big risk either. At 100kg it is not likely to distort under its own weight provided that at least some thought goes into how it's slung and then supported during the cooling phase. In any case the chassis can be checked afterwards and while it is still a bare chassis it's not a big job to jig it and straigten it a few MM if necessary. I would think that in a body off rebuild after a few years on the UK roads this might be a wise precaution anyway for the cost of a couple of hours labour in a good body shop. Just giving it a little tug here and there to fine tune it is not like the time consuming process of fixing it after a an accident. It's got me thinking for later in the year when I plan a body off rebuild on mine, it looks the DBs and will last for ever I would have thought, pretty inexpensive too. Do they make a few holes here and there to get the zinc inside the chassis too?
Jon
Jon
RichardD said:
GreenV8S said:
R8nan said:
the company who did mine could do either hot zinc or galvanize.
What's the difference, in your view? The protection that Zinc gives is galvanic, so whether you're using hot dip in liquid zinc, or cold spray with a suspension of Zinc, it's still galvanising.There we go :-
"The process of hot-dip galvanizing results in a metallurgical bond between zinc and steel with a series of distinct iron-zinc alloys."
All that heat must do something
over and above zinc paint.Sorry if misunderstood your query and repeated what you already know.
RichardD said:
Another question. If the hot dipping is risky, then wouldn't it have been possible for individual tubes to be galvanised prior to welding up in a jig.
You can't weld galvanised steel (unless you grind off the galvanised coating, which kind of defeats the point).GreenV8S said:
You can't weld galvanised steel (unless you grind off the galvanised coating, which kind of defeats the point).
Agreed, but what about, for instance, just replacing the outriggers the sportmotive (and others) method. Would it not be better to galvanise them, and where the parts are welded to the chassis give a good coat of Zinc type paint.I realise this is a bit off topic, just wondering really
You can weld galvanised metal, however it is crap as it is very hard to get a good weld, it spits and spats at you. The fumes are highly toxic as well.
If you were to replace galvanised outriggers then it's only the area of the welds where the coating would be gone. The rest of the chassis would still have protection.
If you were to replace galvanised outriggers then it's only the area of the welds where the coating would be gone. The rest of the chassis would still have protection.
Yep, but with the sportmotive type repair the outriggers are supplied ready assembled so the vunerable parts i.e mounting plates, seatbelt mounts could be all galvanised and the only un-galvanised bits would be where they are attached to the original chassis, which AFAIK are not so prone to rust.
GreenV8S said:
RichardD said:
GreenV8S said:
R8nan said:
the company who did mine could do either hot zinc or galvanize.
What's the difference, in your view? The protection that Zinc gives is galvanic, so whether you're using hot dip in liquid zinc, or cold spray with a suspension of Zinc, it's still galvanising.There we go :-
"The process of hot-dip galvanizing results in a metallurgical bond between zinc and steel with a series of distinct iron-zinc alloys."
All that heat must do something
over and above zinc paint.Sorry if misunderstood your query and repeated what you already know.
RichardD said:
Another question. If the hot dipping is risky, then wouldn't it have been possible for individual tubes to be galvanised prior to welding up in a jig.
You can't weld galvanised steel (unless you grind off the galvanised coating, which kind of defeats the point).By "over and above" zinc paint I meant "hot dipping" being a more complex and advanced process than merely painting as it is more than "stuck" with the high temperature metallurgical bond.
Edited by RichardD on Tuesday 10th March 10:30
ridds said:
Apparently 2 days to get the body off.
I'd say another day to rempve suspension and prep.
Ahem, 19 full days to do a 2" body raise, outrigger repair and reinstall on a Griff!I'd say another day to rempve suspension and prep.
It's very dependant on facilities and you could do it much quicker with a 4 post lift. In a single garage it takes four times as long to do everything
To fully anneal (make it as soft as it can be) low carbon steel you need to get it RED hot and allow it to cool very slowly.
To normalise steel (remove stresses from cold working) you go red hot and cool as quickly as it can in the air.
Ifor Williams (et al) trailers seems to be able to withstand hot dip galvo without problems. So I doubt the temperatures involved would affect such a stiff chassis if done as has been said - correctly.
However if that galvo temperature is held for many hours then there would be some annealing take place, but this may in fact extend the life of a "Work Hardened" chassis at the high streess points and reduce the likehood of cracking in future.
So let us know when you set this business up.
Would also add considerably to resale value me thinks??
ETA- typo
To normalise steel (remove stresses from cold working) you go red hot and cool as quickly as it can in the air.
Ifor Williams (et al) trailers seems to be able to withstand hot dip galvo without problems. So I doubt the temperatures involved would affect such a stiff chassis if done as has been said - correctly.
However if that galvo temperature is held for many hours then there would be some annealing take place, but this may in fact extend the life of a "Work Hardened" chassis at the high streess points and reduce the likehood of cracking in future.
So let us know when you set this business up.
Would also add considerably to resale value me thinks??
ETA- typo
Edited by VPower on Sunday 22 March 19:59
ridds said:
Apparently 2 days to get the body off.
I'd say another day to rempve suspension and prep.
Yep, took me 2 days to get body off using Dyno Torques two poster ramp. Its the seized bolts that are the pig, but then i had access to air tools to cut them off. But getting all the bushes out was even worse, horrible job. But a proper powder coat will see the life of the car surely? I dont expect to have to do mine again. The fact is the chassis was not prepped properly from new, and the finish simply fell off. I'd say another day to rempve suspension and prep.
Brummmie said:
The fact is the chassis was not prepped properly from new, and the finish simply fell off.
I was horrified during factory visits to see untreated chassis stacked up outside getting rusty, and I rather doubt that they scrupulously removed all the rust before they put them in for coating.with reference to galvanising, hot dip galvanising will give you a coating thickness of 90 microns, this being standard BS spec, if you use any spray type galvanising you will only be getting a coating thickness of around 10 to 20 microns, and as mentioned earlier it will not bond to the metal due to the lack of heat, also hot dipped coats the inside and the outside of the tubes, obviously spraying will not.
INHO any form of spray coat galv is a total waste of time and money, it won`t last 5 minutes.
just my 2p worth
INHO any form of spray coat galv is a total waste of time and money, it won`t last 5 minutes.
just my 2p worth
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