A 1 mm thick steel plate, 1000x1000 mm is 7.8 kgs.
Same size and thickness aluminium is 2.8 kgs.
I have my trailers hot zinc dipped when they are new but
the zinc dont get into all of the square tubing anyway.
The Roadster frame would need some pretty big holes to
get the hot zinc inside in all the right places. In the lower
main section (under the floor) are several ribs welded into
the frame U-profile before the top was welded on. I think
somebody have pictures of this on their homepage. These
ribs will make it difficult for the molten zinc to get into all
the places in the frame. It's molten metal, not a fluid. The
frames were spot-welded and gas-welded at the factory
as I dont think MIG-welding was invented or at least not
used by the industry in the 1960's. The "old" steel dont MIG
weld that well either. There were no high strength steel
available either.
Frames for cars like Lotus Elan that had a large center tube
can be hot zinc coated on all surfaces because they dont
have any closed sections. You have descibed a good way of
cleaning and coating a frame. Alkaline bath, remove the rust
but not the paint, then sandblast to remove all paint and dip
the frame in hot zinc. You need to drill some 10 mm holes to
let the hot air escape from inside the frame in the zinc bath
or the frame will burst from the pressure build up. The holes
will be needed for the derust too. There are some derusting
baths using what we call "lemon acid" that will not remove
metal or paint. It will only remove the rust. You will need to
treat the frame inside with waxoyl or similar rust protection
after the hot zinc.
Thomas
Sel_Aganovic@hettich.com.au wrote:
> Hi Listers,
>
> I stripped the chassis last night completely, and I could just lift it when
> it is on it's side, resting it on my shoulder.....My guess is about 100 kg
> or less, definitely no more.....
>
> I need to clarify one point here. My main concern is protecting the chassis
> from the inside, as this is where the original rust came from. It is on the
> back bend, where the "skinnier" section, meets the"thicker" section, just
> before the lead spring pick-ups.
>
> I can't see the point of protecting the outside, when there is 35 years
> worth of mud and other crap trapped inside, that needs to be cleaned out
> and treated.
>
> Thomas, you said that the galvanising won't treat the inside ? Why not,
> there are drainage holes in the bottom members, front cross-member is
> hollow,and I drilled some 10 mm holes in the "X" to let the molten metal go
> in, and air to escape......
>
> As for the 450 C, the chassis looks like it was MIG/TIG welded originally,
> so this temp will not affect the welds.
>
> I am pretty sure that they did not temper car chassis in the 60's, but
> could be wrong on this one.
>
> So this is my plan...
>
> Alkaline strip (no acid)
> Derust bath
> Hot dip galvanising
>
> Re the retaping of the threads, this will probably need to be done, but it
> is not a major task...
>
> Any feedback/info is welcome....
>
> Cheers
>
> Sel
>
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