I know this could go in the Technical Area, Body and Styling forum, but it’s not exactly a problem, more a query out of interest…
This is something I’ve wondered about for quite a while ever since I saw the mx-5 restorers video on the rear arch repair and in other less detailed videos of theirs.
Now, I’ve read stories, seen videos etc. about restorations of cars (not MX-5s) where they talk of having to add in supports while welding to stop the whole car twisting, bending, breaking etc. while working on such things as the sills.
When my MX-5 failed the MOT on rust, I originally thought it was going to need all the rear sills and rear arches doing (they looked pretty bad externally).
On mentioning this to the local garage who were going to do the welding, I was told that wasn’t what needed doing, and that such work was considered a full restoration. They didn’t mention cars twisting, bending, breaking etc. but it was implied it was major work that required very specialist treatment.
However, in the MX-5 restorer YouTube videos I’ve seen of them they just pop the car on a ramp, lift it in the air, chop off the outer bits, weld in new inner bits, weld on new outer bits and job done (in so far as welding) even in the case of the rear arches they just chop all of it out in-situ on a normal car ramp.
So, my question as someone who has never welded is really - how come the MX-5 appears not to need any form of structural support while such work is being carried out?
Thanks 
It depends on how much work is needed, certainly older cars like MG’s/Beetles etc. will have frames bolted or welded across the doors if the entire sills are cut out to ensure they don’t move. The MX5 is quite a strong tub and usually the middle of the inner sills don’t seem to go as much as the outers or each end. That means the inner sills can still provide integrity whilst the repairs are done. Also if you do one area at a time then it’s not as bad.
A few years back we stripped a Mk1 SWB Landy down to the ladder chassis. We could lift one corner by more than an inch while the other three remained on the floor. The bolt-on ali body gave it the stiffness!
We were only repairing a few outriggers and an engine mount, but it was quicker to strip it all off and true-it-up with three big spirit levels than try jacking up and hoping.
The main problem was in it being early enough for that chassis to have been stove-enamelled, even inside the boxes - impressive, and this needed to be chipped/ground off before welding.
It likely was that kind of era that I’d read about, so thanks for the response.
I never realised there were any vehicles stove-enamelled, did rust go under like underseal or did it stop it in its’ tracks?
The early landies lasted MUCH better than the later non-stoved ones. The evidence speaks for itself.
Quite a few vehicles were, mainly because paint was so bad. The early beetles, for example. They had a really good TV ad in the late1950s or early 1960s, supposedly showing the paint shop process.
The commentary on the B&W TV went something like this (faded memory from almost sixty years ago)
First we paint it (shot of bare body shell being dipped deep in the paint bath)
Then we dry it (shot among air jets)
Then we bake it (shot in long oven)
Then we paint it again (shot of spray booth)
Then we dry it again (shot among air jets)
Then we bake it again (shot in another long oven)
…
And then it rains (shot from behind of finished car driving out of the factory into a waterfall of rain)
I’ve looked for this ancient ad a couple of times to refresh my memory, but without any luck.
It didn’t do them any good though did it? The beetles rusted away just like anything else at the time.
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