Classic cars forum & vehicle restoration.

[petermeachem]

You would think that the older a car is the rustier it would be but that doesn't seem to be the case. Colwyn500's Fiat seemed to be more rust than steel. Price doesn't seem to affect rustiness either. I was just reading the Armstrong Siddley thread. Presumably an expensive car but it looks quite rusty.
My Austin 1934 on the other hand really isn't rusty. I stripped a door today and was assuming the door bottom would be shot, but no, just surface rust. It's not as though it was very well painted either. Under the wings was red oxide and black cellulose and an awful lot of surface rust but no holes. The paint came off very easily. I don't know if that condition is typical for 30's cars. I would have thought that for a fairly common car like an Austin that if it was a problem someone would be making repair panels
My three Midgets were all in dire condition, largely down to lack of paint I think in the cills and every other box section, but then the floors fell out too.
Modern cars seem to be fine. My Honda has a wee bit of rust in a wheel arch but it is 16 years old.
Why do some cars rust away and some not?

[peter scott]

I think the quality of steel was better pre-war and post-war it's not until we get into the 1980s before manufacturers see a benefit of effective rust proofing.

Peter
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https://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[Mog]

My Beamer is 16 years old and does not have any rust. It is left in the street 7/24 . My 1987 Mid Wheel base Landcruiser is in the garage as I know it would rust away very quickly, if left in the street , being only about 100 meters from the sea.

[petermeachem]

I've heard before about steel quality but shouldn't paint negate that? Is paint that porous?
Is it poor design leading to mudtraps? Midgets have some crackers

[colwyn500]

I have always gained the impression that until technology developed watertight, compressible door and boot seals and more watertight, mono-coque construction, people generally made a greater effort to garage their cars; this might have helped pre-war cars to last so well.
Although modern surface coatings have done wonders for bodywork preservation, basic design is the greatest saviour or killer of a car's structure.
In my opinion, drainage and ventilation of panels, internally and externally, are the key factors that help to slow down corrosion on a car.

[roverdriver]

My observations have been that in general earlier cars built with a full chassis were less prone to major rust problems. This might be partly due to the fact that pre-1930 cars tended to be higher above the ground as well. Of course in Oz we don't have salt on roads to worry about, and also the further inland that a car resides, the less deep rust is to be found.
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Dane- roverdriver but not a Viking.

[baconsdozen]

I think a lot is down to the composition of the steel. I've worked on steel hulled boats of all ages. Some of the really old ones were made of a steel that went black when it corroded but the layer formed seemed to then slow down further corrosion.
Italian cars of the 70's and 80's seem to have a terrible reputation for rust no matter what make,maybe that steel was more rust prone.
Older cars have fewer nooks and crannies for mud to build up in and were of a simpler design with more flat or gently curved surfaces. Any welding,drilling or sharp bending provides places rust can start from and old cars had less of these.
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Thirty years selling imperial hand tools for old machinery(Now happily retired).

[Keith D]

Rust has traditionally been the car owner's worst nightmare!

Vintage cars were generally made of a high carbon steel and had thicker panels. Most vintage car rust problems seem to have been caused by the cars being abandoned in paddocks in all weathers for anything up to fifty years!

Once panels were pressed from one piece of steel (in the thirties) they became far stronger and resistant to flexing and no wooden frames were needed. Therefore manufacturers were able to use thinner steel panels. This all lowered weight and allowed them to use smaller engines. It was a snowball effect.

As chassis' were replaced in the fifties, we ended up with double and even triple skins, to give the same strength. There is an immediate problem with areas that could not be reached, even to paint properly initially. And most rust starts from the inside and bubbles outward so it is not generally the outside gloss paint that allows water to penetrate.

I don't think that better door seals reduced the problem as I had a 1987 Mitsubishi Colt (kept under cover) that started bubbling paint on the bottom of the doors within a few months of buying new. Yet in 1992 I bought a new Mitsubishi Lancer coupe and this was left out in all weathers, yet when I sold it in 2000, it was completely rust free.

I understand (from an auto engineer) that car manufacturers started using a steel with a high zinc content and this seemed to kill the rust gremlins around 1990.

I think the early Vauxhall Victors in 1957 were probably the all-time worst car for rusting. A shame as they such a pretty car when first on the market.

Keith

[petermeachem]

The only perforations on my car are where the wings bolt to the body which must be quite a good dirt trap. The only write off bits are the running boards which are sheet steel with rubber glued on top. The steel has evaporated more or less completely. There are no box sections at all.
I don't see why steel thickness makes a difference, it only rusts on the outside and I don't see how the rust would be affected by thickness.

[alanb]

The thickness of steel makes all the difference, if rust eats into the steel from the outside at a x thou a year a sheet of steel twice the thickness will last twice as long.
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old tourer


Morris 8 two seater

[petermeachem]

Only if the steel is rusting agressively. By and large mine isn't. It has some small areas with pitting so if the steel was thinner they would be perforated but 99% of the rust is just on the surface and hasn't visibly pitted but has grown on the surface from small paint blemishes (that's what it looks like anyway).
Look at the gutter here http://www.oldclassiccar.co.uk/forum/phpbb/phpBB2/viewtopic.php?t=13107&postdays=0&postorder=asc&start=30 (sorry I keep using colwyn500's car for rust examples). It has holes all the way along. My gutters were also a bit rusty behind so I took them off. The only pitting is right at the rear end

[colwyn500]

Peter, my car is a recovered Rustaholic and as such is happy to be used as an example of a rusty car (made good).
I think my car is a good illustration of the way that rust becomes a problem. It rusted where water repeatedly gathered and couldn't properly drain away.This was in some different places to other rusty Fiat 500s and because it was not used for long on the road, some of the normally rust-prone areas escaped quite lightly.

[vitesse]

[norustplease]

I think that the turning point comes when car structures are made up of folded box sections with vulnerable spot welded flanges rather than open channel chassis members. This plus the wing on a typical thirties car is a smooth teardrop type shape which has few mud traps and dries out quickly.
Enclosed sections suffer from condensation as much as water penetration, and are very difficult to adequately rust proof.

I suspect that a lot of cars rot from the inside out, especially leaky soft tops, and cars with dodgy window seals.

My worst rotter was a project VW Trekker, which I was heartily sick of welding by the time that it was finally finished. Interesting car, but my wife hated it, so I moved on.
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1953 Citroen Traction
1964 Volvo PV544
1957 Austin A55 Mk 1
Boring Tucson SUV

[petermeachem]

Good point about condensation. My worst ones were 3 midgets that all had the same reg no and my tr7 which failed its first mot on rust. The midgets rusted in the cills, box section behind the seats and some super mud traps at the forward rear spring mounting and under the front wings. I once got rear springs from a scrapyard. The car had been crashed but otherwise looked as though it had been cared for, all shiny. I unbolted the rear mountings and the U bolts and then just pulled them off the car, the front mountings didn't exist.