RUSTY 1974SD455 Trans Am on FB 10k miles parked since 1980
 

Seller posted a video on Youtube.
10k original miles.
Parked since 1980.
Very nice interior except headliner.
Red/black/rust
Undercoated, so the floors and frame rails are good.
OMG it's rusty.
$35k

https://www.youtube.com/watch?app=de...dz4lOpcLTR9f0o

Never seen a trunk lid rust away to nothing like that before.

Kind of a sick irony. I'm gonna "save it" by letting it rot.

In 1973 and 1974 GM used some recycled metal in the sheet metal used for body stampings, likely bought from overseas. It rusted anytime there was moisture present in the air. The paint didn't need to even be scratched as it actually rusted from the inside out. I've seen many examples living right on the lakeshore in Erie PA that rusted even when not ever driven in the winter.

I recently sold a 1973 T/A that had the same affliction, and body panels were rusted through that car in 1977 with only 17,000 miles on it. I bought new GM replacement fenders quarters and rear body member, and they were put on the car in 1979 that never rusted in 40 years. Parts that weren't replaced in 1979 continued to rust, such as the floors and frame rails. If I hadn't replaced the other parts in 1979 that car would have looked as bad if not worse than the car in the video, My car had 19,000 miles on it, and had been stored since 1980, until I sold it in 2019. There were pinholes in the floor of the car even though there was no surface rust, even though the paint and primer was still attached, it literally rusts from the inside out.

I spun a rod bearing in the engine in 1980 and never fixed the engine, so the car sat inside for the most part, with an original 1973 T/A hood that also rusted even on the underside of the hood bracing. When I sold the car the hood was junk from inside to outside, top to bottom. That hood was completely stripped in 1979, primed and repainted before it was reinstalled on the car, it was rusted everywhere. The new GM panels installed and painted also in 1979, were still not rusted after 40 years. There was definitely different types of metal used used in the stampings I bought in 1979.

Some GM cars were much worse than others, but almost every 73 or74 GM car I owned, or worked on for customers, suffered from this bad metal problem. Exposure to road salt compounded it, and expedited the problem.

GM is't the only car maker to have run into this problem, Ford had frames in 1965-67 that rusted just as bad. In their F series trucks from around 1971-72 they had a recall that they replaced defective body parts at no charge because of this defective metal. I had a few customers that owned these ford trucks that got about every bolt on body part replaced under that recall.

Toyota also used some of this bad metal on their 1995-2000 Tacoma frames that came under recall when the frames just literally fell apart under the trucks, and were a safety recall.

GM was aware that the metal used in GM bodies in 73 and 74 was subject to this rust problem, however they ducked their responsibility, and never recalled any of this stuff.

And they are still producing stuff that rusts WAY to quickly. See quite new GM trucks all the time with rusted out bed sides.

Although I agree about the GM late model trucks (Dodges are even worse in the quarter panels), these panels rusted in 2 only years on my 73 Grand Am that was also low mileage, not to mention the 73 GTO I owned, that rusted prematurely also. All three of my cars were low mileage and were driven very sparingly, if at all during the winter. They literally rusted while parked under cover.

I had customers that owned GM vehicles between 73/74, that were daily drivers that by the time they were 5 years old you could throw a hat through the holes in the body due to the severe rust issues. Although GM kept the same body architecture until 1977 for most body styles, the later cars after 74 never rusted as quickly as the 73/74 models did.

73/74 cars and trucks would develop huge blotches right in the middle of a quarter panel, or fender, the rust was under the paint, and eventually the paint would fall off. Then the assault stated from exposed metal, and before you knew it there was a gaping hole that was no where near a panel edge, or pinch weld.

I have noticed that the rust problems on the 73/74 GMs seem to not happen in dry climates, mostly where there is constant humidity is when this problem rears it's head. just my observations having owned a few Pontiac muscle cars from this era. At one time I owned the 73 T/A, 73 Grand Am, and a 73 455 GTO at the same time, all were afflicted with this type of rust problems when the cars were between 2-6 years old. The GTO and the Grand Am both had rust around the rear wheel wells that required major reconstruction of these areas to repair the rust.

I wonder if the problem had more to do with whatever priming or rust treatment that was used on the bodies during construction back then (or lack thereof.)

I was going to share an image, and express shock at the crazy rust on the trunk lid (you can see the top panel rusted away ontop of the bracing...

Thanks very much for sharing your insights!

This might lend to explain some of the weird rust my brother's '73 had on it - the passenger side start of the rear frame on the floor, looked like it was dipped in acid - there was no rust to be seen, but it was as though it dissolved from the inside out - even though it was in otherwise fantastic shape.

We've got a couple of weirdly rusted areas on our 1974 SD.
 

It lived somewhere in the south early in its' life - I'm thinking Mississippi, but my memory is fuzzy.

Then moved to SoCal for a couple decades and finally ended up with us about twelve years ago.

One vertical area on the driver's fender almost looked like what unruhjohnny described, like it dissolved. Also has rust in the trunk floor, and a little in the passenger-side floorboards. Frame rails look good though.

We 'presumed' that maybe the fenders had been acid-dipped for racing (?), since the previous owner did a little drag racing with it.....

Now there is a second probability. Factory defective sheet metal.

I'll have to get a pic of the fender when I'm at the warehouse next time.

Do you know if this sheet metal was used in all 1973/1974 Firebirds for the entire year? My '74 was built in January of 1974. Was driven a couple of winters and then parked also in the 1980's with 49k miles on it. Had only minor rust in the lips of the quarters. No big patches of rust and the floor pans/frame rails were absolutely perfect, not a pinhole. Being a Wisconsin car, I would have expected this car to rust like this SD as It sat in a garage for years until I bought it in 1997.

I didnt think the looked that bad over all. I think my 77 was far worse from the start. I think that car would have a lot more value if it were restored. Rusty and crusty only goes so far in my book. Original condition value is one thing, but not with that much decay. May be a good buy at $35k.

As far as the rusting goes, Pop bought Pontiacs all through the 60's. When he could afford, he stepped up in 1976 and bought an Olds 98. That car was rusted through in a year. Last GM product he owned for a LONG time.