How much rust is too much?

[Mopaardvark]

Hey guys, I have a 77 volare coupe that's been undrivable for a while due to a broken 7 1/4 rear. I've finally gotten motivated enough and found a liberty rear to swap in. Upon getting the vehicle up on blocks I found there were rust issues far worse than I had anticipated. My drivers floor pan is very well ventilated and the frame rail underneath that is missing a large chunk as well. Can I just form some metal to match what's supposed to be there and weld it back together? It seems that the unibody is a little more complicated that just plating over things. I've read that the rails are only 16ga, that seems pretty thin. How have you guys dealt with this?

 

[BudW]

That frame rail will need to be addressed before one jumps over any train tracks.

FMJ's are getting a bit harder to find but they are still out there. Most M-bodies do not have the "factory installed rust option" that most F-bodies were built with. Matter of fact, I would say that most M-body cars have done really well overall through the years with the rust issue. Also, the '88-89 M's also use galvanized steel for most of the body.

The front floor pan and frame rails are the same for most all of the F & M-body cars with the exception of a few miscellaneous welded-on brackets that can be removed and added back on.
The rear floor pan length depends on if a 2 or 4-door F or M-body, but a 4-door rear floor pan can be cut down if needed for a 2-door.
Using a spot-weld removing drill bit, and some time, you can remove a floor pan and frame rails from a newer M to fix your car.

For a while, a company was making a steel sleeve to weld on over your existing frame rail. I think called a "safety cap" or something to that effect, but they making 'em quit a while back.
There is someone here who might also have frame rails and possibly, a floor pan for sale (not me) so you might make a post in the parts wanted section and see who bites.

It is a bit of work, but several people have successfully replaced the floor pan(s) and frame rails - so it can be done. You might even to find threads here about it with step-by-step pictures.

I don't have the rust issues you have, but I do plan on doing some spot weld removing to upgrade my radiator core support (going from 18" to 26" wide radiator), A/C firewall (my car was a non-A/C car) and a larger trunk pan (much larger spare tire area).
BudW

 

[Mikes5thAve]

What's the rest of it like? That's a very common spot for rust on the older ones and like BudW said there used to caps to fix it with.
How much does the car mean to you? Typically if its only isolated to one area like the frame its one thing to spend the money and time on it but when you have to deal with floors too or a second area you're usually better off finding a cleaner car to start with. If you're only fixing it up and working on it as a project that's what I'd do. If you've had it a while and it has sentimental value its a bit different.
Don't forget too that it'll have an effect on value too. Most people aren't going to pay nearly as much for a car that's had major work like that done when there are others out there that are more rust free.

 

[Mopaardvark]

I've had the car since 2005, I'm the second owner. That is the worst structural spot, but there are others areas . I'm not worried about resale value, it's rolled the odometer a couple times already. To me, this car is more for fun and having a backup vehicle. I'm more concerned with safety and hearing your guys input and maybe some fabrication tips.

 

[Duke5A]

That rail needs replacement, not a patch, and if the rail is that bad it brings the rest of the car into doubt. I honestly wouldn't do it. Find another car.

 

[Aspen500]

Sometimes how much rust is too much all depends on if you can do all the repairs yourself, or have to pay someone to do it. Then there are cars where the rust is so severe there is no repair possible either way.

 

[Oldiron440]

I did bodywork including frame repairs along with race fabrication for over 45 years, I have found if the panel needs to be replaced and isn't available new or fabricated because of rust then it too much rust. You can't repair rust you must replace it.

 

[Aspen500]

Rust..........this was my dad's '68 Coronet that he bought new. It went to a local guy who is taking the rear axle and there's about 2 other parts that are salvagable. Loading it on his trailer yesterday, it almost broke in half. We were pushing it on with the bucket on front of a tractor. It got high centered so he lifted the back end with the bucket while pushing. i was in the car steering and heard all sorts of crunching and snapping sounds and,,,,,,both rear doors popped open. Now THAT car is too rusted to repair. The rear subframe rails,,,,,,,,,,,weren't (along with the trunk floor, torsion bar x-member, etc...............). I didn't get any pics of the underside yet but the guy who took it is going to get some. Poor car..... I never mentioned it here but, he passed away suddenly and very unexpectedly, back on August 15th.

These are from a few days ago when it was still sitting where it had been for the past couple three years behind the house.

 

[BudW]

Sorry to hear about your dad.

What is the white car beside it?

 

[Aspen500]

1962 Valiant V200 4 door. It's about in the same category as the Coronet, except the subframe rails were replaced many moons ago and made from 1/8" steel so they're still good. Otherwise, a few good parts and the rest is scrap, hate to say. There's a '74 Gold Duster in the garage that's also in the parts car category. The '62 Fury is not a parts car, needs a total resto but is vey restorable.

 

[Mikes5thAve]

The joys of living in the rust belt and having decent storage.

 

[Aspen500]

Valiant and Duster, not intending to hijack the thread.