Front Frame Rail in-place repair

[yesterdayze]

Hey guys, I introduced myself yesterday on the introductions forum and mentioned that I just purchased a 71 Dodge Charger and would be pestering all of you with some questions on a few things here and there.

I have done restoration work before; in fact I grew up doing it with my dad mainly on Chevelles, Impalas etc but always wanted a mopar, specifically a 3rd gen charger. I'm not a hack and like to do things correctly even if it means taking more time to do so. I have my own shop AKA converted heated garage and lots of tools. What I don't have is a lot of money so I have to make do with ingenuity.

Okay, phew, all the said here is my problem.... The charger I bought had had the drivers side door sold off of it and was never recovered. So it sat with rain coming into it for a while. That rain pooled on the floors. The damage was a drag but fairly easy to blast and patch for most of the floors... (from underneath they still look great)



But there was some bad damage mainly in the front drivers side section of the floor pan where most of the water went and eventually ate through the floor there.



Out the floor it went and into the drivers side frame rail. The cross member it attaches to seems fine and appears to just have surface rust but nothing inside it.





Looking under the car you can see that the underside is VERY solid and clean except for that frame rail. The frame rails bottom is rotted completely out of it. That said once you go about an inch up the sides of the frame rail it seems pretty solid. Once you are above the curve up in the frame rail it seems solid there as well.



I was curious though how thick these pieces should be. The area above the curve seems solid, no real rust or shale when poke around inside from one of the factory holes. That being said, while it tings just fine and doesn't sound punked if I take a ball pien and give it a moderate whap I can dent it on the bottom. If this is only like 12/14 gauge steel I can see that but I assumed it should be thicker? The frame on my El Camino would have left my wrist ringing had I done the same thing to it. Admittedly those cars are not uni-body so I am looking for a point of reference.

Here is my thought, and I am hoping for feedback on it..

I have a plasma cutter - or should once I get the replacement semiconductors in monday (bought as-is). I'm thinking pull the engine to relive weight and since I need to at some point anyways. Pull the fenders hood etc then cut the frame rail about 1.5" up from the bottom along one side leaving the other side intact. Sandblast the crap out of it, cut and weld in a reinforcement plate on the inside then cut off the other side 1.5" up and repeat. Finally I would bend a new bottom half of the frame, including the tab that connects to the back cross member, pop some slots in it to use for welding to the frame reinforcements, then put it in, butt weld it (angle the edges for surface) right to the old frame, grind it all smooth and call it good.

The red would be cut out, the green would be added on the inside, the red would then be rebuilt as one piece and put back in. The hole would then be re-drilled.



Any thoughts on this? Cautions? Past experience doing this? Best gauge steel to use (I will measure it but should I go thicker)? I would LOVE to just get an entire new used front clip for the car and just replace it all as one piece but I could afford shipping or the possibly the piece but not both haha.

Thank you all for reading this rather long explanation and all the questions... I want to make sure I supply all the details I can. The help and feedback is appreciated and I will be posting updates as I go along. As I am new to this site please let me know if I post in the wrong area. I've been reading the directions and think I am good ;D

PS. Are the emoticons intentionally mixed around like an inside joke? I keep getting so confused when a wink prints a grin, a smile prints a , tongue prints a drool, half grin prints a crazy... I end up feeling like I have gone half grin, I mean crazy haha

[aspenrt360]

hey there i have done work like that before on an f body and it worked out fine for me took a bit to get it to look like i wanted though. that car is still on the road ten years later. you may want to look at auto rust specialties they have a slip on cap for that all pre formed you just slip it on and weld. put two on the rear frame of a buddys duster it was a great help and works really nice! they were not crazy expensive either. cheers

[yesterdayze]

aspenrt360 - Good to know! That is encouraging. I have done frame work before, just never on a unibody that rust challenged. I did see the caps and contemplated it but as I have access to steel and a bender I figure keeping the frame the same width might be nice. I will keep that in mind though.

[boy1cuda]

I do frame rust repair all the time and you would be surprised as to how thin the frame rails are. They get their strength from the "box" shape design. When I first started repairing frames I was expecting the frame to be a lot thicker.
I like the "slip over" repair covers for vehicles that your driving and don't care about looks or value. They are definitely the easiest solution and I have no doubt that they are strong but it won't give you a "seamless" repair and if you go to sell it or show the car people are going to see that a repair was made.
Whenever I can I cut out the frame from a solid donor car (junkyard car) and then butt weld them together. If I can't find a donor piece then I fabricate the piece much like you described (depending on the extent of the rust). I also use thicker metal than what was used in the factory and fabricate it in a way that the extra thickness is inside the frame so that the side of the frame that you can see is flush and seamless. In either way I still build "cross" reinforcements inside the frame rails to make sure that it is stronger than what it was when it was new (and believe me that's not to hard to do).
I guess your decision just depends on your level of skill and how much you care of the looks of the finished repair. Good luck.

[yesterdayze]

Excellent! I was worried that something was very wrong with how thin the frame seemed but I could not find any scale coming off or depressions to indicate it had rusted out en-masse.

Skill wise I have no doubt I am not nearly as good as most people here. I just do this for a hobby. That said I do fairly well and have been doing if for a long time. Guess I will just have to go for it and let you guys know how it turns out.

Thank you for letting me know I am heading in the right direction! Definitely a good thing. I will keep this thread updated.