1968 frame rail repair

[Johnny41782]

Hello to everyone here. This is my first post of what I believe will be many and I hope the great minds here can help! Five years after buying my 1968 Dodge Charger from a kijiji ad I have finally got the funds to start. It is a complete car and the previous owner stripped it down and had it media blasted to reveal quite a bit of rust as it was a Wisconsin car but I did get it for a good deal. Im going to start out with frame rails, floor pans and chassis stiffening components as it will have a big block. The only rusted part of the frame rails is the first foot back from the radiator support. My question is should I replace the rusted section or just cap it? Ive been searching this forum and other places and have been unable to find the right answer. I don't want a show car but I don't want a fast easy fix either that Im going to have to deal with down the road. I want to do it right. I have the time.

[Dino]

Welcome!   

Do it once and do it right.  Either replace the rusted part or replace the entire rail, depending on the severity of the rust.  Capping is putting lipstick in a turd; it might look better, but it's still a turd.

[Johnny41782]

So if I do decide to replace it instead of capping do I have to replace the whole rail or can I just splice in the section that is damaged? It's not more than a foot and the rest of the rail is ok.

[bill440rt]

Rails are mild steel in these cars, not HSS or UHSS steels like in modern cars.
I'd say a new piece could be sectioned in, but I would not just put a "cap" over it. Have the replacement rail sectioned in properly, and you may want to make a sleeve insert that fits inside to join the two pieces.

[green69rt]

You may be able to section a new piece in but, I wonder about what you will see when you open the rail up.  I had the same problem as you but decided to replace the whole rail.  When I started cutting the old rail out I found massive amounts of rust almost from the beginning to the end.  There was considerable bracing inside my rails that was completely rusted out.

I tried to take some pictures of the old rail that I saved so you can see what I'm talking about.

[Mike DC]

     
I won't say you should never cap/patch a rail.  

People say "you should do it right."  But IMO a lot of muscle car guys & restorers tend to neglect the more subtle effects of replacing a panel. 

You can't just unzip & reinstall weld-on panels without some side effects.  Warping panels.  Re-heat-hardening the weld areas again.  Factory-done welds in tight areas that are impractical to redo.  Reproduction sheetmetal that is only "pretty close" to the same thickness & alloy quality.  Etc.  Even when you do repairs 100% correctly by the book, nothing is ever 100% all the same again.  Restorers just make it look that way.

So its not always a question of "Should I fix this the right way or not?"  Sometimes its a question of whether the compromise of a patched panel is worse than the traumatic effects of replacing the whole panel.  A unibody rail is a very significant piece of the structure to go casually hacking out over a few small holes way out at the front of it.    


How did the panel rust, exactly?  Study it.  If it's rusted from the inside-out all over the place and this weak area in front is just where it's showing the worst, then its probably better to replace the whole thing.  

Or is it rusted there for a specific reason?  Underneath the battery box was a common spot for a combination of reasons.  Factory holes in the rail, the shape of the rail causing water/etc to accumulate & sit there, the lack of anything in front of it to protect from road salt splashing up, etc.

Take something like an icepick (or a sharp small phillips-head screwdriver) and a hammer, and start whacking various areas of the rail to see where the sharp point punches through.  You could also drill a few small holes to check for thickness in other places.  Etc.  If you have a rail that's rusted in a few specific areas and the rest is pretty solid then you might wanna patch it.

   

[green69rt]

   Good advice.

[Johnny41782]

I will get pics

[Johnny41782]

So the rail looks pretty solid everywhere else just the place in the front. How hard was the rail to replace green69rt? Ive got welding skills but I am worried about not keeping everything straight if I remove a rail. If I just cut out the rusted parts and treat and coat it for rust and cap it wouldn't that strengthen the rail anyway? What do you guys use for protective coating. I heard good and bad about por 15.

[Cncguy]

Rust bullet is a better choice to protect.

[green69rt]

So how far back do you think you need to replace?   If it is anything over about 6 inches behind the radiator support then you are into the area that the K member bolts.  I would guess that there is a lot of stress in this area.   Inside of the rail are some fairly large reinforcing plates and bracing along with the threaded parts that hold the K member and front bumper supports.  I'm having trouble trying to visualize how I would go about replacing the various supports and then add the outer rail??   Maybe some other folks on here have done something similar and can chime in.

In any case I would bet that you are going to have to buy a complete frame rail from AMD.

[warpspeed]

I am going to have the same issues with a RT/SE Challenger.  Only one rail is complete.  One is rusted out, and the two rears are smashed from a minor accident from behind.  After all, I want the car to be right when I finish it.  The belief is, value wise, and best for the car after doing a ton of work and money into it, replacing all the rails will be my only option.

[Mike DC]

 
The Chally has 3 bad rails out of 4 corners?  You're starting with a pretty bad body for a stock resto.  Probably not worth it unless it's something you are really attached to.  IMO you might have more fun doing a fully custom job under there if so much of the stock chassis is bad. 


Don't they reproduce that whole 1970 Challenger unibody (in legit steel) now, like with the early Mustangs & Camaros?  I know that was announced in magazine articles a few years ago. 

     

[warpspeed]

Yes, Mike, you are right.  But, it won't matter.  Unique experience to bring a RT/SE back.  Want to do it as a retirement project.  If I can make it to retirement, ha, ha.  Besides the 68 Charger wasn't much better than the RT/SE when I got it ten years ago.  It was a long haul, but, looking at the Charger today, I think it is worth it.

[Pat1973charger]

There's a young guy over at moparts that had a very badly rusted RT challenger he put all new rails and almost all the rest of the car as well. The car came out really nice. Here is the link to the thread http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=7150205&page=0&fpart=all&vc=1

[warpspeed]

Yep!  That looks like the process I will have to go through.  Maybe not quite as bad, BUT!!!  Thanks for showing the thread.  It will help.

[Pat1973charger]

Yep!  That looks like the process I will have to go through.  Maybe not quite as bad, BUT!!!  Thanks for showing the thread.  It will help.

No problem!

[Johnny41782]

Ya thanks for that thread! My damage isn't as extensive but after lots of pondering and with the replies here I think I'm going to replace the rails. What are the major anchoring points? I mean the welds I have to cut off. My transmission crossmember is still fine so I think I'll do one rail at a time. How do you guys get rust inhibitor into the inside of the front rails too?

[green69rt]

Ya thanks for that thread! My damage isn't as extensive but after lots of pondering and with the replies here I think I'm going to replace the rails. What are the major anchoring points? I mean the welds I have to cut off. My transmission crossmember is still fine so I think I'll do one rail at a time. How do you guys get rust inhibitor into the inside of the front rails too?

The rail attaches to the torsion bar cross member and the floor braces, under the floor.  Then to the firewall brace ( a couple of spot welds), then the inner fender and lastly to the radiator brace.   Look at those braces that are under the floor,  sometimes they are in bad shape or get torn up when you pull the rail so you might want to get them at the same time you get your rails.

If you intend to replace the whole rail then take the time to build yourself some kind of jig so everything goes back the same way it comes out (somebody got a picture of their's??) 

The rails from AMD come with the shock tower but it is not attached so you don't have to replace it if you don't want.   The rails from AMD come EDP coated so there is some protection inside the rails already but it doesn't hurt to spray more stuff around.

[Johnny41782]

Thank you. Yes I think I'll build a jig like that guy did on that challenger project thread posted here.