Front Left Frame Rail: Repair or Replace

[nicka]

After media blasting the 71 Barracuda, I come to find out that I've got some rust issues on the front left frame rail.  I opened it up to find all 3 sides are impacted. Note, I'll be replacing the left inner fender.  I'm guessing that the frame rails are 1/4" thick? 
Repair or Replace?

[Shane Kelley]

That area has a lot of stress on it.   I would recommend replacement. If it's bad there chances are it's thin in other places down the line. I would also peck around with a pick hammer on other rail and make sure it's solid as well. It's to much time and money building these cars to take a chance on a failure down the road after the car finished. 

[7E-Bodies]

I have experience and prior employment in auto body as well and wholeheartedly agree with @Shane Kelley. Spend a little more now for peace of mind AND SAFETY later.

[JS29]

  And while your that far into it, I would look into the US cartool stiffing kit. 

[Dmod1974]

You're in a similar boat that I was in; my car rotted in the exact same place too.  With the inner fender already coming off the job will be cake.  Only a couple dozen or so spot welds at the core support, floor, splash panel, and torsion bar crossmember and it's on the ground. 

I had all of my panels mocked up (hood, inner and outer fender, K-member, core support) and welded in other than where they weld to the frame rail so that I could simply lift the new one into place and ensure it fits in the same way the old did.  Use the K member to help align and hold it as well, and take a ton of measurements in addition to leveling and supporting the car properly.  Download a frame chart too.  If it's anything like mine, you may have a rare change to make it more square than when it rolled off the line.  That and who knows what kind of potholes, curbs, etc. that car has seen in 45 years.

I used a jack stand at the torsion bar crossmember and another on the rocker on that side to ensure it wouldn't shift.

Getting the shock tower aligned to the frame rail, inner fender, and supports was the hardest part of the job for me.

[BFM_Cuda]

If the rest of the frame is sound, like very solid, I would patch it. Also depends on your welding skills and proper sized replacement metal.

I try to hold on to spare pieces through the years from past projects, probably too many...   

I don't know your skill level, and I know how much new rails cost, so I hope it works out well for you either way.

[Rdchallenger]

Found mine was rusted in the same spot. I made a patch that would fit snug inside of the frame rail. Put a couple of self tapping screws in to pull the patch tight then welded, seam sealed it, and etch primer.

[jimynick]

You can fix anything if you try hard enough, it's just that it may not be worth the effort, and I say that as an old bodyman, too. Sometimes, despite how much lipstick you put on Petunia, she's still a piggy, but you have a chance here to regain appearance AND safety, so I'd change it out, too. For what it's worth, I changed the rt frame rail of mine because it had a kink in it- I could've fixed it. Know what I mean Vern? 

[nicka]

Checking AMD for a Front Left Frame Rail and I see a Shock Tower with it. I've already removed the front floor so that should help.  The car sits on a frame table. That rust  location is definitely a high stress area.   

[jimynick]

I think you're going the right way here. Having the floor out definitely makes a difference. I spun the K-frame bolts out and when I slid the new rail in, just put the bolts back in, clamped it in at the torsion bar crossmember and cowl, tightened the bolts and welded the rail in. Not exactly easy peasy, but not that difficult either. Go for it, you'll get a warm glow one day as you look at your creation and have the knowledge that if you're out with your kids, the rail isn't going to hurt anybody! 

[HP_Cuda]

Definitely replace. Last thing you would want to give way under torque stress.