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Hey guys...hadn't been on in a while, but I was looking to get a few opinions on my driver's side inner frame rail. Here's the deal - I cut out my floors doing the long pan replacements from the firewall to the backseat, and while I was at it I cut out the short firewall patch replacement on the driver's side to replace the mangled metal from whoever did this before I got there:happyhapp. In doing so, I now have the entire length of the frame rail open and exposed on the driver's side all the way up through the torque box that I can now see inside.

Two problems I need to address - the first is inside the torque box where the frame rail overlaps there is a quarter size hole, however it's only the torque box and does not go through the frame rail to the outside (in other words it stops at the frame rail and doesn't go any further). I pried around in the hole to see the extent and the quarter size is all it is - it stopped flaking and got to hard metal. So would it be a safe bet to just weld in a little piece of metal and plug the hole, much like an exterior panel would be put on, or are we talking ripping out the torque box and putting a whole new one in (which may be overkill for the size of this hole)? The moisture probably got there because the idiot that did this crappy patch job before me smashed up the firewall, drilled a bunch of holes, and glued the torque box and the firewall together with a crapload of bondo, of which that bondo joint eventually split open. Welder, anyone??:headscratch:

The second question is the frame rail itself. Over the years of use the frame rail's end where it's bent and welded together is now pinched with a "v" in the end. My original intent was to fix this by just popping the welds, reshaping the end, and welding it back together, but the more I tried to do this the more the end started basically imploding on itself. So I picked up an M121 replacement rail and my question on the rail is this - how much of it do you replace? Knowing that I'm going to put subframe connectors on (but I haven't ordered them yet so I don't know how far up they will go on the frame rail), I'm trying to determine where to replace the rail. Is it ok/acceptable to just cut the tip off of the rail and just weld on a new, non-bent end, or should I cut up to the tranny tunnel mount and replace it to there, or go ahead and cut out the rail completely and replace the entire thing?

If I only do a partial replacement, which I've heard of some people that have done that, is it recommended like I've read to basically cut the original rail a little long so the new frame rail slides onto the old rail a little bit so you have something to weld on? Another idea that my buddy and I looked at was cutting and replacing it in two different lengths - basically cutting back to the tranny tunnel mount on the right and the torque box on the left, with the intent of spreading the stress lengthwise down the rail instead of having a short weld in one spot (for instance cutting the rail straight across). My only concern on not just replacing the entire rail is the huge factory weld on the torque box that I'd be cutting through to remove the old rail and risk damaging the torque box in the process - that direction seems more like the more I start taking off, the more damage I risk to other parts (ie the torque box) for such small patch jobs. I'm just trying to do this right the first time, but not go overkill here on the replacement parts.

Also, I've seen one guy that cut up some "L" bracket steel pieces and welded those lengthwise inside the rail for added rigidity. Sorry for the long post...any thoughts on this stuff?
 
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