how bad is this rust?
If the damage really is just at that rail because of battery acid, replacing the rail may be worthwhile. That assumes the rest of the rails are in good condition.
As far as making a generic patch, I think that ship has sailed. If you look in this picture, it appears the front of the rail is no longer lined up with the rear of the rail. Actually, in this picture it looks like the front of the rail is hardly even connected to the rear of the rail. A patch wouldn't even lay flat between the two sections.
I have patched frame rails before, and I don't think there's anything wrong with it if the damage is localized. But, it this case, I think the damage is too extensive to just use a patch. A patch needs good sections of rail to locate it, with your rail you wouldn't be patching, you'd be fabricating a new rail piece by piece, and that isn't a good idea.
Which means you're going to need to do some precise measuring. Leaving the inner fender in will help line things up, and so will the K member. But, you still have to make sure it all lines up. This is especially true since the damaged section includes the suspension mounts for the left front wheel. By the looks of it, I would guess that the alignment of the front left wheel has already been effected.
With the amount of damage to that frame rail, I would want to replace the whole rail. I'm not saying it CAN'T be sectioned, but, that's not what I would do. I definitely wouldn't try to patch it. I would at least want to section the half of the rail that's damaged. The section that crackedback has looks a little short for the section that's damaged in this case, although I'm sure there are plenty of cars that section would work for. Even with sectioning, you want to make sure that you cut everything back to good metal so you have something solid to weld to. Once you've done that on this frame rail, Im guessing you'll have less than half of the rail left. Plus, its actually EASIER to replace the whole rail, you don't have to worry about lining up two different sections of rail, getting the intersection of the two rails straight, getting at the entire length of the joint between the rails to weld it up, etc. When you replace the entire rail, you have more intersections to help locate it and no long welded joints, just the factory spot welds. After all, that's how the factory designed it, and how the factory put it together - there's a reason they did it that way...
If the damage really is just at that rail because of battery acid, replacing the rail may be worthwhile. That assumes the rest of the rails are in good condition.
As far as making a generic patch, I think that ship has sailed. If you look in this picture, it appears the front of the rail is no longer lined up with the rear of the rail. Actually, in this picture it looks like the front of the rail is hardly even connected to the rear of the rail. A patch wouldn't even lay flat between the two sections.
I have patched frame rails before, and I don't think there's anything wrong with it if the damage is localized. But, it this case, I think the damage is too extensive to just use a patch. A patch needs good sections of rail to locate it, with your rail you wouldn't be patching, you'd be fabricating a new rail piece by piece, and that isn't a good idea.
Which means you're going to need to do some precise measuring. Leaving the inner fender in will help line things up, and so will the K member. But, you still have to make sure it all lines up. This is especially true since the damaged section includes the suspension mounts for the left front wheel. By the looks of it, I would guess that the alignment of the front left wheel has already been effected.
With the amount of damage to that frame rail, I would want to replace the whole rail. I'm not saying it CAN'T be sectioned, but, that's not what I would do. I definitely wouldn't try to patch it. I would at least want to section the half of the rail that's damaged. The section that crackedback has looks a little short for the section that's damaged in this case, although I'm sure there are plenty of cars that section would work for. Even with sectioning, you want to make sure that you cut everything back to good metal so you have something solid to weld to. Once you've done that on this frame rail, Im guessing you'll have less than half of the rail left. Plus, its actually EASIER to replace the whole rail, you don't have to worry about lining up two different sections of rail, getting the intersection of the two rails straight, getting at the entire length of the joint between the rails to weld it up, etc. When you replace the entire rail, you have more intersections to help locate it and no long welded joints, just the factory spot welds. After all, that's how the factory designed it, and how the factory put it together - there's a reason they did it that way...
