My truck had a flatbed when I bought it but part of the deal was I got a regular bed with it. It's solid floors and in decent shape other than a small bend in one rail and a small dent that will pop out on the passenger side and of course the usual wheel arch rot above the tires that's been bondoed up before.

I've got 4 foot long patch panels for each side and I'm getting ready to attempt putting them on along with the rest of the bodywork, I'm still learning bodywork so my question is about my approach to putting them on.

My plan is to cut out the rust until I have all solid metal to work with then trace the patch panel to fit and then just stitch welding it on to keep heat down and minimize warpage. I have a plasma cutter, air saw, air shears, cut off wheels and mig welder to use. A friend offered to let me use a flange tool but I've never messed with them, will the results be better if I flange the panels?

Any tips or guidance would be appreciated the mechanics are all new on the truck now I want to make it look as good as it drives!

 

The flange joint is easier to fit and weld as cutting does not need to be as precise and it is a lap weld vs butt weld. Works best on mostly flat panels. Flange joint around the compound curves of the wheel arch may not work very well... a butt joint carefully fitted and stitch welded would work much better. If you do any lap joints, a coat of weld through primer first in the lap area will help prevent rust down later on.

A couple of other suggestions... best to get an inner fender repair panel as well if you don't already have one. I did mine with outer panel only and had to take a lot of time to cut and fit and weld metal to replace the rotted edge of the inner fender.

Also after welding and grinding, I like to use a first coat of waterproof filler in case there is any porosity in the welds. JB weld or "metal to metal" filler works. Then regular body filler to smooth things out.

 

First you'll need a spot weld cutter to remove the wheel well liner that causes the wheel arch rot.

See that dark area? That's where dirt, rock, and mud was trapped and never dried out because Ford's fricking drain holes are too few and too small. I cut big reliefs out of the outer flange so it can be easily flushed out. If you don't do that, then the whole wheel arch rot process will start again and guess what ya might be doing in a few years.

 

Thanks for the tips so far guys, I'll stick to my original plan of butt welding the seams. The inner structure seems solid as it's not rotted very high up yet on mine.

I'll definitely enlarge the drain holes so it helps prevent it again, this is my towing truck though so it won't see bad weather or mud ever just highway time mostly hauling my jeep.