Well I'm kinda new at this rust repair on my truck. I was hoping to find some cab corners so I could just cut this out and weld in a new piece but I can't find any prefabbed corners. So now I'm kinda stuck. These angles are well a bit more than I really wanted to deal with. I was thinking I could just tack in a bead and slowly filling in the hole. But I wanted some input first.
Here's a pic of the damage ignore the rust eating navel jelly. Rock knocked the crap out of the corner days before I deployed and by the time I got back it ate through. Big hole is maybe the size of a quarter.
The first thing you need to do is grind away ALL the bondo in the cab corner and see what is is you are dealing with. That cab corner has rusted that bad because what whoever fixed that corner in the first place didn't coat the back of the panel with a wax oil, or other form of corrosion prevention. When you weld a pull tab, or unispot pin onto a panel to pull the damage out, it burns all the paint off the back side of the panel. And if you do not re-coat the back side after you are done, it will rust..... guaranteed. Alot of shops will skip this step, quite frankly because it is a pain in the ****, and to do it properly you need to pull the interior trim panel to gain access, which includes pulling the back seat, upper seat belts, upper trim panel, rear body trim, ect...... That's why it's a pain. All that extra work to just squirt a little bit of wax oil on it? This is the end result. Most of the time, people do not own a truck long enough for this slow and methodical rust to find it's way through, at least to the original owner. By the time this rust finds its way through, the owner has traded the truck off, and it is somebody else's problem.
If you were the owner of the truck when this repair was done, and still have the paperwork to back it up, the shop who did this repair is on the hook for it. Their lack of care caused this.
Let's assume that you were not the original owner, and you have no idea of the history of this repair. You would have better luck wrapping your lips around a valve stem to blow up a flat tire than to try and start welding up these holes. The rust is far too advanced, and by the time you grind away all the bondo and get into the extent of the damage it will quickly become clear. You need to get a replacement cab corner. First, start grinding and figure out just how much steel you need. Then call a salvage yard near you and find a replacement corner, and weld it is place. To do it properly, you are going to need to remove the box, remove the rear interior, and replace the entire rotted out section. I'm guessing 14" high, and 8" in towards the rocker should about do it. Pretty much cut it at the lines that that picture shows, but a little taller. Do it once, do it right......and wax oil it when you are done.
There's zero bondo there. Truck took damage from a big rock getting tossed by my rear tire it chipped the hell out of the corner. I didn't have time to properly protect to prevent this from happening. I picked up some sheet metal last night. I'll be cutting the bad out and tacking in some new steel. I'll have to find a replacement corner soon enough I'm sure.
Well, that white layer sure looks like bondo in the picture. It also looks like a rust hole on the inside of the door opening (where rock chips are impossible). I've never seen this rust eating naval jelly before, so I'm not sure what exactly it is, or how it is supposed to work. Sounds kinda gimmickey to me. Do you have a pic without any of that jelly on it? That pic really does give an indication of a heavy coat of bondo. Either way, grind it away to the point that only solid steel can be found, and cut and weld from there. Good luck.
The white is the primer under the paint. I bought the truck used but I know the guy that had it before me. Big insurance salesman and he bought a new truck every other year so I got this truck just over a year old at half the price. I've seen a few emails out to salvage yards. I know the cabs are out there just hoping one of the yards will cut the part out.
The white stuff surrounding the rust is not primer dude. The factory has an "E" coat, a sealer, base, and clear coat. Either that white stuff in the picture is the result of the jelly you put on, or it is bondo. Ther is no way, no how, no chance that that is primer. Arount the outer edges of the paint you already ground off, that outer edge shows the color coat, and the primer under it. It goes charcoal, (color of truck), light grey (primer), and white (suspected bondo layer) Unless that jelly you applied has done something strange, and there is an optical illusion in that photo, you have bondo in that cab corner. Doesn't matter if your friend bought it new or not. The dealer may have had transport damage repaired, and not informed him.
I hope another tradesman can pick up on this, but that absolutely gives the definite look of bondo. From those pictures, I'd bet large on it. Can you wipe off any and all effects of the jelly junk you smeared on there and snap another couple pics? This has caught my attention in a big way.
I did a bunch of rust repair on my 97 f250 right about this time last year. Here is a pic of my most challenging patch. This was my first attempt at anything near proper bodywork (back in the mid 80s I did some awful repair jobs on my F150 that consisted of expanding foam and beer cans topped with bondo, needless to say, it didn't last).
This cab corner/rocker combo area was the trickiest for me, and it took me a while to even get some idea of where to start. With with a lot of forming and pounding and cutting and welding, it eventually took shape. I then used fiberglass filler to fine-tune the shape and regular filler to smooth. Most importantly, I got primer, paint, and rustproofing on the back side to make sure this doesn't come back.
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