I'm replacing sheet metal around the wheel well and need some expert advice. I wanted to replace as little metal as possible so I only cut out about 1.5" past the rusted through area. I'd like to leave the inner wheel well in place if possible.

I planned to flange the existing metal, then use panel adhesive to put my new piece in. Problem is I cannot flange the areas circled in green because the inner well is still welded near the ends (should've been obvious to me before I started, but oh well).

Ideas for the best way to fix it, keeping in mind I want to replace as little as possible?

 

Hmm, I don't know exactly what i am looking at, but how about flanging what you can, then what you can't cut a piece of metal and glue and clamp behind the old metal, treat the backside, and then glue you peice in. Fit the piece before clamping or screwing it in. As long as most of the patch has a flange to glue to, if you have a small spot you could just fill in the butt seam with some adhesive and it should be okay then finish up when blending in the patch with filler. Sometimes there might be a glue line will show when not replacing the whole panel. Might want to do a search and study up on that and the best way to deal with it. We glue in a lot of panels at work on semis, but replace the whole panel gluing like the factory.

 

Should've explained a little more. 77 Ford F-150 rusted through on the bedsides just over the wheels cause there is an inner fender well (the light colored and rusty area on the bottom photo) that traps mud and moisture. Very common problem on these trucks. As you can see in the bottom picture I've cut away all the rust present on the bedsides in the top picture but the inner fender well (or whatever it's called) is welded to the bedside wheel lip where the green circles are so there's not enough room to get my flange tool in.

Guess I could cut the rest of the spot welds out of the lip that are holding the inner well and lip together and bend the inner well back, but I didn't want to risk bending up my good sheet metal in the process. Make sense or do I need to add another pic?

 

your better off welding ,forget the panel adhesive. Buy a patch panel then drill out the spot weld on the inner fender well and reweld to the new patch panel.
Just my 2cents worth.
Rich

 

But if I flange the existing metal to place the patch in, I can't get any rustproofing behind the weld, regardless of whether I can bend back the inner well for access. Won't it just rust through where I've welded it in?

 

It appears you need a inner wheel well also. I had to replace both inner and outer wheel wells on my 95 F-150. I welded the new inner and glued the outer to the inner on the inside. I butt welded the outer to the box side. Make sure you cut back far enough into good metal so the rust doesn't come back. My .02 worth

 

Was planning on patching the inner till you said that.
How long have the butt welds on the box sides lasted? That was one of my concerns, the other being the ease of burn through when butt welding sheet metal (I've not welded much in about 10 years).

 

I wouldn't butt weld the patch in,(you can do it though) flange your existing area after getting the patch panel to the size you want. cut your patch to lay in your flanged area then spot weld or mig in place.
This all depends on the tools and welders you have at your disposal.Use a weld thru primer ..
Rich

 

I would butt weld instead of a lapping it myself and try to keep a tight gap between the piece you are welding in and the new patch. I don't like the idea of two overlapping pieces of metal if I don't need to when welding, panel adhesive would at least give good protection when it coated between the two piece unlike welding which will burn off most coatings. On a lapped seam moisture could get between the two pieces and the inside should really be seamsealed too. Overlapping seams always seem to be a problem area for rust. Also I would drill out the spotwelds around the lip till your through the outer panel without drilling through the inner, or use a spotweld cutter or griner on them, and spray a weld through primer there where it overlaps the inner. Weld through primer I believe melts and kinda reflows into the weld. If you truly can't get to the back to treat it is there a place you can drill a small hole inside somewhere to get a rustproofing wand into and spray some some rustproffing/ cavity wax inside to treat. Or maybe you could just tack a few spots along the flange, weld up your other three sides, not building up heat, then grind of you tacks along the flange and sneak up through that opening and hopefully hit the backsides of the welded seams with some rustproofing-cavitywax, then spray a weld through primer on the wheelwell overlap area and spot weld that in. Just trying to throw out some ideas.

 

As I said, A butt weld will work, but for a novice to keep from warping the side is tough . I've done it both ways.the inner panel on those trucks alows for rustproofing to be sprayed on the back side.with special wands.
Also if this was a show truck and meant to last forever,you would replace the quater panel for longevity.

No argument from me either way will work.I just hate panel adhesive ,I think it is a cheap way out and takes away from the trade.anyone can squirt glue.
Thats like Macco !!!!! sorry for you macco lovers
Rich

 

Not a show truck, just a weekend hunting/fishing/home depot/take the family out riding truck. If glue holds up and it is a cheap way out and anyone can do it, that's 3 good reasons for me to do it!

Seriously, I read in another thread that a guy as a test glued one side, welded the other and the welded side was rusting through within 5 years. Did he prep it properly, coat it, and take care of it, I don't know. But the glued side he says was still in great shape. He said he'd write up a description of what he did, but I don't think he's done it yet.

I think I can weld it, especially if I flange it, but if there's less work required with the glue, and it holds up well, and I don't have to worry as much about corrosion in the overlap, it would be hard for me to argue against the glue.

Thanks for all the expert advice. Whichever way I decide to do it I'll be better informed about the process and how to do it properly.

 

I did pretty much this same repair on my crewcab early last summer. I had the same fears as most hobbiests - panel warpage and/or panel burn-through.

The answer (for me) was to take the rusty sections I had cut out and hack off sections of the patch panel I'm not going to be using them, and bevel the edges and practice welding until I got my mig welder set correctly, and got the technique well enough that I'd not be grinding for the next 250 hours of my life. After a while, I "got it" and was able to weld in the panel:



While I butt welded the panel in, I seriously "cheated". I'll explain that further down. What I did was cut out the rusty area as necessary all the way through - from the painted bedside through the inner wheel liner which as you know is a structural piece. Here is a picture of the patch welded in from the inside, but it also shows how the inner fender was hacked as at this point in the photo series I hadn't covered the hack-work from the inside yet. I did that last, by taking a section of the patch panel left over,



The "cheat" is that it's not a true buttweld. What I did was bevel the edge of the cut section of the wheel arch with my angle grinder, to something approximate of a 45 degree bevel. When I cut out the patch panel to slightly larger than the hole I made in the wheel arch, then hand trim it down to proper size using the angle grinder - BEVELING IT AS CLOSE TO THE SAME AS I DID THE WHEEL ARCH. Like so:




Here is how the grinding of my tack beads looked after an hour or two of grinding. Obviously more to do, but it's not looking to bad considering I haven't done this type of repair more than once before, and at least a decade ago.

 

Did you explore the idea of gluing in the patch panel?

 

Once the outside is ground and shaped reasonably well, it's time to attach the inside. I seriously considered just coating everything with POR15, rustbullet, or even spray on bedliner and leaving it open, however I decided to repair it at least "somewhat" correctly.

I took a piece off what was left of the patch panels, shaping it with my angle grinder until it overlapped the opening I had made earlier in the inner fender liner. I "adjusted" the curvature of this piece with a ballpeen hammer while resting the patch piece on a stack of newspapers. After reasonable shaping I had it fairly close, and torqued it the rest of the way with my hands, until it was fairly snug around the opening. Since it wasn't going to be butt welded, but essentially laid on top, I moved the welding power up from "A" to "B" (out of "D") and just nailed my bead through the top through to the bottom for one inch, then started another bead about 3" away. Since this is inside the wheel well I wasn't terribly concerned about appearances so I went with what seemed easier than beveling everything to near perfection.

Once that was done, I ground off what beads I had to, could do, felt like doing, then drilled a one inch hole (with a bimetal hole saw) in the wheel liner towards the outside of the bed, but not through the bedside (obviously that would be bad!). Through this hole I sprayed in POR15 all around. Up, left, down, right, all around 360 degrees. I let it sit over night, then repeated it in the morning. Let that sit overnight, then plugged the hole with a pliable plastic hole plug of some kind, which I put expoxy under the lip so it wasn't coming off.

I did both sides of the bed in parallel, and I think it turned out AOK. While my repair came out reasonably well, I didn't clean up the usual dings, scrapes, nicks and such from my actually *using* my truck as a truck. I could have skimmed those dings (unrelated to the wheel arch repair I just did) but honest I couldn't be bothered. She's not a show vehicle, and I was happy with the rust being gone and the bed being painted the same color as the original (ford "YY" code white-ish).

 

Good point fred, that you made me think to bring this up, if someone hasn't already. The panel adhesives likely won't be as likely to corrode between the lapped area as you won't be burning off corrosion protection, BUT they still aren't recommended for structural panels like rockers, your inner wheelwheel. For the bed side it would be okay to use it, but not to patch the inner. Vehicles are using more and more adhesives today, with some I believe are mostly glued exterior panels to the inner structure. But the recommendation is still to not use for structural panels and large panels like a complete box side you would still need to place a few spotwelds on the panel like the lip at the front of the bed and back by the tailight. Adhesives have been used on door skins for years and they are more widely accepted today and used in more applications. The clamping or screwing of the panel should be done while curing, since this is what gives the bond strength. Also heat will soften the adhesive and may ruin the bond, so you don't want to weld or torch right next to the seam that is only held by adhesive and spotwelds are not placed.