I just received my patch panels from Howell's for the '27 Tudor. There is a small spot on the driver's side of the cowl at the very front, and a larger area that's bad on the right rear corner behind the fender. Howell's had patches for both of these areas, and for less than $100 for all four so I decided to try them.
The patches look to be of good quality although the cowl patch seems to need a good twisting either before or during installation.
My question for those of you with MUCH more body experience (we're talking cars here) is: should I use the whole patch or only cut out what I need to replace? I understand the bad spot will be larger than it first appears, but the cowl panel is quite big compared to what should need cut out. I plan on using the whole rear corner due to the size of the problem area so that's not a problem.
Sometimes I think it would be easier to "hide" the repair using a larger panel, but then I think that I'll be welding a lot more to put it in, creating a larger area to hide too.
I would make the panels a reasonable size and use them . When I redid my touring I spliced in the panels with a copper backup strip and pop rivets. I welded in the panel and removed the backup strip and welded up the rivets.
Here's a shot of the area in question. (Thank goodness the body wasn't as bad as the hood, apron, and other pieces around it.) I can show a photo of the patch panel over this area tonight.
I only used the part of the patch panels needed on my 26 roaster. Just cut panel to match the bad part and butt welded on place.
Personally, I'd only use what was necessary...making sure you cut back to healthy/weldable material on the original panel.
I bought the same patch panel and it wasn't close to my car's profile, so made my own.
You can see some rot-out just above the patch, and that got it's own fist-sized patch later, once the panel was stabilized along the bottom.
Invest in a "Flanging tool" that goes on an air chisel. It provides uniform skin stretching and less warpage when welding. Used it on all 3 panels on both sides of my 26 coupe and youd never know it unless you look from the inside...
Thanks guys. I think I'll cut out the bad spot this weekend and see how big the patch should be, then trim accordingly.
After that, I need to decide how to strip the body. The original plan was to have it soda blasted by a contractor that was going to go to my friend's shop, but I can't afford to have my friend finish it (he charges a very fair rate but I have too many irons in the fire). The shop is 200 miles away so I'd have to find someone else to do it, and I don't think anyone will blast on-site in my neck of the woods like his guy will. Dad wants to strip it with a wire brush in the drill and grinder, but I don't think that properly cleans the metal and won't get in the corners or insides very well either. I can sandblast it myself but I am afraid of warping it.
I always make the patch first. Figure out how big you need to go, then make the patch. Place the patch on the panel and mark around it with a pencil. Then cut the panel and trim to the pencil line - leaving the line. The patch should fit perfectly.
TIG welding is preferred over MIG. When you weld it the weld is going to shrink which will create a low spot along the weld. If you TIG weld it, you can then go in with a hammer and dolly and stretch the weld back out to get a nice smooth panel. MIG produces a hard weld which you can't stretch. You can grind it smooth but you can't really shape it - at least it will be a lot harder to shape.
Be sure the old metal around what you want to patch is thick enough to take a weld. You can burn thru the old metal and create more problems and have a bunch of pin holes.
As for stripping I used a liquid aircraft stripper that worked quite well. The old Ford paint was tuff in some areas and required a second or third application but I got my car down to the bare metal. Just be sure to clean it good before priming.
Be sure to look at both the outside and inside of the panel to be sure that the outside is not just a skin which looks good. All the rusted area should be cleaned up. Then remove the thin or rusted out portion, and then the inside should be sealed including the portion behind the wood so the rust will not continue to spread.