Technical Fender openings

Searched the archives, but don't find anything on how to use wire to strengthen fender openings. I'm thinking about welding in some pretty stout wire, maybe as big as 3/8" (it's a '40 Ford coupe), but I'm not sure what would work best to form the wire/round stock, and whether or not to remove the existing lips..........appreciate your help here.

 

Ron Covell covers it in his "basic techniques for steel" DVD also there's alot of metalworking how to's on youtube. hope this helps

 

I just did this very thing on my '36 coupe. I used 1/8" diameter wire (rod) and welded it to the inside lip of all the fenders. I roughly bent the rod to the shape needed then carefully tacked near the center of the opening. I worked my way around the edge tacking about every 2 inches or so. Then went back and skipped around and completed the welding. I made the wire fit flush to the fender lip so when you feel the lip the wire is almost not noticeable. Just feels like a smooth inside edge. Lots of work but it really added some stiffness to the fenders, and I think will virtually stop any cracks from starting.

 

I've done some wheel well opening work but never just wire replacement. I know on Model A type fenders there is actually a set of die's used to roll over the edge around the wire. I've always used tubing. It's stronger and don't bend or brake like solid wire. Usually I'm doing a non stock shape. I generally make a wood buck to spring the material around so both sides come out the same. I then cut and trim the fender to meet the new shape right on the lower edge of the new tube and Tig weld it on. I like working with .065 Hyd. tubing however my last job was with 1"x1/2" .095 rectangle tube. Again a wood buck and Tig welded to the lower edge. I think you'll find round tube easier to work with for your first time.
The Wizzard

 

I use smaller 3/16" round stock, unless you want a big flare on the opening. Lots of little stitch welds, and lots of moving around to avoid warping the metal. I'd assume you would be removing the factory lip. I removed all mine, but just to the minimum needed to get the shape I wanted. Mine only needed a larger front/rear opening, not higher.
This was during mockup before the suspension was done and lowered to fit into the opening:

 

Thanks guys, this will all be helpful.

 

My rears were done that way. Just make sure you go all the way with the tube/rod.

On mine they stopped 3" from one end of the run, and the fender cracked right there due to the dramatic change in stiffness.