Early Fender Repair Advice

I wanted to start a thread about my weekend ambitions to see if folks that have done this before have any suggestions/advice or comments before I start cutting and welding.

My fenders are pretty rusted and Bondoed out:


This weekend I'm planning on cutting out the supports, and replacing the missing metal with 18ga that I cut to match paper templates (thanks for the advice @dnee007!)


And then once that's done, spot welding the new supports back onto the new sheet metal.

I like Fitzee's method of overlap and angled cutting and tack welding butt welding sheet metal outlined here:


Has anyone else done this? Got any pointers/advice?

Also, what's up with all of the holes that pock my fenders - which ones should I fill and which ones have a purpose?

 

I've been using that method with decent success on my body repairs. Like warloch mentioned, it takes a bit of practice to get good at it. The hardest part is "inside corners" like you have towards the back of your passenger fender.

As he also mentioned, don't worry about getting super close to the rusty spots. I had to redo a few repairs with a bigger patch, that came out MUCH better than the tiny patches I was trying to do (fixing a rusty spot weld for instance).

I found that the areas where I had too much gap, my copper spatula tool worked as a great backer to fill the spot.

Do short tacks, moving around the whole panel. Zzzzt.....move. zzzzt.....move.

 

If you don't have a panel prep tool or a flanger, you can sink the bead after welding by heating red hot and hammering it down. Depending on location, looks, bondo, etc.

I made my own flanging tool from old vice-grips. Or you can buy them.

 

Thanks you guys. What do you think about the overlap / diagonal cut method in the YouTube video above?

 

Both have their place. Overlaping is easier because the metal thickness is doubled and you can make sure you have good base metal to weld to. Be sure to use weld through primer, because the overlap leaves places for moisture to get in.
If you butt weld, don't get in a hurry, and move around to keep from warping the metal from the heat. I try not to make the patch panel have sharp corners, too much heat in one spot.


I form the patch panel and lay it out on the body and scribe the line to be cut. I rough cut the bad part out roughly and then cut it out precisely to get a good fit.
For Mig welding, I leave a small gap, for Tig, it fits tight.


I use blue layout ink and scribe the line to trim for fitting the patch panel.



Dave

 

Thanks.

If I understand the “overlap” method outlined in Fitzees video above it’s only technically an overlap until you do a 45 Degree cut So the overlapped panel fits via a snug angle with zero kerf with the patch panel. I practiced this a few times this week with scrap 16ga and it worked well.

Since I’ll be at the Roundhouse I will have access to MiG and Tig, but my Tig skills are pretty rudimentary so I’m thinking with my limited skill set that wire feed 0.023” will yield superior results.

 

We’re able to purchase new supports?

 

Yes Kaiser Willys has NOS braces:

NOS Inner Fender Brace (2 required) Fits 55-71 CJ-5, M38A1

 

That’s fantastic! I started one of my fenders a couple years ago, but wasn’t able to find the brace.

 

Thanks again, I just ordered a set.

 

Good information. Doing just a small section at a time forces you to let it cool and avoid distortion.
That looks like a good process. I'm guilty of rushing it and then dealing with heat distortion.

Thanks for that info.



Dave

 

I was hoping you weren't just re-skinning the inner area and keeping your rusty brace/support. Definitely get fresh supports! The only good metal is white metal after blasting. Any of that dark metal will quickly come back and haunt you.
-Donny

 

No, I'm doing both the skin and the braces. I'm moving slowly though and trying to do it a step at a time, with the skin first. Started by filling in some of the fender flare holes along the rim of the fender. The Fronius TransSteel 2200 welder that I borrowed has a crater fill function somewhere in the menu but I haven't found it yet...


Got the patches shaped and cut and tacked on over the weekend. After work today I will be cutting through the fender along the patch panel at a 45, and starting the stitching in. Then once that's done, I have to get some weld-thru primer from the FLAPS, and then I'm going to tack the brace back on along the edges since I don't have a spot welder. I left the top and bottom on fr now to help the fender keep it's shape as much as possible.

I tried to made a foldover at the bottom of my patch panel, which seems to have worked for the inside segment (under the hood), but on the outside (the place where you put your beer while your camping) I have to figure out how to replicate the 1/8" foldover somehow.

There's a bit of an airgap under the patch panel, I stupidly started at the top and worked my way down to the fold, and it would have been much smarter to start at the fold and work up to keep things tight to the panel, so I might cut from below and work my way up to try and alleviate the gap as I stitch.

Although I am originally from Hawai`i, no I don't weld in barefeet....

Here's a view of the backside:

The press-brake we have at Roundhouse is a donated old Harbor Freight model that wasn't cared for very well so it's not very good at nice clean accurate bends. Have to think about this one for a while. About the only thing I can think of it to make a much bigger bend and then cut it down, it would be great to repair this in a way that preserves the foldover where the two parts of the fender come together. Something I am sure someone with much more skills than myself could do handily.

I like NOS parts - the braces will be a perfect fit.

 

Tried a lot of different cans of weld thru primer. Expensive, cheap, all seemed to clog up and no longer spray.
Got a quart of Rustoleum Cold Galvanizing Compound, brushed it on and it worked well.

Rust-Oleum Professional 20 oz. Flat Gray Cold Galvanizing Compound Spray-7585838 - The Home Depot



Dave

 

Correct me if I’m wrong but I always thought you were not supposed to run an arc through anything galvanic because of the toxicity of the fumes?

 

Seems like I remember that now that you mentioned it.
Welding galvanized and breathing the fumes can make you sick.

I stand corrected. It worked years ago, but I guess I lived in spite of it not because of it.

"Pay no attention to the man behind the curtain." Good point.


Hopefully you can get some good weld through primer spray cans now.


Dave

 

If you are going to replace the whole brace/rib, I'd suggest you skip the weld-through and paint everywhere with epoxy primer. I would definitely skip trying to piece-in that brace and get the replacement part from Kaiser-Willys. Maybe that's what you are doing ...

Then I would patch in the fender completely, paint with epoxy primer, remove the remains of the old rib/brace, and plug weld the new brace to the fender. No weld-through needed. Suggest you review the body work thread from Robert at MP&C at GarageJournal.com MP&C Shop Projects - The Garage Journal Board

 

Yes that’s exactly what I’m doing, apologies if I wasn’t clear. I just left pieces of the old brace while doing the patch to help the fender keep it’s shape.

so @timgr to make sure I understand you - after patching, I would be drilling holes in the brace before clamping it down and then plug welding through those holes, correct?

 

Yep. Robert (see thread above) uses a twist drill with the end ground flat to scrape away the fender paint inside the plug weld holes.

He also skip-welds his sheetmetal butt joints with dots every inch or two, and planishes the dots after each pass to remove shrinkage. Repeat until the entire line is filled in.