Need a little guidance on quarter panel patches

[His-N-Hers Woodies]

I need to patch both panels. The other side is a little worse than this one. Where is the best place to make the cut so it'll be easiest to butt and blend in the patch? Best to take it all the way rear to the seam at the rear? I've never done this before and I'm sure experience would be great to have when doing this job. Thanks for the help.

[440sixpack]

Even here in the high desert rust in the lower rears is a common problem. and you heed to check the drop offs on the inside too.

If I were doing that rig I'd come up into the flat area and go all the way back. you don't want to be on a body line that's a nightmare to finish with bondo and you will be using some bondo.

You could only go part way back but there are two problems with that, one there is probably rust farther back, and two then you have another weld to smooth out with bondo.


The old trick is to cut your patch just above where you want to make your weld then use screws to attach it to the body. then take a cut off and cut BOTH the patch and the body at the same time. this insures your cuts match as well as possible. then remove the old metal and begin your replacement project.


Be sure to only do stitch welding and cool it well. if you ty to just run a bead it will look like a crunched beer can.

[tgreese]

The usual reply is "replace rusty steel" ... but that looks quite minor and I'd be tempted to fill it if it's no more extensive than it looks. I presume you can reach the back side of the fender steel, and you can take the area around the holes down to bright steel. If you prepare the surface, choose the correct filler material and properly top coat it should be fine for a long time. You cannot use bondo, but you could use a glass fiber polyester putty like USC Duraglass. If the holes are bit too large to fill with just putty, it's possible to spot weld a backer to the inside of the fender and then fill and top coat. All this depends on your removing all the rust from around the rusted-through spots, either with abrasive disk, grinding or media blasting.

[Full Size Jeeper]

This is what mine looked like after I took all the bondo off of a previous owners repair.

[Full Size Jeeper]

This is what mine looked like after I finished fitting it.

[Full Size Jeeper]

If you go to build threads, you can see several different repairs on the rear quarters. If you go to my thread, most of my quarter panel work is on the last three pages.

[babywag]

Yep Full Size Jeeper has it right, I'd do similar and only replace what is needed.
Doing a full lower patch for a small section just makes no sense.

[Kaiserjeeps]

Metal shrinks when you weld or put significant heat to it. So when you weld it depending on the type of welding, have an air hose in your lap and be ready to shoot air on the weld right away to keep the heat down or the heat spread down to a minimum. TIG welding is the least amount of heat made. So one, to three drops of metal can be laid down with a quick blast of air to cool it. If you are using a wire feed which is the most commonly available welder for people to use, just put two stitch welds down followed by cooling. After you cool the spot you welded, you should move to another area of the panel and do two there. Cool it and move to yet another spot. You will find that this is a slow process, but very rewarding when you are complete with that stage.

Before any welding happens, you will find that a tremendous amount of time goes into fitting the patch panel to fit perfect. Look above at Full size jeepers patch. He has a perfect gap around the entire patch being held in place by the inexpensive clamps that you should be able to find at Harbor freight, eastwood etc. If any part of your patch panel is touching the parent metal, meaning no gap, you will find it will buckle terribly later when welding. It makes more work and when I have had a gap grow shut, I have run a body saw through to keep the gap there. So most of the time is fitting the patch.

Every weld in a panel should be planished when done. Using a air sander you remove most of the weld but leave about a papers thickness there. Then using a body hammer and a dolly behind gently tap with an ON DOLLY strike easing your way down the weld. This stress relieves the metal and on dolly strikes stretches the metal which will help bring it back to the original level before you cut anything out. So body filler is kept to a minimum that way.
When I had my wife hold the dolly inside the quarter on the weld, I marked the entire weld from 1 to 25 on both sides. I could tell her 5 (tap tap tap) Ok 6 tap tap tap, and so on. That way I was able to make the on dolly strike and she was a great help. You can definitely tell when you make an on dolly strike by the bounce and the resonant "chink" you get from it. You will know.

You don't have to plannish it, but it will help the metal and keep you from filling a big crater with filler. Use long rulers and a sharpie for finding highs and lows. Keep your cuts away from body creases as Joe said and the picture Full size jeeper shows above. See how his upper cut is inches from the crease? That allowed him to get a body hammer and even a sander to get rid of his weld and not dent the crease with a missed strike or gouge it with a sander or grinder on the weld removal. . When using filler and doing sanding around creases or body lines, tape the edge or area you are not sanding or filling. Tape will keep filler off where you don't want it yet, and taped before before sanding keeps the sanding block from gouging the stuff next to your work. Do one field at a time. Then tape the area you sanded and then sand the area that was taped. It will produce arrow straight and fantastic looking lines.

Some aftermarket panels have creases or body lines that are not stamped well. If you have a patch in place and the crease needs adjustment at the cut line on both sides of the cut, you can weld in most of the panel then carefully drive the steel in the crease to match the area next to it with carefully dressed chisels. Go light on the hammer strikes and only move the crease. Sneak up on it as one of my old bosses used to say. Same with removing the parent metal. Cut it back to good metal THEN cut your patch to fit. Cutting an edge three times is better than one big cut and a 1/4 inch gap that now needs filling. It is pretty slow work doing this stuff.
There is some of this metal work I describe in my build thread early on. Between FSJ'ers thread, my thread and some others you should see what it will consist of.
You can indeed do it and think about how much you will save and the pride you will get from it. And of course we all expect you will post up and show us too.

[His-N-Hers Woodies]

OK the second one went better than the first. I can't get inside the panel to planish it as you describe. This side fit better than the other side, i'd say just as good as full size's. I did take my time and let the welds cool, but I didn't hit them with air. I made a dozen or so tacks an inch or two apart and then grew each one by a quick squeeze with the MIG gun. I wound up with a bit of a bow on this side. Is this normal or is my technique off? Or can this be fixed with a hammer like you describe? Thanks for all the help.

[His-N-Hers Woodies]

Even got my yoga-teacher wife in on the action.

[babywag]

A bow or warping is fairly common on patch panels when welding.

It can be fixed using different methods.
The metal is thin and can be manipulated. Sometimes all it takes is some pressure on the backside and a heat gun on the outside.
*If* you can get to the backside of the weld the method Kaiserjeeps described is the way to go.

Is the bow above the weld as well? If not then it's a little tougher to straighten out.

[threepiece]

Even got my yoga-teacher wife in on the action.

Wait till she gets some hots funneled down those boots. Now there is some action!

[His-N-Hers Woodies]

Wait till she gets some hots funneled down those boots. Now there is some action!

You're right that wasn't the best outfit. Worst she got was a mosquito bite though.

[Kaiserjeeps]

Metal sure moves a lot when you weld on it eh? It is amazing what happens sometimes. When I have a panel that moved away from where I want it, I found a super incredible tool that attaches to a little 4.5 inch peanut grinder and really helps when metal needs to be shrunk back. If the metal "oil cans" then it needs shrinking. It is kind of hard to tell from the picture, but it looks like it receded from heat or shrunk back. So plannishing would grow it back into place. That is a very hard area to reach. I have used dressed pieces of steel to get in tight spots. Or a stud welder to pull from the outside. Anyway the shrinking tool I am refering to is a shrinking disc.... You can pull low and high spots back in plane way easier than with a hammer. Shrinking hammers are a farce. Don't ever buy one thinking it will shrink. They don't. A shrinking disc, Especially high spots this tool is so controllable and makes things better big time. I use straight edges like a steel ruler and look for lows and highs. I use a mildly dampened rag (not super wet, just moist) to cool and pull metal. You will find that you can apply a shrink to very specific areas and really reduce the filler needed. It has to be done on bare metal. No paint or filler can be where you shrink. That stinks and fouls the stainless shrinking disc.
The link to this tool.

http://www.wolfesmetalfabrication.com/sdisc.html

The other thing that will make warping worse is an on dolly hammer strike. Off dolly hammer strikes will help move metal, but on dolly forces the metal to want to move away from the eraser sized impact site between the hammer and dolly. It stretches metal and makes tension in a radial pattern. I often over work a spot and that is where the shrinking disc really makes you look good.
So plannishing a weld is a quick process moving along striking just long enough to relieve the welding tension and help get rid of any shrinking influence the heat made. I frequently check before any hammer work, during and the end where I am willing to fix the rest with spot putty or filler.

It looks like the panel might have shrunk back some from the heat. The hard part is determining if it has indeed shrunk back, and needs some mild area stretching to bring it back into the natural plane, or it has grown and stretching will just make it deeper. Try to use a big smooth rubber mallet and try to bring it out if you can get a decent strike on the back side. Read about the fairmount method and first in last out. Meaning in your case try light mallet strikes away from the weld area near the edges of the bowl shape dip and work your way to the weld area gradually. Check it a LOT with a ruler front to back. Starting in the deepest area first makes a ton more work. The Fairmount method will explain.

Your work is looking really good. What you are encountering is very normal for sheet metal and patch panels. As you guys are discovering, it is time consuming. Just get it close and go for the filler. It is just nice to keep that as thin as you can. Again, looking great!

Keep us posted.