advise on some patch panels..

[socapots]

Hey all.
So here is my issue. I'm not a very experienced body man, but would like to try to tackle this problem on my own.

I have to weld in a couple of patches on the roof of my 76 impala. the area that the patches are to be put have no access to the back of the panel.

Im wondering what the best way to go about minimizing/undoing the shrinkage that will occur when i am tack welding these pieces in.

Also. is it a good or bad idea to have the patch meet the original metal on a body line? I'm thinking bad because of the shrinkage that can occur when welding.

here are a couple of pictures, and any help would be greatly appreciated.
Thanks all.

the area where the holes are is right in the middle of the roof just over the bodyline above the rear window.

close up of the holes if it even matters.

 

[socapots]

Hmm
Perhaps not enough pictures, I'll try to get a more detailed shot soon.

 

[03protege]

We have a very awesome thread in this section that a master craftsman put together. Hopefully someone has that link bookmarked and can share it.

 

[lilredex]

This one??

http://www.garagejournal.com/forum/showthread.php?t=53534

 

[rodknocker]

The thin posterboard you get at walmart basically mimics the properties of metal meaning, if you can bend the card board without it folding over, you should be able to shape your metal to do the same. That being said, you'll need to cut way beyond the visable rust until you get into clean weldable metal. Once you cut out the rusted section, cut a piece of your cardboard a little larger than the hole, put the shiny part of the cardboard towards the metal, rub your palm in the dirt then press it all around the edges, this will give you the basic pattern to cut out and transfer to the metal. When you weld it tack it only, then go around and tack keeping your spacing about 2" away from each other to minimize warpage. These are the basic steps, also make sure the metal is clean when you weld

 

[socapots]

This one??

http://www.garagejournal.com/forum/showthread.php?t=53534

thats the one!!
thanks guys, and thanks for the poster board note as well. muchly apprciated.

 

[MP&C]

the area that the patches are to be put have no access to the back of the panel.

Can you remove the headliner for access to the back side (and eliminate a fire hazard?)

 

[socapots]

Can you remove the headliner for access to the back side (and eliminate a fire hazard?)

on the look through the holes it looked like metal behind it..

but in efforts to keep fire hazards to a minimum i should make sure whats under there. The more i look at it the more im thinking of pulling all the windows and making sure all the channels are rust free.

and thank you for all the information you have given in your posts.
A question though. If there is no access to the rear of the patch area, what can be done instead of planishing. Please forgive me if this is in the other link above. I have seen the post before but still need constant review of it. lol.

 

[Rodhotz]

And look for wires their are some up there and sometimes going down the sail panel.

 

[socapots]

Hmm. Another thing I didn't think of. Thanks. Still have not had a chance to look at it again. 2 little kids Is keepin me busy.

 

[MP&C]

This hole looks like it started from the inside. Many cars/trucks that are left outside to the elements in widely varying temp changes will form condensation on the inside of the roof, where it will eventually drain to a low spot. When you remove the headliner I would look for signs of water that has run downhill, as you may need to follow it to insure you don't have rust issues elsewhere from that moisture.

As a sample, note the very evident lines where water has run down inside the roof of this truck....

and the damage it caused.... Plain and simple, condensation damage.

So if similar "trails" are found in your roof, follow to see if they caused rust elsewhere that may be in need of repair as well.


Back to your roof, seldom is the damage restricted to what is visible. I have found that typically only about 1/3 of the damage will be visible. Only by opening up the area will you see the full extent. As far as you original questions, placing a seam at the body line just above the window opening may have limited access for planishing the welds. Any weld is going to shrink the metal, so if there is no access to remedy this, the shrinking effects will likely cause a depressed area at the body line. If I were to do such a repair, I would look at accomplishing the following....

1) insure all of the rust is removed by inspecting the inside as best you can, an inspection mirror and bright light work wonders to inspect an area around window frames/roof lines above doors and windows (as viewed from inside the car, headliner removed) An ice pick also works well to identify weak areas with pitting coming through from the back side.

2) insure you have access to the back side of the welds for planishing, to stretch the area of the weld and HAZ.

3) less welds are better. Not to say make the patches small and many of them, but for example, if you can make your patch extend all the way into the window opening, the ONE weld parallel to the window will introduce less shrinking in the panel than if you had cut up to the body line crease, as you first mentioned. This would give you TWO welds parallel to the window, for more heat, more shrinking.

So making the panel large enough to remove all of the rust issues, and making it in as few pieces as possible, will help to minimize shrinking. I would suggest cutting a patch similar to the picture below, given such a cut removes all the rust, and the welds are accessible for planishing....

In forming the panel, once the crown of the repair panel is shaped the window flanges and body line can be added using a tipping wheel in a bead roller...


Here are some samples of what can be accomplished with tipping wheels..


http://www.garagejournal.com/forum/showthread.php?t=149532


http://www.garagejournal.com/forum/showpost.php?p=2952976&postcount=76

 

[socapots]

lol.
now i want to buy one. haha.
But it makes sense to cut the patch in the fashion that you have shown.
I have a feeling i will not be getting to it this season. *****. but id rather do it right then just have it done.

 

[Milton Shaw]

Having worked in GM assembly plant in the 60's no finish paint is put on that area. It just has primer and then glue and fabric, so any water is going to get under it and rust it out. Remove the inside and the glass as you will have weld splash marking the windows (don't ask how I know). The edges of the body where the window molding sit will also be rusted out and holes big enough to put your hand through in both corners. Those pieces need to be folded into a 90 and then used with a shrinker/stretcher to form the curve around the window. Lots of work but worth it in the end to keep water out of the new work. Fabric covers were used on a lot of bodies that they could not get the metal to look right if painted, so the mfg code was changed to vinyl cover and sent on down the line.

 

[2mJps]

If that was my car i would fiberglass it. It will last just as long and would be very simple to do. Sorry but if you have never done this welding new steel in will be a job. Are you going to put fabric back on it?

 

[Big-Foot]

I would give serious consideration to cutting out the rust and use a flanging tool to create a nice step, then bonding the patch panel in place.. No heat involved, the epoxies are exceptionally strong..

I hope I don't get banned or get this thread locked by not recommending a harbor freight tool...

http://www.eastwood.com/flanger-and-hole-punch-combination-tool.html

I've bonded some pretty huge panels and a friend's shop does quarters and door skins now by bonding...

Let us know how you get along..

 

[MP&C]

For something that will be covered up or the seam not visible, such as reinstalling the vinyl roof over the repair, I would agree that panel adhesive would be a suitable option. For the quarters and door skins you mention, I hope those aren't flanged repairs down through the middle of a panel, you'll see a ghost line in the repair before all is said and done.

 

[socapots]

Thanks for all the advice. I am still unsure as to what I want in the end. I like the vinyl look. But am also a huge fan of patterns on the roof.
Still unsure if I will even get to a repair this season.