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post #1 of (permalink) Old 12-23-2001, 09:44 PM
MarkF
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Best way to install patch panels

I'm in the process of fixing some bad spots on my 86 CJ7. Specifically the area under the rollbars are shot. I picked up a piece from Quadratec called the step brace or something like that which after cutting is perfect to cover the spots I need. My quesion is what is the best way to install, Weld or rivit? My welder (Craftsman 90Amp MIG w/ gas) even on the lowest setting sometimes burns through the sheet metal. Adjusting the speed helps a bit, but that is lot to weld if I completely go around the entire patch (10" x4" x 4).

I'm looking for the best way to do this. I used my grinder and sawzall to cut out the rusted areas. I sprayed Rustoleum primer on the floor and on the bottom of the patch. Then I started to weld and hammer the patch as I did the install. Not sure how to do the corners (where the vertical meets the horizontal). Any advice is appreciated.

Thanks
Mark F

1986 CJ7, Chevy 350, D44/D30, more to come shortly
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post #2 of (permalink) Old 12-24-2001, 02:23 AM
**DONOTDELETE**
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Re: Best way to install patch panels

Don't bother riviting, welding is the best way. You just have to find ways to control the burn through.

When I did my CJ-7 it had rust in the same places, under the roll bar and in the foot wells.
I made my own panels and used a flanger to make lap joints instead of butt joints.
The lap joint helped with the burn through problem but if I were to do it again I would use butt joints instead.
The problem with the lap joint is getting them sealed afterwards. If you can't seal them up they will rust out.

If you look at some of the work the Hot Rod people do you will see they tend to use tight butt joints.
They clamp everything in position then tack weld it and then fill in using short welds. Let things cool down as you stitch things up or the heat will twist things out of shape.
http://www.so-calspeedshop.com/whats...ine/srmay.html

Another thing that I've seen used is these little panel clamp blocks that hold the two pieces tight together for a good butt joint.
http://sites.netscape.net/nickwarchol/willysmb4.htm

As far as controlling burn through there are a number of things to consider.
First, if there is any rust pits the metal will burn through, there just isn't enought metal left. Cut back the metal till you have clean metal and use a bigger patch panel.
Use the smallest diameter wire you can get for your mig. The smallest I have is 025. The wire diameter controls the heat of the weld almost as much as the settings do. The opposite is true when you are welding thick material with the mig, use the thickest wire you can.
MIG's are CV machines (constant voltage), so like the flow of liquid through a pipe under constant pressure the cross section and length of the arc determine the heat.
Also, weld in short strips, as the surrounding metal heats up its more likely to burn through.
If the metal warps out of position it will also want to burn through.
If the back side is open you can try using a brass or copper backing block. The block supports the weld and also absorbs some of the heat and the steel wont stick to the copper.
On my next project I think I will try making a panel block and backing block combination.

The following pictures are of the flanger I used and a test butt joint I did recently. The weld penatrates nicely without burning through.






post #3 of (permalink) Old 12-24-2001, 07:58 AM
MarkF
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Re: Best way to install patch panels

Damn nice job on those cuts and welds.

I'm going the overlap route, cause there is no way I can cut and measure well enough to do butt welds. My goal is to weld both sides (when access permits) and cover both sides with POR15 and then Herculiner. I hope that will slow down the rust in the overlap areas.

I forgot about the thinner wire, I probably have some around, it has been so long since I welded thin stuff I forgot I have thin wire.

Thanks
Mark F

1986 CJ7, Chevy 350, D44/D30, more to come shortly
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post #4 of (permalink) Old 12-24-2001, 10:33 AM
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Re: Best way to install patch panels

Dont know if this pic is good enough but you can see how I went about things . My rear floor was bad so I rebuilt it too and made my own wheel houses . I made my "step plate" or traverse section as I call it . 3 pieces of 16 ga., each overlapping a couple of inchs and then just stitch welded the plates to the tub (what was left of it .
I used my Lincoln on about 50 amps with 023 wire and Blueshield gas . I sure got to know how the tubs were constructed . I kind of reverse engineered mine [img]/wwwthreads_images/icons/smile.gif[/img]. Hope this helps and if you need any advice , just yell .What gauge metal is the section you bought ?




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post #5 of (permalink) Old 12-24-2001, 11:47 AM
 
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Re: Best way to install patch panels

Welding is the best bet, but you dont waht to try to run a continious beed around the panel. You should spot weld it into place, and spot weld inbetween each of the other spots. Continue until your spots are not more than a couple inches apart. Actually you can spot weld them until they all connect if you wanted to. You just dont want too much heat in one area because you can make the metal brittle, and the heat will warp the panel. Once you have all your spots down, you can grind the high spots of the welds and use a good body seam sealer. It should do a good job.

TJ

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post #6 of (permalink) Old 12-24-2001, 11:55 AM
MarkF
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Re: Best way to install patch panels

I'd guess the guage I'm using is 18 or 19 (standard cheepee replacement). So how close do I do the spot welds before going to the seam sealer?

1986 CJ7, Chevy 350, D44/D30, more to come shortly
post #7 of (permalink) Old 12-24-2001, 02:38 PM
 
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Re: Best way to install patch panels

You can spot them until the spots connect (continious), or you can do it until the spot welds are aprox 2 or 3 inches apart (if its along the entire step panel. The smaller the panel, the closer you want the welds. Just keep structural integrity in mind and use your judgment.

TJ

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post #8 of (permalink) Old 12-24-2001, 04:49 PM
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Re: Best way to install patch panels

Thats probably why your burning through easy in spots . Tough job to weld 18 or 20 ga. to that heavy original tub section . Not enough heat and your in trouble later and to much you burn through . That was the reason I made my own from 16 ga. Do as the poster above said , little bits at a time . This probably wont help with the section your doing now , but I found when I was spot welding the inner wheel houses in , I had a buddy spray or mist the outside so as not to warp the body panels . You can apply this technique where necessary and it works well . Good luck .



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post #9 of (permalink) Old 12-27-2001, 08:44 AM
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Re: Best way to install patch panels

Just weld short beads and keep a wet sponge or rag handy to cool the welds, this how we always did panel replacement at the body shop. Alternate your position around the panel and take your time. I suspect that your craftsman is a lot like my hobart and doesn't have the infinite voltage adjustment. It takes a little tweaking, but it will weld pretty good on sheet metal, you just need to find the right travel speed and wire speed. Also, focus the heat a little more on the thicker peice and just let the weld run into the replacement place. I have always welded about an inch at a time and cooled the welds with the sponge to prevent warpage. If you do get a warped spot, you can pull it down with a torch. Heat a spot about the size of a dime to almost white hot and cool it rapidly. The rapid cooling causes rapid shrinkage. I have seen good body men pull out some huge oil can wobbles with this technique. If you can, get some scrap and practice welding, it makes a huge difference. One more thing, you said you sprayed primer on the piece you are putting in, make sure that there is no paint in the area you are welding. Hard wire really likes to weld clean metal and has real difficulty with dirty stuff.

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