Reinforcements for whole floor removal

Mopar Body and Trim

  1. Tylinol

    Tylinol Active Member

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    Hi everyone. Over the winter I'm overhauling my '69 Barracuda notch. I'm getting ready to replace the floor pan with a whole pan from AMD. I've heard that it's important to brace the body when removing the floor pan. I've seen that some people jack up the car at various points, which I'd rather not do because my garage is small and it's helpful to be able to roll the car back and forth. I've also seen a method that involves welding steel bars on as temporary reinforcements.

    This seems good to me, and I have two pieces of 1" x 6' box iron ready for this purpose. I'm trying to determine which would be a spotter spot to weld it:

    1. From a spot on the metal behind the rear door panel (around the rear window crank area) to a spot in from of the door behind the plastic kick panel.

    or

    2. Connecting the frame rail below the rear seat to the frame rail by/on the rear transmission mount - or even further ahead too (I have 6ft). Potentially, I could scrounge up another piece of metal to join the two braces, creating an "H" under the car.

    I favor the latter approach, but wanted some more experienced input. My car is fairly original, and the door jamb paint is in great shape, so I'd rather not weld to it. The frame rails area is easier to weld too and won't be in my way as much when I'm working, but I want to make sure it will provide the necessary reinforcement.
     
  2. moparmat2000

    moparmat2000 FABO Gold Member FABO Gold Member

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    I took my sons car, a 69 barracuda notch this far apart to replace all the floor metal from the firewall pinch weld to the rear valance. It had hacked in pop riveted aluminum mini tubs, hack relocated springs, and subframe connectors previously installed.

    I wanted to put it back to stock and remove the spring relocators as well. I left the subframe connectors and a small piece of trunk floor at the ass end tying the rear valance and frame together just so I could roll it around to sandblast it all inside and out. That small piece I eventually removed and discarded when I did the trunk pan and rear valance replacement.

    I rolled it around on its rear leaf springs and front suspension to push it outside to sandblast the inner and outer sides of the framerails. The only extra bracing under there was the subframe connectors. If all your doing is replacing the main floor tub and just pushing it in and out of the garage, then you shouldn't have to brace anything providing the engine and transmission are out. I say that since I dont know how the extra weight pressing down on the torsion bar crossmember and torsion bars is going to affect things with the floor out. Granted mine is a bit extreme as far as dissassembly, I also made sure it was level before welding in any floor panels. As far as bracing it front to rear you would be surprised at how strong your rocker panels are providing theres no rust thru. They are essentially the mid body framerails on a unibody car.

    Check out my build thread 67/68/69 cuda dilemma and start on about page 16. You will see how far I had it apart and rolled it around on suspension. Heres some pix after sandblasting and before epoxy priming though. When installing the floor pan, remove one door, and the steering column, then roll down the quarter window on the same side as the door you removed and fit the whole pan right in from that side of the car through the door and window hole.

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    Last edited: Nov 21, 2020
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    • moparmat2000

      moparmat2000 FABO Gold Member FABO Gold Member

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      Transition pan, wheel houses and trunk floor installed. I will install a New AMD main floor tub after I upgrade the subframe connectors, and mod the torsion bar hoop for a 42RH O/D trans. Then I will roll down the quarter window and remove the passenger door to feed the main floor pan through.

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      Last edited: Nov 22, 2020
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      • moparmat2000

        moparmat2000 FABO Gold Member FABO Gold Member

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        As far as spot weld removal, I have that shit down to a science. And nope I dont use spot weld cutters. I use an inline air grinder, a ball rotary file, a hammer, and a thin scraper to slide between the 2 pieces of steel to break em apart after grinding the welds with the rotary file to weaken them. You grind the welds down on the metal you are discarding, not on the metal your keeping.

        It's hard to describe, but you want to grind on and around around the raised edge around the perimeter of the spotweld, NOT the center of it. Your wanting to weaken the steel sheet your removing. Sometimes you make it thin enough that you cut through and see a little brown from surface rust between the two sheets of steel. Take your time on grinding and separating the first few to not damage the underlying metal till you get the hang of it, and then after that it all starts to go pretty quickly.
         
        Last edited: Nov 22, 2020
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        • moparmat2000

          moparmat2000 FABO Gold Member FABO Gold Member

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          Heres pix of inner fender and main floorpan I removed for replacement due to rust and butchery. I cut it out with a cutoff wheel, leaving strips of the old metal spotwelded, then using the rotary file, grind the spotwelds down on the side I was discarding, then using the hammer and sharpened scraper, slip the scraper between the metal sheets your separating, and hammer into it to seperate, and peel it out. I would recommend the same on your floor replacement. You can see my 8 year old son separating spotwelded pieces on a parts car i ground down with the ball rotary file. This method makes it really easy to seperate it. Just wear gloves or you get steel splinters in your hands.

          Remove the old floor in large chunks being very careful to not cut into any brackets or anything you need to save. If using a cutoff wheel to remove sections of old floor, cover up everything including the glass. Red hot sparks from a cutoff wheel or grinder will embed themselves in glass and plastic. Make note by keeping the sections of the old floorpan that have the parking brake cable lead, and speedometer cable clips so you can spot weld these items in place in the right spots before installing the floorpan. Also weld in your inboard seatbelt anchors prior to pan installation. It's harder to weld this stuff in upside down. Also measure your rear seat mounting hook location since you will have to install these as well.

          With the old pan out. This is the perfect time to clean out inside the torsion bar crossmember and weld in reinforcements inside it to reinforce the torsion bar lugs to the crossmember, then treat it with Por-15 or some other rust inhibitor. Also the AMD floorpan outboard side stamped holes for the seatbelt anchors are not in the same spot as a 67-69 barracuda, they are further back. You will have to measure and drill these holes in the correct spot to line up with where your anchors are in your rocker panels. The inboard holes on the trans tunnel however are in the correct spot.

          In my last pix showing the trunk pan, I fitted it into the car, then used a silver sharpie marker to draw the outline of the framerails and flanges that overlap, then pulled the pan back out and drilled for my spot welds in nice equal spacing using a unibit to make 1/4" holes. Floorpans are held in with big honking assed spotwelds. Then deburr the holes so the pieces fit tightly and use a weld thru primer on both mating surfaces.

          Depending on what I have to clamp together, I use a mixture of cleco pins, visegrip clamps, toggle clamps and self tapping screws to hold the pieces together so I can rosette weld the holes. In the last pic you can see the trunk pan with the drilled holes, and the screws pinning it down in spots holding it tight to the rails prior to rosette welding. After you weld everything up, remove the screws your using to pin it in place, and fill those holes up with weld too.

          I hope this all helps you out.
          Matt

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          Last edited: Nov 22, 2020
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          • 78kitcar

            78kitcar Well-Known Member

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            I cant contribute any thing to this thread, I just wanted to say Matt your shop floor makes me sick!! It's cleaner then my kitchen table!!
             
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            • moparmat2000

              moparmat2000 FABO Gold Member FABO Gold Member

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              78kitcar thanks. It's not always that clean though. I get most of it swept up when I do a project, then use my air blower and "air broom" the dust out the door. I hate laying on the floor to do something and have dirt and crap stuck all over my clothes.
               
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              • matthon

                matthon Well-Known Member

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                This sounds easier than a spotweld cutter, which I've used, also used an air grinder with just a regular cut off on it.

                What type of ball?
                Iirc, there are the stone type and metal ones as well.
                 
              • moparmat2000

                moparmat2000 FABO Gold Member FABO Gold Member

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                I will post pix of the ball files I use in a minute.
                 
                Last edited: Nov 22, 2020
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                • moparmat2000

                  moparmat2000 FABO Gold Member FABO Gold Member

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                  What I also do when chiseling the pieces apart is when I hammer in the scraper or separator in between the sheets to seperate the spot welds, if it comes to a dead stop, sometimes theres not enough ground out to seperate the weld, or try positioning the scraper coming in from the other direction. Sometimes you have to grind a little more. I have a custom separator I made from a piece of .050" stainless steel 1&1/4" wide with a sharpened edge, and handles made of 2 pieces of 1/8" thick plate aluminum bolted to it for smacking with a hammer. I also have a piece of .063" stainless about 2&1/2" wide and 2 foot long with a sharpened edge for separating floor pans from framerails. It too has a smackable end on it.

                  Now I do use spot weld cutters in certain circumstances since they also have their place doing stuff like this, like if I am removing a sheetmetal part that I will then reinstall. The RH inner fender on my sons cuda is a solid piece, however I will carefully remove it so I can sandblast both front framerails , and upper control arm attach points on the framerails then apply epoxy primer. The LH inner fender I chopped it out destroying it in the process because it was junk and I was replacing it anyways. With the spotweld cutters leaving raised "nubs" It helps me to center the RH inner fender when i reinstall it afterwards.

                  The reason I dont care for spot weld cutters for everything is you can drill too deep with them and start cutting into or through the metal your trying to keep if not careful.
                   
                  Last edited: Nov 22, 2020
                • moparmat2000

                  moparmat2000 FABO Gold Member FABO Gold Member

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                  Matthon and enquiring minds, Heres pix of my implements of demolition. M41334 carbide burr, and my home made splitters. The M41334 is all over ebay in single and dual cut. The dual cut works faster, stays cooler. With all the spot welds I ground down to take this 69 apart to repair, and take the 69 cadaver apart I used only 2 of these carbide burrs, I ran em dry, with no lubricating oil either. Still a lot cheaper, and more efficient than spot weld cutters in more ways than one. I am still using the second one.

                  With spot weld cutters you also have to grind down the remaining nub when installing new panels. You still have to grind smooth after using the ball rotary files but it's not near as much additional work. Again, wear gloves, and eyewear. I prefer disposable latex gloves to keep the small metal splinters out of my fingers. A box is cheap at china freight, and they work great for picking up dog poop in the yard too lol.

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                  Last edited: Nov 22, 2020
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