Replacing bed floor and small rust repair? First time metal work...

[posulli88]

Hello All,

The majority of my jeep is rust free (or at least I think). The only areas I can see rust are in the truck bed floor and some on the interior bed sides. There is dimpling and holes that have broken through. There is also rust that has broken through on the interior truck bed sides near the floor seams. Would you replace the entire bed floor for this:








My understanding is I would have to take out all the spot welds lift up the flange and then put in the replacement bed floors. Has anyone done this before? I am new to metal and body work but figured this would be a good first project. Any advice suggestions on going about this? What about the bed sides? just cut back until there is no rust and replace that are with new metal? Again any suggestions are appreciated.

[joe]

Depends on you goals. For me it's a pickup truck and if used as such the floor gets torn up so "I" wouldn't get too crazy with pristine repairs. Those little holes in the floor I would open up till you have solid metal for the weld to stick too. Then grind flush, prep and paint. On the sides I'd cut out the rotted section back to solid steel and weld in a clean patch piece. That's just me and again it's a trucks cargo bed not a 57 Chev resto. I would also drill holes at the front of the box floor at the bulkhead to let any standing water drain out. While your at it crawl underneath and look for any punky floor sections and mounts soon to rot through.

[posulli88]

The only issues with the holes in the bed is they are through out the corrugated sections so I would need to replace them with patch panels from an existing bed or new patch panels because of the shaping. I think I can get away with just flat sheet metal patches on the side because I don't think the rust is up into the molded sections (it will be close though). Again I have never really done much metal work so this will be my first stab at it ahah.

[tgreese]

If you are handy with wood, I'd suggest making a press mold from hardwood and hammer or press the corrugations. It's a simple shape, and you can make patch panels with the same profile fairly simply.

[posulli88]

Thanks Tgreese. I am much more comfortable with wood so could easily make that profile. What type of press do do you think I would need for that? I have a 20 ton mechanical arbor press.

[mwood65]

They sell the floor pieces for truck bed repair but I don't know if the spacing is the same.

https://shop.advanceautoparts.com/p/keystone-collision-truck-bed-floor-gmk4144731731/11749659-p?c3ch=PLA&c3nid=11749659-P

[tgreese]

Thanks Tgreese. I am much more comfortable with wood so could easily make that profile. What type of press do do you think I would need for that? I have a 20 ton mechanical arbor press.

Probably. I expect it will matter how large a patch you want to press at one time. It looks like you need to make strips going perpendicular to the corrugations. If you use a wooden die, it can't be very large and still be rigid enough to press evenly. I would press one corrugation at a time, and keep the strips narrow, like 1.5-2 inches or so. Maybe it could be wider...

My inclination would be to make a rectangular pocket as the mold, and a rectangular die that's narrower than the pocket. Then allow the steel to bend and make the angled sides of the corrugations.

You're going to have to build a jig and try it, then evaluate your tests and modify it as needed.

[backroadin']

If your work doesn't come out as good as you would like - remember that a nice bed mat will make it all OK!

If it was my truck, I'd leave it - I think it's a bigger project for a first-timer than it looks unless you're just covering holes/sections with patch pieces, which doesn't sound like the way you want to go. The holes in the floor part I would think would be easier to do than the corners. I like the wooden die idea. Can you weld or will you have to farm that out?
That said, I've done a lot of metal work patching holes and making panels for my jeep and it was all first time learning. Some came out nice, some was/is crude, but I learned alot and I had fun, so I'm glad I did it. My jeep is fairly crude anyhow, so my lesser stuff doesn't stick out too much!

Best of luck with the project!!

[posulli88]

I have done very little welding. Part of me owning this truck it wanting to learn new skills so I want to do all the welding on the truck myself. Obviously I am going to need to practice on scrap and get comfortable enough before starting on the truck. I am pretty OCD and patient which often helps me work through and learn new skills, which I have thoroughly enjoyed with this truck.

I can get a completely new bed floor from Bj's for about $300 shipped which is not bad. But it sounds like it could be a very big process to replace. My end goal is to have a truck bed thats good enough so I can put bed liner in it and use it...

I just have never seen a post on IFSJA (I have searched) of someone replacing an entire bed floor so I wasn't sure the full process and if it would be too much for me to do as a beginner in auto body. I am willing to take on the challenge as I am somewhat enamored with having a new bed floor that I can instantly treat and cover with bed liner for best protection, just want to get a better sense of how hard this would be.

I appreciate all the feedback so far on the patching and that prob with be the route I go, but I am curious about the full floor replacement.

[backroadin']

Well, you can alway replace the bed some time after you do the patches. Then you'd have some experience!! And you'd get to drive it more.

Post pictures on your progress - we love looking at pictures!!

[Cliff]

This may sound like sacrilege to some folks, but I would use fiberglass. I have had excellent results with fiberglass cloth and resin, both in finished looks and strength. You could do all the patchwork from the underside/inside, and then apply a quality bedliner like Durabak. Even if you patch from the visible parts of the bed, you can blend it in pretty nicely and the Durabak would conceal anything, like those rust pock parks.

[tgreese]

If it were mine, I'd patch it. I expect the bed floor replacemetn panel will only give you the large central panel that's corrugated. I recall the small flat panels in front and behind the wheel houses are just flat steel, cut to shape. To fix the side wall, you will have to cut out that section of the panel and fabricate a replacement. That area is double-walled and well known as a source of rust, in particular in the outside seams. One of the POs of my J10 drilled holes in the inner bed panels and must have sprayed cavity wax or similar anti-rust treatment inside the double-walled panel. These holes were filled with plastic plugs.

It looks like the worst areas of the bed floor are above the hat channels that go across the width of the bed. I would repair those holes and treat the inside of the channels liberally with something like cavity wax or Fluid Film.

The places where it's rusted through I would replace with new steel. You could fill the pits with a polyester or epoxy putty after bringing the surface back to bright steel appearance. I'd use a glass-fiber-filled polyester putty like USC Duraglas to fill the pits.

Welding body panels does not require much of a welder, or a whole bunch of skill. The cutting-out and panel fab is much harder than the welding. I'd suggest you review the MP&C projects thread on Garage Journal for some insight into this process. https://www.garagejournal.com/forum/...d.php?t=182565

[threepiece]

I applaud your desire to repair your FSJ and learn new skills. My FSJ's have been a great avenue of learning for me over the last 35 years as I too have what others have described as an extraordinary amount of patience.

I repaired my bed floor with patch panels that I made. For this I made a press tool made from steel, you may consider making one too.

First I would carefully remove a section of damaged floor. Be sure to cut perpendicular to the floor beads and include a portion that is undamaged so you may make an accurate tracing of the cross section on a piece of paper after removing all burrs. You can then use this tracing to design your tool.

Using your paper tracing, measure the depth and spacing of the floor beads. With these measurements you may find standard "flat bar" steel from a steel supply catalog that will fit in the spaces. You can then tack weld these "flat bar" pieces to a larger and thicker piece of steel. You will need at least three pieces of flat bar to make one bead form.

Here's a tip: If you add a fourth piece of flat bar in the right place you could use it as a locator for the next bead. This way you would not have to measure and fuss for setting up the next pressing operation.

Here's another tip: If your press is lacking force you may be able to hammer form the part. For this you would need a hammer that weighs 12lb. or more and a suitably massive support underneath.