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Floor repair

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I am starting this topic for advise, and suggestions on repairing rusted out floors on Datsun 521 trucks.


I do not have a sheet metal shear, or a sheet metal brake, but I do have hand tools, a mig welder, and oxy acetylene torch set. 


Since I first made this post, I bought a 30 inch Harbor Freight sheet metal brake.  This happened December 2014.


This is what I have got.



My current plan is to cut smaller pieces of steel, then fit them into the floor.  Once I have the smaller pieces fitted, weld them together, and then fit the one, or two pieces back in to the cab.


My thought on needing a piece of steel with a sharp bend is to just buy a piece of sheet steel at a local steel yard, that is too big, and have them put a brake bend in it.


This is the first piece of steel I fitted in to my cab.


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Cut flat pieces and tack weld them into position.


See how the tunnel was raised with flat pieces, this is a body drop.

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But i dont have any rust on the floor of my truck.....none at all....yet lol. Nice keep up the good work and pics.

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More pictures later, and I got some toys today.

Ideally, I would remove the cab, so I could get good access to both sides of the weld, to clean the metal, make nice pretty butt welds, and repaint the metal as it is done.  I am not ready to pull the cab off this truck.


I am thinking of laying the new metal on top of good floor metal, and lap welding the new steel to the old steel.  I can clean the top surface of the old steel


My plan for clamping the pieces together is to drill 1/8 holes, through both pieces.  Then drill a bigger hole in the top piece only.

Then use screws with nuts and washers to pull the two pieces of metal together.  Remove the screws one at a time, then weld the hole, by doing a circular lap weld in the hole.  


I plan on pulling the cab in the future, but not just now.  

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My thinking is that with self tapping screws the head of the screw will bottom out on the top sheet of metal. If there is a gap between the two pieces of metal, the screw will stop turning when the head bottoms our without pulling the two pieces of metal together.

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If your drill spins fast it will keep spinning in the first one and then it can make its way to the next layer. I do this all day long at school and work when we replace a quarter on wrecked cars. If you don't think it will work that way you can drill 1/8 holes in the new pice and then use zip screws in that hole

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The toys.

I got a punch, and some 3M clean and strip disks today.

The punch.


The 3M Clean & Strip disks.


The punch is handy for making metal slugs, for filling holes.


The clean and strip disks are really good at removing old paint, old plastic filler, and rust off metal.

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Also if you are over leaping the new pice over the old one put weld thru primer where the two pices meet to help keep it From rusting out right away I just did this to my 520 had to make the hole bottom of the truck frome one rocker to the other

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I used to think epoxy primer was expensive, until I bought a can of the weld through primer.

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More work was done on the floor.  Yesterday, I bought a piece of steel, and cleaned it.  It has some minor rust on it, and oil, or whatever they put on steel to slow down the rusting.  I used paint thinner (mineral spirits) to clean the oily gunk off it, and then used the clean and strip disks to clean the steel.

Today, I took the clean sheet to a friends house, and used his metal brake to put a bend in the ends of the steel.

tonight, I cut the steel and did another bend in it.

Here is a trial fit


Rear outside corner.


Front outside corner.


Front inside corner


Rear inside corner.



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I did more work on the floor today, but first, how I got this far, and what I did to get there.


Like I mentioned, I started out with a piece of steel, I had a local metal retail place cut a piece of steel 22 inches, by 48 inches.  I cleaned the steel, and then took it to a friend that has a sheet metal brake.  There, I put a 90 degree bend 3/4 of a inch on both of the 22 inch long sides.   This 3/4 inch, bend or flange is going to be against the door sill, or inside the rocker panels in the cab.  Sorry, no pictures.


Then I made a template out of cardboard.  I used some pieces of cardboard that had an aluminium face, just because I had it. 


Because the pieces of cardboard I had were too small, I taped two pieces of cardboard together.  That is the blue tape in the picture.


The cardboard is nice for making a template, because it bends like a sheet of steel would, but much easier.  And you can cut it with a pair of scissors to fit.  So, after some trimming, here is the cardboard fitted into the cab, where the new piece of steel will be.


Then you take the cardboard, and lay it on the steel, and you have a pretty good idea of where to cut the steel.



Next, I had to put a gentle bend in the rear end of the new floor piece.  This is how I did that.


Because the steel already had a flange on the end, I cut the flange with a cutoff wheel where I wanted the bend to be.


The other two edges of the steel do not need a bend.


This is how I made this piece, the kick panel that goes forward of the new floor.


First I put the bend in the long side, clamping to the bench with  the 2 x 4, sorry no picture.  Then I cut a V-shape notch in the bend, and made the shorter bend on the front side of this piece.  But that will leave a sharp crease, where the V-notch was.   I want a rounded corner on this piece, to match where the transmission tunnel meets the floor, and kick panel. 

I tack welded the outside end of the flange, after the second bend.  Then I cut the bottom of the notch with a cutoff wheel.  Then I took a body hammer, and tapped down the peak of the bend.  This of course closed the gap made by the cutoff wheel.  I used the cutoff wheel and cut a new gap, and hammered the peak of the bend some more.  After several cuts, hammering them closed, and cutting them again, and hammering again, I had a nice rounded corner.  I then welded the cut. and ground the weld off smooth.




The new pieces of steel are going to need to be painted, but first, I want to fit them in to the cab.   I put the larger piece in the cab, and for now, I am just using a few screws to hold it in place.  My plain is to later, after painting the good, or at least useable metal on the cab, and the new metal is to just weld the pieces in the cab, in the holes made for the screws.

Here is the main floor piece screwed down.


A closer view of the front on this piece,


and the back of the new piece.


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Nice work  :thumbup:

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I am in the process of welding the two floor pieces together.  With the main floor piece in the cab, I took the piece that is going to be the kick panel, and set it on top of the main floor piece, and held it in position, and tack welded the two pieces together.  I then removed the tack welded pieces out of the cab, and using the holes already drilled in the main floor, made marks on where I wanted to cut the two pieces for a butt weld.

Here is the main floor after cutting a section out of it.


and here is the much smaller kick panel piece.


After fitting the two pieces together, several times and lightly grinding down the high spots, I tack welded the two together, and then put the welded piece back into the cab.



Here is a picture under the truck. 


The fit looking pretty good, considering that the new floor is only attached to the transmission tunnel by one screw, and along the back of the new floor outside of the frame rail under the truck.



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Even though I have not posted much, I have been working on the floor panel.  I finished welding it, straightened a little weld distortion, and then worked out this.   There is a dimple in the floor of a 521, where the body mount bolt goes.  This is how I made that.

First, I took a piece of 1/4 steel, and cut these parts out of it.


They fit together like this.


And by clamping the larger piece between the floor pan, and a larger piece of steel, running a 1/2 bolt through into the smaller piece, and tightening the bolt, it made this dimple in the floor pan.


and after doing that, I took a hammer, and put a slight bend in the top edge of the kick panel area on the floor pan.



I am thinking I am ready to primer, and paint this floor piece, clean up the cab metal, and primer it, and then put the new floor in..

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Nice work again with that home made dimple die lol grass roots at its finest. 

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More work has been done on the floor, specifically the metal piece that forms the right wheel well, that goes between the floor, the firewall, and the door post on the cab.  The piece I am holding a ruler up to.



I also checked the outside ot this panel.



Then I cut the bad section off with a cutoff disk, in an air die grinder.  There are two lines in this picture, I made the first cut, and still has a lot of bad metal.  I could tell, because the cutoff wheel cut the bad metal really fast, so I made the second higher cut.



This is after the first cut.



Then I cut a small piece of metal to replace the section I cut out.  Several trial fits, and slightly grinding high spots down to make the piece fit better.


More fitting the new piece.


Still more fitting the new piece.


Finally a fitting, getting ready to weld.  I try to back up areas I am welding with a piece of copper.  For me that really helps prevent the weld blowing through the metal.  Even though it looks like I am ready to weld, I still took this apart, and did more grinding and fitting.


The other side of the clamped piece. 


And more fitting.  This time I did weld.  The very first weld bead was right in the middle of the clamp.


Then I did a test fit with the floor piece I made earlier.  Between the last post I made, I was able to spray the first primer on the main floor.  



And here is a picture of the weld beads.  At this point, I went and had dinner.



After dinner, I went out, and ground the weld beads on the inside of the cab.


Another picture.


There are a few pinholes, but I think this is progressing nicely.  I also did more cleaning fo rust off the cab sheet metal, that will be under the new floor.



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This morning, first I drained the tank on my air compressor, and cleaned it up a bit, and tightened some leaky air fittings.

Then I took a trouble light, and looked for pinholes in the weld, and rewelded them, and then ground the welds off again.

Cab side of weld,


and the wheel side of the weld.



I also got some epoxy primer on the floor pan that will go onto the cab.




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Nice work man. Definitely have skills!!

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I have been doing some more work figuring out how to make 521 floor pans.

This is why.

Ratsun left side floor.


The same floor, looking back to toward the seat.



This is the left side floor in Dragon Two, a longer term project.



This is an extra cab I got, the right side floor in it.



The left side floor in the cab was worse, and has already been cut out.   Today, I spent some time cleaning rust off the remaining floor, and sprayed some primer on the floor, under the seat and the front of the left side.



This is the under seat area of that cab primed.



I have made a new floor pan for the right side of this cab.



and I am working on a pan for the left side of the cab.



Here are the two pans, out of the cab, laying on the grass.FloorPansinGrass_zps572c4c55.jpg


To be honest, I am having a little difficulty figuring out the contours of the corner of the floor under the gas pedal.  I am going to make a small section just for that area, and weld it in to the left side floor pan you see.  I also have to make the bottom section of the wheel well, but I have already done that once, on Ratsun.


I really do not see a way I could, with my beginning welding skills, I could weld new floor pan pieces in to a cab on a truck, too much stuff in the way.  My current plan, and they have been changed a lot, is to get good floors in to the extra cab, off a frame, so I can weld it, and seam seal it, then swap that cab on to Ratsun.

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Feel free to make replacement floors for the 521 lol. I'll be your first customer. 12 years of damp carpet did this



Before I removed carpet..



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I am trying to figure out easier ways of making floor pans, with out having all the fancy tools, like a sheet metal shear, a bending brake,  that kind of stuff. 

Like I mentioned, I start with a piece of 24 x 48 18 gauge steel, and I take it to a friend, that has a brake to put a 3/4 flange, or 90 degree bend in the two shore ends.

After that, all my cuts are with a 3 x 1/32 cutoff disk, in a die grinder.  All my bends are done on a steel saw horse, that I just clamp the sheet to, with another piece of steel bar on top.


The right side front floor piece is easier to make than the left side.  The most difficult part is the area right under the gas pedal.


Once I have a repeatable process down, to make both floor pans, I will post it.   I have thought about making a few extra floor pans, but right now, there is a lot of time in making and fitting one.




   Glad to see you got another 521!

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What gauge sheet metal?  Milwaukee makes a sheet metal shear.  I have this tool and with practice you can even cut radius'. Sweat tool!






Also Check your local Craigslist.

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Clean metal with a wire brush in a drill to bare clean metal on top and bottom of floor and tunnel. A 1" wider clean area all the way around. If you are going to patch just the hole under the gas pedal, I would square the left side and top of the hole. Leave the tunnel and the angled section of floor alone if good metal. Make rectangular piece of card board for a template, cereal box is what I use. Before your first cut the box use a ruler to make straight lines straight lines and make this card board larger than you need. I cut the box with a razor knife so I can cut the side and the bottom, 3 sides, 2 folds is what you want from corner of the box. This will allow you to split the angled corners in the short 90 degree bend where the bottom meets the narrow side of the box. Lay the cardboard on the top of the floor after cut to desired size and draw around it with a Sharpie. Tape the loose corners to set your angles you need to the floor and the tunnel you need with with metal duct tape from your local hardware store, a half inch over lap of the existing metal is all you need all the way around.Might need to use tin snips to cut the tunnel side of the patch. Try to keep about a 1/2" over lap all the way around. This is just a rough bending guide now. Take a drill with a 3/16 bit in it and drill holes centered a quarter inch in from the inside inside of the the lines you just drew on the floor and the tunnel spaced 1 inch apart all the way around the inside of the lines, the holes are for plug (spot) welding the patch to the bottom side of the floor. You can use a bench vise and 2 pieces angle iron a little longer than you longest length tack weld to each side of you bench vise jaws. If the angle iron is longer by more than an inch, vise grip the 2 angle iron pieces together after you position the metal and clamp in the bench vise. I use 1" x 1"x 1/4" angles for up to 18 gauge. Bench vise needs to be bolted down to an solid rigid surface. No "C" clamps holding bench vice. Slowly bend the metal checking the angle as you go after you bend both angles you are ready to put in place. On a patch of this kind I fit it to the under side of the floor/tunnel. I use magnets to hold the patch to the under side of the floor and tunnel. No sure what your welder is, I use mig small wire .023 for gauge sheet metal and the lowest heat (amperage) setting that leaves a good penetrated spot weld. Practice on some scrap to get your welder setting. now you are ready to spot weld your patch in. After the welds cold grind flat if desired. Seam seal all edges of the metal on top and bottom of the floor and tunnel. your Patch is done!!! Sounds harder than it is and this method works easiest for a person with limited welding skills. Remember for spot welds you can count start 1001 1002 stop. If you need you can count to 1003 if you need more weld to each hole providing you do not burn through.

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