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Project Marina, Rust Repairs – Part 1

The time has finally come. I couldn’t put it off anymore. I needed to cut out the rust.

I have really been procrastinating on this work, as I have never really done bodywork like this before. The closest was fixing the rust on the Corolla, which was minor compared to the scope of this work.

The main goal was to cut out and replace the steel on any rust that could cause an issue come WOF time. There will still be some more bodywork to do down the track, but once the car is on the road that will be easier to do.

So that means I need to cut out the rust in the two front floor pans, the LH B pillar and LH outer sill. When you consider the car has been off the road for 26 odd years, and most of that stored outside, that’s not bad!

The front floor pans had been badly patched years ago by a previous owner, using rivets, sealant and some tin.

The B pillar has a hole in it, behind the window seal, which means that the quarter window needs to come out.

And the outer sill is perforated the whole way along, especially toward the rear.

I started with the floor pans, as in theory, it should’ve been the easiest place to start and then build up to the harder sections.

The first job was to grab a hammer, screwdriver and chisel, tear off the patches that had been riveted on and see what they were hiding.

This big one on the RH side was the first to go. Instead of drilling the rivets out, I used the chisel to just cut through them

So, it was covering a patch of very thin metal, with a drain hole that has rusted out. The circle hole is meant to be there, as it is used during the manufacturing process but usually has a steel “paint tin lid” plugging it. Obviously, the hole rusted out, the plug fell out, and it was covered over from there.

There is also a recess pressed into the steel, which just acted as a rust trap over the years

There are a lot of other small holes and thin metal on this side, so I originally marked it out to cut the whole lot out, but I’m a bit hesitant as finding the spot welds is proving hard due to the rusty metal (and it’s spot welded to a couple of different reinforcers under the car).

The LH side was a similar deal. A few patches… This one up against the inner sill gave me some concern as it has a big bead of sealant running down along the sill.

Sure enough, the steel under the plate is ruined, as is the section of the inner sill where it met the floor.

Another rusty drain hole, as well as a couple of screwdriver sized holes next to it (which had their own patch)

Toward the tunnel, there was a large patch made up of a couple of smaller ones, which was shaped to fit the indent in the floor panel

That one was bad. Big hole under it, and lots of holes poked in thin metal with a screwdriver. There are also a couple of other smaller holes I undercovered.

Out came the paint pen, highlighting the extent of the damage.

The only thing to do next was to grab the grinder and cutting disc

This little brace for the gearbox support was a bit of a surprise. It was also full of rusty chunks from the floor disintegrating.

The inner sill needed to be cut out too as that was barely holding together and was full of sealant. To access this better, I cut a hole in the outer sill (which is stuffed anyway)

It was pretty ugly in there

I carefully removed the inner sill section and peeled it off the jacking point brace

Now, a warning. I’m not a professional, heck, I’m barely a beginner at bodywork. I know the basics thanks to a course I took a couple of years ago, but that only covered the basics of welding, not cutting out rust, making patch panels and working with less than perfect steel. I am winging this.

I have a semi-decent welder, but had previously been using flux-cored wire, which I swore after welding the Corolla, I would not bother with again (it did the job, and it has a place, but it’s just more work for the same result). This time I converted the welder to take a standard 0.6mm (as recommended to me for bodywork) solid wire, and shielding gas.

Anyway, so I bought the steel that was recommended to me for this sort of work, which turned out to be thicker than I really should be using; 1.2mm. The original steel is about 0.8 to 1mm. I figure the thicker steel cant hurt in the floor and sill areas, and I will use some thinner steel for other panelwork as needed.

The first patch I needed to make up was for the inner sill, as everything attaches to this. I did some CAD (Cardboard Aided Design) and cut the panel out so it was a reasonable fit. I left the bottom a bit longer, as that will get trimmed later when I do the outer sill.

I’m embarrassed to show these initial welds, but it’s all part of the process. I had been having serious issues with my wire feed, which I fixed after this section was done. I went over this a couple of times to make sure it had penetration and then ended up welding both sides. It needed to be strong.

I know, I know, I needed to clean the surrounding metal better. The other issue I had was my gas regulator was DOA and the flow meter didn’t work, so I just turned the gas up a bit and ran with it. The welding on the inside was marginally better.

I plug welded the brace to the new inner sill section, but also later went around and welded the edges right onto the panel too.

The front section of the inner sill is where I started to work out the issues with my machine, and more importantly, technique. There are some better welds here, but far from perfect. Due to the weird shape, I chose to lap weld this patch instead of butt welding it in.

Once the inner sill section was in place, the first floor section went down. More CAD, but this took a couple of tries to get a nice tight fit. This has a 90 degree bend on the side to meet the sill.

The welding is still a bit ugly, but it’s strong and has decent penetration.

As the saying goes, “A grinder and paint make me the welder I ain’t”

I carried on again today, and really started to get into the swing of things. The first patch was to join the previous one, up toward the rear of the car. This is a weird one, as it has to start off flat but curve swiftly up to join the existing floor.

I made this section slightly oversize with CAD, bent the flange on the side and then notched it

The notches allowed me to gently bend the panel in the vice. Once I was happy with the curve, it got welded in place. The next patch, the one that joins on next to it, was a real pain to make. This had to match the curve of the new patch I just welded in, but also match the curve of the existing floor both on the other side and above it. The easiest way to shape this was to make the biggest bends in the vice and then using a hammer and dolly, fine tune it into place. Some additional finessing was done once the panel was tacked in.

This welded in a lot better. I’m reasonably happy with it.

There is a small patch welded on next to these, which is just covering the small hole I cut out.

Finally, I made a large patch to start filling the area above the exhaust and torsion bar. This is plug welded to that gearbox brace, and then butt welded all around the edges. Unfortunately my poor cordless grinder ran out of batteries as I was cleaning up the welds on this patch, but some weld through zinc primer and that was me done for the day too.

I still have that one hole to fill, and then I’ll move onto the RH side. I’ve learned a lot doing this side, so hopefully it will go a bit smoother, and quicker.

A second grinder will be added to the collection soon, as using the one grinder for everything is just a real pain in the bum and it’s chewing through the batteries. Having a corded one at the workbench for just cutting will help immensely.

Having dialled the welder in a bit better, and ironing out some of my issues with that and my own technique, my welds are getting better. That last patch needed minimal cleanup with the grinder. Once that floor is completely welded I’ll scuff the whole thing up, seam seal the welds and coat it in a zinc rich epoxy. Everything will be covered by carpet eventually. It will need undersealing under the car again too, but that will come once I have both sides done and can jack the car up to get under it.

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Rob Murray
Rob Murray
2 years ago

I would always recommend using corded angle grinders, the cordless ones always eat batteries, no matter which manufacturer you use.