Sill Patch Welding

Today I welded in the patch panels I fabricated yesterday for the lower sills, right and left sides. The stock I used to make the patches was 18-gauge galvanized sheet metal. Galvanized metal can release some toxic fumes when it is heated, as in welding, so I am always careful to work in a well-ventilated area and also take the precaution of removing the galvanized coating from the edges of the metal I’ll be welding. I used a wire brush along the edges of both panels on both sides of the metal before getting started.

My first step was to drill out the holes in each patch where the fenders mount onto the sill. I used a 3/8″ bit.

And I repeated the same on the driver’s side.

I found some nuts that seem to fit the bolts that held the fenders on the one side that hadn’t rusted out, though I’m not sure those bolts were original. In any case they were a 5/16″ 24-pitch nuts. I welded them to the inside of the patch panel using my mig welder and moving around the outside perimeter of the nuts using small spot welds.

Here you can see the nuts through the holes I drilled from the underside. The holes are oversized a bit but will allow clearance for the bolts to go through.

Then I held the driver’s side patch into place and tacked it with three spot welds at the corners.

And then I started welding across the top. My technique is to weld the metal into place using numerous spot welds, rather than trying to lay down a continuous bead. This way I am able to keep everything relatively cool and yet still get good penetration of the metal. I worked in three clusters along the top of the patch, welding a spot in each cluster and then moving on to the next cluster.

I worked my way all the way around the bottom of the patch in this manner. I had to do some hammering of the patch with my 5-pound sledge hammer to bring it into shape along the way.

Then I moved over to the passenger side. After ensuring it was a good fit I tacked the patch in the corner.

On this side I wanted to get the top welded in first so I could make the other edges fit and manipulate the shape of the panel as necessary. So I worked across the top with spot welds, allowing some time to cool in between welds.

Then I moved down the right side and then the left side of the patch.

And finally I welded the bottom.

And I finished off the process by grinding down the welds using my angle grinder.

Sill Patch Fabrication

Today I spent most of the day fabricating steel patches for the worst-rusted areas of the front fender sills, the area under the front fenders down close to the ground. This is the area where the front fenders bolt to the underside of the body, and an area where the fenders are apt to rust as well as the sills. Although relatively solid, rust holes had begun to penetrate the area and the best course of action was to cut out the rusty sheet metal and replace it with solid steel.

Starting on the driver’s side, I just drew up and cut-out a patch from poster board big enough to cover the rusty area, then I taped the poster board up onto the sill in order to trace the cutting perimeter onto the body.

I traced the outline using a black Sharpie marker.

On the passenger’s side I did the same, and it required a patch of a different shape.

The nice thing about using a poster board template is that I could then lay it flat on my steel stock and trace out the shape the patch would need to be before bending. I used 18-gauge steel for the patches. I cut out the patch using a pair of electric sheet metal shears.

I cut out both the left and right patch panels the same way.

On the driver’s side I made a rough bend in the patch panel so it would have a curve similar to the sill. I just sandwiched the lower edge of the steel between to short lengths of two-by-four and pulled up on the upper edge to bend it.

Then I cut out the rusted sill area from the body just using my Dremmel with the little cut-off wheel. The thin Dremmel cut-off wheels were used up pretty quick so I had to keep switching in new ones.

After cutting halfway around the top I could see that there was plenty of rust inside the sill. In fact, I could see where the bolts that connected the lower fenders into the sill had rusted and broken off in their nuts. I finished cutting out the rest of the area.

Here is the removed rusted-out sill area and a side-by-side with the new patch after I fine-tuned the shape of the patch a little more.

I cleaned up the edges of the remaining surrounding sill using a cleaning wheel on my drill.

Since I had to cut out the nuts that the fenders bolt into at the bottom of the sill, I will need to drill holes and weld in some new nuts onto the patch. I marked the location of the holes in the patch.

Then I moved over to the other side. Instead of using the Dremmel I used my angle grinder furnished with a metal cut-off wheel, which went much faster through the sill. This was definitely a better tool for the job!

There was less rust inside on the passenger’s side but I still had to clean up the remaining metal using a stripping wheel.

Here is the patch panel bent roughly into shape alongside the cutout.

I prepped the inside areas of the sills on both sides by washing them out using Simple Green and also spraying on some Metal Prep to address surface rust. Then I painted on a coat of Eastwood’s Rust Encapsulator. The Rust Encapsulator is supposed to seal in rust and prevent any further deterioration.

I just applied a generous coat of Rust Encapsulator using a brush.

And I did the same on the other side.

Rear Fender Patch Panel Weld Dressing

This morning I used my grinder to dress-up the patches I welded into the rear fenders, where I had cut out some rust. I used my 4 1/2″ angle grinder with a stack of three cut-off wheels on top of one another. Using the edge of three, rather than one wheel, gives me a wider footprint for grinding and as I tilt the wheels up and down I am able to taper my grinding a bit, which is useful in transitional (i.e. non-flat) areas of the body. First I dressed the welds on the single patch on the right rear fender.

Then I switched over to the left rear fender, which had two rust patches.

And I moved on to the lower patch.

After grinding I used a wire brush on my drill to clean off the metal and remove any scale that was left. The repairs were solid, though with some dimples left around the welds. I kept at it until the metal was clean.

Rear Fender Patch Welds

Tonight I welded in the small rear fender patch pieces I fabricated previously. Since the patch steel I bought was galvanized, and welding-up galvanized steel can emit some dangerous fumes, I first used a wire wheel to remove much of the zinc coating from the patches, particularly around the edges. I also was sure to weld outside with good ventilation. The patches fit well within the cut-outs, which I cut to size. For the thin sheetmetal of the roadster body my MIG welding set-up consists of .023″ solid-core wire with CO2/Argon shielding gas.

So with the patch in place, the first thing I did was tack weld the patch at the top. Again because the sheetmetal is thin, rather than try to lay down a continuous bead around the entire patch my technique is to weld the patch with numerous spot welds, working around the patch until the entire thing is welded in. If I used a continuous bead I would probably heat the metal and burn through before long; using multiple spot welds enabled me to allow one end of the patch to cool a bit while I work on the opposite edge.

As I worked my way around I also shaped the patch a bit to try to conform it to the shape of the fender lip.

The result was pretty ugly, but strong with good weld penetration without blowing lots of holes in the fender. The welds will clean up nicely later. I also welded in the two patches on the left rear fender.

Rear Fender Patch Cut-Outs

Late this afternoon I cut out the rusted areas I need to patch on the rear fender lips. I used my cut-off wheel in my 4 1/2″ grinder to cut out the areas and then grind the edges of the holes until the patches I’d previously cut fit. The first one I addressed was on the right rear fender.

After cutting a hole the right size I applied some Eastwood Rust Encapsulator, which should neutralize any rust inside the fender lip, inside the exposed area.

And I did the same on the left rear fender, cutting out to areas where rust had penetrated under the old filler, and then applying Rust Encapsulator inside.

Rear Fender Patch Cut-outs

The first thing I did this afternoon was cut-out some steel patches for the rusted holes in the rear fender wheel-well lips. I roughly measured the size of the three patches I’d need and cut them out of 18-gauge steel using a metal cut-off wheel in my angle grinder. I shaped each as a rectangle, and rounded the corners because welding sharp corners can be a challenge. I find it easier to weld the radius of a rounded corner.

Here is a picture of the rusted hole in the right rear fender lip that I intended to patch, and one showing that my patch was large enough to do the job.

I traced out the perimeter of the patch on the fender using a black marker.

Later I will cut-out the bad sheetmetal and weld in the patches.

Body, Sheet Metal Prep

This afternoon I prepped the body tub’s bare sheet metal to prevent surface rust from forming. I used Metal Prep, which is an acid-etching product that removes surface rust from bare metal and leaves a thin protective coating that inhibits more rust from forming. Regular humidity in the air can cause bare steel to flash-rust, so the coverage afforded by the coating prevents that exposure.

I started in the cabin, where I treated all of the bare metal spots on the rear shelf and on the firewall, areas that were exposed when I removed seam sealer. I also treated the entire floorboard area, which was exposed when I removed the tar undercoating.

I wore rubber gloves to protect my skin from the acid. I sprayed the Metal Prep on using a regular spray bottle, and then rubbed it into the surface using a scouring pad.

Then I sprayed another light coating of Metal Prep and wiped off the excess with shop towels after giving it around a minute or two to work. Drips can be pretty messy, so I am always careful not to use too much.

Here are the final results in the cabin.

I followed the same procedure in the trunk, and in the engine bay.

I also treated the rear panel and both rear fenders. On the picture of the fender you can see some drips that resulted from the Metal Prep gathering in the side-molding channel and then flowing down–that’s what I was trying to avoid.

And I also did the rear shelf and the front cowl areas.

Body, Rust Removal Part II

This morning I continued to address the rust inside the cabin and, to a lesser extent, the engine bay. Yesterday I used a wirewheel to mechanically attack the rust. Today I used chemical means.

I bought a chemical rust neutralizer from Halon Marketing called Rust Away. The liquid is blue in color and can be used to soak parts, or applied onto rusty areas to convert rust. It uses tannins to convert iron oxide into iron tannate, which is black. I applied it to the footwells of both sides of the floorboards by laying on paper towels and them pouring the Rust Away on. The paper towels held the solution in contact with the rusty spots I was targeting.

The instructions recommend allowing rusty parts to soak for two hours; I allowed for three before removing the still-soaked paper towels from the floorboards. Visually the rust appeared converted.

I repeated the process on the passenger side.

Also the cracked firewall in the brake master cylinder pocket had some rust developing inside. I treated that area by laying paper towels on the engine bay side, then tucking the edges of a couple of towels down into the cracked area.

Then I soaked the paper towels and allowed the solution to work for several hours before removing the towels.

With all of the seam sealer and other adhesives removed, it will be time for one more washing before I begin the bodywork in earnest.

Body, Rust Removal Part I

This afternoon I continued preparing the body for bodywork by starting to address the rust spots inside the cabin.

In the footwells there were several areas where it was clear water had rested on the floorpans and caused rust. Some of this I’d characterize as “surface rust” while some of it was less superficial in its penetration of the metal. On the driver’s side the floorpan was still very solid (thankfully). The worst area was around the drain plug but there were several rusty patches. I began by using a coarse wirewheel on my drill to remove the surface of the rusty patches.

For the most part much of the rust came off leaving pitted steel, but in some areas there was rust I couldn’t get off mechanically.

In one area the metal had thinned enough such that my rust removal opened a small hole in the floorpan. I continued underneath the car with a more aggressive abrasive wheel where the rust was accumulated on the outside of the metal.

I was able to thoroughly clear the rust away from the area around the hole.

And I got the majority of the rust on the underside, leaving just the pitted steel and some rust-colored dust.

On the passenger’s side there were a similar collection of rust spots, though not as bad as on the driver’s side–the rust had not spread to the underside of the body on that side.

Body Panels, Prep for Bodywork

Today I spent some time preparing the body panels that I removed from the tub. This involved mechanically removing any remaining spots of paint as well as any adhesive or other remaining surface rust, then sanding the remaining paint smooth and washing each panel one final time to remove any paint stripper residue. Finally, I stabilized the metal so it will not immediately begin to rust.

I started with the trunk lid. The top was fairly well stripped, but the underside had a full coat of paint as well as some glue residue around the edges of the lid where the trunk seal-gasket had been glued. Originally on the roadsters the rubber trunk gasket was mounted on the lid itself rather than on the body. Here are shots of the top and underside of the trunk lid after stripping:

Here is a close-up of the glue on the lid. I took the lid outside and removed the glue with a wirewheel mounted in my drill. I also hit any rusty spots or other areas where necessary.

On the inside of body panels I intend to leave the existing paint and just paint over it. However, I needed to sand the paint to give it some “tooth” as well as remove any remaining junk on the surface of the paint. I hand-sanded using 100-grit paper.

Then I just washed down both side of the panel using the hose, applying some Simple Green and giving a good scrub with a scouring pad. Then I applied more Simple Green and gave the entire panel a final thorough rinse. Here is the cleaned trunk lid.

Next I moved on to the driver’s side door. The passenger side will have to wait because it has a big dent on it that will require further attention. On the driver’s side I used the wirewheel on the outside to remove any remaining small spots of paint.

Then I did the same on the inside, removing any rust or adhesive and doing a sanding on the paint. I washed the door completely as with the trunk lid.

And I followed the same procedure to clean up the hood.

In general stripping a car to bare metal is risky because bare steel is apt to begin rusting immediately upon being exposed to water, or even to any humidity in the air. Invisible surface rust can begin forming and then fester underneath a new paint job, eventually leading to bubbles and even structural damage. To try to prevent this I am treating the bare sheetmetal with a Metal Prep product. This kind of product is an acid-etch that chemically removes rust and leaves a thin protective coating on the metal that temporarily discourages rust. The etch also has the additional benefit of providing some “tooth” to the bare metal which will help paint adhere. I bought a gallon of Metal Prep from Halon Marketing in Pennsylvania for around $28. I apply the stuff from a spray bottom which I clearly labeled (the liquid is green, so I wouldn’t want to confuse it with Simple Green) and I always wear gloves and safety glasses when I work with this stuff because it is acid after all!

On the truck lid, I first sprayed the surface, then agitated it with a scouring pad to remove any surface rust. When the Metal Prep does interact with rust it can create fumes so I always make sure there is plenty of ventilation when using it.

Then I applied another light spray to the surface, and wiped all of the liquid away using a shop towel. I’ve found less is better provided I cover the metal, because over-applying the metal prep can create runs that need to be removed later.

I followed the same procedure on the door and then the hood. Spray and then scour…

Then spray again and wipe off the excess.

Here are a couple of pictures of the hood after it was treated.

I repeated the process on any bare metal exposed on the inside of the trunk lid, door, and hood.