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.

Jack Hole Plug Repair

Tonight I made a quick repair to one of the jack hole plugs that was damaged. One of the little arms that holds the plug into the lower sill underneath the door was broken off and missing. The plugs cover up a small metal tube inside the sill where a post from the OEM jack is inserted to jack up the car. I’ve heard horror stories about the jack slipping out of the tube and gouging up the door. Maybe this happens and maybe it doesn’t, but to me it isn’t worth the risk so I will never jack the car using the original jack in the sill. But when I got the car it had only one plug in place, I was lucky to find the second broken one inside the car and will repair it and put it back into place for an original appearance. I started by stripping the red paint from the plug using a Clean & Strip wheel from 3M.

Here is the good side of the plug, showing one of the arms that holds the plug into the tube. The other arm was missing altogether.

So I just cut out a narrow strip of 18-gauge steel and welded it into place.

And with the repair made the plug popped right back into its rightful place.

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.

Engine Bay Sheetmetal Repairs

This morning I continued with welding sheetmetal repairs in the engine bay.

Before I did that I actually noticed a very small second hole in the driver’s side floorboard. Yesterday I welded shut one hole that measured maybe 1/4″ in diameter. This second hole was about half as large and located over by the door sill. I welded it shut with just a few short bursts from the MIG.

Then I used the Dremmel with the small cutoff wheels to grind off each weld flush to the floorboard.

In the engine bay, on the passenger’s side of the car, there were several holes where non-original accessories, for example the electrical fuel pump, had been mounted. Since I’m taking the engine bay back to stock configuration, I needed to repair any of these holes. Here are a couple of pictures of the holes toward the front and also two up higher in the engine bay.

Prior to any welding I removed any surface dirt and/or rust by cleaning around each hole using a 3M Clean & Strip Disk.

Then I welded up the holes using .023″ welding wire and Argon/CO2 gas. The lower rails of the engine bay were made of thicker sheetmetal, but on the sides I tried to back up the metal with some solid steel plate in order to diffuse the heat and prevent melting through.

Here is the finished result before I started grinding the welds.

First I began grinding off the proud welding metal using two cutoff disks mounted into my Dremmel.

Then I decided to mount three cutoff wheels in my 4 1/2″ angle grinder and use the edge of it to try to further smooth out the welds. This worked very well and provided a much broader footprint for flattening the welded areas to the surrounding sheetmetal.

On the firewall, in the niche where the brake master cylinder resides, there was a crack in the firewall. From what I’ve heard this is fairly typical and caused by the force of stepping on the brakes; the sheetmetal on the firewall eventually fatigues and can crack. In addition to repairing this I plan to install a firewall brace that has been invented to shore up this mounting point and therefore remove any slop in the brake pedal motion. Before beginning the repair I cleaned the area with a wire brush, on both sides of the firewall.

Then I re-aligned the sides of the metal where it had split by tapping on it with a body hammer.

Then I welded the two cracked sections back together.

And then I ground down the weld flush with the sheetmetal.

When I bought the car it had hoodpins, which are not original to the roadster. My intention has been to remove them. I removed the pins themselves and then I wanted to seal the holes they had been mounted to. I began by trying to raise the metal around the holes, which had been bent downwards to install the pins. I just used a heavy hammer to pound upwards from inside the cabin; no need to be delicate as I plan to fill the dents later. The main reason to try to roughly straighten the metal was to minimize the amount of filler required later. Here are the holes where the hoodpins had been.

So I just welded over the holes. Later I plan to fill the indentations so eventually there will be no evidence that the hoodpins had ever been installed.

Body, First Welding Repairs

This afternoon I used my new welder to repair some holes in the body sheetmetal. Welding closed holes is a good place to start to get a feel for welding sheetmetal, because it basically consists of blobbing into and over the hole a lot of welding wire and then cleaning up the mess later with a grinder. If you blow through the sheetmetal, which is easy before you get some experience with setting the voltage and feed-rate to appropriate levels, well then you’ve just got another hole to patch. Also, fixing small holes in the body doesn’t really constitute making structural repairs, so it is okay if the weld penetration isn’t great. For sheetmetal I use the thinnest welding wire I can (.023″) in order to keep the voltage as low as possible.

So after practicing on a lot of 1/8″ steel stock I bought at the hardware store I jumped right in to making repairs in the body. The roadster sheetmetal is very thin, so it is easy to get the weld to hot and melt right through. Trial and error with the voltage set-up allowed me to minimize this. Also, I found it necessary to back up the sheetmetal with a steel plate to effectively thicken the area and allow for better heat dispersion. Finally, I welded in very short bursts, essentially just making a long series of spot welds, which prevented too much heat build-up.

On the driver’s side floorboard there was a small rust-through that I cleaned up using an abrasive wheel. To prevent welding over rust, I used rust-converter on the hole and the area around it. To get a clean weld it is imperative that the metal be completely clean and rust-free.

I wore my auto-darkening helmet, welding gloves, and protective clothing before welding. By making each tack slightly longer in duration (by holding the trigger down sequentially longer each time) I found that he material I had previously deposited would melt into the new tack, creating one single weld-pool and allowing me to control the shape of the repair better.

In the trunk there was a hole by the jack bracket. I used a wire wheel to remove the paint from around the area and did the same on the underside of the body. I started welding up the hole from the bottom, building up tacks from the sheet metal rim around the hole inwards towards the middle of the hole, where tacks from either edge of the whole met.

After building up a lot of welding wire I moved to the inside of the trunk and built up some tacks on that side.

Then I used my Dremmel with a pair of small cut-off disks mounted in tandem to grind down the welding blobs I had created to smooth out the metal.

I quickly realized that the body that I had painstakingly washed so many times was getting covered in grinding dust!

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, Final Washing

This afternoon I gave the body another washing in order to remove the seam sealer and rust particles, as well as the solvents used to clean up both.

I started out by sanding all of the areas where paint removed, in order to rough them up so the new paint, when eventually applied, will adhere. I used 120 paper and sanded the rear area of the cabin.

I was also careful to sand all up underneath the dash on the firewall.

Then I started washing inside the trunk, where I had sanded previously. I sprayed with the house to wet everything down, then sprayed Simple Green on all the surfaces.

I used scouring pads to scrub all of the remaining particles of seam sealer that had flown off the wirewheel onto the sides of the trunk as well as any of the solvent I’d used to remove the sealer itself. I also made sure to scrub the recessed areas where the drain plugs are in order to remove any rust neutralizer that may remain on the surface.

After the trunk was pretty clean, I gave it several more good rinses with the hose.

The Simple Green is an excellent de-greaser and the trunk came clean and dried quickly in the hot Texas sun.

Likewise I wet down and sprayed Simple Green throughout the cabin, giving every area a good scrub with the scouring pad.

The cabin and the firewall came clean and, after I drained the water, dried quickly.

Here is the underside of the firewall after the final (I hope!) washing.