Seamless Design / Chassis Update

I’ve been posting this progress on both an Audi forum and a forum focused around the rally community. This allows me to get as many different perspectives during the build as possible. The more eyes from different perspectives now, should save me time and energy later.

One of the things the rally community became adamant about while I had the engine bay so empty, was to stitch weld parts of the chassis. I fought this notion with some effort because I knew the magnitude of the work required to pull this off. Eventually I decided to settle on welding the seams that are readily available now, and to return to other parts of the car later.

From the factory, the chassis’ are constructed of unique pieces of sheet steel. These different pieces are held together in a few different ways. First, the manufacturer will create a small overlap in two pieces and use a “spot weld” to hold these two pieces together. Spot welds are created by placing electrodes over the lapped joint on either side of the sheet steel, the current then creates a “spot” of weld.

spotweld

Credit: Robot-welding.com

These spot welds are great for the economical purpose most people have for their cars. In rally conditions however, where the chassis will see far higher stresses than the engineers planned for, these welds can come apart. Especially if the car ends up in a ditch, an occurrence not all that uncommon in rally.

The solution then is to weld these overlapping sheets to each other. But in certain areas, OEMs will also (or sometimes in substitution) use an adhesive. These adhesives are incredibly durable and therefore, hard to remove. This creates a lot of work to dig up this adhesive and prep the steel surfaces for welding.

Here you can see the spot welds exposed:

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The fix is to lay down a bead of weld approx. 1″ long spaced approx. 1″ apart:

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The welding of this process actually goes quite quickly although the surface prep takes some time. For areas that are covered in the adhesive I mentioned above and are hard to get to (tight corners) the rally community provide a nice solution. The solution was to take 1/16″ flat bar stock and hammer it into a 90 angle then place into the corner and weld.

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Placed into the spots pre-prep:

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Then prepped and welded (apologies for my beginner level welding):

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Also, while there was a lot of bare real estate, I added some new chassis grounds:

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I then applied some engine bay paint after many many hours of prep, where you can see the beads if you look closely like an ant trail around all the metal joints. Also what is not really visible is the number of welds done underneath the engine bay where various pieces of sheet metal come together:

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Now this was a considerable amount of work just for the engine bay. If I had more time, I would extrapolate this process for the entire car – adding significant strength to the whole chassis of the vehicle.

I had to do some other work on the chassis of the vehicle that pertained more to preventative maintenance than performance enhancing feature. The vehicle came to me with a damaged rear rocker panel. It’s clear the vehicle collided with something and that caused an open gash which has allowed salt to begin to corrode the steal in the area.

Here’s how I found it:

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I started by hammering the indent out from the inside, and then opening up the area with a grinder:

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Then using a cut-off wheel, I started removing the decayed areas:

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While grinding off the finish for weld prep, I noticed the affected area was worse than originally thought. You can see the left-hand side of the opening has some weaknesses in it and had to be removed further:

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More cutting yielded:

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So I took a page out of “Project Binky”  and created a cardboard template and then created a piece to be welded in. Here we go:

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I’ll need to come back and add a picture of the finished product here. But as you can imagine it was a lot of prep work, welding and then POR-15 to protect it on the outside, then rustoleum spray primed inside and I’ll be using seam sealer on the inside edges. Pictures to come!

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