A-Pillar Repair

Note this repair is currently in progress. I will update this page from time to time, whenever I have new information to share.

When I first bought this car I didn't even realize there was rust in this area. In fact, I didn't even realize there was rust here until the car came back from the stripper. A carelessly installed radio antenna most likely allowed water to enter the A-pillar. And once inside, the water was trapped between the A-pillar and the top of the front column, causing rust to form on at the bottom of the drip rail and the back side of the pillar.

A-pillar 01

Water leaked in through the antenna hole and caused the rust seen here and in the next picture.

A-pillar 02

Rust on the back side of the A-pillar.

It's a good thing I work slowly, because it took me quite a while to decide how I wanted to repair this mess. Fabricating complicated patches from scratch for an A-pillar is way beyond my abilities, so what I needed was an A-pillar from another car. Eventually, a local purveyor of used BMW parts notified me that he would be cutting up a square taillight 2002. He kindly supplied me an A-pillar and a rear window parcel shelf for the cost of a few Sawzall blades.

With my replacement part in hand I set about to remove my A-pillar mess. First, I welded in a piece of 1-inch square tube to reinforce the pillar before I started cutting—if you're paying attention you'll be able to see it in a few of the following shots. Next, I marked my cuts and tore into the A-pillar with a hack saw, a body saw, and a Dremel with a small cutoff wheel. Actually, I was very careful. I wanted to remove the outside of the A-pillar only, leaving the inside intact.

A-pillar 03

A rare action shot. I am prying up the back of the A-pillar. There are a lot of welds in this area, and it did not give up easily.

Now I was stuck and frustrated. Once all of spot welds were drilled out and all of the seams were cut, I was still unable to get the darn thing off. Turns out that there was one more weld that you can't see from the outside. After pulling the pillar open from the top I discovered that the back side of the A-pillar is welded to the top of the front column on the inside. After cutting the weld with the indispensable Dremel tool, the pillar was finally free, but quite mangled.

A-pillar 04

The secret weld. It's also easy to see how moisture gets trapped between the A-pillar and front column.

A-pillar 05

Ugly, isn't it?

A-pillar 06

And uglier still. I've got my work cut out for me!

Before I could start on the A-pillar, I had to do something about the rust on the upper portion of the front column. After making a cardboard template, I cut out a piece of 16-gauge sheet metal and formed it in my bench vise. 16-guage sheet metal is difficult to bend and it was necessary to heat it first with a torch. I used a big 'effin hammer and various pieces of scrap pipe to get the contours as close as I could. Fortunately, most of this gets covered up by A-pillar.

A-pillar 07

16-guage sheet metal for the front column.

A-pillar 08

It was heated with a torch and bent around various pieces of scrap to get it into the correct shape.

A-pillar 09

Making all of the bends in the proper place was difficult. This is the result of my second attempt.

A-pillar 10

The rusted section is now ready to be removed.

A-pillar 11

Well how 'bout that, it almost fits!

The front column patch was first tack-welded into place. After I was confident that the A-pillar replacement piece would fit, I completed the welds and ground them smooth.

Unfortunately, the replacement pillar that was cut from the other '02 also suffered from some of the same rust (where the A-pillar meets the front column) that had claimed my original one. The rot was not quite as bad, but it was probably a few years away from rusting completely through. This is worrisome, because I originally thought that my rusty A-pillar was caused by a leaking antenna hole. However, my replacement A-pillar had no antenna hole. Moisture must have been getting in some other way, or maybe it was just from condensation. Whatever the case, when I work on the other side of the car I plan drill a couple of test holes into the A-pillar, where it meets the front column. If I see that telltale puff of red dust as the drill bit passes through the first layer then I'll know if I've got problems.

To repair my replacement pillar, I made a patch out of 20-gauge sheet metal using the same approach that I had used earlier on the front column. Except that 20-gauge is a lot easier to bend, so I didn't have to use any heat. When I was satisfied with the shape of the patch I tack-welded it into place and tested the fit. When I had it right I welded the rest of the seam and ground the welds smooth. Also in this process I stripped the old paint off, removed any remaining surface rust, and put a coat of POR-15 on the inside of the pillar.

A-pillar 12

The A-pillar replacement piece took quite a bit of careful trimming and filing to get it to fit just right.

A-pillar 13

This is the rusted section of the replacement A-pillar after it had been removed.

A-pillar 14

After tack-welding, the fit is checked.

A-pillar 15

Then a final pass with the welder.

A-pillar 16

And after grinding the seam smooth, two holes for plug welds were drilled and coat of 3M Weld-Through Primer was applied.

It took a few vise grips and some final massaging to get the A-pillar repair into place. Then, when satisfied with the fit, I took a deep breath laid down a couple of welds to tack it into place. I then moved around with the welder, carefully checking and adjusting as necessary, until the piece was completely tack-welded.

I then proceeded to carefully weld until most every gap was filled. There were however, a few tight spots that I was unable to weld because the torch of my MIG welder is too large to fit. I plan to fill these areas with small amounts of JB Weld.

A-pillar 18

After the first round of welds. You can't see them in this picture, but plug welds from inside the passenger compartment replicate the original spot welds.

A-pillar 18

After the final round of welds.

A-pillar 19

Most of the welds have been ground smooth.

A-pillar 20

A little more grinding yet to do, but the repair is nearly complete.

I still have some grinding and filling to do, then I will coat the interior of the pillar with POR-15. Stay tuned for the final details.

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