Tech Photo-Journal #1 -- Door Crunch Repair

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Repair of minor, pre-existing collision damage on the passenger's door.

Above is the 'before' picture. The damage is a compound (some ridges and mostly valleys) with damage to the factory bend at the center of the door running horizontally end-to-end. Looking down the door, the center was noticeably caved in. The steel door rib, directly behind, prevents fixing this with just a hammer and dolly. The door panel's damage doesn't show that well in the picture, but it's there.

First steps were to remove the mirror, and then to strip off the paint. Haven't done too much collision repair, and for the first time had the correct tools for doing the stripping.

A pneumatic angle 'grinder', from Harbor Freight, along with a three inch mandrel, and 'roloc' ScotchBrite discs worked great. Three grades of discs are shown -- Sears sells a kit with the mandrel and one each of these discs, plus a couple of grinding/sanding discs.

The paint stripping only took about 20 minutes, and half that was waiting for my little 120V air compressor to catch up. A bigger, 240V compressor would be much better. Stripping the damaged area revealed good metal underneath, a skim coat of Bondo, a thick red primer coat, and a thin gray primer coat. No evidence of the original paint, so it appears this door was stripped and repaired previously, only to be smushed while still in primer.

Time to break out the new stud welder -- bought some time ago from Harbor Freight for $77 (during a great sale).

Here's the welder and a test weld on some scrap. The metal must be clean -- no paint, etc. What the sales info in various catalogs doesn't tell you (usually) is that this welder (lowest end version) requires a 20 (!) Amp (120V) circuit -- most (not all) residential 120V circuits are 15 Amp. Also, that no smaller than a 10 gauge extension cord is to be used with it. Fortunately, I had put in a 20 Amp circuit previously for the 120V MIG. I also had recently bought a 25 foot 10 gauge extension cord -- they are very hard to find. Got mine from an RV supply house that I found with Froogle.

An adapter is inserted into the gun (easily falls out), and then a stud is put into the adapter. Together, they are then pressed against the metal until the outer ring (which is the ground for the applied current) is pressed against the metal too. The gun is triggered to weld the stud to the panel.

The welder came with three sizes of studs, 2mm, 3mm, and 4mm. I guessed that the middle size, 3mm, would be best for this damage and metal thickness. Here's the test weld close up. Turned out great on the first try! Of course better than any on the real work piece ...

Here's the first round of studs attached to the valley of the S-shaped dent. The instructions said to trigger the welding gun for only 0.5 to 1 second, but I found 1.5 seconds to be optimal (don't want a weak joint, or to burn through -- leaned toward the weak side, however). The welding process does make a little smoke, so ventilation is needed. Also some sparks if you pull back the gun too early -- so wear goggles too, and heavy gloves ('read and follow the unit's directions').

After pulling the first set of studs with the included slide hammer, much of the dent came out. But more studs and pulling were needed.

The large lower portion of the dent was concave -- pulling it brought it to about even, but was very floppy (in - out drumming). Using a body hammer on a ridge on the upper portion of the dent, above the body line, did the trick! It forced the lower half to pop and stay out. Nice and strong now. The stud on the dinged-in body line pulled out, leaving a small hole. Will have to fill it the next time I fire up the MIG.

Here's with all the studs removed. Many of them pulled off, or just fell off by themselves. Some came off easily with a slight twist. Instructions say to cut them off, then to grind. Instructions, what instructions? :-)

Here's after using a 4.5 inch grinder with a 120 grit flap disc.

This is the 'final' result of the stud welder and pulling, and a little bit of hammering. Not bad for a first try! Still need more hammer and dolly work, and then to Bondo it (yes, the car has and will have more Bondo on it -- not a show car).

The only other apparent use for the stud welder on this car is a deep bend in the driver's side fender, just behind the bumper (off the car). There's a couple of holes to fill from a previous attempt with a regular slide hammer, but the same process as above is needed with the stud welder. The metal seems heavier there, so I'll probably use the thicker 4mm studs on it, someday ... make that someyear. :-(

A page visitor has another good use for the welder -- to attach replacement studs. For example, the studs that hold on the clips for the chrome around the windows, on the rocker, etc.