bmwe30nut

I have a week off this month. I work out of the 'home' area (only go home weekends for a brief period). So....have a whole week to work on cars, so I need to get some things done.

Fluid changes in one car (easy enough).
Front fender paint and replacement in a TJ Wrangler (not too hard).
Try putting some bearings/seals in an AX-15 trans to get it ready to swap into the TJ (2005...NSG-370 trans in it pops out of 1st and Reverse now).
A few other miscellaneous things that need done to various cars.

But: My younger Daughter's XJ (1999) needs some substantial rust work. Passenger side rocker is rusted through. Driver's side has patchy rust (not through it yet). Driver's door front edge is rusted out at the bottom. Floors look good (well...with the exception of where a prior owner patched the Driver's floor with a road sign...but that's got no rust around it)

I haven't welded in years...but have a 110V stick welder (Schumacher) and MIG welder (ditto...but no manual came with it...but there's a full tank of gas...but I've really only used a stick welder before). I'm pretty sure I'm going to cut the bad areas out (probably the whole rocker on the Right side). Weld in new rockers and an outer door skin (can't find a good replacement door anywhere locally....PA salt screws things up pretty well). Not sure on which welder is best, and if I should get Flux core wire (.030 or .035?) for the body work.

I'm going to go slow, do the 'hidden' welds (and some practice on sheet metal) to get refreshed a bit, then the visible areas.

Once the rust is out and the new parts are in, I've got questions. I don't know bodywork at all.

I'll tack weld the parts in place, then move around to not overheat the thin sheet metal. Body filler over the ground down welds to get a smooth look.

Then what? Primer over it? (Any recommendations for a good rust resistant primer?).

Any areas with minor rust (but not weakening the metal)...sand down then POR15 type stuff?

The car's color is Desert Sand Pearl. I'll need to get some spray cans (I have a compressor, but no dryer in line with it to get a real spray gun). Clear Coat?

Thanks for any thoughts, info, etc....

(In 'theory' my Daughter is paying for the stuff...somehow that never happens and I don't ask for the $$, but I'd like to keep it fairly low budget to keep the car on the road for her).

awg

I use .023 wire for panel work, that is the smallest diameter, gas shield, anything else is too hard to control burn through on thin sheet metal 18-20 gauge, preferably I back it with copper strip

It does take a fair bit of practice but you can do pro quality work, and it will work on thicker, although really, you should use the right wire and associated parts for thicker metal

I would only use stick on metal 16-14 gauge

exasemech

AWG pretty well covered it but1) your stick welder is not what you want for sheet metal.
2) if your mig machine will use gas ( probably argon/CO2) use gas rather than flux core. Use.024 wire.
3) if you haven't done it for a while practice practice
practice before you start burning holes in something you care about . takes a while to just figure out what works best... push/drag/stickout/wire speed/volts. Then there's the whole hand-eye thing. It's fun when it works

Jim Malcolm

IMO, replacing the rockers w/ steel tubing is MUCH easier than trying to replace it with sheet metal. I used the method were you weld a piece of angle to the inner wall of the pocket, which the tube then sits on, giving nice easy joints to weld.

I learned to weld fixing floor pans on my XJ with .030" flux core. If you work outdoors, flux core is commonly recommended as wind will blow the shielding gas away. While blowing holes sucks, you learn A LOT about welding sheet metal by filling them back in...

I didn't actually use the can of POR15 I bought, so yes, my opinion is based solely on what I've read, but POR15 isn't all it's touted to be. Much like powdercoat, it doesn't actually bond to the metal in any way. It's relies SOLELY on mechanical tie-in with surface roughness, be it from rust or abrasion. If you apply POR15 to a nice piece of new steel, it will come off as one sheet in short order. It will look PERFECT from the outside, right up until it falls off. Only then will you see all the rust that formed under it. I personally multiple small surprises when it comes to dealing with rust than one great big giant surprise...

The professionals use 2-part epoxy primer. Not only is it literal glue, but since it's a 2-part and doesn't require evaporation to dry, it doesn't have little microscopic holes in it. POR15, being a moisture cure urethane also doesn't have tiny holes in it either, so not really a differentiating factory, but compared to regular ol' paint, ... Any paint supply company that services your local body shops will carry a suitable 2-part epoxy product line.

Make sure you use a 2-part seam sealer otherwise you'll get shrinkage that will prevent you from getting a nice smooth finish...

tlc1976

I also use .030 flux core. I used 18 ga for the panels and 16 ga for uniframe repair. I’ve welded down to about 22 ga and could probably do thinner. You just have to learn the feel, and infinite adjustments for feed and heat helps too. I started with a Century 130, now have a Forney of similar specs. At least it doesn’t have to look like a stack of dimes, as long as there’s good penetration without blowing through, you’re good.

I used 3 heavy coats of Rustoleum professional grade. I could have used more expensive finishes, but in any case the rust will come back and you’ll have to keep up with it. So I went with what was cheap and readily available.

bmwe30nut

@Jim Malcolm

Where to get the (presumably) 2x6 Tubing? Cost vs. 'factory' style Rockers (about $50)? (My Daughter says a co-worker has a some for his jeep that he's going to give her...factory rockers that is).

Thanks!

Jim Malcolm

I should note that "easier" for me is generally a subjective thing... I hate body work, that's why I love my Jeep. It doesn't have to be pretty, it just has to work... To me, it seemed easier cutting the rocker off in a straight line to butt up to the tube than it would be trying to remove the whole rocker and replace it nicely. I could very well be wrong...

I used 64" of 2x6 tubing and 62" of 1/8" x 2" x 2" angle per side. Some people don't use the angle, but it seem to make things easier and stronger.

I live in a semi-industrial area, so finding a steel supply house was not an issue. Any fabrication shop should be able to order you some when they place their next order. It may make things easier if you say that you need 2x pieces of 64" versus 1x piece of 128".

There are also places you can order these materials online and have them delivered by UPS/FEDEX/etc since they're not especially long or heavy...

awg

One thing to note, that makes 2 part urethanes SO much easier to use for major rust repairs, especially primer coats

Just use a brush !

Works just dandy, spraying requires masking off, more respiratory protection, clean guns etc etc

so for a floor, 2 coats of primer, and or primer/filler, fine for topcoat

Brush can be used for external panels, but more sanding

To do finish work, I use a gun

2 pac is much better than POR15