Mr Project

Ok, I just bought a 135 amp MIG welder and am planning on repairing the rust in the wheel well on my '79 SA. Here's a couple of questions:

1 - I'll be cutting (wheel, not torch) and then welding on the wheel well outer area (the body) and the inner area (the famous FB/SA rust). How much of an issue is the fuel tank going to be? I am thinking of draping a large wet towel over any tank or lines in the area and wrapping another wet rag over the fill tube (with fill cap in place) and shutting the gas door. Is that good enough or do I have to (ugh) remove the tank?

2 - Anybody have experience with replacing the wheel well sheet metal? I would love to have a rust-free outer wheel well to weld in, but I don't. Is it feasible to buy sheetmetal and form the 'lip' that I need to? Any tips here? Or, even better, anybody want to sell a rust-free outer wheel well from a parts car?

TIA!

Pele

iTrader: (28)

The wheel well needs the suspension bracket, so I'd say you do need the rust free wheel well rather than some plain sheet metal... I'd like to see how you do this, as I'd like to do the same thing.

As for the fuel tank, I'd drain and remove it. You can never be too careful.

Being that you're using an electric MIG welder, I'd remove any solid state electronics from the car too. (Radio, ECU, Alternator/Voltage regulator, gauge cluster etc.) There is a slight chance that these could be damaged.

lotsacars

Just a couple tips, nothing that really addresses your questions, though

1. Get a fire extinguisher or three for your garage. It's unbelievable how fast a fire can get out of hand.

2. Undo your positive battery cable and when you ground what you're welding attach to one of the pieces of metal you're welding. That way your circuit shouldn't include a path to your ecu, etc.

I plan on doing what you're doing this summer as well, though not to the extent it sounds like you have to. Try to take pics!

JEC-31

A good rule of thumb is that if the car is not perfectly free of rust, then the gas tank is probably rusty to some degree. Maybe it's just a little surface or maybe it's completely shot, but it still needs to be fixed or replaced.

Taking the tank off is easy with a jack and some tools.
1) Block front wheels.
2) Jack up car from rear differential.
3) Place jackstands under rear axle.
4) Undo filler neck from outside of car.
4) Remove gas tank shields (many strange hidden bolts, have fun).
5) Get rags, undo 3 little hoses at top of tank (use a non-hot lighting source!), get gas all over you hands, undo level sensor plug.
6) Loosen the big bolts for the straps holding the tank up .
7) Move jack right up under bottom of tank with large flat cushion.
8) Remove big bolts, while steadying tank on cushion.
9) Lower tank with jack.

Mr Project

Jec - Thanks, the gas tank is perfectly serviceable, I'm just concerned about safety.

Pele - I assume you mean the bracket that mounts to the inner wheel well. I haven't figured that all out yet, but I'm fairly confident I can replace the inner wheel well sheetmetal with new sheetmetal, and then use a thicker-guage metal to repair the bracket separately. Then I'll re-attach the bracket and seal everything up.

My biggest concern is fabricating the outer wheel well. I'm not sure how I'd replicate the shape and the lip with plain old sheetmetal. I could probably take a mold off of a good car and make a fiberglass replacement, but I really want to fix this with all metal.

lotsacars - I can identify with your name. Yeah, I'll get my extinquisher charged before I touch a car with this thing.

And yeah, I'm thinking that unplugging the positive and grounding on the new panel should be ok. I'll unplug the ignitors, but otherwise this is an SA with no stereo, so electronics are pretty limited.

Here's a picture of what I'm calling the outer wheel well... Put this in the 'Before' catagory.

300zx

I have weld with the gas tank on your not supposed to but if you a willing to run the risk like me then do it. Nothing happen when i did it but i aint saying that nothing cant happen. Even at work i dont take the gas tank off. a fire ex. is a good idea and it you got a wet rag on the gas tank nothing should happen.Also if you are welding under the car wear welding gloves because when the hot peice of metal it hot it hurts.Does the welder have Gas??

Mr Project

No, I need to buy a tank of Argon soon. I've been practicing a bit with the flux-core that came with the welder, but I'll use gas when the time comes.

lotsacars

Wow! You've got your work cut out for you. Good luck

JALVORD_2003_68

As to your question about welding I would say a few things:
1st, do ANY welding with a MIG welder(i assume your using CO2 or argon gas) in a low wind enviroment, secondly, the recommended wire speed and heat combination is a ballpark figure so do some practice on like material and fine tune the setting. Don't weld the entire length because with sheet metal it will cause sevre warpage, so spot weld or tact the metal every 6 or 8 inches. And finally metal prep is important with normal metal, and even more so with sheet metal, make sure your metal is clean (free of corosion, paint,etc) and dry.

Good luck using your mig welder, you might find it easier using a gas welder. Any, let us know how it turns out.

nosajwrx-7

Mig welder is the way to go, definitely use gas (argon or stargon(sp)) and use a small wire like .023! Just to add to JAVLORD_2003_68, Always make accurate patches and butt weld everything don't overlap. You will find it will come out better and it will be easier to do the finishing touches later. Also, after you tack every 6-8 inches or 2-3 depending on the size of you patch (use your own judgment), go back and split the distance with tacks up to about 1/2", keep doing this until your done. Doing this will limit the heat applied to any area at one time ultimately reducing warpage. Then grind smooth and finish with a filler. You may need to go back and fill pinholes after grinding.

Mr Project

Heh, yeah, my work is 'cut out' for me. Or will be, in this case.

Thanks for the tips, guys, good info. Do I need to keep making 'tack' welds until I have a sealed seam, or is it enough to get them .5 inches apart? I ask because I had some welding professionally done on another car and he just tacked until the tacks were an inch or so apart.

nosajwrx-7

I would close the seam, If you don't and it is possible for moisture to get behind it, rust could bleed through your paint down the road. I just figure while your at it, it can't hurt to be safe. Plus it is good practice!

BadAssRX-7

i just replaced the pass side wheel well on a 84.... you could put a 5 gallon bucket in the hole i used my mig to do all the welding and then siliconed the welds just to make sure they dont leak

Mr Project

Did you get a good wheel well from another car, or use sheetmetal to re-create it?