welding floor on WDX with stick or mig?

[Jason Mills]

My WDX has rust holes in the floor, around the cab mounting bolts. I am looking at it as a challange to save a truck, and boost my level of expierence a bit. yet I hope to have a finished product of good quality.

In my limited experience, It seems that mig welding is easier to control, so it shoud be a no brainer, but have I heard that it makes for a very hard weld bead? or some thing like that which makes it less approprate for body work? If that is the case, should I spend a few more weekends praticing with the arc welder? It is a AC only machine. I have been using 80AC rod that I got from the local welding shop, is there a better rod out there for body work?

[MoparNorm]

The MIG is specifically designed for sheet metal work, lower heat ranges and easier to use. However no matter what you use, get some scrap sheet metal to pratice on before you attempt to weld on that historic sheet metal. Arc welders are nortorius for burning holes in rusty sheetmetal, even in experienced hands.
MN

[HWooldridge]

MIG is definitely the way to go. Choice of shielding gas and size of wire dictate penetration levels. I'd start with .025 to .030 wire and straight CO2 shielding gas. Cut the rust out to clean metal and put in a patch to fit. Weld, grind and finish with the body filler of your choice.

I can almost guarantee you will not be happy with the results from a stick.

[Jason Mills]

Thanks for your guidance. I plan on sandblasting the parts first. Then I will spend plenty of time with the mig.
I figure that I only want to do this project once and be happy with the results.

[Gordon Maney]

Tell us a little about your 1990 truck.

[Jason Mills]

The 90 is on its fourth owner. It needs some paint, and a good clean up to be presentable. at the moment it is being neglected, as the 46 has center stage.

Never the less, It is just a basic truck: Getrag, Air (does not work, have not bothered to investigate) and a AM/FM cassette..flatbed, and a great motor. I started out looking at the VW TDI and ended up with a Dodge Diesel.

I am Consistantly amazed by how it will usually begin running almost instantly upon the starter moter turning it over. It is a rare day when the motor has to turn over as often as modern day spark ignition engine, although I have not driven in in the cold of winter yet.

Other aspects which interest me about it are the vent windows(and the vents down by your feet). I feel they are a throw back to pre-air conditioning. As is the overall design... Granted the newer ones are better all around trucks.

[Jimmy]

I am working on the same thing.

I am trying to do the same repair. I have a little welder - a Lincoln Pro-MIG 135 that is set up to use 0.025" wire. I just got it and haven't used it yet. We had a bigger MIG unit at my workplace that used 0.035" wire. I can weld heavier stuff than the cab metal with the big unit, but tend to blow holes in thin stuff. I am hoping the smaller wire will help. I should know later today.

Does anybody know the original gauge of the floor pan and cab panels?

How about pointers for the welding?

I do have one neat trick that one of my coworkers taught me to fill in pin holes:

Put a heavy piece of copper on the bottom side of the metal. Then you can just make a little puddle where the pin hole is and it will harden in place. Then grind it smooth. The copper keeps it from blowing through, and if tight enough, keeps the backside nice and fair.

[Bruce]

Great Trick

Hey Jimmy,
I will have to remember that one! Is there any trick to keeping the copper in place? I also has the pro mig, with shielding gas, but I need more practice.
Thanks,

[Jimmy]

I've always used C clamps and those funky vice grips that welders use to hold the copper, but I have only done it at a bench. I have been thinking how to do it in the cab. I think I will use a piece of 2" x 2" wood cut to length and two wooden wedges to jam it up tight.

I tried the 0.025" wire today and it is much easier than the 0.035 wire. With the voltage on A and the wire speed on 2 I can fill in pin holes pretty well with no backing. For most welding on the cab I set the voltage on B and the wire speed on 2.5.

What are you using for gas? I have the argon/CO2 mix because we had some at the shop, but I am wondering if it behaves differently with Co2.

[HWooldridge]

Argon gives deeper penetration with hotter arc and CO2 gives a more stable arc with moderate penetration. CO2 is also cheap but can only be used on plain steels, while Argon can be used on stainless. A blend of the two gives some characteristics of both. I used straight CO2 for many years and finally switched to a blend. Quite honestly, I can't see any perceived difference between the two.

[Bruce]

Still A Rookie

Hey Jimmy, Hollis,
Well I checked and it is Co2, and I'm almost to the point where I can make a nice bead. But a bead isn't neccesary for filling pin holes and such, so I might get started on some of the little stuff. If I wanted to try the argon gas or blend, do I get the tank refilled w/it or simply purchase a new tank with it pre-filled, or is it worth the effort?
Thanks Guys,

[HWooldridge]

I don't think they will swap mixes in tanks - bad practice for things that might go BOOM! I had to lease my CO2 tank because they were not legal for a gas company to sell to an individual (something to do with liability because of the size of the tank). The lease was $10 a year or some such figure. The argon/CO2 bottle I have now was purchased and belongs to me but it is a smaller size.