I did a search and read some stuff. But do you have to take the back seats out and roll the rug up to weld on full length sub frames?

 

No you do not....but if you are not experienced and doing it yourself you will want to keep close eyes on things just to be safe.

 

Whenever you do ANY welding, always remove materials that are flamable, especially carpets, wiring and upholstery. You have too much invested in yourself, why try to cut corners? You can replace a car when it goes up in flames, but what about self injury, or worse, causing injury to a helper or building. It only takes about an hour to pull an interior, takes about 1 second to regret you did not!

 

This is true and I would recommend it for a beginner or novice just because of the inexperience....however when welding frame connectors in a Fox you are not welding to metal directly in contact with any flammable parts and the proper way to weld does not mean keeping heat in a specific area to get it hot enough to ignite things. I have welded in probably a hundred sets of frame connectors and never removed interior for the standard variety of frame connectors....but I am experienced and know what I am doing.

I do NOT recommend that a novice do this though....there is a big difference between a good weld and a booger weld that just lays on top of the metal and if you do just sit there and weld a straight bead rather than stitch areas and let it cool before going back then you will warp the metal and get things hot enough that you could ignite something.

Now...with all that said there are exceptions.....one being that if you are working on a car that has been undercoated then ABSOLUTELY remove the carpet and be certain you have a water bottle or extinguisher nearby as undercoating can and will catch fire.