Alternative to welding for minor floor rust:


remove any loose rust, wire brush
treat all rusty metal with phosphoric acid based metal prep like ospho - let sit 24hrs (follow the directions)

get some 2:1 laminating epoxy resin that takes 30min or longer before it "gels". There are a lot of good epoxies today, just get one that isn't too viscous and has a good working time.

get some fiberglass matting (cheap). Break it up and use it to fill and cover all the bad metal.
Tape off any holes that may drip through.
Saturate the fiberglass fibers with the freshly mixed epoxy (make sure all air bubbles are out of the fiberglass before the epoxy thickens up).

Wads of the fiber/resin can be shaped to fill and cover all the bad metal.



Only use enough epoxy at a time that you can work into the fiberglass matting before it kicks off. Alcohol works good to clean any uncured resin up if you get it on your hands.

Make the epoxy/fiberglass layer(s) thick and it will be super strong and seal the metal off from any future rusting.

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1985 300TD 1981 Scirocco 1.6D conv 1986 Golf 1.6D 2003 Golf TDI