Do I use bondo to fill a custom chopper gas tank weld?

Question

I am building a chopper, and I'm doing some welding and stuff to the tank/fenders. Do I use bondo to fill/smooth everything out? Do I put it over the whole tank/fenders, or just the weld? Do I have to worry about it cracking later? Do I do it before or after the primer goes on? I want to weld in my struts for the rear fender, so it's a strutless, or kind of. Then make it look like they are not in it.

Any tips?

Answer 1

Assuming you have ground down the welds, you can use a little filler as a cover...do it before you primer, sand it smooth, make sure it's clean and fully cured, then primer. Hope this helped.

Answer 2

If you're talking about filling any potential holes in the weld with Bondo, I would say absolutely not. Gasoline is a solvent and if works its way into holes in the weld, it will eventually eat through the bondo and paint. Fill hole with more welding material then grind down as much of the high spots as possible. For a nice smooth seamles paint job, use body filler all over the tank and then sand it down evenly. You should do the same on all larger pieces being painted like fenders, battery boxes, oil bags, etc.

Answer 3

it has to be a plastic body filler that has flex agent you know that gas tanks expand and contract right, they make pbf specifically for gas tanks. i cant remember the product name. i have seen it break away and ruin the paint when it is applied to thick. my advise to you is build up welds where you need and grind it smooth. The fenders can be preped with bondo. you might ask someone in a body shop what the name of the tank filler and the max thickness it has to be.

Answer 4

I would use lead. If done right, you will need very little bondo if any. Then use glazing putty for the finnish. Rolf H. W. PS. Lets see some pics when done!