My64 Mustang289

What are the pros and cons of doing it yourself with bondo?

ThanksDad

It's a lot cheaper than going to a body shop if you can't weld.
It is not recomened for filling large holes.
It is not structural.
It will not hold up like a welded repair.

With 3 kids and a mortgage I am on a budget and I can't weld. My car has bondo in the quarters, wheel well, and door bottoms. I put fiberglass in my drivers side floor as the damage there wasn't to bad.

If I could weld, had a friend who could, or could afford it, I would have all the rust cut out of mine and have new pieces welded in. Since none of the above apply I used bondo and a little fiberglass.

ky

weld repairs require bondo[&:]

any car needs bondo. everycar has small dings. but thats what its made for. small dings and wrinkles. if its a nice dent, then it should be popped or pushed out as far as it can and then bondo to get it smooth so theres no wrinkles.

Tony R

theres always lead for the old timers out there. I thought about trying it but am afraid of doing more harm than good.

HGC

Bondo takes practice but it can be mastered. The nice thing is if you screw it up you just sand or grind it out and try again. You can't really hurt anything by trying. Don't get it too thick. Like true66gt said, it is intended for smoothing and small fills. Electric orbital sanders are not usually a good way to sand it down. The orbital action tends to leave a line where the bondo and steel meet. The pros use air sanders with a straight back and forth action but you can do the same thing with a long sanding block and little work. Don't just look at your work. Run your hand over it with your eyes closed. You'll feel the high and low spots and other imperfections.

Tony R

I dont like to use my neumatic air sanders because I tend to go too deep. I like to do it all by hand. I might use an orbital at first to knock it down to a managable depth so I am not spending too much time on one spot.

My64 Mustang289

OK thanks everyone that really helps me out alot. I think I'll start work on it tommorrow hopefully

kilgorq

When using a long block dont just go back and forth in one spot. Angle your cut across your work and then do it again at the opposit angle. Basically create an X. Changing the center and size of the x every few strokes. Start with a corse grit likes 40 then cut it a little low. Clean it up real good and add another coat of Bondo but go out a few inches past your repair area. This time cut it with the corse grit untill you start to take away the edges. Finish it off with the finer grit (150) . If you are not sure where you are with it. Spray a little paint on it as a guide. You will find your low spots becuase they will stay black.

HGC

Kilgorq is right about the sanding pattern. Generally I use 80 grit, then 100, then 220 and finally 400. When you are finishing it, use a very light touch...just enough to take out the marks from the heavier grits. And in a lot of areas you simply can't use a block (compound curves). When you use your hand try to use your palm and not your fingertips. Your fingertips pressing down on the sandpaper will leave grooves. And I think Kilgorq meant to sand it after you spray a little paint on it. The block won't take the paint out of the low areas and you can see them. I actually use primer for that. And one last thing...a common mistake at first is to use too much hardener in the mix. It does not take much, as is evidenced by the tiny tube of hardener you get with a full quart of Bondo. The Bondo brand comes in several quality levels and I spend the extra couple of bucks for the premium stuff.

ford65stang

too much hardner will make it crack, not enough hardner will never get hard.

Practice makes perfect, go with your gut on how much hardner