Body Filler for Inner Fenders

[68BarracudaTT]

So I did some rust repair on the inner fenders of my car. I butt welded in some new metal and ground it all down; it turned out pretty good, but not perfect. I want to skim coat it with something to smooth it all out, but since it will be near the exhaust, I want to make sure I use something that will hold up well to heat. I see All-metal, Lab-metal, and high temp. Lab-metal as some metal filled body fillers that seem like good candidates, but I don't have experience with any of them. Does anyone have any experience with these or something else that can handle under hood temperatures near exhaust headers? They are small areas, so I am not too concerned if its difficult to work with or sand.

Thanks for any and all input.

Edit: Picture added for clarity

 

[Ron816]

any pics of the repair?

 

[68BarracudaTT]

any pics of the repair?

Not all the spots, but I would say this is representative; It is the battery box area (It was rusted through and I removed the large support from the backside since the battery wont be under the hood). The other two areas are the closest to the exhaust where the shock towers (braces?) are.

 

[Ron816]

That’s far enough away I wouldn’t worry about heat

 

[Syleng1]

All metal I’ve worked with before. If done properly is some pretty good stuff. Very hard to sand once fully cured. I’ve actually used what I call a cheese grater used for plastic filler when it is like 70 percent cured to take down the high spots. It handles heat rather well but any place that gets exhaust got it will bubble and peel/crack.
After seeing you photo. I would not worry about heat there.

 

[HankRearden]

That needs next to nothing for filler. I would just use some plastic filler thinned with plastic reducer from usc. A quick sand coat of filler primer and done.
Also Ive been using summits brand of plastic filler and Im really surprised and how smooth and easy it is to work.

 

[jos51700]

If you're that worried, would it be that hard to section in the pieces in question? I'd think once the filler was more than 5-6 inches away from the exhaust, there'd be no issue. Is this a street car, resto, race car....?

 

[68BarracudaTT]

Thanks all for the reply’s so far, I have updated the original post to show the area that needs some filler. It is just some self etching primer on there right now, but it will come off when I figure out what to fill it with.

 

[68BarracudaTT]

If you're that worried, would it be that hard to section in the pieces in question? I'd think once the filler was more than 5-6 inches away from the exhaust, there'd be no issue. Is this a street car, resto, race car....?

Its going to be a race car, but I would like to get the area better looking while it is all apart. I did the best I could with the welder and grinder, but there are still some pin holes and a bit of waviness I would like to smooth out. Also, I added a picture to the original post of the area in question.

 

[ESP47]

That needs next to nothing for filler. I would just use some plastic filler thinned with plastic reducer from usc. A quick sand coat of filler primer and done.
Also Ive been using summits brand of plastic filler and Im really surprised and how smooth and easy it is to work.

Have you been using one of these two?

 

[HankRearden]

Have you been using one of these two?

View attachment 1715995193

View attachment 1715995194

yep. the top one

 

[ESP47]

yep. the top one

Thanks they're half or a third of what the other stuff costs these days so I'll try them out. The reviews are saying that the second one is actually more lightweight than the lightweight one. I may give that a shot first.

 

[340sFastback]

I always like to skim some fiberglass filler over weld seams because it is water proof and keeps moisture from getting in any pin holes that may be there.