Seam sealer and undercarriage body seam questions

[funknut]

I've never done any work with seam sealer before so looking for some tips and info on which way to go.

I will be replacing the full front floor pan and want to seal up interior and exterior seams as best I can. I am not super concerned about the OEM look, and I'm sure it's going to look a bit sloppy as it's my first go at this. What I'm really after is first, the best way to keep moisture out, and second, if possible a slightly idiot proof method.

I plan to epoxy prime everything before applying sealer.

First question, for exterior seams I've read of people using fiberglass reinforced body filler instead of seam sealer. I'm not sure if that's because they are going for a smooth look or if it holds up better than seam sealer. Would a modern (3M, Evercoat, Eastwood, SPI, etc.) seam sealer do well on exterior seams? Is there a significant advantage to using a fiberglass filler instead?

There seem to be lots of choices with 2K, 1K and brushable seam sealers vs. the cartridge type. The 2K stuff seems to be about double the cost and I'm not sure if there's any real advantage except that it cures faster?

Lastly, any ballpark of how much of this stuff I will need to do the entire interior cabin? Enough to seal seams, not glob it on the way the factory did. ;)

Anything else I should consider?

Thanks!

 

[PurpleBeeper]

1. I recommend using seam sealer, not fiberglass resin as seam sealer. Body filler will crack.
2. 1k caulk gun type urethane seam sealer is what I would recommend
3. You will need about 3 tubes, maybe 4

 

[69L48Z27]

What are you using seam sealer for the exterior? Not sure what your working on but only seam sealer I can think of is the drip rail. I would use a 2K self leveling seam sealer for that. I’m not following the fiberglass instead of seam sealer.

On the inside 1K is fine IMO. Shoot all the seams with quarter inch bead and then smooth out with a brush or your finger. Apply more where needed.

 

[funknut]

Thanks for the reply. I'm replacing the floor pans and I'm still debating doing the one piece vs the individual L and R floor pans. If I do the L and R sides separately then I'll have a weld seam along the tunnel. I will butt weld them in but I'm a newbie with a welder and will want some extra insurance against pinholes. Would primer be enough or will I need some kind of sealer/filler as well?

Thanks!