[Goatboyjohnny]

Does anyone have a diagram of where the factory put seam sealer on the underbody of a 66 built in Pontiac? Or was there no seam sealer on the underside?? I would think there would be at least in the seam between the inner and outer wheelhouses.. also at the seam where the floor meets the firewall, and floor to trunk pan...? Any help is greatly appreciated.

[ZeGermanHam]

Are you trying to perform a 100% accurate replication of how the factory did it, or just interested to hear what others think makes sense?

[Goatboyjohnny]

Factory correct, but always open to suggestions.

[Goatboyjohnny]

Anyone??

[Jeff Hamlin]

Most of the cars I have seen all appeared to have no seam sealers under the body. You will see variations of application on the upper firewall and in the trunk area.

If you think about this make sense seal the top/upper seams so moisture does not migrate down into the lower portions of the body, Leaving the underside unsealed allows moisture to have a was out if it dose. get in.

I looked in assembly and body manuals and there was zero information I could find on sealants other then glass.

So it really is your call if you wanted to do so.

Cheers.

[Goatboyjohnny]

Thank you Jeff, that all makes sense for let any moisture that gets in out, and grat info about no info in the manuals.

[ZeGermanHam]

My '66 was so covered with thick undercoating put on by the previous owner that I couldn't tell you where it originally had seam sealer. After I had my body sand blasted, I applied seam sealer in the following locations:

- Along the seams of the trunk floor braces (will be hidden under the gas tank)
- Rear edge where the trunk pan and taillight panel are pinch-welded
- Along the bottom edge of the trunk pan "drop downs" where they're pinch-welded to the quarter panels
- Seam between the inner & outer rear wheel housings and down at the rear lower corner of the rear wheel opening where it meets with the lower quarter panel
- Transmission tunnel lap joint

I didn't seam seal any of the main floor braces because the factory didn't use any there, and in my case, I sprayed on undercoating that seals everything up pretty good anyway. I do think there is some merit to seam sealing the main floor braces in order to keep water from getting inside them and then being trapped in the "trough", but it would look very unoriginal to add it there.

[Goatboyjohnny]

Cool, thanks alot. I have a little bit of welding left to do, and surgery on my hand Monday.. probably goin to slow me down a bit lol, but I'll post pics after I get her sealed up and painted.