HappyCarGuy Posted April 27, 2020 Share Posted April 27, 2020 Hey folks, I just finished welding up some patch-panels for my driver's side rocker panels. I'm worried, though, about the inside of the panels collecting moisture and re-rusting from the inside out (from the drain holes in the back of the panel). Has anyone had experience with filling the rocker panels with a water-/flame-proof expanding foam to prevent water from getting back into them? I read a couple of old hot rod forums, and they said that using foam would trap moisture. Any thoughts/experience on it? To clarify, I'm already welding in patches - I would NOT be using the foam to fill the rust holes. See pictures (don't mind the beginner's weld and messy look - it's not done yet) I don't really want to use slip-ons, because it looks like they may have different curvatures/shapes than the OE rocker panels. If these rust out in a few years, I may have to go that route, though. Link to comment Share on other sites More sharing options...
SpecialWarr Posted April 27, 2020 Share Posted April 27, 2020 I would tell you to drill 1/8" holes in the bottom and shoot them every year with P.O.R 15 type product. Sent from my SM-G390W using Tapatalk Link to comment Share on other sites More sharing options...
Slartibartfast Posted April 28, 2020 Share Posted April 28, 2020 That looks like it'll putty out just fine. And yeah, skip the foam. Water will always get in one way or another, better to let it drain than to hold it in place where it'll fester. The rocker has drains from the factory (along the bottom seam IIRC), so make sure those aren't stopped up. POR15 is supposed to be great when properly applied, but from what I've read, it can be fussy to work with if the surface isn't clean enough for it, so regular spray paint may serve you better here. Sometimes you can get the nozzle from a can of PBlaster or something (with the straw) to fit the spray can so you can shoot it into tight places. An oil undercoat isn't a bad idea, either. Oil coatings can't lift, peel, or trap moisture, and they wick into seams where paint might not go. One guy I watch on Youtube swears by bar and chain oil, cut with thinner so it sprays better. I've also heard good things about Fluid Film, but it sounds like it washes off easier. Link to comment Share on other sites More sharing options...
adamzan Posted April 28, 2020 Share Posted April 28, 2020 I tried the spray foam thing once, it just rotted out after a few years anyway. I think if I had to do it again, I would just get the vehicle oil sprayed. Link to comment Share on other sites More sharing options...
FirstGenFreak Posted April 28, 2020 Share Posted April 28, 2020 (edited) Spray foam will just collect and store moisture. My proven method is to spray first with a rust convertor, which neutralizes rust (and it will form almost instantly on an exposed weld) and then irrigate the area with either Lanolin or Fish Oil. Also, use some seam sealer to fill the gap where the wheelarch meets the sill, do it before you spray the colour and it will look nice. Edited April 28, 2020 by FirstGenFreak spelling Link to comment Share on other sites More sharing options...
HappyCarGuy Posted April 29, 2020 Author Share Posted April 29, 2020 Haha, yeah, there will be much puttying to fix some of this ugliness. Thanks for the replies, guys! I like the idea of getting a straw to spray some protector up inside of there. I may try to drill a small hold near the bottom/back and just do my best to spray oil undercoat strait up onto it. I tried to coat the inner rocker as best I could while I had the pieces cut out - we will see how well it holds up. I have never heard of cutting the bar and chain oil - that is interesting! I may use that as a secondary coat. And yes, the seam sealer is already on it's way here! Hopefully those beads/seams won't look anything like my welds. I'm picking up some brush-on frame paint from Eastwood, so hopefully it will get that rust stopped. If this rocker panel rusts out again, it's not the end of the world for me - I'll just fab something else or use a slip-on. But I'm really needing to get the frame rust stopped now. I'll post some updates soon! Link to comment Share on other sites More sharing options...
HappyCarGuy Posted May 8, 2020 Author Share Posted May 8, 2020 The welds are getting better! :) I'm moving on to the passenger side. I picked up some Fluid Film to hopefully prevent rust. I'm planning to SpecialWarr's advice to drill small holes in the bottom to assist with drainage. It will also give me "access holes" to spray the Fluid Film up inside. Seam Sealer should be here today, so I should be able to move forward with body-work/filling and paint preps. Link to comment Share on other sites More sharing options...
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