Hey, I am having my car repainted soon, among other things. Well, I had the interior and carpet out. I found some rust on the passenger side floorboard. I wirewheeled it down, and there were maybe half a dosen small holes that showed up, and one larger one that is maybe an inch long and a half inch wide. I think that the large one was cause when I nicked the floorboard w/ a cutting disk, and it spread from the little slot. I have attached a pic of the worst spot before I wire wheeled it. I also applied a rust converter to at least keep it from rusting more till I decide what I am going to do with it for sure. I am planning on having the holes patched. I think that the one I posted is the only one that will probably need a patch. I think that the others could actually be filled in with weld(is this alright). I had a friend suggest actually replacing at least that whole front section of the floorboard from behind that front seat brace forward because the rust would come back no matter what I do, but I would have to cut it out and replace it which involves taking it loose from the subframe. I just dont feel comfortable with that especially since it is such a small hole. I plan on taking the rust converter off and seeing if I can grind the rust down to flat bare metal where it is pitted to eleminate rust from coming back. I went at it with a wire wheel until I got rid of the rust color but I was told that wasnt enough. Any opinions/suggestions would be appreciated. The floor is still real solid even after I wirewheeled it down. I am ~300 lbs and it holds me fine. Like I said it is just small holes. That surface rust you see cleaned up real well.

Thanks

Ben

 

personally what i would do is to cut a square out and weld in a patch. i wouldnt even bother welding all the little holes. just weld a big one. . as for tearing into the subframe, if i am thinking correctly right now that is far enough from the seat mount and it is not directly attached to the subframe so go and weld. i wouldnt worry about it.

 

That is a closup on the biggest. The small ones are spread out and on both sides of the subframe, so I couldnt just replace a square and get them all.

 

Here are a couple pics of the other holes. Sorry about the quality, but I dont have a good camera available. The White color is from the rust converter. I put 2 coats on. The first turned black, like the bottle said it would, and the second kinda just stayed white but kinda see through. The pics kinda make it look worse than it really is though. I circled the small holes in red.

Ben

 

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Just to put things in perspective, the hole on the bottom right of the first 2 pictures is about an inch long and maybe half an inch wide. The rest are quite a bit smaller. Also, the crap on the part of the floor that is still blue, is glue w/ strands of insulation stuck to it, not rust.

Ben

 

I can't tell for sure what that looks like, I'm sorry but the pictures are just too bad. But I will try to help you out. If the surrounding areas are in good shape like you said, it's all good metal, I'd just fill the holes rather than cut the whole thing out. If you're really worried about rust, you're going to have to do a lot more work anyways, so don't worry too much about that, unless you want to go the whole nine yards. Rust will always return, unless you take complete measures, and even then, nothing lasts forever.

As far as patching the holes, I'd try to get a piece of copper or brass and have a buddy hold it under the hole, or hold it under there with something, and then just weld over it. The weld won't stick to the copper/brass. As long as you tie your welds to the surrounding metal, you'll have a nicely filled hole you can grind down and finish off.

If you want to truly rustproof your floorpan, you're gonna need a sandblaster, and then some Por-15.

Mathius

 

As far as the sand blaster and por 15, I thought that I had always read that you are not supposed to sand it clear down w/ por15 because it needs something to adhere to? Sorry about the quality of the pics. With any luck the car wont be driven in winter in the salt anymore, but I cant gaurantee that yet, and I am hoping to do as much as I can to prevent the rust.

Ben

 

To clarify on what you heard, POR-15 doesn't adhere as well to bare metal as it does to rust. That's true. However, to get the true benefits of POR-15, you not only have to apply it to bare metal, but you also need to make sure you coat both sides of the panel you're working on. It does you no good to apply POR-15 over an already painted surface. All you're doing is locking in the bad paint, and allowing it to rust inside the coating of por-15.

Mathius

 

I realize that you dont want to apply it over paint. Would it be feasable to only use the por15 on the bad area of the floorpan rather than stripping the whole thing? Can you paint over por15?

 

You could very well use Por-15 over the bad areas only. I only mentined sandblasting the whole floorpan because you mentioned you were worried about rust coming back. If you're getting rustholes in your floorpan, chances are the whole bottom of your floorpan is in need of help on some level or another, unless you have some kind of water damage on the interior. You're going to want to rustproof the whole bottom of the car to completely eliminate it, and I'd do the inside as well if it were me and I already had everything stripped out.

As I said, the most efficient way to do it is sandblast it out, otherwise you're running the risk of trapping the rust inside whatever rust proofing you use, which makes it worse. Even with the rubber-like underbody coatings, or on a truck, if you use a spray on bedliner, this is true. If you trap wetness, rust, grease, whatever underneath the coating, you're going to have problems. The same goes for painting a car even.

Yes you can paint over Por-15. They make a special primer to use for it, but I don't think it's required in any way. Someone else could chime in here. I think TPI383 did his whole car in POR-15 inside and out, ask him for more details on that. I would just use regular primer, I don't think the POR-15 primer is actually required, just preferred for better adhesion.

Mathius

 

Well, the rust did start from inside the car. The car is more rust free than my Cousins 89 fomula, or my friends 86,87, or 89 Iroc, or my brothers 91RS in all the spots other than that one spot on the floorboard. It appears it had a leak there. I have the fenders and gfx off of the car, and for being in this area of the country it is really in good shape as far as rust is concerned. I think that it must have been garaged most of its life or something. I plan on at least stripping down that entire area top and bottom for some sort of rust proofing, but I think that I am going to at least leave the rest of the interior alone, and maybe most of the bottom because like I said, there isnt much rust other than that one area and it seems to have started from the inside from a leak or something.

Ben

 

I had a fairly significant problem on the driver's side floor pan. By the time a cut out the problem area, I had a rectangle that must have been 1 x 6 or so. I painted with POR-15, used their mesh cut to size, applied their putty, then repainted. This was perhaps, three years ago. So far. Perfect. I've been so impressed with their products, that when I converted to 1LE brakes, I not only painted the spindles but the a-arms and springs as well. Next, the rear end (brake upgrage coming this summer).

JamesC

 

On the same subject, but a different note, I plan to POR-15 my entire car inside and out (Michigan uses salt..bastards..) and I'm not too worried with the inside being a problem, but underneath the car, anyone have an idea of the best way to paint this? The only logical and cost effective way I can think of is blocks, but it doesn't seem like there would be enough light. One more thing, is it safe to use POR-15 on metal brake lines? I'm not gonna sand them for obvious resone, but they aren't rusty and I don't want them to be, I like the idea of replacing with SS braided lines, but they are awfully flimsy and hard to make look good in the hanging proceedure. Thanks for any insight!

Nick

 

I have the braded brake lines, and new hard lines in the rear. If you are to worried about it I think that they have stainless hard lines. You might have to bend them yourself though.

James C, it sounds like it worked good, but I dont know about replacing the floorboard with filler. I think I am going to weld som metal in there, and try to do some rust prevention to keep it from coming back.

Ben