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Floor pan / Front floor brace welding questions

1661 Views 9 Replies 4 Participants Last post by  hmott
Just ordered a new left front floor pan and front floor brace this week. I've drilled out the spot welds in preparation for putting the new brace and pan in this weekend. Until I pull the brace out and get a look at the bottom of the floor pan, I don't know how much (if any) rust is in there.

Questions I have are:

1) If I do have rust, will grinding out the rust get rid of all the rust? I don't have access to sand blasting equipment so I can't go that route.

2) Could I apply Rust Block (Por15-type product) into the area between the floor plan and the brace prior to welding?

3) Should I just stick with using the weld thru primer on the bottom of floor pan I?

4) Should I put anything else down between the brace and floor pan to keep rust at bay prior to spot welding the two pieces together?

5) When welding in the new floor pan section, I am undecided if I should lap weld or butt weld the pieces together. I've never welded before so this is my first attempt at it. I am concerned about rust starting in the area that is lap welded so prefer to butt weld. If I take my time, how difficult is it to butt weld the floor pan?
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1. I didn't sandblast my floor panel braces. They were pretty rusty though. I used metal etch and soaked them for a week. Most of the rust was gone.

2. I used an epoxy between the brace, but you could use Por there as well.

3. I used weldthru on the bottom of the pan where it braces against the brace. That should be fine if yours are EDP.

4. Weldthru should be fine, that's all I did on the bottom. If I could do it again, I would epoxy the area that lays over the braces.

5. I would suggest lots and lots of welding practice before doing the pans. This can be a very frustrating process. I used sheet metal screws to keep the two panels tight, and then plug welded them. One problem was the panel kept lifting up when I would try to tack them in. Just be sure you are putting enough pressure on the area you are welding and hold the panel a few seconds after till the metal has cooled. I tacked mine and then as soon as I let go, the panel lifted up about 1/8".

Good luck and make sure to pratice on similar material before attempting.
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I had my entire floor out so the cross braces were cleaned out and painted.

Take out one side of the floor, trim to about 1-2" rough overlap so you can get an idea of what needs to be trimmed. Clean out the channels and spray with epoxy. Lay new pan over the top and use sheetmetal screws to hold in place. Go under the bottom side and mark the outer edge with a sharpie to get the outline of the braces on the pans. Pull out the pans and drill holes about 1/8 /-1/4" off the outer edge so you can plug weld to the cross braces. Space the holes on the crossmember about every 2" or so. IMPORTANT: MAKE SURE TO Grind off the epoxy or you will not be able to weld the new pans to the brace.

I think you would be better off not butt welding the panels. Overlapping them will be much stronger, using a plug weld. That's how I did the toe sections and along the sides by the doors. You are going to have to fab up a piece to run down the center of the floors too. Click on my link in my sig and look at all the floor pan pics, this will help out.

Go buy a gallon of Southern Polyurethane. It's awesome stuff and for $130 you get 2 sprayable gallons of epoxy that will spray much better than any PPG DPLF.
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I'm going to try and pour epoxy into the the supports after there on, and roll it over on the rotisserie, anybody had a luck with that.

Seems like I read that someplace. Pouring it in.

I shouldn't butt in here, you're giving him good advice SS396boy

Pour in epoxy?? Hmm, why not brush or spray it on? I tried brushing it on and it went on realllllly thick. I think a foam roller/brush would be the way to go.

I sprayed my SPI and loved the way it sprayed. Lay's down smooth as glass even with a cheapo HF touchup gun, I couldn't believe it!
I'll save the ppg dp90 and buy some of the cheaper stuff to pour down the holes, where do I get that spi:) .
Price wise, cheaper. Quality/sprayablity far from cheap. I would not say's it's cheap by any means. You can order from You might wonder why you are paying so much for that DP40 after you try SPI.
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