I'll be replacing the floor brace on my '69 that supports the rear of the front seat and contains the seat belt anchors. Since the floor is also rusted through in this area, once that sheetmetal is cut out, it seems that I might be able to drop the brace in from the top, then add the sheetnetal over it. This would seem to be a lot easier than going up from the underside with the frame rails in the way.
Has anyone done this? any tips?
Thanks,
Rich

I have done it this way.

It worked, sorta.. mounting it to the floor is easy, but you really can't get at the area where it needs to weld to the rockers. It might be easier if you welded to the rockers before putting floor back over it, but not by much.

The president of our local Chevelle club is doing the same thing. www.chevelles.net/tristate (http://www.chevelles.net/tristate)

Here is what he did/doing.

Only remove the floor directly above the braces {assuming you will replace the L&R floor pan, so keep the hump metal). Do 1 at a time. Sheet metal screw the braces to the rockers & metal left in the hump. Then do the other brace.

Only then do the floor. He also had to add metal on the inner rockers where some rust holes where when he removed the braces.

All this work trys to maintain the integrity of the car. He did all this with the body off the frame.

Crankshaft, doing this is pretty much like building a house. You got to start with a solid foundation, then build the framing, subfloors etc.

The foundation of a car would be the frame, without it, you got nothing but a weak hunk of metal. I would start out making sure the frame is straight and strong. I recall you were building a 71 vert on a hardtop frame right??. Get your new frame welded up, boxed whatever and make sure its straight.

Now when I did my 70 I started on the floors first. Like before starting at the foundation. Every floor, every time Ive craweled under the car Ive starred and thought how to do this the easiest and safest way for me and the car. Each time I get the same answer...You need to lift the body off the frame slightly. This is the ONLY time I do any mettal replacement off the frame PERIOD. The reason so is because when I do the floors I replace the braces that run across the floor and weld to inner rockers. With the car sitting on the frame you simply dont have room to remove those braces and weld them back on properly.

Now when I say lift the car I mean pick it up enough to slide 4X4 under the car across the frame, so the car is still sitting on the frame just ontop of those 4x4's. I had one under the cowl one in middle the other right before the rear wheel.

Beofre I go any farther I should mention that since have a vert you NEED to brace the body. You should have braces going across the jams and then in a X pattern from one jam to the other. Once you lift a vert off the frame its like taking your back bone out your body, all you will be is a lump of flesh. But if you brace the vert in the right spots you dont have to worry about the car bending in half. Trust me Ive seen it happen, lucky it wasnt me doing the work or had to fix it cause it got fuc$%^ up in a hurry.

Ok when I do floors I start with the braces first. You can do the floors first but I just do the braces, its a routine. I start on the first brace. I carefully remove it by drilling out the spot welds that hold it to the floor and inner rocker. Dont just starting cutting floor along with the brace cause you will need that old floor to help aid in installing the new one so leave it in place. Beofre I remove it I trace its position onto the floor and inner so when I go to position the new one I know where it has to be.

Now with the old brace out, you can mock up the new brace to floor and inners. Position the brace to the trace mark left by the old brace. Continue to fit and tweak the brace til it fits nice and snug to the floor and inner. Once you have the fit you want you can screw it to the old floor and inner or place a few tack welds. Dont fully weld to the inners yet as you might need a slight adjustment later when doing the floors. Screws will hold that brace in place no problem, hell the whole back half of my chevelle was held together with screws for 2 years and didnt move 1/64 of an inch.

Once you have the first brace in place, move to the second brace, repeat process. Now comes the tricky part. If you need to replace the inners you can now do so. It would be easier with the braces not srcewed into them but I feel screwing them on the old inner first helps position the new brace correctly. Remove any spot welds holding the inner on and any screws you have from brace to inner, just make sure that the end of brace is held good to the floor. Now you can replace inner. The outer rocker and new braces will aid in positioning the inner right. The more alignment spots you have the better the fit and faster the fitting.

Also that rear or third brace isnt repro'ed you must make do with what you have or find a better used one. Also if you have to replace the third brace and the rear seat panel, now is the time to do so. Removing the rear seat from the topside is a bitch you have to remove those braces that weld to the inner quarter to floor, drill thro 3 layers of metal...NOT TRICK. The best way is to remove that third brace and replace the rear seat from the bottom side. This way you dont need to rmove those braces and only drill thro 1 layer of metal. All you need to do is drill those welds out from the inner to seat panel and then bend that lip down so you can slide the new panel in. If done from the top you have to bend the inner quarter lip and rocker lip up, that rocker is pretty heavy gauge to bend, that inner rocker is thin stuff bends easily. Now you can postion the new seat panel over the inner lip and to inner wheel wells and that seem at the back. Plus doing it from the top you drill thro 3 layers of metal on that seem also. that one sucks. If memory serves me right the seat panel is the bottom layer..talk about easy.

Fit the seat panel to every thing a few times checking its fit to third brace, you might find that you need to tweak the rear panel some what to fit the brace. Once you have the fit you like you can screw the panel and brace in place, few tacks there and here for good measure. You might need to adjust the rear panel somewhat to fit the new floor, but not much as you have tons of alignment points on that panel.

Ok now on to the floors. When I do mine i do the whole floor in the two halves, not front and back sections left and right, that system is for the birds. I bought mine from paddock because they were the only company to offer a full florr that included a tranny tunnel. No other company offers that floor. The best thing about that is, #1 you have a fresh unmolested tunnel, #2 you have only one seem to weld shut the length of the floor instead of two like the others. I do my floors one half at a time. I do the driver's side first. I start by laying the half over the old floor and tracing its outline onto the floor. That way I knew somewhat where at floor covers. Now I cut about 3 inches inside that trace mark that is on the tunnel and firewall. Now am only dealing with two halves of floor and not one full floor. Remove any spot welds still on that floor half. Now with the old floor half out you can now go about fitting the new floor half to the car. Fit the floor to the braces and to the old remaining floor. Since you allready fit the new braces to the old floor, those braces are in the proper position, you need to tweak the floor to fit the braces. Continue to tweak, fit the new floor half with the braces and old floor half til you have the fit you like. Once you have the fit, screw it down and a few tacks. Now do the other side of the floor.

The whole reason I do the floor replacement piece by piece is because you fit each new piece to the remianing old pieces, making the fitment of the car better and easier. It sounds like a lot of time to do piece by piece, but it saves time. The last floor I did I thought I would try it a new different way, since every thing would be new-braces-floor, I would just start up the plamsa cutter and start cutting. BIG MISTAKE It took three times as long as I was constantly fitting this to that and then moving it around to get the fit. I only knew where the floor would go to the rockers-cowl, braces to the inner, didnt knew where the braces needed to be on the floor and the heighth they needed to be etc. You want to teach your kids an education on four letter words replace the floor that way

When I get feeling back in my fingers Ill do the rest of car...Eric


Ok lets see, now that you got the new floor front and rear seat panel and braces installed, what I do now is remove those 4x4 from under the car body and lower the car back onto the frame. Now I run bolts up through into the braces, now know that the braces will fit to the frame holes. Now I put all my bolts back into the body if you can. No need to tighten them down just snug. Now is when I start fully welding panels together. Weld up everything you can with the body still sitting on the frame, what you can get you can lift the body back up and weld, but get everything you can with the car sitting on the frame.

If you are replacing the outer rockers dont weld the lip to the floor, just need to remove those welds later on so leave them unwelded. Also the seem where the front floor meets the rear seat panel, on mine the overlap meet before the 3rd brace. So the easiest way to make a nice weld for that seem is to cut the seem right on the lip of the 3rd brace. this way you have a nice buttweld for the two floor halves but have a backing for the weld-the brace lip. Plus making the seem on that lip provides an undectable welded joint from the bottom

Now you got the floors welded and done, time to call it a day :rolleyes:

wow, sevt, that was beautiful.. I wish I'd asked before I started on mine. Thanks for posting.