Sequence of sheet metal replacement

[69Mach1 M code 20]

I'm going to be replacing several structural components of the undercarriage and wanted to check on the proper sequence of replacement based on feedback from guys that have been through this glorious exercise in fortitude.

I'll be replacing the torque boxes, toe boards, floor pan, and floor supports. Is this the proper sequence?

[Ridge Runner 1,202]

With everything cut out ,floor supports first ,then torque box ,then floor 

[69Mach1 M code 20]

Thanks.

[Midlife 840]

Try to remove one piece at a time and then replace it.  If you remove too many items before replacement, the car may likely fold in half.  Many people weld in square or tube supports to keep the car aligned.

[Ridge Runner 1,202]

You will have to have the torque box out to remove the floor support and the floor needs to be out to do any of it ,but yes ,support the frame rails and the rockers it is best to have atleast 8 supports / jack stands ,frame rails ,in the front each side at the rear of the frame rail just before the torque box the rocker just behind the torque box and either the rear of the rocker or the end of the rear frame rail 

[69Mach1 M code 20]

I purchased the two piece torque boxes based on the recommendations of web reviews sometimes making it easier to fit into place. 

The one detail I'm not sure about; after the two panels are welded together as well as to the rocker / floor support / subframe, is the top of the box where the two torque box panels join then welded to the firewall / toe board? I see several spot welds where the toe board is welded to the angled panel of the torque box about half way down but I'm not sure about the top. 

I haven't started cutting yet but am just planning things out to do it right.

[69Mach1 M code 20]

Attached is a photo of the driver's side toe board. The flange on the left, adjacent to the Sharpie, is bend downward towards the torque box. Should this be bent 180 degrees upwards towards the floor side, or just trimmed off?

[Ridge Runner 1,202]

It is supposed to bend up ,for some reason the make them with the bend the wrong way . I usually hammer it flat and then put it in my sheet metal bender and bend it up . It can be hammer and dolly up

[latoracing 257]

The flange does go up, but on convertibles (which I seem to work on all the time) it is removed. The two pieces of the torque box weld to the upper seam area of the toe board and should fit fairly decent. I prefer to butt weld all my repairs but you can see the remnants of the spot welds in the second picture where it is welded to the top flange of the torque box. I also prefer using two piece torque boxes. Much easier to install.

[Cantedvalve 128]

So how would one go about this if they are starting with a floor assembly and a full firewall?

[latoracing 257]

I'd think that the torque boxes and all the lower structure would be in place, install the firewall assembly, then the one piece floor. 

If you have a replacement lower assembly (outer rockers, floor pan, rear frame rails... all put together) then the firewall would have to go under the front of the floor pan and over the floor supports. Guess it depends on how far apart the body is and what all you're replacing. Having the front frame rails attached would dictate quite a bit. 

[jmlay 92]

On the full firewall I removed & replaced in my 69 fastback there was no flange. The flange seen from the interior is the flange on the TQ box. The firewall was trimmed to set inside the TQ box flange. 

[Cantedvalve 128]

Well, mine is the Dynacorn assembly, so the floor supports and the inner rockers are already in place.  Front apron assemblies need to be there for the torque box uppers, at which point getting the firewall in is kinda like a contortionist squeezing into a ketchup bottle.

[Ridge Runner 1,202]

The flange at the lower portion of the fire wall ,the toe board ,is missing because the torque boxes pass through between the toe board and the rocker ,the upper flange is needed because that is what attaches to the outer cowl panel .

The toe board sets on top of the torque box

[69Mach1 M code 20]

Got the torque box all buttoned up and started fitting the floor pan.

I measured 6 inches from the edge of the rocker panel to the centerline of the hole for the seat track. (The camera angle makes it look different than 6 inches).

The passenger side is all original and I've been using that for reference dimensions as I reassemble the drivers side. The passenger side measures 5-1/2 inches. Can the new panel be this far off? It's a Spectra Premium panel. Was this panel made on a Friday afternoon or is this expected?

 

[aslanefe 352]

Don’t know if the panel was made on a Friday afternoon but Spectra premium panels do not impress me much. They claim to be a little thicker than Asian repro panels but I find that most Asian panels have better contours/details. The exact location of that hole does not matter much, it is an access hole for seat fastening nuts. You may have some inconvenience installing the seat but should be okay with it being 1/2 inches off.

[69Mach1 M code 20]

I forgot to mention one other feature that was off 1/2 inch as well. The flat area that makes contact with the flanges on the floor support. 

I called NPD last week and explained the situation. I asked them to measure the ones they had listed as "imported" and claiming that the stamping dimensions were better than the Spectra panels. NPD is only 30 minutes from my work so I was planning on picking up a better fitting set of panels. They measured the access holes and claimed they were off even more than the panels I had. 

After stopping by the Barley School of Metal Working for some supplies, I decided to tackle the floor part of the project today. I ended up cutting off 1/2 inch on the flange side and bending it upwards like the originals so the Pebble Beach judges wouldn't notice.

 

[aslanefe 352]

11 minutes ago, 69Mach1 M code said:

I forgot to mention one other feature that was off 1/2 inch as well. The flat area that makes contact with the flanges on the floor support. 

I called NPD last week and explained the situation. I asked them to measure the ones they had listed as "imported" and claiming that the stamping dimensions were better than the Spectra panels. NPD is only 30 minutes from my work so I was planning on picking up a better fitting set of panels. They measured the access holes and claimed they were off even more than the panels I had. 

After stopping by the Barley School of Metal Working for some supplies, I decided to tackle the floor part of the project today. I ended up cutting off 1/2 inch on the flange side and bending it upwards like the originals so the Pebble Beach judges wouldn't notice.

If you are worried about Pebble beach judges, you are in trouble; 69-70 do not have drain holes on front floors and the ribbing around drain hole on repro front floors is different :)