Tips for replacing lower cowl

[71_dramaqueen]

I'm planning on replacing the lower cowl and lower windshield pillar patches on my 71 challenger this winter and I was hoping to get any tips or pics on how to go about the job.
I am a noob to body work but not to metal fab or welding.
Feel free to direct me to any other posts on the subject I might have missed.

thanks folks

[4Cruizn]

I have to suggest that you post some pictures of what you are trying to fix or replace so we can assess the situation!  I'm sure there are members here that have done what you are going to tackle . . . 

[anlauto]

"lower cowl" is the whole firewall......right ?

[71_dramaqueen]

After removing the upper cowl I believe I need to replace the firewall/ lower cowl (same piece) as well as the upper cowl. Dynacon is making an assembled unit currently.
In addition to this I need to put patch panels on the lower pillars.

My questions are chiefly:
-How/ where exactly should the car be braced properly for firewall removal?
-What should I use for spot welding? Lots of rosette welds, spot welder, or a special MIG tip?
-Things to watch out for

[71_dramaqueen]

1

[dutch]

hard to say from these pics what the firewall actually looks like,  but I`d have it blasted before making any drastic cuts.   I`d try my very best to save that firewall.   
- when you remove the firwall, you`re left with a whole pudding-like unibody...  I`d strongly recomment putting it on a jig first,  then worry about bracing.
-spotwelding will give you the most factory look and the least distortion of the panels.
-make sure you have a car left when you`re done cutting...It`s a small step from firewall to inner fenders to a-pillars to roofskin.... oh well...you get the point   

[jimynick]

I just did this a couple of months ago and it's not a walk in the park. Your largest problems are that you still have the frt inner aprons in the car. I bought and welded in 3/4" angle iron from the middle of the w/s pillar to the middle of the door opening onto the inner rocker, then I tied both sides together across the dash area and then welded in a corner piece to tie the cross piece to the verticals, thereby triangulating the setup. The car remained on it's suspension. We also changed the hinge pillars, inner and outer, at the same time and the front floor section as well. We spot welded/bonded the upper cowl to the firewall first. The fun came in when we tried to tie the firewall lwr flange into the frt flr flange and we had to use a jack with a 4x4 chunk to push the floor up to meet the firewall. You can remove the firewall from the hinge plrs, but it'll be a biotch to get the firewall both under the w/s plrs and over the hinge plrs. We salvaged the lwr w/s plr brkts and perhaps if you replaced them after cutting them off, it would help getting the firewall in. There's two filler type brkts that go from the inr fndr aprons that you'll need to replace or R&I to get the firewall loose. One goes down the length of the apron and the other ties the apron to the cowl behind the hinge area. I can't tell from the pics, but if the face of the firewall is still ok, you could section the new top in to the lower and that would be a whole lot less work. You say you're a welder and there's a place to prove it. Mine was punky all over and especially around the master cylinder area, so if your's is too, I'd bite the bullet and put the whole panel in. Hope this helps a bit.