mig welding a long thin panel

[Monkey Harris]

Now that changes things a little,I'd be now inclined to plug weld along that edge,get yourself a punch
http://www.ebay.co.uk/itm/Joggler-P...627634&hash=item1c4d6534c6:g:BTMAAOSwm8VUy5mr
Thats a 5mm dont use a drill as you might put the orange panel out with drill pressure you could always open the holes bigger with a step drill say 8mm
Space your holes out neat and plug weld away,it would have been spot welded originally anyway.

Just had a though,this strengthening bar on the inside i take it the flange part of the new panel fits over the top?
Can you do a photo if poss of a dry fit?

Great reply..
The whole side would have been one sheet, think like a panel van,

The new panel I have is a repair part,
The inner strengthener is just a C channel that is spot welded to the outer whole panel,
I think the repair panel, will sit inside the c channel,
it may fix to it,
I don't know as I've not removed or measured the outer skin yet,
Will report back when I get a better idea..

 

[Burdekin]

They're more prone to rusting with moisture getting in behind. Also not fully welding it you may get issues with the filler cracking along the seam.

You could possibly bond it with one of the automotive structural adhesives. Not done it myself but one advantage is it also seals the joint.