Well, it never rains but it pours. When attempting to butt weld the nicely shortened roof with the MIG welder, I got blow-though after blow through. I set the heat down as low as I could, left more wire out, angled the tip along the work piece, and tack welded – in short all of the known tricks for MIG welding yet the result was still a horrid unacceptable weak mess. The biggest mess and the most blow-throughs occurred in the hollow sections where I could not put an aluminum heat sink behind the metal. I was thinking that I must be one of the worst most unskilled welders ever and was starting to lose my mind. The end results are so poor that I cannot even bring myself to post a picture of them here. It is just too distressing and embarrassing.
So, I trolled the web for answers and canvassed a few fellow welders, told them of my problems, and what I had done to attempt to compensate. Lots of hmms and buckets of sympathy, but no real solutions. Two common themes kept coming back: how thick is the metal (really) and is there any rust on it anywhere?
Well, I took my micrometer and did some measuring. I thought all the body panels would be 22 AWG. Not so!. It turns out that parts of the roof were 24 and even 26 AWG. First aha moment! Unless you are superhuman 22 AWG is about the limit for MIG.
Second aha moment! As for the rust, many of the hollow sections of the roof a several layers thick, and had a fine layer of rust between them, that could not be cleaned without destroying the roof.
So I took a fresh sheet of 22 AWG, cut it in half, butted the pieces together, then tacked and burst welded them. No problem!!! Third aha moment. Maybe it isn’t me after all.
So, I now essentially have a weak ugly roof that could be used but with lots of body filler. But I could not sleep knowing how weak it is, and the poxey holey surface that lies under it, and I detest body filler.
I did another experiment. I took 2 pieces from an older roof, bashed some 1/8″ holes along the edge of one of them, overlaid the 2 pieces and attempted a spot weld joint. That worked! Fourth aha moment.
So, the rules are very clear for old 2 CV bodies:
- Thou shalt not weld anything with even a surface film of rust. The metal must be cleaner than clean!
- Thou shalt not attempt butt welds on such thin and uneven metal. Overlaps and spot welds are the order of the day.
- Thou shalt use an aluminum or a copper heat sink behind the panels to be welded
- Thou shalt curse the slaggy, unevenly rolled Saar region steel that was used to make this car.
So, where to we go from here? Well, since welding the hollow sections are not practical, I will need to bend up some door hoops of new metal and some new roof top edges using plywood formers, tubing packed with sand, lots of muscle, and a bit of heat to prevent spring back.
I will essentially be building a new skeleton to support the sheet metal. Then I will salvage the panels and spot-weld them to the skeleton. Where necessary to add new sheet metal, I will hand-form it, overlap it onto the old metal, offset the seams with an edge bender. and spot weld the whole thing together. Future blog entries that follow will document how .
We are now a very long way from the original plan of simply tacking in a new floor into the car and getting rid of the roof to build a Barbot replica.
Rust in 2CVs is a given. If you find a used 2cvand are not prepared for a huge and increasing project, do not get involved if there is even a trace of rust on it. Good luck on finding one in the condition! Deuches have a myriad of places where horrific structural rust can hide.
Having said this, I can tell you that this is certainly the most interesting, challenging (in a good way), skill testing, and mind-expanding projects I have ever worked on. At this point, I am convinced that Bob is starting to think I may be slightly mad- and he may be right.
And oh yes, did I tell you how much I hate body filler?