Trying to MIG weld several sections of the rocker seam to 0.125 thick SFC's. No problems welding the square tube to the thicker subframe ends, but when it comes to welding the seams in several areas its like I'm welding on dirty metal.

Much of the wire ends up as spatter, and what does make it to the weld area ends up as blobs with little penetration. I'm left with an ugly area with little strength.

Prior to welding, I wire wheeled all the paint off every visible part of the seam (down to bare metal) plus about a half inch around the weld area. I used the lowest amperage (I think its 30A). In one or two spots I got a good looking weld, but I have a HECK of a time elsewhere.

What would be some things to look for? Anything special I should look for, any special prep tips? Anyone else had this problem? I'm guessing there may be some stuff in the seam thats interfering (that I can't reach)?

 

There is some kind of a coating that you need to take a grinder to. I tried the wire wheel route too and it didn't work well.

 

The metal is galvanized, and you have to remove coating for welds to stick.

 

Welding to galvanized steel isn’t any harder then to aluminized steel. It does some extra popping and sputtering but it welds fine. The issue is to make sure that you do not inhale some of the gasses giving off when you do it, since they can be quite poisonous.

WRT to your problems, I suspect that you’ve got one of 2 things going on… something is actually contaminating the weld, most likely pinched between the 2 sheats of steel that were welded to make that rocket seam, or more likely, have you pounded all of the rocker pinch seam over so it actually touches the connector? I would be fairly difficult to weld a light piece (rocker) to a heavy piece (SFC) in that position if they aren’t touching to begin with.

 

The last set I welded on was with a 220 mig, and it seemed that the heat from the first crappy weld burned off the coating, and the second pass over that welded fine. Or could of been cause I was hungover too. I had the same problem welding a galv. piece on the rear body panel. Popped and stunk bit didn't want to stick.

 

Tim, I’ve never seen a more appropriate avatar in my life…


When Mike and I (at the time, mostly mike, it was my first time welding anything, so he just let me bitch things up and then went back and fixed it) did the GW SFCs on my ’83 we ran out of shielding gas and he did them with the big buz box (I think it was a Lincoln tombstone, or possibly a century knock off) that they were using at the old shop to weld up cat walks and railings, and that worked fine.

I’ve done a few since then and as long as I made sure that the 2 pieces were touching I didn’t have any real problems (bend it slightly so it’s closer to the SFC then normal and then clamp it on either side of the weld before welding). The only thing that I could think of that I probably do different then most is that after trying this kind of stuff a few times and getting pretty frustrated with trying to keep things properly shielded (shielding gas is heavier then air, making it hard to keep it around these kinds of welds) I came to the conclusion that some -11 flux core works much better and does the job much faster. OTOH, I’m one of the few people out there that seems to think that flux core is easier then gas shielded mig…

 

Thanks guys for the replys.

I used a giant pair of vise grips to press the rocker seam against the connector where the gap wasn't too large, and I used pieces of 0.125x1" stock between the rocker seam and the SFC where the gap was larger. I figured the second (or third attempt) would do better, but I was wrong. I quit trying so I wouldn't mangle the car.

Next time, I'll definitely do some more grinding (I thought I was brilliant with the wire wheel by not removing any metal, oh well), just have to take care & not grind away too much.

On a side note, as far as leveling the car, anyone can do this themselves with a service manual (from Helm, not chiltons or other Pep boys garbage) and either a tram gauge or a level surface. The manual gives specs of many chassis points' height from a datum plane parrallel to an imaginary center line of the car. No problem (from what I understand) if you have a tram gauge, I don't so I improvised with a garage floor that was verified to be level. I took most of the vertical measurements, your call how many you want to take.

Just resting the car with its tires on a level surface is not enough IMHO. It MAY be right, but too much room for error. It is a good starting point though to make your measurements. First I raised the car up, rested it on its tires, and went to town with the measurements. My car is straight w/no accidents or damage so luckly all the measurements I made were within spec. I had three jacks ready in case something was a bit off, I was going to see if I could even it out by strategically applying pressure at various points to get it right on. Of course, if some measurements are way off the car could be tweaked & should be taken to a shop IMHO. The local collision shop wanted $250 just to get the car on the machine, so I was going to try to avoid this.

Anyone else ever try this?

 

Yea, I did exactly that at one point with my ’83 years ago. I went and figured out exactly how out of flat the garage floor was and in what direction and adjusted for it, marked all the pick up points on the floor using a plumb bob and started measuring. I found everything to be in spec but the wheel to wheel distance on the passenger side was about as far off as it could be and still be in spec.

The funny thing was that at one point that car got t-boned and I ended up pushing the passenger side door pillar and rocker out with a combination of heavy timbers, some bottle jacks and a sledge hammer. Afterwards I checked all that out again and found that that dimention was the only one that changed and now was really close to perfect.

 

Glad to hear that I'm not the only one.

I did notice one funny thing about my particular car. There is one spec (I believe its labeled as either "H" or "I") that references the bottom surface of the rear unibody "rail" in the back by the control arm hole. Though the surface was in spec, the hole that mounts the control arm is higher up than the other, which I think is strange (I would have presumed that this would be controlled tighter during manufacturing). I had always planned on reinforcing this area (didn't do it yet), I can just correct it then. I do wonder at what point powerwise it would make a difference at launch.

 

I'm not sure that that is really a shock... off the top of my head I remember a lot of the specs being +/- something in the 1/8-1/4" range which I thought was just insane but they seem to work that way. I'll tell you that they are much more consistent tolerance wise then a comprable year fox chassis mustang, which are literally all over the place.