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MG MGA - lead load or Mig weld?

HI I've a small rust split just at the edge of the on the MGA wing flange ( in the centre of the picture). I was wondering if its best to lead load or Mig weld? its about 1 mm wide by 1 cm the metal surrounding appears sound although thin. I don't like the idea of body filler/filler glass as they are porous or does any one know of a new product. Also when fixed what's the best rust treatment to use. I'm going to use epoxy primer after. Any suggestions would be much appreciated

DJ Joy

You need to cut out the rusted area and weld in a new piece. MIG, TIG or gas doesn't matter.
Lead loading does not adhere to rust or to thin air!
You can lead load to fill the surface after patching if you need, or easier, body filler.
Epoxy primer is the best.
ArtPearse

You'll probably find that the edges of the hole formed by rust through are wafer thin and you really need to enlarge the hole by filing until you get to a decent edge thickness. Otherwise when you come to welding you'll burn away the edges very easily.
Then I would place a hole sized piece of sheet metal under the hole and pencil the outline on the sheet. Cut out the pattern with tin snips so that you will have around a 1/16" gap between the sheet and the hole edges.
Now you can start welding .
I found the best way to weld these small pieces is to support the piece in position using a brass block underneath in one hand and the torch in the other. Make a quick (<1 sec.) weld to join the piece to the body and then cool down the weld with a damp rag. Do a second blob weld as far away from the first as you can and repeat the cooling. Then you can fill in between the two blobs with more welds until you've filled the gap completely.
At this stage don't worry about how the job looks because it won't be pretty. Now use a grinder to beautify the weld. When you've got the weld blobs flush you may find one or two holes you've missed so you will have to repeat the welding.
You can dress the weld afterwards with a hammer and dolly to remove any stress build up by the heating but you may not need this.

As for rust removal I'm a great believer in phosphoric acid and I used a lot of this during my body restoration. You can get a litre of 80% PA for less than £10 on Ebay and this will make around a gallon of 10-20% solution. After treating with this the metal is ready for priming i.e. an etch primer or, as Art says, epoxy primer.

I wouldn't bother with lead loading because you need spotless metal to do this well. Body fillers have come a long way in 50 years and they are so convenient to use. ............................Mike
m.j. moore

Lead loading is quite an art. I received training in it at evening classes a number of years ago. It takes a lot of practice getting the heat just right. In the early stages I ended up with more lead on the floor than on the panels. Unless you are already trained or have someone who can do it I would avoid it like the plague.

Steve
Steve Gyles

If you use body filler in any way that is open to air it will absorb moisture, swell, and crack all your nice new paint. The only way to fix that is to do as the others say, cut back till you have good thick metal and then welds in a patch to fix the hole.

Alon the wings is a great place for moisture to get trapped, which is by so many cars have rust here. A quick filler job will look great at first but very quickly look worse than if you had done nothing at all.
dominic clancy

Lead isn't that difficult in the grand scheme of things. It's easier to learn than welding, for example. And done properly, the bond with the underlying steel is superior to that of any plastic filler.

-Del
D Rawlins

Ever thought of brazing it? I tried that on a welding course some years ago and it was quite straight forward - but the steel wing must be spotless. You could fill from the back first with either lead or brass and then fill in from the top and file back. Much better than plastic filler but not as quick.
Cam Cunningham

If the surrounding metal is good you can just mig weld the hole directly. Use a piece of copper behind to block the hole and absorb the heat. A piece of old pipe squashed flat works well. The secret is to work slowly, letting the wing cool between weld blobs. So easy to say, but I find that is the hardest thing for me to do, as I want to keep welding...

If you are not familiar with flap wheels, these are perfect for dressing off a job like this after welding.
Neil MG

This thread was discussed between 25/02/2015 and 27/02/2015

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