Primer between plates?

[rikrobson]

I'm reparing the inner wings on My 2.8 Cari and there are strengthening plates over the single skin inner wing at the strut tops. These have has to be replaces as the original ford method was to spot weld then paint. This has resulted in water penetrating the gap between the two plated and rusting from inside out. The inner wing has been repaired and the beads ground flush.

I've cleaned up the upper surface of the inner wing, which is is now bare metal and I am in a position to fix the reinforcing plate which is painted with a black primer, the same as new panels come in.

I really would like your input in how to treat the bare metal surface which will be hidden by the reinforcing. This will be plug welded just as the original wasn't seamed but spot welded on.

Would i be better using a standard zinc primer and remove where the plug welds will be or use a weld through primer? I plan to seam-seal also round the edges, but may seam.

The cut out section in the 2nd picture has been replaced, I just didn't get a photo, I will post later.

 

[Bigjoe]

I would use a weld thru primer personally and then seam seal the join or seam weld the plates if i wasnt going for originality.

Regards

Joe

 

[rtbcomp]

I would also consider stripping the existing primer off the new parts and repainting. Quite often parts are painted just to stop corrosion in storage.

 

[the snooper]

the strut top plates that you have removed are not original the rot underneath them is the reason they are on they have not rotted from the inside out.
i have fitted plenty of these on capri`s over the years

 

[droopsnoot]

Would i be better using a standard zinc primer and remove where the plug welds will be or use a weld through primer?

My experience with weld-through primer and plug welds is that you'll have to remove some of the primer or the welder won't arc. Maybe it's me, or my welder, or my primer, but removing some makes plug welding work much better for me.

 

[rikrobson]

The plates are the original and the ford spot welds were drilled out. The reason the rust started in the sandwich is that the car was left in a barn in Aberdeenshire for 3 years, being dripped upon. Water then ingressed and once it started there appears to have been no stopping it.
Any hoo Got some ali-zinc primer and slapped that on. Will be re welding the top plate in the near future

 

[steveo3002]

have you thought about a couple of small holes in the top so you can trickle some thin paint or wax treatment in there after its welded?

then wipe some seam sealer over the holes you made