Rear wheel arch

[driftwood]

I'm hoping to fit my new rear inner wheel arch, (technically speaking, it's a rear outer wheel housing), this weekend. I was planning to spot/plug weld the arch lips together like they do at the factory but my experience with weld through primer is that it prevents a good weld. There is also the issue of rust returning between the panels where the paint burns away, so I have decided to bond the arch lips together. I will be using Tiger Seal as apparently it can stick diarrhea to a wet blanket and seals very well. Should I paint the mating surfaces or clean down to shiny metal? Any advice would be appreciated.

[BHadley]

These need to be welded together its a structural area, could you not hire a spit welder with some long tongs? Body shops I've worked in long ago just used to MIG them on with plug welds an inch at a time to the end of the panel then carry on filling the gaps in the same manner.

Save the tiger seal for after welding and grinding and the primer stage

[BHadley]

Damn iPhone.... Its spot welder not spit welder

[driftwood]

Is it structural? I'm talking about the exterior join where the rear 1/4 panel folds back in, above the tyre and meets the inner arch/wheel housing. Hope it's not too structural seeing as most e30s are made of filler in this area.... Mine definitely was!
I did some research and 3m do a 2 part panel adhesive and dispensing gun and In some applications, the bond is also backed up with spot welds. My reasoning for using the tiger seal is that it sticks really well and will also seal the join at the same time. I can't paint the area afterwards because there will be no room for access with a brush or spray can due to the way I've made the repair panel.

[appletree]

I've used UPOl weld thru on my roof skin and it's worked fine with TIG which I would say was hotter than MIG. Halfords of all places was cheaper than eBay for it if you wan to give it a try.