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MG MGB Technical - Top panel shroud seams

I'd like to clean up these seams to avoid further damage on my 74 B. The old paint is chipped and cracked along these seams on both sides of the car. I know it's a small job but what's the best way to repair this? For example, should I use a rust preventive primer under touch up paint or use a thin coat of a body filler?

Thanks in advance...
bld Doughty

The rust almost certainly extends underneath, so the only certain sure way is to remove them, derust and prime the panels, prime the strip, refit and paint. Easy for the front wings, less so for the rears. When I restored my roadster 20 years ago these strips were available in long lengths, and one of my rear strips had rotted through in the centre section. I dug away at the worst part of the old strip until I could get a Junior hacksaw blade down through the gap between the two panels (the thickness of the flange on the old strip). I hacksawed along in each direction through strip and spot-welds until I had got rid of all the corroded parts, treated the panels as above, dropped a length of new strip in the gap and welded it in from below. After painting you can't even see where it was, and neither has rust come back (so far). But on the V8 where I have tried to sort it in-situ the rust just comes back.
Paul Hunt 2010

As Paul says, the front is easier than the rear. The filler section is actually a thin piece of steel in capital "T" shape and the leg of the "T" is spot welded. On the front seams it is only welded to the edge of the wing (fender), so you can unbolt the wing and grind it off and treat it properly.

On the back of the car the filler strip is welded between the rear shroud and the wing - so there are three pieces of metal welded together - a recipe for disaster. To compound this error, the maker assumed that paint alone would stop the rain getting in to this joint - WRONG. Short of doing some pretty major surgery like Paul did, it is very difficult to eradicate. Sanding it over, applying rust preventer, filler and repainting generally only holds it for a while, but if you aren't in the business of a big job that's your only option.

When I rebuilt the body of my car I fitted new filler strips on the front with lots of seam sealer, so hopefully the water won't get in. On the rear I left the filler strip out, filled the joint and smoothed the top over as on the RV8. I think it looks nice.
Mike Howlett


Well written, thanks for your input. Your experiece with this gives me a clear picture to proceed to my next step to get the best results. Actually, I'm just concerned about the front for now, sorry I didn't mention it. The rear shroud and strips are good so I'll take care with those to avoid any rust.
bld Doughty

Are you speaking about the "T" strip between the rear wing?
rich osterhout

Presumably ... from the subsequent posts
Paul Hunt 2010

This thread was discussed between 28/06/2010 and 29/06/2010

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