Rear panel / wing seam

Technical MGB discussion
BrianMac
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Forename: Brian
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Rear panel / wing seam

Post by BrianMac » Mon Apr 20, 2020 11:33 pm

MGB GT mark 1, 1967


Hi everyone,

I noticed that the rear seams on both sides of the rear panel (where the car number plate is fitted) were filled by a previous owner of my '67 GT. Deep rust has developed at the lower part of the area on one seam so I wish to repair it. In cleaning out the epoxy filler used to fill the seams, I noticed welding had been done and an attempt had been made to simulate the appearance of the seams with a grinding wheel. This wasn't a success, so I suspect this is the reason that the seams were filled.

I would greatly appreciate clarification from some of you on how the rear wing panel (HZA4222) meets the rear panel (HZA4217). For cars post possibly the mid-'70s, the panels meet by way of pinched 90 degree folded lips on both panels to form a seam. I understand from my investigations that earlier cars, such as mine, that the seam was made possibly by a rebated flange on one panel, which slides behind the other panel. If so, is the rebated flange on the rear panel or on the wing panel? The seam in the early cars were filled to a flush finish with lead loading.

i think the wing panel overlaps on the exterior of the valance; can anyone confirm this?

Many thanks for reading and any help,

Ian Fozzard
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Re: Rear panel / wing seam

Post by Ian Fozzard » Tue Apr 21, 2020 7:45 am

Morning Brian. I'll take a look at my 72 BGT this morning and see if I can help. I am near Edinburgh, are you anywhere close?

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

BrianMac
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Re: Rear panel / wing seam

Post by BrianMac » Tue Apr 21, 2020 10:20 am

Good morning Ian,

And thanks for the post. I am located in Dublin, Ireland at this time.

Someone referred me to an exploded body parts sketch diagram, such as found in supplier catalogues. It shows the rebated flange on the wing side, but this is counter to what appears to the case in my car, and the diagram has an obvious error. It shows the two aforementioned panel meeting at the mid-point of the fuel tank filler aperture, which we all know is incorrect. So the sketch may not be a reliable technical reference.

Below the seam, it appears that the wing panel wraps to the outside of the top of the valance section of the rear / valance panel. Can you confirm this?

Thanks,
Brian

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Peter Cresswell
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Re: Rear panel / wing seam

Post by Peter Cresswell » Tue Apr 21, 2020 10:37 am

Brian,
The rear panel in question on a chrome bumper car does bisect the fuel filler hole, and the seams were lead loaded when the bodyshell was built. This may have been because it would have been very difficult to seal the area around the fuel filler to stop water (or spilt fuel) from getting into the boot if the seam was left exposed. When the rubber bumper cars were introduced, the centre panel was made wider and wholly contained the fuel filler hole thus making the need for a flat surface not necessary.
As the panel was part of the rear valance and these are notorious for rusting away, it seems your car has had some reconstruction work in this area and they have used the wrong panel, seam butt welded it rather than spot welding (as there wouldn't have been a flange on the part attached to the wing) and then tried to make it look like a rubber bumper visible seam.
Chrome bumper - invisible seams; rubber bumper - visible seams!
Pete
1969 MGB Roadster
2011 MG 6 TSE Magnette
2007 Mercedes SLK
Plus 32 other cars since 1965

BrianMac
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Re: Rear panel / wing seam

Post by BrianMac » Tue Apr 21, 2020 10:51 am

Peter,

Thanks for your reply. So the two panels should meet at the middle of the fuel filler aperture and not to the right of it? If so, that is a surprise to me.

Should the rebated flange be on the wing or rear panel section? As the wing section fits over and to the outside of the valance, it would appear, logic indicates that the rear panel fits behind the ring section, so would have the flange.

My seams were flush finished with epoxy filler, unfortunately. I would be interested in opinions on what course of action I should take to repair the seam sections. I don't envisage replacing rear / valance sections. On this, is the original HZA4217 still available?

Many thanks,
Brian

Ian Fozzard
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Re: Rear panel / wing seam

Post by Ian Fozzard » Tue Apr 21, 2020 11:05 am

Brian, just had a look at my 72 BGT. This rear panel is as left the factory. The joint on the fuel filler side runs vertically through the filler aperture. The rear panel has a "dog leg" or step which sits inboard of the wing panel. It therefore presents a squarish section running down the seam on the inside. The outside is lead loaded, or at least invisible outside.

I could post a photo of required,

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

BrianMac
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Re: Rear panel / wing seam

Post by BrianMac » Tue Apr 21, 2020 11:12 am

Ian,

That's great. This confirms what Peter has just posted. I would love to see a photo of this.

Does the wing panel wrap to the outside of the top of the valance section of the rear / valance panel?

I'm reluctant to replace what appears to be a rubber bumper rear / valance panel on my car. I have made extensive repair sections to the valance rear corners. A replacement would be costly in both time and finance terms.

Many thanks,
Brian

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Peter Cresswell
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Re: Rear panel / wing seam

Post by Peter Cresswell » Tue Apr 21, 2020 11:17 am

Hi Brian
I've just taken this picture of the seam inside the boot of my car. This is of the nearside as it is easier to photograph. If the orientation is wrong, the cables are at the bottom!
rear seam 1.jpg
I am wrong about the flange, as you can see the wing (on the right) goes over a rebated lip of the centre panel (which is to the left of the picture) and is spot welded down the overlap. As Ian confirms there is no visible sign of the join on the outside.
HZA 4217 is listed by Moss as the rear valance panel for a Roadster and they list HZA 4227 for the GT. I'm not sure of the difference but I would guess it is for the lip the rear hatch door closes onto for the GT. HZA 4227 is a bit cheaper than HZA 4217.
Pete
1969 MGB Roadster
2011 MG 6 TSE Magnette
2007 Mercedes SLK
Plus 32 other cars since 1965

Ian Fozzard
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Re: Rear panel / wing seam

Post by Ian Fozzard » Tue Apr 21, 2020 11:25 am

This may help. The rear balance has the stepped lip which fits behind (inside) the wing panel. A very short section above the fuel filler is similar.

Ian F
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IMG_20200421_111911589.jpg
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

Ian Fozzard
Posts: 370
Joined: Fri Mar 27, 2015 8:18 am
Forename: Ian
Surname: Fozzard

Re: Rear panel / wing seam

Post by Ian Fozzard » Tue Apr 21, 2020 11:35 am

For completeness this is what the top of this area looks like, looking outwards from the boot. A long strip is welded along on both sides of the tailgate latch to provide a neat finish.

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

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