New roof panel fitting

New roof panel fitting

This is a bit of an important milestone for me – fingers crossed this will be the final major new panel that I need to weld in before the shell is “complete” (but let’s face it there are not many old panels left at this point!).

Once again I have a nice shiny Heritage panel to fit. I think I placed the order for this way back before the first UK lockdown last year, but supplies from BMH seemed to become a victim of the pandemic and it was the end of summer before it arrived, so it’s kind of fortunate that I’m very optimistic in my estimation of when I think I will get to particular jobs or I might still have been waiting for it now!

I’m especially glad to be fitting this one, since with the heroic amount of packaging it had arrived wrapped in from Rimmers to keep it safe, it was taking up an area of space in my storage shed about the size of a large king-size bed, so I’m glad to have that out of the way.

After a couple more hours invested in removing the Heritage stickers, it’s on with the fitting. And this proved to be one of the easiest panels of all to fit so far. I think that because at the sides and back it’s meeting original metal, and at the front it only meets the new screen frame (which was also a very precise and easy fit), there is a very small margin for anything to have become misaligned. It really did just drop into position first time, with only a couple of clamps needed to pull things in.

The only fettling it needed was to cut off two tags on each side, which I assume were used in the manufacturing process, and some trimming back at the joints with the top of the A-pillars (the new panel has excess material here, which actually helps to get a very close fit).

I would be spot welding the joint with the top of the windscreen frame, so I stripped all the paint from that flange (applying weld through primer to the inner faces).

I decided to plug weld the back lip on since there is no access for the spot welder, and thought it would be difficult to glue it since it did need a little bit of pulling in to get it properly flush. I pre-punched all the plug holes before fitting.

I did however decide to glue both the side rail joints, as I had done with the other side seams, since access is so restricted for any kind of welding. I used Bondtech 20-minute automotive glue, applied liberally down both rails and across the A and C post joints, it should hopefully help to make sure it’s watertight as well as strong. I had sanded the paint back beneath the glue and on the lip of the new panel to ensure it was bonding metal to metal.

With the glue clock ticking I got the panel straight into position and fully clamped down in as many places as I had clamps for. Whilst the glue set I got straight on with spot welding the front joint.

At the back I again used self tapping screws to make sure the joint was close fitting for the plug welds, since it’s impossible to get any clamps into this area. Care needs to be taken here – during my trial fitting I pushed the panel down to so that it touched the reinforcing section beneath it and put a single screw in to hold it temporarily. The bottom of the lip was meeting the line of where the lip of old roof panel had been, so looked correct, but when I did a test fit of the tailgate to check the gap, the curvature of the roof was completely wrong. The centre of the roof was sitting about 5mm lower than the tailgate edge.

I removed the screw and let the panel spring back to its “natural” state and then rechecked with the tailgate, and it was a perfect fit. I then compared the lip of the new Heritage panel with the remnants of the old roof and found that the lip was indeed a few millimetres deeper on the old panel, so just a reminder to carefully check the fit before committing if you’re attempting this job yourself.

Doing it for real this time, I put a screw in every other hole and found the fit to be excellent.

With such a great fit it was an easy and pretty neat job to quickly plug weld all the holes, remove the screws and then plug the rest. The only thing I find slightly difficult with this technique is that sometimes the holes which were screwed can be more tricky to get a tidy plug weld on. Since the screw hole obviously goes through both panels it’s easy to feed the MIG wire through the hole instead of actually plugging it!

With it all welded/glued in place I cleaned up all the joints and etched-primed as usual. I had left the clamps holding the sides in place for a good 48 hours or so before removing them, plenty of time for the glue to fully cure.

I used a power file (handheld belt sander) with coarse grit paper to grind back the plug welds at the back since it’s quite a tight spot. Slow going but produced a very neat result.

I had also bonded the seam where the roof meets the top of the C-pillar – this was originally spot welded, but there is no access, and I felt glue was a much cleaner solution than plug or seam welding this. This will need to be filled at a later date to replicate the original lead loading used in the factory to cover these joins.

An inside view of the finished result. I had also taken the opportunity to strip and treat some surface rust on the top of the dash rail, and it all got the etch primer treatment.

I still need to cut out that reinforcing section in the middle of the windscreen, I’ve just been enjoying the unique “split-screen” MGB look a bit too much 🙂

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