Headlight popping off - 1969 911

[gridgway]

I have a problem with my nearside headlight in that it comes off at the top where the lip on the wing and the rim of the light are supposed to overlap.

Is this a common problem? I looks like the critical element is the position of the tab at bottom that the bolt goes in to.

I can't quite understand how it works as the angle of the bolt (or is it a screw) at the bottom effectively pulls the headlight up, thus loosening the overlapping lips at the top.

All in all I suspect the tab at the bottom (which is not original) is not in the right position. Although I guess there might be a re-fitting knack that I am missing!

All ideas much appreciated as I'm not too keen on gaffa taping the top of the headlight to the wing which is the only other solution I can think of at the moment other than removing loads of lights and operating under the mis-named daylight MoT (not that I actually need an MoT, but I am rambling now!).

Thanks
Graham

[210bhp]

Is the lip on your headlamp ring at the top edge in good order and not bent or slightly nipped in too much?

Regards
Mike

[gridgway]

I think so Mike, but I'll recheck. When I position the headlight in place it looks 'right' and solidly held at the top.
Just going to have another look now.
Thanks
Graham

[gridgway]

Yep confirmed what the problem is by comparing it to the other side. The repaired tab has the threaded hole too 'high'. The distance from the top lip is about 3-5mm less on the side that pops off than the good side. Looking through the screw hole in the light at the bottom to see how the holes match up confirms this. The tab is angled down to try and compensate but it doesn't work.

Looks like it needs some expert help to either remove the tab and start again or find a different way of compensating.

Graham

[redrobin911]

Looks like it needs some expert help to either remove the tab and start again or find a different way of compensating.

Graham

I would have thought if you can remove the tab or cut away the upright part of the tab you could fabricate a strip of metal then drill and fit a rivnut then bond your new "tab" to the headlamp bucket. Today's chemical bonding adhesives are as strong as welding if the area and parts are prepared properly - just my 2p worth.

[gridgway]

Yep, sounds like a good idea. I'm hoping that car car restoring/welding friend and I can do it, but gluing and riv-nutting doesn't sound like bad alternative.
What glue would you use?
Graham

[redrobin911]

The stuff I've seen is in a twin tube with a mixing nozzle, I've seen things like kidney bowls bonded to 911's to avoid the heat from welding and these adhesive are very good. 3m do one but pricey, I'm sure your local welder guy will also know a few alternatives, also consider VHB (very high bond) adhesive tapes - again have a very strong fix. Possibly cut three of four strips of metal, bend ito a tab shape and trial test a few adhesives - then use the one you happiest with. Bound to be some guys on this forum with real world experience - I'd also like to know for reference.

[gridgway]

I was also thinking that if I could grind the nut off the tab welded in, drill a hole lower in it and glue a new nut behind the tab it might work. Getting to the back of the tab in situ to clean it off might be a challenge.

There is quite a range of epoxy metal glues on amazon like J-B weld and a Loctite one. All two part. The 3m one is about £60 for the gun and then £25 for a cartridge of glue which I suspect is single use.

Graham

[Sam]

Is there enough space to weld a [half] nut to the front of the tab in the correct position?

[redrobin911]

I was also thinking that if I could grind the nut off the tab welded in, drill a hole lower in it and glue a new nut behind the tab it might work. Getting to the back of the tab in situ to clean it off might be a challenge.

There is quite a range of epoxy metal glues on amazon like J-B weld and a Loctite one. All two part. The 3m one is about £60 for the gun and then £25 for a cartridge of glue which I suspect is single use.

Graham

I'm sure if you know the right person you can borrow the gun, and the glue. The mixing nozzle is the throw away part, glue can be reused many times over. A typical pack will have the glue and 10 nozzles, use what you need each time. I'll ask Johnny my fabricator what it is that he uses and report back.......

[gridgway]

So to conclude, this is all fixed in the proper way. We ground the welds on the bracket and took it off. It was on top of the remains of the old bracket which was the root of the problem. So we ground that away and fabricated and fitted (tigged) a new one. Took ages, but is now a proper job!
Graham

[leedurrant73]

Hello,

Sorry to hijack the conversation.

Would anyone be able to tell me what thread size the bottom nut is for the tab. As I have a nut missing and want to be sure before I fit a self tapping insert. Would it be M4 thread?

Appreciate your help


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[Lightweight_911]

.

I'm fairly sure it's M5 ...

.

[Ian Comerford]

You can soft solder a nut to the back of the tab if you have access to a reasonable size soldering iron. I did this on mine about 16 years ago, it’s still there

[Boydyrs]

I’m sure there is a speed nut solution available that secures over the tab allowing use on original hole.