The RH headlamp

As part of the pre-roadworthy check I made sure all the lights were working – seemed a simple but sensible thing to do.
The number plate lights worked but were exceedingly dull. Part of the problem was that the lens had filled with crud – the rubber seal is long gone and water etc runs back along the underside of the boot/engine cover and can run into the number plate light filling the lens with leftover dust/dirt etc.
But the main issue was the earth path from the bulb to the relies on the bulb holder and a couple of strips riveted to each other leading to the housing which mates to the mounting screw which finally contacts the body. This earth path was highly resistant!
There is no easy way to correct all this without completely dismantling and rebuilding the lamp, which looked complex. So I simply made up an earth wire with an eyelet to go around the end of the “bayonet” globe and another to go around the screw head.
Result – much brighter lights even more so with all the crud removed.

The left hand headlamp was also very dull. I was expecting the same earth path problem, but that looked OK. I next suspected a 24 volt globe, but no, 12 volt. Amazingly a check showed the globe resistance was very high, so probably about to fail.
Now, the headlamp is marked H4, but the globes did not look like H4 bases. That’s because there are 3 types of “standard” H4, H4, H4 P43 and H4 P45. And I thought the whole idea of “H” globes is they were standardised. This one uses H4 P45, and I found the last 2 at our local Repco.
Fitting them fixed the left hand lamp, but the right hand one did not look right. A quick check against a screen showed absolutely no dip beam pattern. Closer examination revealed that the shield that sits in front of the globe, to force the light into the reflector and then out through the lens and hence the pattern, was missing.

Although the initial signs were I could get a good used, or even a brand new, unit this was not the case. So a bit more thought was required. So I took the lamp off to study how to fit a modern replacement into the retaining bezel and adjustment system. This revealed that the lamp was incorrectly assembled.

Starting at the front is the chrome bezel. Behind that is the lens, pressed against the bezel by a sort of plastic collar about 40 mm deep held in place by a series of spring clips. The reflector fits into this collar with two lugs fitting onto jack screws coming through the bezel and thus angling the reflector for aim. Whilst the reflector was about equidistant from the collar edge all the way around, as one would expect, I realised the collar was not fully seated into the bezel all round. Which meant that the aim was well off, that light was coming from the globe side onto the lens and the black painted on shield on the globe was not fulfilling that function. It also meant the lens was not secured.
So I took it all apart and, with great difficulty, reassembled it properly, replaced the bits of twisted wire holding the reflector in place opposite the screws with rubber grommets of the correct size.
Amazingly, there was now a recognisable pattern and the aiming screws worked as long as one was gentle.

Job done.

This was, however, the first of many bodgey repairs I found.

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